Secrets of the Mesa Boogie Mark I - Is Good Tone Even POSSIBLE with this Amp?
Вставка
- Опубліковано 5 гру 2021
- This is a 1977 Mesa Boogie Mark I with reverb and Graphic EQ. I have had a few Mark series Mesas on this channel before for repair and restoration, but never showed the entire process of dialing in a tone before. So in this one, we'll do a general service and maintenance and then we'll see how hard it is to get a good tone.
#Electronics #Guitar #Restoration
SHOW YOUR SUPPORT
1: Donate via Paypal: paypal.me/guitologist?locale....
2: Buy Merch: bit.ly/GuitologistMerch
3: Send in Viewer Mail. (Contact Me for details at bradlinzy@gmail.com )
4: Purchase an ad! (Rate sheets available upon request at email above.)
5: Buy something from a sponsor and tell them I sent you.
6: Stand in the middle of the street naked screaming "LONG LIVE THE GUITOLOGIST!" Then when the cops arrive, tell them about my channel. - Наука та технологія
Hey Brad, I don't understand anyone sending you nasty comments. You're a great person and you have a wonderful channel. Keep up the good work and don't let the haters get you down they're not happy and want to bring others down with them. God bless!!
Agreed, Frank. Stay free. Rab 🍻 😎
In the span of the last two years, I have had the last vestiges of ‘give a shit’ beaten out of me. I am a forthright personality and I pay a price for it. It’s the natural order.
Yes! Well said.. agree with you 100%
That's the burden of being an equal opportunity offender! I've been a subscriber for a long time, and disagreed with Brad on some things, but I have always respected the honesty.
:)
The way to get these sounding right is to basically have the bass at zero, mid to taste and treble cranked, because those knobs actually are used to shape the gain, you then use the graphic EQ to add what you’ve lost and tame the amp to taste.
These amps shine with closed back 2X12, and 4x12 cabinets the most, and yes. They’re ungodly loud! Lol!
Couldn’t have said it better, especially about the 4x12 cabinet.
@@quantumfoam140 Tone controls must be pre gain stage then, with the graphic being post..?
@@mymodel6 yes
@@mymodel6 That's exactly right.
Super Stoked for this one Brad!
Man youre really good at playing. Ive watched quite a few other youtubers play guitar, and your playing has some of the most soul out there. I hope to be able to shred like you do one day.
Nice of you to say.
I have an old Mesa 'Son of Boogie' that I wouldn't sell for anything. Awesome & rare amp!
My buddy has a Coliseum Series 300 with a 15"speaker in it. Only one was made. It's a fairly bigger combo amp but it's STUPID loud !
S O B's are great. Mines wood and wicker with a 12L. With the limit knob can really drive the clean tone very nicely. Can also play along side my practice amps for shits and giggles. Like you won't ever get rid of this amp.
@@canigetachannel Are there any pictures of it we can see?
@@lecturehc
He lives in Laguna Beach California, but I can ask him for an image.
I have a very early Strategy 400 Stereo, driven by a V-1 Triaxis. A MK-III 200wattEV's A and a Marshall 1960 A w/Celestion PE 185-S's in it. It breaks windows, 500lbs later...lol Randy built them like Tanks.
Mesas are forever. 😋
My Mesa F50 is an absolute tone monster, no eq just std settings, easy to dial up all the tones I like. I previously had Marshall and Laney. Great vid cheers.
Agree, love my F30, my little tone monster :)
Always fun to watch you wrestle with a MESA! Never saw inside one of these. Took me a minute to figure out what I was looking at with those preamp sockets. The board blends in with the chassis!
Thank you for sharing your knowledge and allow us to learn with your work. Recently got a Rectoverb 25 combo and thanks God it is kind of simple inside and easier than the other boogies to manipulate.
Best amp around. Tone for days. Really Big balsy tone. I have the reissue
Great video Brad. Hope that tornado in Kentucky has not caused you or your family and friends any hurt. My thoughts to the victims and families. Sending best wishes from the UK
I have 2 Boogies and don't have any trouble getting a good sound, Tremoverb with EL34a and a Studio 22 plus , Carlos Santana uses a Mark 1 without problems!...Boogies forever!
Nice repair on a cool amp! Good job Brad.
Thanks for an incredible and very interesting video! I own a Mark i combo (#440) and gigged with it for a decade+ but it’s semi-retired now. On mine the best tones are definitely with the graphic eq and boost off. It also likes to have the master up above 4, which is crazy loud, but that’s where it comes alive. I always felt like it was better with an extension cab too, as that’s a tonne of volume for a single 12! Thanks again.
Brad you're a really great player. Your playing always makes your videos much more enjoyable after your repairs. Keep up the great work!
That’s super kind of you to say. I appreciate you saying so.
always enjoy the icing on the cake wrap up test👍🏻😎🤘
Sounds outstanding
NICE JOB! That thing sounds amazing.....wish I could afford one.
You're making me want to get my older PRS out of storage (the ones with dot inlays instead of birds). Sounds good. I like the newer signal generator you're using. I'm still old school with Tektronics and an HP one.
That item on the lower right of the bench at beginning of video works wonders!
Happy Christmas and New year
That was really cool and mesmerizing
i love your intros so much dude.
Dude you’re such a good guitar player man!
I like it when others play boogies, not myself. I had a MKIII red stripe and a MKIV B wide body combo and I just couldn’t get on with them. I tried for three years with the IV trying to dial it in and it made me feel completely incompetent lol. Every now and then I’ll hear some great Mesa tones and want another one and then I remember how much trouble I had...
thank you, Brad!
Good guitar playing Mr. Amp dude
I had a Mark III Purple Stripe. I'd put that amp against anything you can name today honestly. Was there a Lot going on inside the chassis....Hell Yes. The thing was a combo the sized of a Fender Princeton yet as loud as a 100 watt Marshall 1/2 stack. Both Danny Spitz and Brad Gillis used the III's with Great results. The Marks are King for Good reason.
I haven’t watched yet, I’m just shocked you brought in another Mesa!
clean, the boogies can sound darn good. But even after spending days (literal days) with a mark II many, many years ago, nothing I did to any settings didn't make me think ONLY of "Enter Sandman". Aside from clean, they really are only capable of one usable tone, and it's exactly the one I can't stand. :-)
So even though my friend (who owned the music store) let me take it home to demo for a week, I couldn't convince myself that the hype was worth the price. (The whole point of being able to 'try-before-buy') Nothing has changed my mind since. Good graces to those who do enjoy them. Keep playin' and having fun.
I will say this much, as much as I rag on Mesa Mark amps this one did eventually sound pretty fantastic. Also, I bought a Mark III recently that sounds, well, also great. I have spent nearly 2 decades fully decided that those amps were trash until I bought one last month. Certainly, doesn't do everything well, it's more of a recording/practicing amp as that EQ is so sensitive and powerful and the interplay it has with the other controls gives an unbelievable amount of possibilities, but it does have a great tone that's all its own, also, your playing is tops!
Mine is a Mk lll. I use the bass control at about 2 on the dial and the 80hz slider all the way up, the 240 hz halfway between center and top, the 750 hz at -0+ or lower, the 6600hz all the way up, 2200 halfway between center and top. I’ve never have a problem getting a good sound.
I love that intro!!! Great content. entertaining.
Cool video. Nice to watch you work. Do you have a video of how you set up your led readout for voltage amps etc on top of your Variac?
You're such a show off when you get them things soundin good you know. That's the real reason people come round! Nice amp and great sounds.
Yeah, the Mark series (including the Quad Preamp and Studio Preamp) are tough to dial in, but sound great once you do.
@Left Handed Guitars Have you ever seen the Peavey USA rack mount all tube pre amp called the Rock master !?
It's amazing and easier to dial in than the Mesa and has 7 effects loops so it's boss !
It's also got a killer clean channel fender twin reverb type clean channel and then 2 over drives like the 5150, in fact the guy who build and designed the 5150 with Eddie guy's name is James brown and he owns "amp tweaker" company he built from ground up but yeah that's the guy who designed and built the Rock master rack mount all tube pre amp and it does everything from clean clean loud clean all the way through tweed gain on the clean channel and the 2 drive channels cover everything else from vintage Mesa and Marshalls all the way to the high gain 5150 and Mesa rectify high gain so it's really versatile and kills most tube rack pre amps for guitar and they're cheap even though they are USA made in the early 5150 days to go on your tour rack mount and survive they 1980's So I figured I would ask about if you know of this Peavey unit because you know the Mesa and it's short comings so yeah 👍
I wasn't a big fan of the Mark I but I have to say when I spun the dials and push pulls I dialed in a Santana tone. I have to say for that one sound...this amp is worth it. The other thing is one day it stopped working. I found out that the switching jack on the effects loop didn't close and it won't pass signal. I just bent the switch leg, but I just used a patch cable to avoid in the future.
That amp was probably worked on by the late Aspen Pittman based on that dated sticker. What a piece of history.
You have to crank the master to get a truly great tone out of these, which kind of necessitates an attenuator. I got really good results with a Mark III using a Marshall Power Brake. Also, please do an amp build video with one or both of those 807 power tubes that you received-I've got a couple along with the porcelain sockets someone generously gave to me that I'd like to build an amp for!
I've got an old .50 calibre +. It's got one of the black shadow 200w speakers in it. I did a clean up of the amp in the summer, the speaker weighs in at just over 8kg on its own. It's a black hole.
4 stools with 4 legs per stool would be 16 Mr. Wizard 😜 lol great video man! Glad to see some new stuff!
Thanks for sharing Brad!! I had a hard time with a Mark 2a getting tones that i could easily dial in and use fluidly. Pedals were always the goto. However the cleans were always pristine and made the amp hard to let go. Always found you had to roll the bass right off to keep it from crunching out and add some back in with the graphic. I thought you might break into "Rockin in the free world" at one point. Nice job on keeping that amp maintained!! Thanks again for the video on another boogie!!
" I had a hard time with a Mark 2a getting tones that i could easily dial in and use fluidly". Please do not say this, I just bought a MKII 1979 100w head for 2.7K AUD, consider it a good price considering the rarity ...... Maybe someone will laugh....
@@sixjac Hopefully I could clarify or maybe justify my comments on the 2a. I had an 80's Marshall 50w tube amp prior to owning my first Boogie, the mark 2a. 5band eq, 60-100w switch, Evm 12l, pull knobs and such, very different from the marshall. I found the controls at first rather confusing and unusable, they were unlike the marshall even until about a year after having it. Never had a problem with getting a blissful, crystal clear, amazing clean tone out of it but when changing to the Lead channel it was so different and didn't match, lacked in a tight bass. The biggest secret is not to have the Bass control knob up at all, dial in your Bass response with the graphic. I ended up using the clean channel and pedals to suit, kinda gave up on the lead, however I could get a nice singing version of a Santana sound out of the Lead but it wasn't what i was after at that time. The 2a is unbelievably powerful and strong(especially with the Evm12L, i just felt I couldnt get out what i wanted from it with everything that is loaded in it. In heinsight it was probably my inexperience with boogies at the time, Im quite sure you will enjoy the amp, and play with the dials and eventually you will find your sound! Its in there! no ones laughing Sixjac.
Fuck this amp, and god bless you for working on it. I build/play 1957 Princeton clones, and I personally see no need for 95% of this Mesa amp’s features. You’re a kind doctor, taking care of this sad dying beast.
Guitologist: "Yeah this amps alright I guess, maybe.." plays '80s licks for 10 hrs straight...
Mesa on Brad's channel I click. U know sparks will fly lol 😆
I'm the original owner of a '76 Boogie with graphic EQ. The graphic behaves much like yours - volume drop and some distortion added. I wrote Mesa to ask if that was normal and if I or they could do anything about it. Randall himself wrote back with the terse answer, "No."
19:06 From the bright silver-coloured U-shaped structure in that tube it looks to be a Shuguang.
Great vid, cool sound and nice playin'..Ed..uk..😀
Those are/ were the best amps they made , period!
I've been studying your videos for a few weeks and especially enjoy the deep dive of the circuitry that you do on some of your projects. I';m going to ask that you consider doing a deep dive analysis of Mark ii and Mark iii drive channels at the basic level. The Volume, Master, LEAD-Drive, LEAD-master controls are common between the two models and really give these amps their unique drive characteristic that people love these amps for. Personally I don't care for anything post MARK III era because from IV onward they went into the deep end with complexity.
Really the best way to explain the Mark 1 is to start with a Fender Twin/Deluxe/Bandmaster Reverb vibrato channel circuit and add a gainstage in front of it. VOLUME 1 is the boost stage gain control, VOLUME 2 is the stock volume control and MASTER is the master volume. TREBLE, BASS, MIDDLE is the stock Fender EQ.
In the Mark 2 series the overdrive circuit was inserted within the stock Fender circuit where the reverb send/return and dry signal mixer normally would be. The order of the front panel controls changed with the MK2 into it's current arrangement, VOLUME 1, TREBLE, BASS, MIDDLE, MASTER 1 (this one doesn't make much sense, it is the only master volume), LEAD DRIVE, LEAD VOLUME and REVERB/PRESENCE.
The Mark 2A and Mark 2B lead channels used a single gainstage with the lead drive control and the Mark 2C used 2 gainstages with the lead drive in the same position in the circuit and the Mark 2C+ was a refinement of that circuit. The biggest issue with the pre C+ Mark 2s is that the reverb is awful. Boogie didn't really know how to integrate reverb with the new circuit and put the reverb circuit in parallel with the overdrive signal path meaning you'd be hearing reverb from the clean channel while you were playing on the lead channel. To add to that mess, they also put in an effects loop BEFORE the overdrive circuit in the 2C. This is what the C+ upgrade was originally meant to address as well as fixing the reverb.
It was only at the very tail end of this 2C redesign project a couple junior level techs tweaked the 2C preamp lead circuit into the 2C+ as we know it today. From that point on, the Mark 3, Mark 4 and Mark 5 all share basically the same circuit as the 2C+ although Boogie did experiment with the formula slightly with the different Mark 3 color stripes and the Studio, Quad and Triaxis preamps. The Mark 4 preamp circuit went back to the 2C+ specs but as noted, they added all sorts of features that make it more difficult to operate. As much as a PIA the Mark 4 is to dial in it is a true multi-channel amp compared to a Mark 2 or 3 that does one sound exceptionally well at the expense of the other channel(s), that's why having the separate passive EQs and gain controls of the Mark 4 is so valuable in my opinion. I'm not going to get sidetracked and have this go on further than I have already but I am not a fan of the Mark 5, too many compromises and too many deviations from original Mark series formula for me, it sounds nothing like any of the amps it claims to replicate.
I had what I think was a Mark3 fancy Hardwood Simulclass something. I couldn't get a sound that I liked, but more importantly, I couldn't get it to feel right. It was like trying to use a 9 pound hammer for finishing nails. Even the clean sound had a way over the top punchy-ness. I traded it for a Brown Deluxe and I added cash. Part of the learning curve for me.
For a while, i played in a band where the other guitarist used a Mark III (I forget if it was blue or purple striped), and I used a TriAxis; sometimes for recording we swapped amps. I agree with the commenter who said the TMB shapes gain (and how to set the knobs) and the graphic EQ recovers what you lose. Tried them both thru a 4x12 and a 1x12, all closed-back with plenty of wattage. I could NEVER get on with any of the sounds either amp produced. I went back to a Marshall (where I started before the Mesa) and I never looked back. I have NO CLUE how people get good tones with them, but godspeed to ya. Psionic Audio has some great videos with Mesas and their reputation belies the actual design and build quality. Super expensive to maintain compared to my Marshall and the damn MIDI channel switching on the TriAxis would fail about once a quarter.
I really enjoyed this one...as usual Brad. Always enjoy your vids....and I am NOT a guitar player or electronics guy..I just love this stuff..
its funny because I saw the title yesterday and it said "Will it Chug"...& I was just wondering what happened there, Title change......Did Ola say something about that? I think it was a reference to his channel...and I know you were not making fun of him...kind of an homage to him....yes? And his tones....WOW Monster Tones...
"Will it chug" is a pretty common phrase when talking about rock amps. I've used it with friends for a long time. But some thought I was trying to rip off Ola Englund, so I ditched it. Wasn't worth my breath.
A lot of big-time rock stars with their own personal techs insist on using the mesa stuff LOL I bet the amp tech is tempted to just secretly clone the entire preamp with a FET transistor sound-alike and leave the filaments on the preamp tubes hooked up LOL JK that would be a dick move but it would be interesting to talk with someone who specializes on fixing those beasts.
Brad tends to hate Mesa....and I'm here for every second of it! Building their empire on a shameless SLO copy that was the Rectifier is enough to cancel that company alone.
Do you work on boogies still? And where are you located?
What does the "slave" jack and knob do?
All the demo's I've ever seen of Mesa Boogies with the EQ sliders have had them in the formation of a V. Does this matter much at all? I am intimidated by amps with too many tone shaping options. I like it simple.
I wonder if I would love the Marshall Kerry King signature head?, lol. Just plug it in and blaze. I recently picked up a little Fender Champ 20 solid state in a trade, not half bad for quick plugg in and play, fast and simple. I play classic 80's metal, or try to, so I like having the delay and reverb right there off the amp. Thanks for the fun video Sir. I shouldn't comment till the end, I LOVE THE SoUND OF THAT AMP! I like that "Chuggy thing". Might want a boogie very much in short order.
People adjust the Boogies' Graphic EQ in the V shape to scoop out the mids and accentuate the highs and lows of the eighties and nineties metal tonic qualities. Hetfield, a popular Mesa products user, clips out the highs even more to get the "Crunch Berries" sound (early Metallica recordings). I'm not really a huge Metallica fan. I mean there pretty fun guys to hang out with, I just like a broader range of musical variety than just metal.
@@canigetachannel thank you for that information. For real, I appreciate the response. I love ALL sorts of different musical styles, but when I plug in I have a Lizard brain, instinctive metal guitar inclination. It's fun, I like it and it doesnt hurt anyone. Old Metallica still puts the wind in my sail! Was just thinking about re-revisited, the 5.98$ ep. They did that in a garage and it sounds EXACTLY like I would want an album to sound if I made it. Sometimes DIY works out.
It depends on how deep the V is. Marks are VERY mid heavy. Running the 750 slider at unity and the rest in a V just above that basically runs the amp flat, more or less. You don't really start scooping out mids until you put a deeper valley on the EQ. The best thing to do is to get the amp sounding good on its own, then engage the EQ and colour to taste.
I always check the fuse when I get a used amp, I bought a 64 Tremolux and when I checked it it was wrapped in foil. I just got a Mark III and man it was tough to dial in.
I didn’t see any secrets in the video, it seemed a standard repair.
What it remarkable about this amp is it uses the PI stage from the original circuit. I didn’t think Mesa Boogie actually used that circuit. My Mark 1 had an older PI circuit with two 330K grid leak resistors. I did trace it out and later threw away the diagram I made.
That might also account for why the amp is a bit unruly, the later PI circuit allows the amp to be more flexible.
They want to be turned up which is very 70’s too, but not so PC now.
I seem to recall both volumes on 7 and the master on 7 was the Santana sound. While the first volume on 10, the second on 2-3 with the brightness engaged and the master on 10 was the Marshall sound.
Do the Intials on the chassis say "R S"? I was thinking it might be Randall Smith
A Mesa Boogie Mark I should sound better than that one. There's a lot of things to fix there. Replacing capacitors is a good starting point to me! Instead of many people think, what I experimented a NOS BRIMAR or MULLARD 12AT7 are the best kind of preamp tubes to put into the first slot.
Mark Is were notoriously inconsistent, even the later ones, which was one of the main reasons for the Mark II. Some sound amazing, some have nothing but problems.
GUITOLOGIST< I'm confused what is the advantage or benefit of having a separate diode and dropping resistor for the mesa EQ section in the mark II compared to the mark I? what are the advantages of using a separate diode for the EQ section biasing +Vcc for the EQ section?
You can't rebias the output without also affecting the EQ voltages in the Mark I. They're both supplied from the same source voltage.
Tone controls should function to shape the tone from a flat as possible base. I understand their are "signature sounds" to amp brands, but I believe you should be able to tailor the sound to whatever you want.
It would have been good if Brad had recorded the circuit diagram and told us the voltages present on the various nodes.
What is interesting is there are two different P.I. circuits used in Mark 1 Boogies. This one has the early Tweed style circuit while the later ones were more Blackface like. What this means is the amp sounds more Marshall/Tweed like
Hey Brad.I genuinely hope you're well..I've watched your channel from the very beginning from over here in Scotland..I'm a fan both of your channel and of yourself...Right... on to amps....I love when you work on Boogies because I'm a true Boogie fan..but also find it very entertaining..When I see you have a new Boogie on the channel in for repair etc I actually get excited..Get comfy grab a hot cuppa tea and chill and enjoy the show :)There is obviousy something wrong with this amp!It should sound fat and creamy..Input 2 should be pure Blackface clean but fat and chimey..Input 1(Voulume 1+2 cascading)should give that thick creamy sustainy lead sound (Ala Santana)that these amps are famed for?It sounded really thin and nasaly at points..Could it be the cathode bypass caps?Mesa started using the small tantalum series somwhere around the Mark 2 that really didn'd need changing but these early ones are electrolytic and I should think at this stage need changing anyway?Definitely not sounding as it should though Brad..Take it easy pal.
Did I missed something or you just changed 4 caps (and cleaned it up)?
Aha, the first images clear up my foggy mind. For a while I thought of the Mesa Boogie as a light colored amp, that (no guitar in sight then) I mixed up with an amp called Charlie. for years I wondered how this could happen, weren't Mesas Boogies (not the center of my attention) black? How did I confuse those two? Here's the answer. Light colored as well as a clearly visible big speaker hole.
Bang Bang Bradley's wooden hammer came down upon his amp...... :)
I watch only for the high quality cinematic intros.
I watch Boogie videos to see if anyone gets what I would personally consider a decent tone. I owned a Quad Preamp/Stratagy 400…then the 50/50….then a Studio Preamp …then a Mk 2C with a graphic that I had Mike B at Mesa convert to C+. I find these Mesas versatile to a fault and not for everyone. LV the cabs
THANKS BRAD NOT A DULL MOMENT IMA DRUMMER TRY LEFTY GUITAR 🇺🇸👀
Wow! That amp Boogies at even low volume..
I had a couple Mesa Boogie combos that sounded like this amp....just too weedy sounding. As much as I tweaked it, it just didn't do it for me. But I have to say I tried the Triple Crown and enjoyed it very much. Haven't pulled the trigger yet though.
Missing the uploads hope everything’s ok man
I had one like this without the eq in the early 90s. It had a great clean tone like a fender twin but could never get a good distortion sound. It was really loud so I don’t think anything was wrong with it. It turned me off Boogie for a long time even though their later amps were good. Maybe it’s the huge speaker, no breakup at all.
My guess is it had some thing to do with a 150 watt speaker. You would really have to crank that to overdrive it but in this video he seems to be getting a good break up at low volume so I guess that throws my theory out the window.
This speaker is very broke in. The commenter's speaker still might need breaking in. May not get THAT sound at low volumes. Just a guess. Had to use mine LOUD for a while to get that sound. 12 L speakers need volume to express themselves correctly.
Have You Ever Worked On Pedalsteel Guitars?
Just paint the whole circuit board red and all will be solved lol lol...i still laugh at that video and how you reacted..EPIC!!!
"Factory Select" resistor - sounds to me like the value and/or inclusion of a resistor at that point was left up to the tech that built the amp. Just a thought.
I just picked up whats essentially a Mesa Mark 3, its that Acoustic G100T 160 like the combo one you worked on while back, I have the head it's a reverb style, 4 NOS RCA 6L6 and this thing ROCKS, 5 band equalizer, lol, it all works.. reverb tank doesn't seem to work I have it out, don't need it, use an ADA MP1 into a clean channel, great clean channel, this thing can CRANK.. not as cramped for space once you pull the chassis out on this one, single layer board but all the goofy pots connected to it all that goofy nonsense, like to have a hand wired board made for it like fenders have, wired pots so forth, dedicated ceramic tube sockets, the works... maybe convert it to a 15" combo, that be real nice, dunno if the 5 band EQ would stay or have to go at that point?
if you were within driving distance I'd drop it off maybe something you could film.. meh
Sounds like an assload of work.
I missed something.
how does amp work without the cap you said gave you so many problems getting out.
I see no replacement.
great chanel from one brad to another..i got a feeling you cant throw things away..just incase..im the same hehe
I have a boogie dc 3 head I need help with. Can you help me?
I had and sold a Mk III green stripe, because I couldn't get more than one sound out of it at once. It would do beautiful cleans, and scorching leads. But I could never get a rhythm and lead tone that I liked at the same time.
I have a mkiii purple, same deal. Only one channel at one setting can be played at a given time.
Just stick to MK3 and earlier. Mk4 is where Randall got too complicated. Man that thing really Boogies 🤟😎
Guitologist;
I think what you have there is a Mark II. The 1977 date codes point to this. Is there a 12AX7/Fetron switch ?
I didn't see one and if there was you probably would have commented about it. No Fetron option makes it prior to a Mark II C.
My brother-In-law bought his Mark IIC in 1977. (44 years ago.). It has been as reliable as a blacksmith's Anvil.
I re-tubed just the power stage in 1992 with NOS 5881's, that made the amp absolutely awesome.
The non-adjustable bias has long been a bone of contention among amp techs, but this amp has gotten a lot of mileage out of it.
It is a Mark I since it has six knobs. They were made till 1978. Some 77 and 78 Mark 1s had the Fetron.
On the big cap, you could have cut a line down the cap cover and peeled it off, once the cap is out you could pull the plastic over out with pliers.
I had to opt for # 6 cause i'm poor . The cops were uninterested but let me off with a warning . I once got to play through a 100 watt Mesa Boogie head it was awesome . Didn't hear much out of this one but wonder if you shouldn't have fixed that EQ to a Mark II ? interesting watch .
I got a 1968 Super Reverb I never powered it on when I got it and first thing I did was replace the power cord with a 3 prong. It is lighting up but The GZ34 is not glowing at all and no sound is coming out of the Amp whatsoever not even hum. I was told from a few people it could be a Transformer. What would you suggest?
Bad rectifier tube with a bad filament, or open secondary power transformer winding, maybe on the 5V filament. Some amps have secondary fuses to check, but not that amp.
Incredible tone...not every amp has to sound like a marshall...and use your guitar knobs to clean up .
Do the Mark I's really have the graphic EQ inserted in the middle of the signal path like it's shown in the schematic? It seems sort of redundant putting it right after the passive tonestack, I'm curious to know what your impressions are of it's functionality and the usefulness, or lack thereof in shaping the sound of the overdrive channel and/or how it interacts with the reverb circuit?
There are a few moments in the demo where you can hear the difference the EQ makes in allowing you to express or remove different frequencies. That driven, screaming 80s tone isn’t possible without the graphic EQ.
@@TheGuitologist I have a Mk 1 Reissue .....would putting a graphic eq pedal in the FX loop do basically the same thing as M1 with the graphic EQ built in ?
That first 12AX7 is a Yugo - those things always go microphonic after light abuse
Given the size of the magnet on that speaker the transformer are have fun there working at their best. Compounding the tube placement. The choke are have a real field to try and work in . Have to say even in the 80 I disliked those Sprague . 7 years is the peak service life of that cap . Yes they do last longer than that however the cap degrades a lot over time.
I was thinking that too, but more about reverb transformer placement. That’s signal induction across that transformer really close to the PT.
@@TheGuitologist Inductance coupling is rated as to field strength . Thus closer it is the stronger the coupling . If we are talking about EE101 the one must wonder about the skill level and training of the "designer " of this unit . Some of guitar amp design is like a chief flavoring the sound and part of it is basic science where unintended problem are controlled first.
@@johnwilliamson467 I think it's safe to say most guitar amp designers start out as hacks. I've yet to hear of anyone going through engineering school first. No one of any significance anyways.
@@jsullivan2112 😜Well Leo Fender at least designed thing with a tech in mind .Knowing that service would be need on the equipment.
@@johnwilliamson467 Oh absolutely, the man fell just short of genius in many ways when it came to ease of repair and user friendly. He often flew by the seat of his pants but he knew what he was doing. On the other hand, he called vibrato tremolo and gave amps standby switches that didn't need them, so there is that.
Might sound better with the 12AT7 in first valve position
Brad, why not pull out all tubes and check voltages first?
There were no symptoms being displayed to warrant that.
What kind of guitar was that black high tech looking thing?
I;m guessing that you are referring to the Boaz modular guitar ... It's in Development, so see Brad's recent vids for an explanation ...
Great, now even EQ's aren't safe from the mobs. I love the little box of 'bag balm' on your bench! 😂
Great stuff - thanks, Brad!
For sore teets and udders.
I am definitely in need of an oak mallet/hammer, can I buy one ?
Yep. Email me: bradlinzy at gmail
@@TheGuitologist done thanks Brad
I do love the eq arrays on these things, though. More amps should have parametrics instead of hi-mid-lo knobs.
I do ok with hi-mid-lo knobs. I just use a boss eq to really shape.
It's a graphic eq, not parametric...Fixed frequency for each range, not variable range, that's what parametric does.
You should play Rock Bottom by UFO…
This one have four 12AX7 and one 12AT7 - look like Mark I reissue ?
No. Reissues did not have a GEQ.
Maybe it's the microphones, or my headphones, but I didn't much rate the sounds coming out of this amp ... I guess it's all subjective though.
Maybe it’s because Brad is a 44 yr. old metalhead and his ears have taken a hit? IMHO the audio when jammin’ is poor as he doesn’t’ have a well treated room. I had the same problem until I made some effort to tame my room. Now I don’t have to do as much fixing in the mix.