Vox Tonebender questions

gigimarga · March 29, 2008, 05:16:55 PM

Hello,

I am a big fan of Fuzz Face sound and I want to build a Vox Tonebender, but i have a couple of questions before:

1) The SFT337 and SFT363E trannies are very important in the sound of it? I have only some SFT353 and SFT229 from this "family"!
2) If i can replace Q1 and Q2 with another germanium trannies what gains must to have? Fuzz Face style?
2) I saw on Fuzzcentral site that Q2 must to be biased at -4.5V...but how about Q1? It must to be biased too? If yes - how?

Thx a lot all!

slideman82 · March 29, 2008, 05:36:43 PM

Well, you're lucky! I think I never gonna find those SFT trannies... nevermind, if you have some AC128 or 188, will work fine. It's not critical, just have to be Ge. The 1st ranny doesn't need bias, just bias the 2nd. It's like a FF, but sounds more open, it has better definition.
I've just built only one, and it sounds awesome!

tcobretti · March 29, 2008, 06:41:35 PM

If you are talking about the TB Mk 1, IMO it sounds nothing like a FF. It has much more gain and almost sounds like a Rat. I was very surprised by the sound. I like it very much, but it is closer to ZZ Top than Hendrix.

gigimarga · March 30, 2008, 01:17:51 AM

Thx a lot...i will build it tonight!

zombiwoof · March 30, 2008, 03:51:17 AM

Quote from: tcobretti on March 29, 2008, 06:41:35 PM
If you are talking about the TB Mk 1, IMO it sounds nothing like a FF. It has much more gain and almost sounds like a Rat. I was very surprised by the sound. I like it very much, but it is closer to ZZ Top than Hendrix.

If you read his post, he said a VOX Tone Bender.

Al

slideman82 · March 30, 2008, 11:00:35 AM

That's right, it was the VOX Vintage TB, not the horrible Solasound MKI. Oh, try the 2.2k resistor version, is louder, and replace that small output cap with some larger (1uF, for example), so you'll get mo' bass. With the 4.7n or 3.3n output cap, it will sound brighter, perfect for you Vox dark sounding amp, but not for some others, I think. The input cap won't change much the sound if it is 150n or 220n, try both. It's gonna sound really good anyway.

gigimarga · March 30, 2008, 12:01:41 PM

Thx for your answer...but which is the 2.2k version??

slacker · March 30, 2008, 12:47:46 PM

The 2k2 Slideman82 mentioned is the resistor from the power supply to the output cap/collector resistor junction.
If you look on the Fuzz central schematic http://fuzzcentral.ssguitar.com/vox.php it's the resistor that is shown as a 1k.

gigimarga · March 30, 2008, 01:12:10 PM

ok...thx a lot again!

slideman82 · March 30, 2008, 07:35:12 PM

thx! I had forgotten that tip! Also, you can use a 22uF instead of 15uF... 10uF too, all of them will work fine.

gigimarga · March 31, 2008, 07:24:39 AM

I've built it using two SFT242 (gains: Q1=80, Q2=110), a 220nF input cap, a 3.3nF output cap, a 14.7uF electrolytic cap (a 10uf and a 4.7uF in parallel) and a 10k trim instead of 8.2k resistor to bias Q2's collector at -4.5V much easier!

It sounds very nice and i like it a lot...brighter sound...very good for solos, and, as all Fuzz Faces that i now, very controllable using the volume pot (for me this feature it's a big +!).

Thx a lot!

Gus · March 31, 2008, 07:29:56 AM

gigimarga

You posted you used a 10K trim for the 8.2K. Is the trim at about 80% and/or have you measured the trim pots value you set it to?

gigimarga · March 31, 2008, 10:23:31 AM

The trimpot is set at about 80%...i put it because first i used some SFT229 which sounded horrible...i'd thought that could be misbiasing...i'd put the trim and i couldn't obtain more than -3V on the Q2's collector...it sounded very gated...after that i used the SFT242 and all was ok from the start...but i didn't desolder the trim

zombiwoof · March 31, 2008, 10:37:18 PM

Quote from: Gus on March 31, 2008, 07:29:56 AM
gigimarga

You posted you used a 10K trim for the 8.2K. Is the trim at about 80% and/or have you measured the trim pots value you set it to?

On my FF, I used a 10k trim with about a 3K resistor in series, that way the middle position of the pot is close to the normal 8.2k, and you have a range of 3k to 13k for adjustment.

Al

slideman82 · April 01, 2008, 04:22:50 PM

Quote from: gigimarga on March 31, 2008, 07:24:39 AM
I've built it using two SFT242 (gains: Q1=80, Q2=110), a 220nF input cap, a 3.3nF output cap, a 14.7uF electrolytic cap (a 10uf and a 4.7uF in parallel) and a 10k trim instead of 8.2k resistor to bias Q2's collector at -4.5V much easier!

It sounds very nice and i like it a lot...brighter sound...very good for solos, and, as all Fuzz Faces that i now, very controllable using the volume pot (for me this feature it's a big +!).

Thx a lot!

Try a larger output cap, like 1uF. You'll get more bass, and it will be still bright.

sengo · April 01, 2008, 11:35:23 PM

I've wanted to build one of these since I saw this demo:

http://www.youtube.com/watch?v=KbG9hXLvh_I

I have not been able to get around to it. Is that clip accurate sounding?

Nick

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