Wont win any prizes with it, but it’s one of the best projects I’ve done. It’s built mostly from old AT Computer Power Supply parts. The 12AX7 is biased at +300 Volts, so it’s not a starved tube design. It sounds a lot better than using my Mackie Mixer as a preamp. I’m already working on a Two-Tube design with a Cathode follower to drive the soundcard input. I think I will get a better impedance match that way.
Walt
ValveWave-1
Walt
ValveWave-1
Walt,
L_RD knows you have plenty of current available in the B+ rail. It seems to me that a ZVN0545A source follower, as described in MOSFET Follies, would achieve your impedance matching purpose. Grafting the FET onto your existing stuff doesn't seem all that difficult.
ZVN0545A data sheet here.
You mentioned "flavor". A great way to try a NOS tube at low cost is the 7058. GE built 7058s can be had under $10. RCA 7058s cost more.
Edit: Added 7058 remarks
L_RD knows you have plenty of current available in the B+ rail. It seems to me that a ZVN0545A source follower, as described in MOSFET Follies, would achieve your impedance matching purpose. Grafting the FET onto your existing stuff doesn't seem all that difficult.
ZVN0545A data sheet here.
You mentioned "flavor". A great way to try a NOS tube at low cost is the 7058. GE built 7058s can be had under $10. RCA 7058s cost more.
Edit: Added 7058 remarks
That looks interesting, I'll have to try it on a breadboard and see how it sounds. I'll probably stick with 12AX7's as they are easy to come by. I use Chineese brands when I'm breadboarding, but have a small supply of NOS RCA tubes that I use for recording. I'll have a link up within a week or so to the first song that I've recorded using this preamp. I really like the sound. Thanks for the reply and information.
Walt
Walt
I have a sound sample available for my first preamp. It's a section from my latest composition (I'm not much of a picker)...
http://www.safossils.com/valvewave.mp3
http://www.safossils.com/valvewave.mp3
Walt,
I love the look, and the schematic, as I am not a guitar playet, I really have no use for one personally, however I have a very good friend who doesn't DIY, and this looks like a great project that he would find very interesting. I admire this projects form, as well as it's function. however may I ask, did you make your own PC boards? or did you buy them somewhere?
I love the look, and the schematic, as I am not a guitar playet, I really have no use for one personally, however I have a very good friend who doesn't DIY, and this looks like a great project that he would find very interesting. I admire this projects form, as well as it's function. however may I ask, did you make your own PC boards? or did you buy them somewhere?
waltsongs said:
Any Clips or short recordings of the unit dry? (no Effects)
I might just pop one of these together.
Trout
The only effect I added was software reverb to one channel. I'll post a dry MP3 when I get a chance. I cooked the circuit boards up myself using positive etch transfers. If you decide to build one, the transformer windings go all the way around the ecore. They are not wound around the center like a normal power transformer. I'm going to post some more pictures of the transformer as I'm working on a two-tube model already. It uses 12AV6/12AU7, (surplus that I already have). I'll be using point to point wiring on it.
Thanks,
Walt
Thanks,
Walt
Hey, I think dynamically it sounds very good, In fact, very impressive.
That software reverb sounds alot like a bit of chorus also. Nice
What guitar was used? Sounds very acoustic.
As far as the power supply, I am thinking of using a portable hard drive case and making it portable for use with my laptop.
I have looked at a few power transformers from triad and am thinking it might be possible to use the
McTube Style power supply and only mount 1 transformer internally. Use the second externally with the chassis jack already in the case.
Might take a bit of tinkering to get the right combo of transformers but feasible.
Then I can just throw it in my laptop bag and take it on trips😀
Trout
That software reverb sounds alot like a bit of chorus also. Nice
What guitar was used? Sounds very acoustic.
As far as the power supply, I am thinking of using a portable hard drive case and making it portable for use with my laptop.
I have looked at a few power transformers from triad and am thinking it might be possible to use the
McTube Style power supply and only mount 1 transformer internally. Use the second externally with the chassis jack already in the case.
Might take a bit of tinkering to get the right combo of transformers but feasible.
Then I can just throw it in my laptop bag and take it on trips😀
Trout
The power supply you referenced shows B+ at 140. I'm running the 12AX7 at +300 Volts. You can change the resistors to bias the tube correctly at that voltage, but I'm not sure if it will sound the same.
I use an Epiphone 12-string with a lawrence soundhole pickup.
Best of luck,
Walt
I use an Epiphone 12-string with a lawrence soundhole pickup.
Best of luck,
Walt
Yeah, I figured I would use a mismatched pair, 120V/12V@ 2a into a 220V/9V@2a. Should give enough extra voltage to get closer then a few resistor tweaks.
Worse case scenerio I can just get a cheap small plate transformer from Triad.
I really like the portability factor.
Nice sounding Guitar BTW, Ever try any electrics in the unit yet? Maybe a Strat?
Trout
Someday I'll have the budget for one.
The other thing to consider with the power supply is the ripple. It's a lot harder to get rid of 60/120 HZ than 20/40 Khz. I could probably get by with fairly small caps, I just happen to have a bunch of 220 uF caps removed from old equipment. You may need a couple of stages of RC or a series inductor to really smooth the supply out.
Again, best of luck with your endeavors,
Walt
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