diy tube preamp for guitar?

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I just ordered a tube preamp kit from aliexpress,, you can find them on ebay as well. It's for stereos, not guitars. THe inputs are rca. The kit is """6J1 tube preamp amplifier board Pre-amp Headphone amp 6J1 valve preamp bile buffer diy kits + shell"""
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My "guitar amp" is an ion block rocker which has a mic input and an aux input. My plan is to hack up a guitar cable to plug from my guitar into both rca inputs, and then run the rca outputs through a cable that then headphone style plugs into the block rockers aux in.

My expectation is,, it will work, and produce sound. I saw a quick youtube video where someone pulled a few caps out of a similar module to run a turntable,,, but couldn't he have just done so with the "volume engaged"? what would bypassing the volume do for him? why couldn't he just,, turn it up?

edit:::; it appears as though I should try to run the guitar to one side of the stereo preamp, then run the output of that side to the input of the other side, then run the output of the second side into the aux in of the block rocker, to get a two stage preamplification,,,,, perhaps then I COULD still plug into the mic input of the block rocker, but I still intend to plug into the aux,, I mean if it isn't loud enough to drive the aux in, did the tubes even amplify it??

anyway, I know that guitars are a pretty weak signal, probably comparable to a turntables needle output. Should I expect it to work?? If not, should I expect to need to modify it??

people are swapping tubes around,, what's there to know about that?? can I take this 6j1 tube out and plug in a "hotter" tube and get a distortion pedal out of it?? Of course this sort of thing should be like, I know a lot, so I know where to go for info, but basically I can solder the kit together confidently, and hack together an adapter set. I only nearly burned my house down once, and that was lithium batteries on the charger. Luckily I was so close to the batteries, that when they went off, it almost cooked me, so, I was able to fight the fire and keep it contained. those things really go off, by the way......

here are links to the kit I ordered, and the video.

Thanks!!! ,, I did briefly search, but I didn't see anything anywhere about someone doing this. A few people are modifying proper complete vintage amplifiers into guitar amps, but mostly the videos are really long, and more specific about tone,, I just want to first be confident it will work at all.

6J1 tube preamp amplifier board Pre amp Headphone amp 6J1 valve preamp bile buffer diy kits + shell|headphone headset|kitheadphones cool - AliExpress

Vacuum Tube Buffer preamp review and tear down - YouTube
 
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I looked up the block rocker, interesting little thing. You might not get much response to the 6J1 amplifier here. I thought it might be a good project to come up with a circuit to make it into a guitar preamp but it is a little further back in line of priorities. Your best bet would be to feed one channel into the other and then out to the amp. There was someone trying to do what you did on another forum but he was not all that successful in my mind. I did not think he had the capabilities to really get the most out of the 6J1 kit. A guitar distortion pedal kit might do you better.
 
my first plan is no distortion

Mostly, I actually play clean. I don't ever play music for distortion, as I primarily (exclusively most days) play some brand of "classical guitar". It's a potential debate about the difference in guitar styles that can still be played with fingers and read from notation, most of my favorite music is what I describe as "pre jazz music", or more commonly accepted "turn of the century guitar solo arrangements". (if you are a guitarrist and read standard notation, check out the sheet music downloads at meantone.com for most of my favorite songs). I also play a lot of standard classical guitar music.

So, although I'm interested in better learning to overdrive tubes, and bias them etc. I actually didn't have that goal when I ordered the kit,, it's just something that I know is possible, and everyone raves about. My primary interest is in exploring what I can do with my block rocker and electric guitar to get a better, fuller, classical guitar tone. also, I want to avoid pedals such as eq, I've never had a good experience with one, and eq is a complete artform anyway, so I'm just not interested in spending all of that time monkeying with eq knobs. I used to have nice mesa boogie combo amp, I would just play the clean channel, and maybe make sure the knobs were mostly centered.

So, the truth is, my block rocker, which as only a mic volume and a master volume, and a mic input, sounds great. It sounds so good, I actually would take it anywhere and just be happy. It can't do any guitar amp things, but for classical guitar it's excellent. The experiment is just first to see what DOES happen, then see if I can start making plans to maybe one day make a cheaper tube amplifier for my style than the hundreds of dollars even basic kits cost (which are actually for the distortion, which I don't want), or see if the kit I ordered is actually just the medicine,,, and if I understand preamplifiers enough to actually make that kind of plan.

One thing I wonder about is the tubes chosen for guitars vs. the tubes on the market. 12ax7's are generally what you find,,, but if i'm going to play clean the entire time,, is it really necessary to use 12ax7's?? what if I just use the 6j1 tubes?? will the tone be different at low comfortable gain? I know different tubes will distort at different gain, but I don't know if they "change the eq" or voice the tone in other words.

I am also one of these people who really doesn't know anything. My dad knows more, he had a career dealing with electronics in some fashion or another for some times. I could ask his help if it came time to try to do something like bias tubes or design a circuit for distortion. He might not know many specifics but he would know enough learn quickly and be helpful. I may send him a mojotone kit.
 
Different tubes sound different, and the 6J1 is a very different tube from the 12AX7, but the differences can be somewhat subtle, and they mainly come out when tubes begin to get into distortion (the definition of "clean" being very little change to the signal).

Regarding swapping the tubes, it looks like 6AK5, EF95, and 5654 tubes are all similar/equivalent to the 6J1. They should all work in this amplifier, and I would expect them all to sound extremely similar.
 
Just use it as is then. It is mainly clean meant for hifi reproduction. For what you want at this time it might be ok. It would be nice to have some equalization but that may be something you can put in between the two channels if you cascade them.

I thought about a tone stack, but I will have to buy the parts individually, and I will have to basically copy a tone stack from some amp schematic or something. Ideally, I would not copy one, and i would use as few parts as possible, so, skipping the isolating caps and resistors, and just having a few pots and caps.

as you can see above, I actually only have tone controls from the guitar at present, the block rocker is just supposed to be for a kareoke mic and bluetooth phone music.
 
it is received, assembled, and working

I looked up the block rocker, interesting little thing. You might not get much response to the 6J1 amplifier here. I thought it might be a good project to come up with a circuit to make it into a guitar preamp but it is a little further back in line of priorities. Your best bet would be to feed one channel into the other and then out to the amp. There was someone trying to do what you did on another forum but he was not all that successful in my mind. I did not think he had the capabilities to really get the most out of the 6J1 kit. A guitar distortion pedal kit might do you better.

So, I how have the kit, I have assembled it, and I have been playing through it as you suggested for a while today. ,, Firstly, I am 100% certain it is having an impact on the sound, and also I am 100% certain that it is beneficial. I don't have any tone circuit on the block rocker, so it gets a bit harsh,, and running through the preamp does soften it. IS it because of the tubes? well, I don't know. but , I think so.

A lot of what I'm listening to is very familiar,, I've had a blues jr. and a mesa boogie f-50, and they were good, and now I've been listening to the block rocker straight in almost daily for a good bit of time, at least several months, and with several guitars. it sounds good, but it sounds harsh at times, and although it's fine, it is true. ,,, today through the tube preamp (one channel into the other so they are stacked), I noticed many familiar sounds, especially reminding me of the blues jr. I have been playing music like classical guitar and easy solo jazz, so all clean, all fingerstyle notation, melody bass and harmony,,, and a few things are crucially different.

The sound overall is much easier to listen to (although I do think a tone stack would be good and better, especially over time,, I like to change the tone throughout a day to make it easier to listen to or more present) ,, but the notes are clearer. Especially it's easier to follow the bass line during lots of high notes. When the chords are really powerful and major, the sound is significantly less harsh.

it is true that there is some circuitry going on besides the tubes, but not much. There's a 1uf filter cap on the audio signal, and the power has 470uf electrolytics (thats basically all) and there are a few resistors to ground. I don't know the schematic, I was going to look and see if I can find it. ((,,, actually here it is,,,,, link below)) I just followed the pcb. Anyway, I can't be 100% sure that all of the things I mentioned above are from using tubes, it is certainly possible that I'm just happy to lose a bit of treble or something. But,, there's a lot of similarities to the sounds I used to get from my other tube amps, and I am inclined to think it's from these tubes.

AC 12v 1a 6j1 value preamp tube preamp amplifier board preamplifier headphone D | eBay
 
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