Upon second thought, yeah, it must be. They are using the rubber as a seal for the connector and to prevent sharp acoustical reflection points or some such. Because if they just wanted to seal it, silastic would have been fine. They really have gone to town with the sealing, it's seems to be their thing.
EEVblog I used to manufacture amplifiers just like this - the RCA jack construction is such that silastic will ooze down into the barrel and cause problems. The rubber boot prevents whistling noises through any small openings.
All the sealing around the RCA connector, all the rubber gaskets and stuff is the manufacturer making sure the case is air tight, so you don't get 'chuffing/hissing' sounds from the air escaping as the drivers move and the air pushes through the holes. Surprised there isn't a rubber gasket around where the back panel attaches to the case to go with the rest of the attention to detail they included. sealing the pots and everything else. My guess would be that putting a pre-former rubber box around the connector and glueing it in place is quicker than trying to prevent the goo from oozing through the connector from the back.
Yes, would have expected a seal around the back panel in that case. Seems a bit extreme for the RCA connector, couldn't they find one that's not hollow perhaps?
Two donkey’s years later and your video just saved me the expense of replacing my KRK Rokit8 Gen2 speakers at a time that I can little afford new toys. Mine suffered from the same issue. Cleaned up and good as a bought-again one! Thank you Dave.
That black gunk is an A/B potting compound, similar to "Smooth-on Smooth-Cast Onyx" I used similar to pot filters back in the day... What tends to happen is that they have a shelf life, and if you use it after its shelf life, it WORKS but the chemicals debind over time because they do not fully cure and when they break down, they break down into a sort of watery soup that you were seeing there, that weird moisture is what is causing the conductivity, and the corrosion. Often times companies will test a little of the expired compound, and if it solidifies and tests fine, they do a run of product with it, and if it meets spec, they ship it.... This kind of unique issue starts popping up after a few years, likely this became a problem with one or two runs of units well after they were off to a new model line.
Vaughn Saball Wow, great info, thanks! I thought moisture in boards had left when they stopped making paxolin boards - same thing, heat old gear for a few days before switching on
Just wondering, is there a similar compound without this issue? Or can you use some kind of regular glue? Also: How necessary is this stuff (except on components that could move or vibrate)?
Just for accuracies sake, the volume is on the back because these are "studio" monitor, "studio" as in "recording studio". The volume is most commonly controlled by a mixing board, either software or hardware driven, thus the XLR and TS inputs. In the world of Studio Monitors, these are quite low on the scale.
Keep in mind that a lower quality studio monitor is much better than most consumer audio at a similar price. Consider the "all in one" surround system vs. monitors--the monitors win by a huge margin! That being said, the monitors used by full time professionals are in a different league. A normal person will notice a difference in an A/B direct comparision, but it takes a pro to notice the inadequacy of the lesser speaker without having a direct comparison. (I'm not a pro...I don't notice. I've had pro monitors, but I downgraded to "cheap" monitors...because I'm not critical enough to search out and dwell on the flaws of a speaker.)
You're better off not staying in the very lowest price class. But if you do, choose a more established brand that has more to lose if they produce crap. Adam, Fostex, JBL, Tascam, even Yamaha may have somewhat decent speakers in the < $200 price class who I'd trust not to make dumb mistakes like this... hopefully. But your best bet is just spending a bit more. In my opinion good active nearfields start at around $350. My personal home studio pick is/was Adam A5X's, but everyone's room and ears are different, so always do your own testing and comparison at a studio equipment store.
A5X are great. I use Yamaha HS7and am pretty happy with their response. It's no use buying expensive monitors if it's to use them on a non treated room anyway. You'll have reflections up the ass, phase issues, bass out of control etc.. Good enough :) And yes, for the volume control, a Big Knob or similar, or just reaching for the audio interface volume knob is easier :) Speakers are usually out of reach anyway
Welcome to my world. Conductive gunk is the standard in the industry forever in the CB radio world. Since they started using transistors in CB radios they have been using glue that goes conductive and corrosive. I remove that &%*# almost every day. If I ever meet the guy that invented the original "Sony Bond and Bond Lock" I'm going to strangle them. :-)
Dave look like he needs one of Peter's fiberglass PCB cleaning pencils......anda dremel with a brass wire wheel on it!! That shit was crazy!! It looks like the material they were injecting on the line had a mix problem and one of the constituents (likely the catalyst) was in excess and it pooled under the material after the top catalyzed and skinned over. Thus trapping the catalyst underneath.....and most all catalysts are rather corrosive. Especially epoxides which I am sure that is. PS I would be wearing gloves.
Donald Clifton What I always found interesting is the only place I find it is in relatively cheap consumer electronics. Don't find it in high end test equipment, amateur radios, military electronics, automotive electronics. I swear there is some secret dollar figure that manufacturers use. Anything below that price gets the corrosive glue. Spend over that amount and they don't install the plague in your equipment.
Thanks for the video. I have one of the KRK pair sitting disassembled on a shelf for about 2 years - couldn't figure out what's wrong with it, replaced caps, etc. Now I'll give another try by scraping that black gunk first on this one, and then will open the second one to scrape of the gunk as well.
Dave, I know you are busy so if you read this....That was an awesome investigation. I love it when you repair stuff. This is the sort of stuff I run into all the time. Lots of conductive glue, Just that most of my repairs where I find this is from the 70's and 80's. Working on a Sony V-21 communication receiver that is full of it now. Thanks for sharing this repair, I truly enjoyed it.
Isn’t that possibly a planned obsolescence way of making the board? Because looks like this stuff works for few years and after couple years it will for sure end on problems...
Thank you so much for this video! One of my KRK Rokit 8 G2 speakers started to have issues, it would be ok for about 1 or 2 seconds then the volume would attenuate drastically down to roughly 10% of the original volume. After watching your video I opened up my speaker and saw the same black gunk everywhere. I scraped off as much as would easily chip off where it could possibly have been bridging between two circuits. I discovered one capacitor that was becoming corroded with a rusty colored powder and another with some white powder underneath the black gunk. I cleaned them as best as I could and tested the speaker. It has been running normally since. I imagine I may need to replace the corroded bits, but for now it's working great. Thanks again!
That wasn't my takeaway at all. My takeaway was: Awesome. An otherwise good product with a reasonably easy fix. I can snap up damaged ones with this problem, fix them, and have myself some nice ultra-cheap monitors.
Just came back to this video after having watched it when it came out. I bought 2nd gen KRK Rokit 5s like this in 2013, And used them for 7 years straight. I used to turn them off whenever I wasn't using them, and eventually decided to leave them on indefinitely. What I noticed was that after about 5-6 years of daily use, they'd developed an issue where turning them off, waiting for complete discharge of the power supply, then powering them back on would begin buzzing at mains frequency, and would eventually subside back to noise floor. After 7 years, the buzzing would never subside, and leaving them off for any extended period of time, such as my move from South Carolina to Georgia, would cause the lowest level buzzing to rise. Using extra power filtering before the components did nothing, there were no ground faults, and disconnecting signal entirely made no difference. I've finally replaced the KRKs with new main near-fields, but even after just a day of being disconnected, I tested the KRKs again just to see, and sure enough, the buzzing is even louder now, up from an annoying level to an unacceptable, unusable buzz. If I let them sit, I imagine I'll end up with an oscillating amp board. I suppose in about a week or two, I can test again to see if, even in the dry environment of my house, they manage to buzz even louder. If so, then it'll be pretty clear that these will eventually send 50 V to the drivers. Thanks to you, I actually know what this fault is and was informed enough to replace them before running down the line filtration rabbit hole!
The "volume knob" on the back of proper studio monitors isn't a volume knob, it's a trim pot to adjust your reference level (-10dbv for consumer equipment, +4dbv for professional sources, etc). This is why their range is very small. You control volume with the device that's feeding the speakers, usually a USB or FireWire interface like a focusrite Scarlett etc, or in larger studios, an actual mixing console
Same problem here with pair of KRK RP8 G2. Removed all the gunk from both boards on both speakers, replaced all caps on both boards with high quality Japanes caps Nichcon, Rubycon, and sound is now incredible. Also there is no more buzzing or strange noises coming from speakers when they are silent or when music is playing.
I've repaired a number of these with exactly the same issue. Scrape it off, replace anything that looks corroded, replace with a better compound if required. Issue is the same with the RP5's too.
Alexander G I'd recommend doing preventative maintenance if possible. At the very least, identify if you have the black stuff or not. As in the video, failure to catch it early can lead to other components failing or being damaged.
Ollie Brown also as I've been reading, apparently the black stuff gets much worse over time. Thx for the tip, I might disassemble my speakers next week and poke around a bit.
I've been so happy with my RP8 G2's, they have been powered on 24/7 for almost 10 years now here. And the back of 'em is facing the sun when it's up, so I haven't been kind to them. If they fail at any time I'll be sure to see if theres some black-gunk-removal needed. Thanks for the vid! (For the price I think they are really good studio monitors, and from the 8's onward you really really don't need a sub with them.)
Great video! In infinite-baffle (closed/sealed) cabinets, certain frequencies will cause buzzing sounds through any small orifice as the air gets huffed back and forth. That's why the maker seals up all jacks and any other through-hole components accessible from outside the cab.
Thanks for posting this video. One of my (pretty old) KRK RPG2 8's suddenly stopped producing bass. After determining it was in fact the speaker's fault I opened it up and found the same conductive black gunk all over. I chipped it all off and gave it a good clean. Luckily no components had corroded yet and I have my bass back :)
Exact same problem with one of my KRK 6" gen2's: woofer stopped functioning after being powered off for a few weeks - So incredibly grateful i found this video - I have absolutely zero experience repairing things like this, and was able to find the black goo and scrape it off the pcb with a mini screwdriver / paperclip + some rubbing alcohol - Most needed to be chipped away, but some of the goo was "wet" - (wonder if the potting material melts down due to the generated heat, and then starts to grab and hold water vapor?) - Fortunately, the goo was only in a few isolated areas, and took me no more than an hour to clean up - Didn't seem to work at first, but about a minute later, the bass faded back in to its normal level - This video saved me not only ~$150 on a matching replacement, but more importantly, it opened my eyes to that very replacement would have also been potentially problematic down the road - THANK YOU.
This is an extremely common issue on all kinds of powered speakers. I usually just wire wheel it off with a dremel by default, and replace it with solid setting white heatsink compound.
By far and large pro audio gear and gear aimed at professional musicians last from dad to son. It is very rare to see planned obsolence in the hardware side. Software + hardware however definitely does have planned obsolence but that is more or less dependent when new OS cycles in... at some point, drivers stop working and this is not always just an accident. But the whole business really opearted on word of mouth and reputation is very hard to get back A lot of companies found that out in the 90s with cheap digital stuff coming from then poor quality south east asia and korean manufacturing. It took some heavy lessons to know that you just an't cheat when it is about someone else's livelyhood; word of mouth will travel far and bad news travel the fastest. If a piece of gear has crapped on me and ruined my gig, i will let people know about it..
Thanks Dave, Yes the black gunk is all over on my KRK boards also. There should be a recall on these. Too much work to start scraping away only to possibly have them fail again. Thanks for your time finding this problem.
Someone chose that material based on its ability to dampen vibration.....my guess is it was chosen outside of the view of the EE's that designed the circuits and PCB's. Oops.
Factory400 Or the EE chose it based on a data sheet that didn't clearly tell anyone not a chemical engineer that this compound would become a corrosive conductive chemical time bomb undetectable by electrical and mechanical testing. Such a material is fundamentally unsuited for the electronics industry, and there should be warnings telling electronics professionals to avoid it altogether.
that´s the usual problem when you need to look for stuff you aren´t familiar with, and also which needs to be cheap and not exceeding your total spec´t BOM cost. So you rely on what the datasheet tells you and if it´s not fully specified then it might be cheaper than stuff from let say 3M, but you never know what´ll happen over time, as no one are doing long term tests on consumer or prosumer stuff anymore.
Wanted to Thank You for your detailed video! I got lucky, my tweeter vibrated badly when I stared it up! Shut off immediately, found your video, cleaned my gunk around all speaker connections. Looked for any swollen ( whatever they are ) but looked good! Put it back together! Sounds like new! You are very much appreciated! Keep up the good work for the people who try!
Good video, Dave! It was fun watching you experience the black gunk! I've repaired many KRK monitors with the black gunk of death and I have come to love hating the stuff. KRK studio monitors are notorious for using the black gunk but I have also seen it on others including Pioneer studio monitors. I wonder what it is made of, a blend of something with recycled rum and coca-cola? I always scrape and clean it off thoroughly and typically replace all those garbage capacitors with high-quality Panasonic or Nichicon caps as well as replace any poor corroded resistors. I then use a good replacement for the black gunk like Dow Corning 738 or 736 electrical sealant. :)
Not sure if you'll see this, 6 years after the fact ... But can you or someone explain what the function is of the black gunk, and the electrical sealant you replace it with?
KRK RP5 G2 owner here, had my speaker go deaf around 2 years ago. I was troubleshooting it for whole days until I ran out of tools and patience and sent it for repair. Of course it was the black plague gunk in the end.
I think I have the same problem with one of my Rokit 6 speakers. I bought them back in 2010/11. Great speakers I think. Done me a great job with my video editing. It started playing up a few weeks ago. So that's about 8 years of good work out of them. Thanks for the video. Going to try and fix it myself and see how I go!
Wow, that's great. This is propably what's causing one of my Rokit 5 to crackle and loosing volume all the time. Gonna try to clean some gunk away soon.
It's a very old problem. My 1980s Yamaha gear had white glue holding large caps that turned brown, went conductive and ate resistors and wire links off the board. The PCB (that single sided brown version they use) also changed colour and bulged wherever it was in contact with it.
The killer glue issue is well documented, and the Japanese stopped using it in the mid-late '80s. I used to think that was it, but was dismayed to find that similar problems had in fact resurfaced and apparently aren't even that rare. Bummer.
Love your enthusiasm!! Replaced some faulty caps to get rid of buzzing, but now can notice some persistent loud white noise on a single speaker. Hoping that some gunk cleanup does the trick.
Open some 80th HiFi consumer stuff, and you gonna spot it....some become conductive and causes problems... Today vintage is the tube/valve stuff we (at least i) restore and these usual work is to change all the caps, replace some resistors and wires, reflow solder joints and rework the mechanics (radios). But for our kids, it might be the HiFi stuff we grown up with. It´s already there...last week i had a chat with a 18year old guy who wanted to restore his grand-Dads (time is flying;) HiFi stuff. I told him about belt replacements, cleaning (unDusting inside;) checking caps...and so on, and he went, "oh i already did that, but i still got hum and crosstalk and i spot a lot of hardened stuff on all connectors, and after i cleaned it all had vanished"... I really think that is going to be the new stuff we do have to look for as well....
Probably, that crap will be the new leaking cap. Gone are the good old days of replacing a few worn out/ broken/ out of spec parts, we will now going forward be removing crud it seems.
I've been cleaning that conductive gunk off circuit boards since the 80's. Yes, they're STILL using it! Amazing. Harman Kardon used to love squirting it all over the inside of their cassette decks. They would stay in mute or oscillate. Scrape off, replace corroded parts and jumpers, and voila! I've fixed plenty of these speakers too. Other brands are not immune, unfortunately.
Yeah, I've had basically the same journey down the rabbit hole on a Teufel subwoofer (german brand), the gunk was originally yellow, but turned orange and corrosive. A poor 10 ohm resistor had gotten one of his sides chewed off, had to replace him with a wire, since I had no spare resistor. Worked a treat!
My KRK rokit 8 same issue with the black gunk, instead of the tweeter being affected, my woofer would randomly pop. So ended up replacing a failed resistor, and while I was in there I also changed out all the capacitors to some Nichicon Muses and Fine Golds on the preamp board, and higher quality caps for the power side of things.
A really cool video Dave! I've shared it amongst my musician communities - as this sort of product is discussed quite a lot. It is really interesting that the black acoustic anti-vibration "gunk" as you call it is conductive! WoW! Good pickup!
Great video Dave! Really eye opening. I've owned a pair of these exact models for about 6 years now and they've performed greatly for my purposes. I use them as general purpose pc speakers as well as for DJing; where I've pushed them quite hard for extended periods of time (6+ hours of high volume, bass heavy music in party settings) on multiple occasions. I haven't had mine succumb to the fault in the video, although one has developed a low volume crackle on start-up as well as occasional clicks and crackles that can only be heard in silence which from some forum browsing I've found can be attributed to the crap quality large caps on the amp board. But otherwise I'd say they've served me very well for what I paid for them. However I think I'll be checking out some higher quality brands if I ever plan to buy new monitors now that you've uncovered the dirty secret that is the conductive gunk all over their boards. p.s. Somewhere in the video you said this was a gen 1 model, however it is actually gen 2, designated by the "G2" in RP6 G2. Currently the latest model is gen 3. Also in the conclusion you voiced concern about the speakers being sold as matched pairs but they are in fact sold individually, as are most studio monitors to my knowledge, so no worries there!
I was seconds away from making my Rokit 5's redundant as one monitor had a capacitor discharge sound coming from it. I have enough limited electronic engineering knowledge to investigate. Found nothing obvious after a general check over. Typed discharge from speakers into youtube and found your video. Problem solved!!! How many KRK's have been thrown away because of this black gunk!!! Thank you for your video.
Thank you, Dave! You just confirmed my theory! I've recently repaired one of these myself. But it was in it's initial state, it only had static, random noise in the drivers. At first I thought the filter caps were the problem, but nope. I couldn't believe that is was the gunk! The entire day I was speaking to myself: "It cannot be from the gunk...". But aparently... So...lo and behold: gunked removed, everything worked! Actually they are 2nd gen. And no, they didn't called them back.
you would never need to change volume for studio monitors directly on the speaker, most users would change volume and plug in headphones on their daw interface or mixer.
yeah fair enough Dave, your Alesis is fine and slightly different beasty..perfect for your needs. Normally in studios, where your plugging in multiple mics, keyboards etc etc you just set the master volume on the back of the monitors, and that little tone control on these is so that you can sort of Eq/compensate for any sonic anomalies in the room. Generally set and forget once you have em sounding good...and pull the fader down on the physical mixer, or the the software fader. good fix by the way
EEVblog you can get squelch boxes which have XLR in/out and a volume pot - make one tonight when you are asleep and save a bundle! Greetings from Pommyland! :D
Yeah, if I had a real studio I'd do that. I have a typical work desk, so mine are close, within arms reach. My Alesis's have one mains cable, one USB cable, one speaker cable, simple and tidy. Regular monitors would need two mains cables, a doodad volume/headphone box on the desk, a USB cable, and two RCA/XLR cables, messy.
If you're using a usb mic (rodepodcaster..seen on eevblog2) as adc for your voiceover work on vids..that is all you need!! more cable spaghetti is the last thing you need :)
That was a RP6G2. I have been using a pair of RP5G2 for probably close to 10 yrs now and I have no problems with the black gunk. I replaced all the JRC to BB OPA2228 the moment I got them. If you have a chance to lay your hands on a pair of Eve SC207, they sound really good but the power supply died on me after 4 years. Got one board completely replaced and the other piece died with a pop sound and I managed to fix it by just replacing a TinyMOS regulator.
I was tossing up over a pair of these in the 8" version and the Fostex PM842... I'm glad that I chose the Fostex... I have already had a good look around inside and I can safely report that Fostex did a much better job than KRK.
I've used a pair of gen 2 Rokit for 10 years, absolutely no problems (other than mixes that don't translate!). My Yamaha NS-10m's blew a tweeter, and deformed the paper woofer cone in just a few years. I didn't expect this much out of the Rokits, but seriously been rock solid, one of those things that I just expect to work when powering up the studio. No thought given to them. I can't say the same for the 80's analog synths, or the 90's virtual analog synths. I, and many other people would love to see a repair of an Access Virus B, a high end German synth at $1,200 new in '99 - the B version used cheap caps (supposedly) in the power section, and apparently all the B's are going down now, or have gone down. A's and C's and so forth are okay, just the B's! There is one poor repair video on UA-cam, and that is it. I'd really like to know what is going on. Mind doesn't boot now, I'm a real hack when it comes to electronics, but I have to repair it myself, I can't afford a repair tech!
That gunk seems to be the same as that nasty yellow gunk that turns dark orange and becomes conductive over time. I'm amazed the stuff has not yet been banned in products.
I love this video. I have a pair of Gen2 5'' KRKs and one of them has a strange distortion at certain frequencies. A friend of mine also has the same ones as me and she also has one of them with faulty response. We're going to get together tomorrow and scrape together this gunk of death like a support group. This video was very informative, thanks a lot, you're awesome, you're always awesome!
I've had my series 1's Rokit 6's since release, in my studio, never had a problem. I do however have a theory that leaving powered speakers running continuesly all day causes so much internal heat that this type of melting is, I suppose, inevitable in these. Badly designed yes, but like most things they're given a shelf life. Depending on how you take care of them, I would imagine matters a lot with KRKs.
Am I the only one that spotted at least 4 bad solder joints between 12:07 and 12:17 ? As an "aficionado" this is the second thing I check (after the bulging caps of course).
My first ever teardown was a Rokit 5 gen2 that started playing up within 2-3 years. Nothing obvious (no burnt out components) but the black goop was slathered everywhere. Just moved on and bought a second hand replacement cheap. If ive still got the old faulty unit floating around ill send you the tweeter, its probably the same!
I have some Sony powered speakers that use the back steel as heatsink, I simply went there and cleaned the back panel with IPA and sandpapaer and used 2 part epoxy to glue a old CPU heatsink on the outside where they were mounted on the inside, after I changed the power amplifier IC that had died from cooking, as Sony used 1 drop of compound per unit, or had used a small tube per batch. Did a good job of making the new one run cooler, and the heatsink was free from old dead obsolete Celeron 500 CPU coolers. Just did not bother with the fan, as the whole thing uses 20W off the mains in any case. Now runs barely warm.
In this case I think they hope the 'air flow' from the port will cool the heatsink. However there is really very little thermal transfer by the port. Air flows in and out of the neck of the port but not the cabinet volume. JBL published a paper on port aided cooling some time back. Ports designed to create turbulent flow cooled the best but that is the opposite of what you want for reduced distortion.
HP had a run of computers with power supplies that used gunk that went conductive over time. I worked at a school that had some of these. Every fall a couple would go bang when powered on due to the conductivity.
This is not new. I repaired consumer electronics from 1987 to 2009. I've fixed a fair number of devices by simply chipping that conductive glue out. I think it's hygroscopic thus promotes corrosion. As the metal corrodes the metal ions impregnate the material. That's my theory anyway.
Mine was popping and clicking from the tweeter and low level sound I followed this video and now it's working again amazing I really thought I had a blown cap or some sort thanks again mate
I just picked up a rokit 6 for $5 at the recycle centre. Non functional bass amp. Spent about an hour scraping off black gunk of death, and it works again!
I have to say, apart from that nasty conductive glue and other design problems, they are a great value for the money compared to other monitors in the market, possibly the best deep BASS. Sharing this video with all my Sound Engineers, DJs and musicians network =]
I’m impressed that the tweeter hasn’t fried, it very much sounds like the HF amp section has gone DC. I’ve repaired countless DB Technologies Opera cabs where an LM3886 chip has failed and it often takes the (rather expensive) B&C compression driver with it... that speaker will have an active crossover which may be at fault. (commenting at 15.00)
Great video man, I had this problem 2 days ago. I have the 8'' G2 version and only needed to change one tweeter because I blown one in a party. Other than that they really served me well in the last 11 years. Hope to be able to repair it ! Its full of gunk !!!
8:31 You don't see that too often, but i for one, quite like the bottom copper "silkscreened" on the top. That stuff's real handy for troubleshooting / probing / tracing the circuits (not having to flip the board over all the time).
Some one needs to be fired over this! There is a lot to be said for hot snot!!! AND, I bet it would have been cheaper than that black stuff!!! The 1980's called and said "use our shit!" Hot snot FTW!!!! Excellent diagnosis Dave! Shame no-one would pay for for this repair / diagnosis because you can't replace the tweeter! Thanks Dave! Yes your voice is a perfect test martial (nice one!). I'm sure ebay sales of these faulty speakers have just sky rocketed!
I once built a one off circuit and used silicon sealant. It had a weiard fault on it until the sealant cured, so I guess I had the same fault as Dave found but in reverse. Moral is choose your gunk wisely and read the data sheets!
Those tweeters are off the shelf items, just look for same diameter dome ones to fit there. KRK label on them is just a rebadged batch made by some speaker mass manufacturer, I guess they just ordered 10k units of them to get an in house label on them, or bought the regular ones and had some guy in the factory opening the packs and peeling the OEM labels off, and putting the KRK ones on, then handing them to the assembler as the line went on past.
Yep, got a set of rocit 5's here with bad corrosion around all the black goo. Got some corroded through resistor legs too. R100 is burnt out. It was covered in crap. Also got mechanical hum due to transformer / port coupling even though there is a damper strip on port edge. Now to phone the customer! Thanks Dave.
Yes! I am tired of people saying “Bluetooth sounds bad”. Maybe old versions of Bluetooth had bad quality, but as an electronics engineer and musician myself I understand that Bluetooth is usually indistinguishable from a direct connection, assuming that everything is impedance matched to begin with.
BT uses lossy data compression method to transfer audio data. if you're not that picky about quality, it's fine. i use BT whenever i need like on my car but i highly prefer something like spdif or direct analog connection when it's possible. and you don't really need to match the impedance on consumer equipments nowadays. just make sure your source capable to drive your equipment
S. Kojina I am aware of the lossy compression. The question isn’t whether lossy compression is used or not. The question is whether humans can reliably distinguish the difference between a BT (compressed) signal and a straight aux (uncompressed) signal. This is that same debate with MP3s. Even the top dollar audio engineers debate amongst each other whether one can really tell the difference between MP3s and lossless formats. Don’t get me wrong, I have heard crappy MP3 encodings, but most of them I believe are indistinguishable, even as an ameteur audio engineer myself. The problem is that there is no objective evidence stating whether people can actually tell the difference between these lossy formats and lossless formats. We need double blind tests for that.
some could and the other some couldn't. i don't really care if one said there's difference or not cuz.. eh.. i just don't really care. i prefer to enjoy the music instead of listening the system way too much. i do able to distinguish but then, it's a critical listening session. other than that, i just don't care. i even play some 128k mp3s and enjoy them. BT vs direct connection is like comparing mp3 maybe 256k or 320k to WAV. some could hear the difference, some just can't. summary, it depends whether the listener's ears are well trained or not. i, myself is an amateur audio engineer too. i'm not saying my ears are well trained tho. mine's sucks compared to my friends
I used to be the service centre for KRK, that black gunk affected various makes and even the glues Roland, Yamaha and Korg used to secure large electrolytic caused problems.
The spliced tweeter cables are factory too 😀 Nice diagnoses and job I’ve done a few of these, have to replace all caps, remove all that glue and sometimes the resistors and zenner diodes below the glue need replacing.
I have these speakers.... yay... somehow they still work... well most of the time anyway. The left one is starting to sound different. I suspect black gunk of death. Thanks Dave for making this it gives me the confidence to try fixing these myself!
NoChannel Not a chance buddy. Rokits are actually lower end in the monitor world. I'd call them "prosumer" at best. Fine for beginners, but nowhere near one of the best. The Krk vxt lineup is more pro, but still not top of the range.
Krk seems to be a good company. I think this was just some type of a human error quality control mishap. They happen. I know I make mistakes sometimes. Maybe they learned their lesson, and eventually built them better than before, hopefully. Cheers and God bless. Peace!
*ahem*, if I may: Connor's Law: rarely should one ascribe to incompetence what can more easily be explained by profit motive. (I know I'm being a little paranoid, but still. :-) )
What's interesting to know is that I have a (probably younger) 2nd generation Rokit 5 set, and I swore for years the shielding in them was great. Now, I've gradually been spotting more and more RF interference from my cell phone. Never enough to be problematic, but enough to make me think either I'm crazy or something has changed. So potentially this is a problem that will eventually crop up in any 2nd generation Rokit design, since I'm sure the boards are constructed almost identically.
Gotta love these comments about ‘planned obsolescence’! It’s absolute nonsense. No manufacturer is going to deliberately introduce something into their product that will break down randomly and cause reliability issues. It’d be suicidal business practice. They simply made a mistake and picked the wrong adhesive for the job. That’s it, no conspiracies or mischievous intent.
you might get away with "planned obsolescence in x years" with consumer equipments but not professional equipments. it's a suicide to do such thing on professional world.
But this stuff breaks down over time, and likely post warranty in almost all cases. I bet it's fairly predictable, I mean the temperature outside the speakers will vary between 20 and 30 C, not more than that, and inside it's likely also more or less within a 20 C delta. Now I do suspect that on case of this manufacturer it was not intentional but factory fault. But I've certainly seen things before that made me suspect it was likely intentional.
I've had several KRKs come in to my shop out here in Caracas, the BlackGunkofDeath is the main issue, but I always put in new higher voltage power caps, had many come in with strange popping and crackling noises from these cheapos going bad. Great video, hope you are well dear bro !
I'm a retired TV / VCR / Audio / Computer Tech. I serviced all types of home entertainment gear for almost 40 years and have seen this black gunk many, many times. It's extremely hard to remove without damaging traces and component leads. It turns metal green. It's hard to believe they still use this stuff.
The convenience of having volume and headphone jack on the front of the speaker? That's what a USB audio interface is for. I got the Mackie Onyx Artist 1-2 right in the middle of my desk. Got a nice big volume knob, separate volume for my headphones, headphone jack right on the front, and separate volumes for the XLR and TRS inputs on the front as well. Then USB goes to my PC and TRS goes out the back to my two Behringer Truth B2031A's. But if you didn't want to get into all that, the USB monitors are nice to have. You should see the inside of the B2031A's. Really well done in there. Beautiful bi-amp setup.
Exactly same issue happened on Mine. Had to get a repair as it was doing this awful sound and then done a weird thing where it sounded like a frequency sweep. Technician that fixed it also stated the gunk became conductive. So this is definitely a known issue!
Hygroscopic... probably the failure mode. It's got some salty compound in it... attracts moisture, then gets conductive when wet. Bake it, the conductivity will probably go away.
I was looking at buying KRK but ended up "cheaping" out and buying nEar (ego-sys) for about a quarter of the price. My nEar's are still going strong 15 years later. I never turn them off, they are on 24/7 and have been for all those 15 years :D
Could the cover on the phono jack be to block the air path so it all goes through the bass port on the front?
Could be. Pretty elaborate way to do it if so.
Upon second thought, yeah, it must be. They are using the rubber as a seal for the connector and to prevent sharp acoustical reflection points or some such. Because if they just wanted to seal it, silastic would have been fine.
They really have gone to town with the sealing, it's seems to be their thing.
EEVblog I used to manufacture amplifiers just like this - the RCA jack construction is such that silastic will ooze down into the barrel and cause problems. The rubber boot prevents whistling noises through any small openings.
All the sealing around the RCA connector, all the rubber gaskets and stuff is the manufacturer making sure the case is air tight, so you don't get 'chuffing/hissing' sounds from the air escaping as the drivers move and the air pushes through the holes.
Surprised there isn't a rubber gasket around where the back panel attaches to the case to go with the rest of the attention to detail they included. sealing the pots and everything else.
My guess would be that putting a pre-former rubber box around the connector and glueing it in place is quicker than trying to prevent the goo from oozing through the connector from the back.
Yes, would have expected a seal around the back panel in that case. Seems a bit extreme for the RCA connector, couldn't they find one that's not hollow perhaps?
The gunk is carefully engineered to become conductive shortly after the warranty expires.
Two donkey’s years later and your video just saved me the expense of replacing my KRK Rokit8 Gen2 speakers at a time that I can little afford new toys. Mine suffered from the same issue. Cleaned up and good as a bought-again one! Thank you Dave.
That black gunk is an A/B potting compound, similar to "Smooth-on Smooth-Cast Onyx" I used similar to pot filters back in the day...
What tends to happen is that they have a shelf life, and if you use it after its shelf life, it WORKS but the chemicals debind over time because they do not fully cure and when they break down, they break down into a sort of watery soup that you were seeing there, that weird moisture is what is causing the conductivity, and the corrosion.
Often times companies will test a little of the expired compound, and if it solidifies and tests fine, they do a run of product with it, and if it meets spec, they ship it....
This kind of unique issue starts popping up after a few years, likely this became a problem with one or two runs of units well after they were off to a new model line.
Vaughn Saball Wow, great info, thanks! I thought moisture in boards had left when they stopped making paxolin boards - same thing, heat old gear for a few days before switching on
@EEVblog ^Need to pin/promote user/WillowFox (@Vaughn Saball) comment. Excellent Stuff.
Awesome info, thanks.
Yeah, some A/B resins/potting compounds are actually hygroscopic and the water keeps the compounds from reacting as designed
Just wondering, is there a similar compound without this issue? Or can you use some kind of regular glue? Also: How necessary is this stuff (except on components that could move or vibrate)?
Just for accuracies sake, the volume is on the back because these are "studio" monitor, "studio" as in "recording studio". The volume is most commonly controlled by a mixing board, either software or hardware driven, thus the XLR and TS inputs.
In the world of Studio Monitors, these are quite low on the scale.
Keep in mind that a lower quality studio monitor is much better than most consumer audio at a similar price. Consider the "all in one" surround system vs. monitors--the monitors win by a huge margin! That being said, the monitors used by full time professionals are in a different league. A normal person will notice a difference in an A/B direct comparision, but it takes a pro to notice the inadequacy of the lesser speaker without having a direct comparison. (I'm not a pro...I don't notice. I've had pro monitors, but I downgraded to "cheap" monitors...because I'm not critical enough to search out and dwell on the flaws of a speaker.)
Then recommend us decent ones at the same price.
You're better off not staying in the very lowest price class. But if you do, choose a more established brand that has more to lose if they produce crap.
Adam, Fostex, JBL, Tascam, even Yamaha may have somewhat decent speakers in the < $200 price class who I'd trust not to make dumb mistakes like this... hopefully.
But your best bet is just spending a bit more. In my opinion good active nearfields start at around $350.
My personal home studio pick is/was Adam A5X's, but everyone's room and ears are different, so always do your own testing and comparison at a studio equipment store.
Kyôdai Ken - I've had no issues with my JBLs driven through a Focusrite Scarlett.
A5X are great. I use Yamaha HS7and am pretty happy with their response.
It's no use buying expensive monitors if it's to use them on a non treated room anyway. You'll have reflections up the ass, phase issues, bass out of control etc..
Good enough :)
And yes, for the volume control, a Big Knob or similar, or just reaching for the audio interface volume knob is easier :) Speakers are usually out of reach anyway
Welcome to my world. Conductive gunk is the standard in the industry forever in the CB radio world. Since they started using transistors in CB radios they have been using glue that goes conductive and corrosive. I remove that &%*# almost every day. If I ever meet the guy that invented the original "Sony Bond and Bond Lock" I'm going to strangle them. :-)
if he knew it was shit for what to use it, if it's really obsolescence programmed, he can lose a lot of money with a class action for example ...
More like ram the stuff down his throat and poison him with it.
Dave look like he needs one of Peter's fiberglass PCB cleaning pencils......anda dremel with a brass wire wheel on it!! That shit was crazy!! It looks like the material they were injecting on the line had a mix problem and one of the constituents (likely the catalyst) was in excess and it pooled under the material after the top catalyzed and skinned over. Thus trapping the catalyst underneath.....and most all catalysts are rather corrosive. Especially epoxides which I am sure that is.
PS I would be wearing gloves.
First gen Mitsu VCRs were notorious for conductive brown glue. Fixed hundreds of them.
Donald Clifton
What I always found interesting is the only place I find it is in relatively cheap consumer electronics. Don't find it in high end test equipment, amateur radios, military electronics, automotive electronics. I swear there is some secret dollar figure that manufacturers use. Anything below that price gets the corrosive glue. Spend over that amount and they don't install the plague in your equipment.
Thanks for the video. I have one of the KRK pair sitting disassembled on a shelf for about 2 years - couldn't figure out what's wrong with it, replaced caps, etc. Now I'll give another try by scraping that black gunk first on this one, and then will open the second one to scrape of the gunk as well.
Cool, let us know how it goes.
so ...did you fix it ?
Guess not.
Pity.
Dave, I know you are busy so if you read this....That was an awesome investigation. I love it when you repair stuff. This is the sort of stuff I run into all the time. Lots of conductive glue, Just that most of my repairs where I find this is from the 70's and 80's. Working on a Sony V-21 communication receiver that is full of it now. Thanks for sharing this repair, I truly enjoyed it.
The Radio Shop I got a shock there until I realised 'bust' should be 'busy' lol
Ha! Thanks for catching that. Why did they put those keys so close together. :-) Fixed.
Ugh, can't imagine this stuff in a comms receiver, could cause an infinite number of problems.
EEVblog
Trust us, radio manufacturers looooove this stuff.
Isn’t that possibly a planned obsolescence way of making the board? Because looks like this stuff works for few years and after couple years it will for sure end on problems...
Thank you so much for this video! One of my KRK Rokit 8 G2 speakers started to have issues, it would be ok for about 1 or 2 seconds then the volume would attenuate drastically down to roughly 10% of the original volume. After watching your video I opened up my speaker and saw the same black gunk everywhere. I scraped off as much as would easily chip off where it could possibly have been bridging between two circuits. I discovered one capacitor that was becoming corroded with a rusty colored powder and another with some white powder underneath the black gunk. I cleaned them as best as I could and tested the speaker. It has been running normally since. I imagine I may need to replace the corroded bits, but for now it's working great. Thanks again!
Well, I guess Ill stop looking for used KRKs online then!
Not this generation anyway.
That wasn't my takeaway at all. My takeaway was: Awesome. An otherwise good product with a reasonably easy fix. I can snap up damaged ones with this problem, fix them, and have myself some nice ultra-cheap monitors.
TK Street I’m all for easy repairs, but questionable goo and corrosion? No thanks.
Look for some Adam or Focal monitors?
My JBLs are holding up fine! :)
Just came back to this video after having watched it when it came out. I bought 2nd gen KRK Rokit 5s like this in 2013, And used them for 7 years straight. I used to turn them off whenever I wasn't using them, and eventually decided to leave them on indefinitely. What I noticed was that after about 5-6 years of daily use, they'd developed an issue where turning them off, waiting for complete discharge of the power supply, then powering them back on would begin buzzing at mains frequency, and would eventually subside back to noise floor. After 7 years, the buzzing would never subside, and leaving them off for any extended period of time, such as my move from South Carolina to Georgia, would cause the lowest level buzzing to rise. Using extra power filtering before the components did nothing, there were no ground faults, and disconnecting signal entirely made no difference. I've finally replaced the KRKs with new main near-fields, but even after just a day of being disconnected, I tested the KRKs again just to see, and sure enough, the buzzing is even louder now, up from an annoying level to an unacceptable, unusable buzz. If I let them sit, I imagine I'll end up with an oscillating amp board. I suppose in about a week or two, I can test again to see if, even in the dry environment of my house, they manage to buzz even louder. If so, then it'll be pretty clear that these will eventually send 50 V to the drivers.
Thanks to you, I actually know what this fault is and was informed enough to replace them before running down the line filtration rabbit hole!
The "volume knob" on the back of proper studio monitors isn't a volume knob, it's a trim pot to adjust your reference level (-10dbv for consumer equipment, +4dbv for professional sources, etc). This is why their range is very small. You control volume with the device that's feeding the speakers, usually a USB or FireWire interface like a focusrite Scarlett etc, or in larger studios, an actual mixing console
Yep, one doesn't just simply "adjust the volume" on studio monitors :)
Same problem here with pair of KRK RP8 G2. Removed all the gunk from both boards on both speakers, replaced all caps on both boards with high quality Japanes caps Nichcon, Rubycon, and sound is now incredible. Also there is no more buzzing or strange noises coming from speakers when they are silent or when music is playing.
I've repaired a number of these with exactly the same issue. Scrape it off, replace anything that looks corroded, replace with a better compound if required. Issue is the same with the RP5's too.
Ollie Brown rip I have rp5's at least now ill know what to do
Alexander G I'd recommend doing preventative maintenance if possible. At the very least, identify if you have the black stuff or not. As in the video, failure to catch it early can lead to other components failing or being damaged.
Ollie Brown also as I've been reading, apparently the black stuff gets much worse over time. Thx for the tip, I might disassemble my speakers next week and poke around a bit.
Yep, definitely remove it now.
Can you give a recommendation of what you‘re using today instead of the black stuff?
I've been so happy with my RP8 G2's, they have been powered on 24/7 for almost 10 years now here. And the back of 'em is facing the sun when it's up, so I haven't been kind to them. If they fail at any time I'll be sure to see if theres some black-gunk-removal needed. Thanks for the vid! (For the price I think they are really good studio monitors, and from the 8's onward you really really don't need a sub with them.)
Great video! In infinite-baffle (closed/sealed) cabinets, certain frequencies will cause buzzing sounds through any small orifice as the air gets huffed back and forth. That's why the maker seals up all jacks and any other through-hole components accessible from outside the cab.
I've got to say these sort of vids are milk and honey in terms of first phase diagnostics - addictive watching, thanks.
Thanks for posting this video. One of my (pretty old) KRK RPG2 8's suddenly stopped producing bass. After determining it was in fact the speaker's fault I opened it up and found the same conductive black gunk all over. I chipped it all off and gave it a good clean. Luckily no components had corroded yet and I have my bass back :)
Exact same problem with one of my KRK 6" gen2's: woofer stopped functioning after being powered off for a few weeks - So incredibly grateful i found this video - I have absolutely zero experience repairing things like this, and was able to find the black goo and scrape it off the pcb with a mini screwdriver / paperclip + some rubbing alcohol - Most needed to be chipped away, but some of the goo was "wet" - (wonder if the potting material melts down due to the generated heat, and then starts to grab and hold water vapor?) - Fortunately, the goo was only in a few isolated areas, and took me no more than an hour to clean up - Didn't seem to work at first, but about a minute later, the bass faded back in to its normal level - This video saved me not only ~$150 on a matching replacement, but more importantly, it opened my eyes to that very replacement would have also been potentially problematic down the road - THANK YOU.
This is an extremely common issue on all kinds of powered speakers. I usually just wire wheel it off with a dremel by default, and replace it with solid setting white heatsink compound.
This video helped me to repair a speaker for a customer of mine! Thanks for the help, I would never have guessed the goop was to blame.
Yep, planned obsolescence. I've seen a ton of these. If left long enough, it actually eats through the component leads!
Some of that happening here, I think some of the links are marginal.
Good eye opener - I'll be looking for this stuff from now on.
Generally they use an RTV silicone which is inert. I guess someone just didn't do their research in the purchasing department.
By far and large pro audio gear and gear aimed at professional musicians last from dad to son. It is very rare to see planned obsolence in the hardware side. Software + hardware however definitely does have planned obsolence but that is more or less dependent when new OS cycles in... at some point, drivers stop working and this is not always just an accident.
But the whole business really opearted on word of mouth and reputation is very hard to get back A lot of companies found that out in the 90s with cheap digital stuff coming from then poor quality south east asia and korean manufacturing. It took some heavy lessons to know that you just an't cheat when it is about someone else's livelyhood; word of mouth will travel far and bad news travel the fastest. If a piece of gear has crapped on me and ruined my gig, i will let people know about it..
Thanks Dave, Yes the black gunk is all over on my KRK boards also. There should be a recall on these. Too much work to start scraping away only to possibly have them fail again. Thanks for your time finding this problem.
Someone chose that material based on its ability to dampen vibration.....my guess is it was chosen outside of the view of the EE's that designed the circuits and PCB's.
Oops.
Factory400 Or the EE chose it based on a data sheet that didn't clearly tell anyone not a chemical engineer that this compound would become a corrosive conductive chemical time bomb undetectable by electrical and mechanical testing. Such a material is fundamentally unsuited for the electronics industry, and there should be warnings telling electronics professionals to avoid it altogether.
that´s the usual problem when you need to look for stuff you aren´t familiar with, and also which needs to be cheap and not exceeding your total spec´t BOM cost. So you rely on what the datasheet tells you and if it´s not fully specified then it might be cheaper than stuff from let say 3M, but you never know what´ll happen over time, as no one are doing long term tests on consumer or prosumer stuff anymore.
Could be planned obsolescence haha
Wanted to Thank You for your detailed video! I got lucky, my tweeter vibrated badly when I stared it up! Shut off immediately, found your video, cleaned my gunk around all speaker connections. Looked for any swollen ( whatever they are ) but looked good! Put it back together! Sounds like new! You are very much appreciated! Keep up the good work for the people who try!
Good video, Dave! It was fun watching you experience the black gunk! I've repaired many KRK monitors with the black gunk of death and I have come to love hating the stuff. KRK studio monitors are notorious for using the black gunk but I have also seen it on others including Pioneer studio monitors. I wonder what it is made of, a blend of something with recycled rum and coca-cola?
I always scrape and clean it off thoroughly and typically replace all those garbage capacitors with high-quality Panasonic or Nichicon caps as well as replace any poor corroded resistors. I then use a good replacement for the black gunk like Dow Corning 738 or 736 electrical sealant. :)
Not sure if you'll see this, 6 years after the fact ... But can you or someone explain what the function is of the black gunk, and the electrical sealant you replace it with?
KRK RP5 G2 owner here, had my speaker go deaf around 2 years ago. I was troubleshooting it for whole days until I ran out of tools and patience and sent it for repair. Of course it was the black plague gunk in the end.
Sounds like a chance to build a passive volume controller and explain impedance and cable inductance? And maybe compare it to active volume control?
I think I have the same problem with one of my Rokit 6 speakers. I bought them back in 2010/11. Great speakers I think. Done me a great job with my video editing. It started playing up a few weeks ago. So that's about 8 years of good work out of them. Thanks for the video. Going to try and fix it myself and see how I go!
Wow, that's great. This is propably what's causing one of my Rokit 5 to crackle and loosing volume all the time. Gonna try to clean some gunk away soon.
Both my KRK Rokit 6 speakers have been affected by this..its so frustrating as these things aren't cheap. Thanks for the video.
It's a very old problem. My 1980s Yamaha gear had white glue holding large caps that turned brown, went conductive and ate resistors and wire links off the board. The PCB (that single sided brown version they use) also changed colour and bulged wherever it was in contact with it.
The killer glue issue is well documented, and the Japanese stopped using it in the mid-late '80s. I used to think that was it, but was dismayed to find that similar problems had in fact resurfaced and apparently aren't even that rare. Bummer.
Love your enthusiasm!! Replaced some faulty caps to get rid of buzzing, but now can notice some persistent loud white noise on a single speaker. Hoping that some gunk cleanup does the trick.
I never would have fathomed that selastic would become conductive over time. I'd look at it and say "hmm, nothings broken. Must be dead".
Open some 80th HiFi consumer stuff, and you gonna spot it....some become conductive and causes problems...
Today vintage is the tube/valve stuff we (at least i) restore and these usual work is to change all the caps, replace some resistors and wires, reflow solder joints and rework the mechanics (radios).
But for our kids, it might be the HiFi stuff we grown up with. It´s already there...last week i had a chat with a 18year old guy who wanted to restore his grand-Dads (time is flying;) HiFi stuff. I told him about belt replacements, cleaning (unDusting inside;) checking caps...and so on, and he went, "oh i already did that, but i still got hum and crosstalk and i spot a lot of hardened stuff on all connectors, and after i cleaned it all had vanished"...
I really think that is going to be the new stuff we do have to look for as well....
Probably, that crap will be the new leaking cap. Gone are the good old days of replacing a few worn out/ broken/ out of spec parts, we will now going forward be removing crud it seems.
Love my Alesis MK1 Active Mk2 powered monitors, had them since 2007 and still putting in the work today.
POC (planned obsolescence compound)
You made me laugh out load here
I've been cleaning that conductive gunk off circuit boards since the 80's. Yes, they're STILL using it! Amazing. Harman Kardon used to love squirting it all over the inside of their cassette decks. They would stay in mute or oscillate. Scrape off, replace corroded parts and jumpers, and voila! I've fixed plenty of these speakers too. Other brands are not immune, unfortunately.
krk are GREAT!!!!! love studio use of them they sound incredible !!
Yeah, I've had basically the same journey down the rabbit hole on a Teufel subwoofer (german brand), the gunk was originally yellow, but turned orange and corrosive. A poor 10 ohm resistor had gotten one of his sides chewed off, had to replace him with a wire, since I had no spare resistor. Worked a treat!
My KRK rokit 8 same issue with the black gunk, instead of the tweeter being affected, my woofer would randomly pop. So ended up replacing a failed resistor, and while I was in there I also changed out all the capacitors to some Nichicon Muses and Fine Golds on the preamp board, and higher quality caps for the power side of things.
A really cool video Dave! I've shared it amongst my musician communities - as this sort of product is discussed quite a lot. It is really interesting that the black acoustic anti-vibration "gunk" as you call it is conductive! WoW! Good pickup!
Great video Dave! Really eye opening. I've owned a pair of these exact models for about 6 years now and they've performed greatly for my purposes. I use them as general purpose pc speakers as well as for DJing; where I've pushed them quite hard for extended periods of time (6+ hours of high volume, bass heavy music in party settings) on multiple occasions. I haven't had mine succumb to the fault in the video, although one has developed a low volume crackle on start-up as well as occasional clicks and crackles that can only be heard in silence which from some forum browsing I've found can be attributed to the crap quality large caps on the amp board. But otherwise I'd say they've served me very well for what I paid for them. However I think I'll be checking out some higher quality brands if I ever plan to buy new monitors now that you've uncovered the dirty secret that is the conductive gunk all over their boards.
p.s.
Somewhere in the video you said this was a gen 1 model, however it is actually gen 2, designated by the "G2" in RP6 G2. Currently the latest model is gen 3. Also in the conclusion you voiced concern about the speakers being sold as matched pairs but they are in fact sold individually, as are most studio monitors to my knowledge, so no worries there!
Hey, they are probably the best studio speakers at their price point. Buy the tweeter! Repair good stuff before someone throws it away plz!
I was seconds away from making my Rokit 5's redundant as one monitor had a capacitor discharge sound coming from it. I have enough limited electronic engineering knowledge to investigate. Found nothing obvious after a general check over. Typed discharge from speakers into youtube and found your video. Problem solved!!! How many KRK's have been thrown away because of this black gunk!!! Thank you for your video.
The way you speak while doing all this is ....goooood...I am just lovin that..😂🤗
Thank you, Dave! You just confirmed my theory! I've recently repaired one of these myself. But it was in it's initial state, it only had static, random noise in the drivers. At first I thought the filter caps were the problem, but nope. I couldn't believe that is was the gunk! The entire day I was speaking to myself: "It cannot be from the gunk...". But aparently... So...lo and behold: gunked removed, everything worked!
Actually they are 2nd gen. And no, they didn't called them back.
Yeah, most people seem to get static or some such. Mine was super extreme.
you would never need to change volume for studio monitors directly on the speaker, most users would change volume and plug in headphones on their daw interface or mixer.
Sure, but that's no good for my purpose, I don't want another doodad box on my desktop
yeah fair enough Dave, your Alesis is fine and slightly different beasty..perfect for your needs. Normally in studios, where your plugging in multiple mics, keyboards etc etc you just set the master volume on the back of the monitors, and that little tone control on these is so that you can sort of Eq/compensate for any sonic anomalies in the room. Generally set and forget once you have em sounding good...and pull the fader down on the physical mixer, or the the software fader. good fix by the way
EEVblog you can get squelch boxes which have XLR in/out and a volume pot - make one tonight when you are asleep and save a bundle!
Greetings from Pommyland! :D
Yeah, if I had a real studio I'd do that.
I have a typical work desk, so mine are close, within arms reach.
My Alesis's have one mains cable, one USB cable, one speaker cable, simple and tidy. Regular monitors would need two mains cables, a doodad volume/headphone box on the desk, a USB cable, and two RCA/XLR cables, messy.
If you're using a usb mic (rodepodcaster..seen on eevblog2) as adc for your voiceover work on vids..that is all you need!! more cable spaghetti is the last thing you need :)
That was a RP6G2. I have been using a pair of RP5G2 for probably close to 10 yrs now and I have no problems with the black gunk. I replaced all the JRC to BB OPA2228 the moment I got them.
If you have a chance to lay your hands on a pair of Eve SC207, they sound really good but the power supply died on me after 4 years. Got one board completely replaced and the other piece died with a pop sound and I managed to fix it by just replacing a TinyMOS regulator.
I considered a pair of these once. Glad I went for non-driven KEF Q300s instead.
I was tossing up over a pair of these in the 8" version and the Fostex PM842... I'm glad that I chose the Fostex... I have already had a good look around inside and I can safely report that Fostex did a much better job than KRK.
I've used a pair of gen 2 Rokit for 10 years, absolutely no problems (other than mixes that don't translate!). My Yamaha NS-10m's blew a tweeter, and deformed the paper woofer cone in just a few years. I didn't expect this much out of the Rokits, but seriously been rock solid, one of those things that I just expect to work when powering up the studio. No thought given to them. I can't say the same for the 80's analog synths, or the 90's virtual analog synths. I, and many other people would love to see a repair of an Access Virus B, a high end German synth at $1,200 new in '99 - the B version used cheap caps (supposedly) in the power section, and apparently all the B's are going down now, or have gone down. A's and C's and so forth are okay, just the B's! There is one poor repair video on UA-cam, and that is it. I'd really like to know what is going on. Mind doesn't boot now, I'm a real hack when it comes to electronics, but I have to repair it myself, I can't afford a repair tech!
That gunk seems to be the same as that nasty yellow gunk that turns dark orange and becomes conductive over time. I'm amazed the stuff has not yet been banned in products.
I love this video. I have a pair of Gen2 5'' KRKs and one of them has a strange distortion at certain frequencies. A friend of mine also has the same ones as me and she also has one of them with faulty response. We're going to get together tomorrow and scrape together this gunk of death like a support group. This video was very informative, thanks a lot, you're awesome, you're always awesome!
What type of fuse do they use? I have one speak without any fuse and only found info for classic 5.
that high pitch thing you do when you' get excited broke my beer glass mate.
thanks, same problem, different resistor (R100 had gone). All working again now!
corrosive, conductive black gunk of death! How awful is that.
I've had my series 1's Rokit 6's since release, in my studio, never had a problem. I do however have a theory that leaving powered speakers running continuesly all day causes so much internal heat that this type of melting is, I suppose, inevitable in these. Badly designed yes, but like most things they're given a shelf life. Depending on how you take care of them, I would imagine matters a lot with KRKs.
Am I the only one that spotted at least 4 bad solder joints between 12:07 and 12:17 ?
As an "aficionado" this is the second thing I check (after the bulging caps of course).
I saw them too. Little haloes in the solder around the pins. Really shouldn't use a single sided board in a vibration environment.
My first ever teardown was a Rokit 5 gen2 that started playing up within 2-3 years. Nothing obvious (no burnt out components) but the black goop was slathered everywhere. Just moved on and bought a second hand replacement cheap. If ive still got the old faulty unit floating around ill send you the tweeter, its probably the same!
Got to wonder if the heatsink might work better on the outside of the box!
I have some Sony powered speakers that use the back steel as heatsink, I simply went there and cleaned the back panel with IPA and sandpapaer and used 2 part epoxy to glue a old CPU heatsink on the outside where they were mounted on the inside, after I changed the power amplifier IC that had died from cooking, as Sony used 1 drop of compound per unit, or had used a small tube per batch. Did a good job of making the new one run cooler, and the heatsink was free from old dead obsolete Celeron 500 CPU coolers. Just did not bother with the fan, as the whole thing uses 20W off the mains in any case. Now runs barely warm.
In this case I think they hope the 'air flow' from the port will cool the heatsink. However there is really very little thermal transfer by the port. Air flows in and out of the neck of the port but not the cabinet volume.
JBL published a paper on port aided cooling some time back. Ports designed to create turbulent flow cooled the best but that is the opposite of what you want for reduced distortion.
I'm guilty of using steel chassis to transfer heat, it's not that bad provided you are going 'through' a thin section, not along it.
HP had a run of computers with power supplies that used gunk that went conductive over time. I worked at a school that had some of these. Every fall a couple would go bang when powered on due to the conductivity.
This is not new. I repaired consumer electronics from 1987 to 2009. I've fixed a fair number of devices by simply chipping that conductive glue out. I think it's hygroscopic thus promotes corrosion. As the metal corrodes the metal ions impregnate the material. That's my theory anyway.
Mine was popping and clicking from the tweeter and low level sound
I followed this video and now it's working again amazing I really thought I had a blown cap or some sort thanks again mate
LOL at "and my voice is usually very high frequency."
I just picked up a rokit 6 for $5 at the recycle centre. Non functional bass amp. Spent about an hour scraping off black gunk of death, and it works again!
I have to say, apart from that nasty conductive glue and other design problems, they are a great value for the money compared to other monitors in the market, possibly the best deep BASS. Sharing this video with all my Sound Engineers, DJs and musicians network =]
I’m impressed that the tweeter hasn’t fried, it very much sounds like the HF amp section has gone DC. I’ve repaired countless DB Technologies Opera cabs where an LM3886 chip has failed and it often takes the (rather expensive) B&C compression driver with it... that speaker will have an active crossover which may be at fault. (commenting at 15.00)
Managing to strike my electrical engineering and music production nerves simultaneously
Great video man, I had this problem 2 days ago. I have the 8'' G2 version and only needed to change one tweeter because I blown one in a party. Other than that they really served me well in the last 11 years. Hope to be able to repair it ! Its full of gunk !!!
Evil conductive gunk! - FFcossag had quite some videos on this subject.
8:31 You don't see that too often, but i for one, quite like the bottom copper "silkscreened" on the top. That stuff's real handy for troubleshooting / probing / tracing the circuits (not having to flip the board over all the time).
Some one needs to be fired over this! There is a lot to be said for hot snot!!! AND, I bet it would have been cheaper than that black stuff!!! The 1980's called and said "use our shit!" Hot snot FTW!!!! Excellent diagnosis Dave! Shame no-one would pay for for this repair / diagnosis because you can't replace the tweeter! Thanks Dave! Yes your voice is a perfect test martial (nice one!). I'm sure ebay sales of these faulty speakers have just sky rocketed!
Uber Micro Repairs Doesn't hot snot go conductive from repeated heating cooling cycles though?
My voice is finally good for something!
I once built a one off circuit and used silicon sealant. It had a weiard fault on it until the sealant cured, so I guess I had the same fault as Dave found but in reverse. Moral is choose your gunk wisely and read the data sheets!
Those tweeters are off the shelf items, just look for same diameter dome ones to fit there. KRK label on them is just a rebadged batch made by some speaker mass manufacturer, I guess they just ordered 10k units of them to get an in house label on them, or bought the regular ones and had some guy in the factory opening the packs and peeling the OEM labels off, and putting the KRK ones on, then handing them to the assembler as the line went on past.
I hate hot snot. It doesn't stick properly. Always finding bits of hot snot rattling about in things.
Yep, got a set of rocit 5's here with bad corrosion around all the black goo. Got some corroded through resistor legs too. R100 is burnt out. It was covered in crap. Also got mechanical hum due to transformer / port coupling even though there is a damper strip on port edge. Now to phone the customer! Thanks Dave.
Dave, could you bust some audiophile myths? I'd love to see that! I mean, if you aren't too busy busting solar roadways... :)
It was maybe not a dedicated video but I seem to remember him ranting about audiophiles when he got some valve amps (maybe soviet?) in the mailbag.
Yes! I am tired of people saying “Bluetooth sounds bad”. Maybe old versions of Bluetooth had bad quality, but as an electronics engineer and musician myself I understand that Bluetooth is usually indistinguishable from a direct connection, assuming that everything is impedance matched to begin with.
BT uses lossy data compression method to transfer audio data. if you're not that picky about quality, it's fine. i use BT whenever i need like on my car but i highly prefer something like spdif or direct analog connection when it's possible. and you don't really need to match the impedance on consumer equipments nowadays. just make sure your source capable to drive your equipment
S. Kojina I am aware of the lossy compression. The question isn’t whether lossy compression is used or not. The question is whether humans can reliably distinguish the difference between a BT (compressed) signal and a straight aux (uncompressed) signal. This is that same debate with MP3s. Even the top dollar audio engineers debate amongst each other whether one can really tell the difference between MP3s and lossless formats. Don’t get me wrong, I have heard crappy MP3 encodings, but most of them I believe are indistinguishable, even as an ameteur audio engineer myself. The problem is that there is no objective evidence stating whether people can actually tell the difference between these lossy formats and lossless formats. We need double blind tests for that.
some could and the other some couldn't. i don't really care if one said there's difference or not cuz.. eh.. i just don't really care. i prefer to enjoy the music instead of listening the system way too much. i do able to distinguish but then, it's a critical listening session. other than that, i just don't care. i even play some 128k mp3s and enjoy them.
BT vs direct connection is like comparing mp3 maybe 256k or 320k to WAV. some could hear the difference, some just can't.
summary, it depends whether the listener's ears are well trained or not. i, myself is an amateur audio engineer too. i'm not saying my ears are well trained tho. mine's sucks compared to my friends
I used to be the service centre for KRK, that black gunk affected various makes and even the glues Roland, Yamaha and Korg used to secure large electrolytic caused problems.
*[serious]* please go around the lab and talk about/describe the most satisfying knob indents you have.
I'd be demonestised for posting porn
The spliced tweeter cables are factory too 😀 Nice diagnoses and job I’ve done a few of these, have to replace all caps, remove all that glue and sometimes the resistors and zenner diodes below the glue need replacing.
Luckily it's a single sided board, so you can dig right in to scrape that crap off!
Yes, handy.
I have these speakers.... yay... somehow they still work... well most of the time anyway. The left one is starting to sound different. I suspect black gunk of death. Thanks Dave for making this it gives me the confidence to try fixing these myself!
Love repair vidoes!!!
Awesome videos. Intelligence - High. Voice- Ultra- Super High. Painful on the ear drums but worth it.
Rokit stands for RottenKit
XD
NoChannel Not a chance buddy. Rokits are actually lower end in the monitor world. I'd call them "prosumer" at best. Fine for beginners, but nowhere near one of the best. The Krk vxt lineup is more pro, but still not top of the range.
no for the money you are better off going with jbl or yamaha.
Krk seems to be a good company. I think this was just some type of a human error quality control mishap. They happen. I know I make mistakes sometimes. Maybe they learned their lesson, and eventually built them better than before, hopefully. Cheers and God bless. Peace!
*ahem*, if I may: Connor's Law: rarely should one ascribe to incompetence what can more easily be explained by profit motive.
(I know I'm being a little paranoid, but still. :-) )
What's interesting to know is that I have a (probably younger) 2nd generation Rokit 5 set, and I swore for years the shielding in them was great. Now, I've gradually been spotting more and more RF interference from my cell phone. Never enough to be problematic, but enough to make me think either I'm crazy or something has changed. So potentially this is a problem that will eventually crop up in any 2nd generation Rokit design, since I'm sure the boards are constructed almost identically.
Gotta love these comments about ‘planned obsolescence’! It’s absolute nonsense. No manufacturer is going to deliberately introduce something into their product that will break down randomly and cause reliability issues. It’d be suicidal business practice. They simply made a mistake and picked the wrong adhesive for the job. That’s it, no conspiracies or mischievous intent.
lol can you really say with a straight face that Apple doesn't employ this tactic?
HazL - Their business model isn’t quite as crude as dumping dodgy adhesives on the pcb which will cause random failures!
you might get away with "planned obsolescence in x years" with consumer equipments but not professional equipments. it's a suicide to do such thing on professional world.
But this stuff breaks down over time, and likely post warranty in almost all cases. I bet it's fairly predictable, I mean the temperature outside the speakers will vary between 20 and 30 C, not more than that, and inside it's likely also more or less within a 20 C delta.
Now I do suspect that on case of this manufacturer it was not intentional but factory fault.
But I've certainly seen things before that made me suspect it was likely intentional.
ProdigalPorcupine - True, I'll give you that! But they aint much better lol
I've had several KRKs come in to my shop out here in Caracas, the BlackGunkofDeath is the main issue, but I always put in new higher voltage power caps, had many come in with strange popping and crackling noises from these cheapos going bad. Great video, hope you are well dear bro !
will you please tell me the part number of the caps you used? it would be a big help. Thank you
Guessing it should be pronounced "rocket". :)
Dave hi I was with you all the way I used to work for farnell instruments learned a lot from this
I have a pair of these, they’re awesome.
Psyq Watts not this generation
They sound amazingly yes! Hope you can enjoy them longer than this broken one ;)
GlennnD maybe sound amazing in her price range, theyre in bottom of her class. Actually i prefer my Genelec and my headphones
Psyq Watts you have been eating the tide pods.
I'm a retired TV / VCR / Audio / Computer Tech. I serviced all types of home entertainment gear for almost 40 years and have seen this black gunk many, many times. It's extremely hard to remove without damaging traces and component leads. It turns metal green. It's hard to believe they still use this stuff.
What a junk! This ticking bomb is called “monitor” speaker? Hahahahaha:)
It was probably an accident. The contracted PCB assembly house bought an expired or fake material.
The convenience of having volume and headphone jack on the front of the speaker? That's what a USB audio interface is for. I got the Mackie Onyx Artist 1-2 right in the middle of my desk. Got a nice big volume knob, separate volume for my headphones, headphone jack right on the front, and separate volumes for the XLR and TRS inputs on the front as well. Then USB goes to my PC and TRS goes out the back to my two Behringer Truth B2031A's.
But if you didn't want to get into all that, the USB monitors are nice to have.
You should see the inside of the B2031A's. Really well done in there. Beautiful bi-amp setup.
its 4:35 am in india and still not feeling sleepy 😂😂
Thanks for that video. KRK is history for me now.
probably carbonized due to heat
Nope. It's not carbonised - it turns liquid!
Exactly same issue happened on Mine. Had to get a repair as it was doing this awful sound and then done a weird thing where it sounded like a frequency sweep. Technician that fixed it also stated the gunk became conductive. So this is definitely a known issue!
it look wet
Yes, seemed wet underneath, wierd.
dip it in flour to find the wet spot... it worked on my ex girlfriend LoL.
seems like some moisture trapped inside the gunk
Hygroscopic... probably the failure mode. It's got some salty compound in it... attracts moisture, then gets conductive when wet. Bake it, the conductivity will probably go away.
Got one here with the same kinda problems.
Took it apart a year or so ago, looked, checked the net, yep, conductive...
Good to see videos are back on track! Love the repair videos. I hate the "debunk" ones...
I was looking at buying KRK but ended up "cheaping" out and buying nEar (ego-sys) for about a quarter of the price. My nEar's are still going strong 15 years later. I never turn them off, they are on 24/7 and have been for all those 15 years :D