$18 Tube Preamp Test as a GUITAR PEDAL - 6J1 Preamp Board
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- Опубліковано 22 сер 2024
- In this video I bought an $18 6J1 tube preamp board on eBay and set it up as a guitar overdrive or distortion pedal.
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There are tube pedals that cost ten times more but they sound quite similar. Nice job!
They are $30 now. I have ordered the $15 square version kit to attempt something similar as the input to a hybrid guitar amp with a ton control module and a class D amp.
if you want the output impedance and noise issues fixed on that little square preamp i can send a fully debugged modified schematic of it from dropbox or something. Put $20 into the little square 6j1 preamp and you have a line stage that out performs options ranging up to nearly $1000
As it comes, the little cheap one is practically useless however. PSU hum, and mains hum out the ass. Very poorly laid out PCB. The little square one takes some work to perform properly. As a hi-fi line stage it's wonderful, but i was never able to get the noise issues diminished enough to use it with single coil guitar pickups. Ok with stacked pups and humbuckers, but not usable with my strat at all, too much noise.
There is an updated version available on blue PCB with 2uf polypro coupling caps that takes DC power input not AC, and it suffers none of the issues the 12VAC powered one does. But it's usually about 25-30 as well, but it's a lot harder to play around with modifications on that board.
That gain stage breaks up nicely.
It's typical that 1 tube in the gain staging is all it really takes to deliver the valve characteristics most guitarists are after. I have a fair amount of tube gear and tube heads and bought the kit to run on my solid-state effects loop since it's in the end of the signal chain before outputting to the power amps stage.
I actually went to college for electrical/electronics engineering, but kits are sometimes a good place to start before designing circuits from the ground up.
*For $13 on Amazon, it's ultimately cheaper than buying all of my own parts and cannibalizing a free schematic online.*
Your demo shows it delivered the tube texture people are after, so it's not $13 wasted.
I did something similar, but I found a cool preamp pedal and used one of the Fosi mini amplifiers and got about 120w at 8ohm mono. Built it into one amp head case. Sounds pretty cool.
Fantastic experiment man, probably adjusting the value of cathode resistors/capacitors you can modify the headroom and the clipping according to the guitar frequencies. Keep on bluesing man!
Thanks! I will probably take a look. I actually think it sounds really great the way it is as more of a full frequency boost / thickener.
@@KleyDeJong Do you think one of these circuits, or maybe a tube headphone amp circuit, could be used to drive a reverb tank?
interesting. the small cheap tube amp added way more in quality tone than its price.. nice job
In many events, adding 4v/v (12dB) gain gives sweet improvement. More than 10v/v (20dB) gain tends to harder setting up.
Hey thanks for all your videos. My favorites have been the schematic analyses, as a rookie hobbyist. Not sure if this would interest you but I would love a breakdown of a small tube preamp like this. Or even a FET preamp. Or any breakdown at all haha (your Electra video got me through my first few builds)
It would be great to get more drive ( distortion) with less noise. I think this is a great start to a DIY distortion pedal, yet it is still noise reduction is a must. You could play around with the caps and try to rid it of noise but still get that distorted sound. Nice project.
Two ideas for more drive would be to run the input into a basic clean boost stage like an LPB-1 - then run that into the tube input 1. A second idea would be to add some clipping diodes on the output before the master.
Hard to know how much of the noise is from the pedal, possibly poor filtering. Or from having a totally exposed electronics circuit with all the lighting I have in the basement. I have been looking at building an enclosure.
I do think the tubes provide some pleasing compression and light grit.
here is a tip, since this needs a low voltage power supply and you are using it for an effect.......you'd be better off applying this to an amplifier board in a modern amp that uses an IC based solid state reverb in its circuitry. Point being, the power rail for the IC could be tapped as your power supply for this tube board. This seems to be a chinese tube set up for each tube to operate as a triode.....so the 2 tubes in this board would be like a 12ax7 style tube as a single tube since the 12ax7 tube family are dual triode tubes...2 triodes in one glass capsule. Keep in mind that since this is a 2 triode situation, when you run them one in to the other......the signal flips 180^ each time going from grid to plate.....so 2 triode sections puts the signal back in phase with its input at the output of the 2nd stage......and it appears to work OK with this contraption as a feeder to the front end of the amp with the low level guitar signal as its driving signal. Its a question of the quality of those chinese designed tubes and how cheap they are to get replacements. They might sound OK at low level signals, but then they could be squealers if jacked up to higher gains.....or they could go microphonic when jacked up after a period of time......they might not have designed the guts of the tube to be solid....the mica spacers and all that in the guts should keep the guts solid and not subject to vibrating....but you never know. Keep in mind I mentioned a 12ax7 family tube....as that's the easiest reference to understand as a common dual triode tube......but that would also cover the 9 pin based tubes common to modern guitar amplifiers like the 12at7's and 12au7's and 12ay7's.......each with a different MU...whether they be high MU like a 12ax7 or a low MU like a 12au7......and the points in between with this family of tubes. The MU refers to the amplification factor.....a 12ax7 is 100, a 12at7 is like 60, and a 12ay7 would be like 44. SO they step up or down for gain depending on the application needs. You don't want to overload a tubes input to make it go wacky and not operate well
I'm not sure if you are aware of what you are doing...... But the JCM 800's (Marshall) used one triode section ahead of the basic circuitry which was the tweed bassman/plexi circuit with the cathode follower. Essentially this was the factory version of the hot rodded modified amps where they used the ONE WIRE mod to send one channel into the other channel to get the signal boost. In the case of the JCM 800.....it used one section which flips the signal 180^ in the high gain mode. LANEY did the same thing but used both sections of the tube so the signal was in phase with the input (guitar) on both the high gain channel and the regular gain channel...the AOR series I think it is. Keeping in mind that the tweed bassman/plexi circuitry is a 2 channel amp design just like the tweed deluxe. BUT this is just a basic simple over view of that. The JCM 800 had a switching circuitry in the high gain jack and thats where the hidden second channel is......the low gain jack is the straight bassman/plexi circuit......so it appears as a single channel amp
Yeah, tone adjustment would be good. I'd prefer a mid/treble boost, I play Tele country twang.... so I'm always looking for a boost like that.
Love to basic sound of it. Warm.
Very interesting! I think you could do some grounding that would reduce hum.
Really gives me Vox AC30 vibes the way it sounds tbh
This sounds excellent!! I wonder what 2 of them would sound like?
the unit itself is two channels .
This is great! Good old DIY spirit! Rock on
seemed like a great boost to kick the front end of an amp that isn't quite gainy enough, and the price is superb. good example of bang for buck diy.
Yeah I agree, it works great for that. I'm thinking about adding a tone stack after the second gain stage. It has PLENTY of output to spare. Lots of potential here.
I love the way you say......China.....great experiment.
Absolutely worth plug it in🎉🎉🎉2stage amplified per channel now becomes twice destorted 🎉🎉🎉
Go with Vox tone stack and run it into an effects loop and skip your built-in preamp
Thanks for the tip and great tone !
Good experiment bro....thank for video...
Tell me that amp head is made from a brownie pan! F'N AWESOME
Yes! I've made two amps using a cake pan as a chassis. Search for '5e3 cakepan'
@@KleyDeJong lol thats pretty slick my dude... I've made all kinds of pro audio equipment and never thought darn this Cakpan sure looks like it would work.. lol.. nice man...
@@Chupacabramusic I really love it to this day. It wouldn't survive gigging or shipping, but it works great in my basement.
@@KleyDeJong right..lol.. wufff... I have tons of studio equipment that is rigged for the sound but wouldn't last a few days on the road.. lol.. too funny.
Sounds cool. Like to have one in "volume pedal" enclosure
That's a good idea...
@@KleyDeJong" I'm an idea guy, Chuck"
very cool, totally convincing!
Very nice video,wondering what we can achieve if we stack 2 of these in series 😅
there is NO GAIN on this , its not a pre-amp , its simply a buffer with unity gain ( ie no change )
Hey kley - I’m really enjoying ur UA-cam stuff- this kinda reminds me of the butler tube drivers early on - everything’s coming back around now - u should work into a pedal - Cheers!
Thanks! Yeah I think it turned out pretty good. It would be a pretty large pedal, but I will try to find an enclosure.
I wonder about using that amp to power traditional guitar pedal circuits, like you can get in the Mod kits, instead of using the transistors or op amps the kit comes with?
Wow them suckers could be used in lots of ways. It'll help players understand how they can get their sound. Cool 😎
hi dear, is there possible to preamplifier a dynamic mic ou a guitar adapting a plug or respective cable? if yes, can wee add tube distortion?
cant beat that pricing
The correct power for this preamp board is 12v AC 500ma?
I ordered one but I want to power it correctly
sounded pretty good to me! i'm thinking about putting one in a pedal, but the shape of the board is a little non-condusive to that. maybe i could chop off the rectifier / filtering section of the board and run it on DC. i wonder what it would sound like on 9V...
There was PLENTY of output and the actual tube circuitry can't be that complex. I had low expectations, but this did quite well.
@@KleyDeJong for sure. i'm still trying to figure out how they make -31V and 17V with the 12V input tho
They make smaller layouts with similar hookups. They might be split up around the board instead of In a line like this. Also look into the staccato modular preamps. 8pin DIP SOCKET READY!!! All of them cheap preamps and even the power amps are all decent little things to start a project around. Of course you'd adapt layout to more friends designs but for R&D you can't beat these things. I want a prototype board. A board with prototypes of all the most popular tube pedals out there. They're rare to find. People don't come off them much.
did you connected the gain knob without any eletronic component? direct in the out board and out jack?
This is awesome and I have questions... Do you think you could stack these, perhaps in series, to effectively have 4 gain stages? If so how so? Also, if I just use one and If I add a tone stack between the gain stages (treble, mids, bass and presence), where would be the best place to put a gain pot? TIA
Yes absolutely. At some point it will fall apart or turn into a fuzz. Could be cool.
You just keep running output into the next input.
Gain pot is a volume control early in the signal path. Probably just after the first gain stage.
@@KleyDeJong Thanks for your reply mate. My plan is to run 2 of these, a tone stack in between both boards, a gain control between each tube and a master before the output. Huge pedal but should be an equally huge sound 🤘
$39 now!
Tried using this plugged into a powered speaker studio monito. Cleans are good, but cant get tubes to breakup at all. Do I need something to up the input gain?
I just got one and was wondering which of the “12v” points you used as the power ground?
Doing same thing what value are you using for the gain pot? I have a 100k B ..
I think I used a 100k audio taper pot. Worked well.
I need to add an adjustable output potentiometer::: What value?
Please try with humbucker..
Is there anything similar that can be used as a small low wattage power amp?
Did you connect the guitar directly to the preamp? If yes how did you deal with the high output impedance of the guitar?. In other words, does that preamp has a high Z input?. I do ask since the clips sound very good.
Yes I did. I don't know what the impedence situation is, and it may be suboptimal. But I loved it as an always on thickener.
This is another good video on this preamp:
ua-cam.com/video/Mek_b0MZd-k/v-deo.html
How do you think this would sound plugged in a solid state poweramp?
Update on this ? i would love to make one with a 3 band EQ to boost or overdrive the mids and highs of my Marshall.
ua-cam.com/video/Mek_b0MZd-k/v-deo.html
sound great , only if the buzz noise was annoying , any way to get rid ? any mod needed to the board for that?
Easy, put it in a properly shielded enclosure. High-gain amps amplify everything, noise too.
Sounds as good as a valvecaster to be honest. If not a little more rounded. A valvecaster has a bit more of a brittle OD.
Guess I’m buying one.
Though there was lots of hum/buzz did you fix that?
what value/type of pot is the volume control?
Are those stereo 1/4 inch jacks? Or would normal guitar jacks work?
Normal would work fine.
@@KleyDeJong Thanks! I’m trying to figure all of this out. 😅 Do you, or anyone you know of have a basic diagram or schematic for this setup? No pressure if you don’t, just wondering since it would be very useful to me.
@@jtmchannel7640 tagboardeffects.blogspot.com/2012/02/offboard-wiring.html?m=1
@@KleyDeJong Thank you!!
Im not trying to post too many comments but no one has answered my question. What AC adaptor is everyone using to power this ?
I think these preamps use a DC adapter. Inside there is a DC converter, a circuit that boosts voltage to the desired level.
sounds good and looks like fun.... but my ears can't distinguish enough difference from a plain ol' tube screamer to justify carrying around a 12v AC supply
Can someone post a link or a model # of an AC adaptor that will work for this? Plz. :-) Sorry I lost the piece of paper I wrote down the info on. I just got the preamp today and now i dont know what AC adaptor im buying. Thanks
Also does anyone have good instructions on how they wired up all the pots and what not ? Thanks.
A lot of people will love this. But for the more decerning, the voltage is really too low to get a really good sound. Needs to be around 160 volts plate voltage. Your opinion may differ. I've built more than a few tube preamps at various voltages. It's not the only consideration, of course, but low voltage means bad tone.
Did you ever add the tone stack?
ua-cam.com/video/Mek_b0MZd-k/v-deo.html
@kley de jong can this preamp go straight into my audio interface without the need of attaching it to a poweramp or cab?
Sure!
@@KleyDeJong so basically, it doesn't really react as a normal tube preamp. I mean i won't face any issues with the valves blowing up due to the absence of a poweramp or guitar cabinet as a normal preamp would do right?
@@KleyDeJong moreover what did you do to improve the circuit to actually get the most out of it and refine the sound and gain stages?
@@john_sandilau I'm not following you. In my understanding any tube preamp does not require a load. You need a load on the output stage because of the transformer. The Output Transformer takes your high voltage, low current signal off the plates of the power tubes and converts it into a low voltage, high current signal. High current needs the load.
@@john_sandilau I didn't tinker with the circuit. I just added inputs and outputs for signal flow.
are those 9 pin tubes? could i replace with 12ax7s?
No it would not work with a 12AX7.
They are 6v tubes, 6AK5 works.
Does anyone have a wiring diagram for this?
Dear Jim, un the following video you can find a schemahic around 5:13 that uses the same tube. I hope it helps. ua-cam.com/video/99twje4Q4X8/v-deo.html Regards!
Was it ebay or Amazon?
eBay
CHY-NAH
Are you chewing a gum or is it part of the guitar technique?
Wondered this too lol
Dude turn off your friggin dryer