Vox Tonebender vs Fuzz Face Circuit and low gain transistors

[Brian W.]

I've always thought the Vox circuit was a bit more usable than the Fuzz Face in a band environment [not as "woofy" and bass-heavy]. I'm messing around with some low-gain silicon transistors and will probably make a 3-transistor Tonebender as well. The low hfe trannys seem to sound better.

[vintagekiki]

Tonebender (attachment) uses germanium transistors (SFT, AC, OC), which in themselves have a modest hfe.
Low (modest) hfe, the transistor later comes into saturation and the sound is better.

[Brian W.]

Tonebender (attachment) uses germanium transistors (SFT, AC, OC), which in themselves have a modest hfe.
Low (modest) hfe, the transistor later comes into saturation and the sound is better.

The germanium Fuzz Face is an easy transfer to a silicon circuit and the Vox can have some values changed along with using NPN transistors to achieve the same end. The bias of Q2 needs a bit of tweaking as well.

[vintagekiki]

https://www.freestompboxes.org/viewtopic.php?f=19&t=30600
Vox - V816 Distortion Booster: GE an SI versions

Look at these two links. You will not be disappointed.
https://www.freestompboxes.org/index.php

https://stompboxes.co.uk/forum/index.php
^{You must log in or sign up}

[Brian W.]

https://www.freestompboxes.org/viewtopic.php?f=19&t=30600
Vox - V816 Distortion Booster: GE an SI versions

Look at these two links. You will not be disappointed.
https://www.freestompboxes.org/index.php

https://stompboxes.co.uk/forum/index.php
^{You must log in or sign up}

Oh yeah....I remember the Freestomp site! I discovered it when I was making silicon treble boosters a few years back. The trick was finding a transistor that was close to sounding germanium. Thanx for the links.....I can get lost in those sites! When I first started playing in bands my first "effect" was the Vox Distortion Booster [plugged into the guitar]

[vintagekiki]

my first "effect" was the Vox Distortion Booster

[vintagekiki]

https://www.electrosmash.com/fuzz-face
Fuzz Face Analysis

https://www.electrosmash.com/germanium-fuzz
You Can Build the Perfect Germanium Fuzz

https://fuzzcentral.ssguitar.com/schematics.php

http://www.kitrae.net/music/music_big_muff.html ¹⁾

http://www.geofex.com/article_folders/fuzzface/fffram.htm ²⁾
The Technology of the Fuzz Face

[Brian W.]

Anybody have a preference for either the TB or FF circuit? The input and output caps alone make a difference in the personality of the pedals but there are also other facets that change the bass / mid / treble / output .

[vintagekiki]

http://www.voxshowroom.com/us/misc/v810.html
Vox V810 Bass Booster

http://www.voxshowroom.com/us/misc/v806.html
Vox V806 Treble Booster

https://www.freestompboxes.org/viewtopic.php?f=19&t=30597
Vox - Deluxe Distortion Booster V8162

[vintagekiki]

In the beginning, pedals mostly used universal purpose semiconductors so-called TUP and TUN transistors.
These are low or medium gain transistors (BC107, BC108, BC182, BC183) and these pedals are still unsurpassed today, they have that recognizable vintage sound.
Analyze vintage schematics, you will notice that there was not much philosophizing about biasing, technological solutions, only 2-3 transistors a few resistors and capacitors and you get a lot of sound.

https://worldradiohistory.com/UK/Elektor/70s/Elektor-1977-07-08.pdf
tup-tun-dug-dus (page from 7-79 ...)

https://www.histo.cat/e/TUP-TUN-transistors-DUG-DUN-diodes-PNP-NPN

[Brian W.]

I'm wondering if anybody has done a sonic comparison with these circuits. The 2.2 uf input cap alone on the Fuzz Face makes a big difference [then, there is the feedback resistor...]

[35L6]

This is a great circuit and a good first project if anyone is looking for one due to the low parts count . I've built a few of them . I take a different approach than most , instead of scouring the planet for obsolete transistors I believe that whatever is in that old radio over there will work . I've built one with PN2222 which is probably the most ordinary transistor on earth . I adjust the Cs and Rs to make it work . Aim for about 1/2 supply on Q2 collector and adjust the feedback resistor for best fuzz . As simple as this circuit seems its surprisingly complex , due to the feedback . You would think gain would not matter , more gain means more feedback which means less gain , however it seems device gain does make a difference . I have no idea why . Anyone have any explanation ? Also the output impedance is not what you would expect and its hard to take measurements at the base of Q1 .

[Brian W.]

This is a great circuit and a good first project if anyone is looking for one due to the low parts count . I've built a few of them . I take a different approach than most , instead of scouring the planet for obsolete transistors I believe that whatever is in that old radio over there will work . I've built one with PN2222 which is probably the most ordinary transistor on earth . I adjust the Cs and Rs to make it work . Aim for about 1/2 supply on Q2 collector and adjust the feedback resistor for best fuzz . As simple as this circuit seems its surprisingly complex , due to the feedback . You would think gain would not matter , more gain means more feedback which means less gain , however it seems device gain does make a difference . I have no idea why . Anyone have any explanation ? Also the output impedance is not what you would expect and its hard to take measurements at the base of Q1 .

Yup, I built a few FF's, Tonebenders, and Treble Boosters awhile back and then recently became interested in the finer points of shaping the tone and distortion qualities. I just finished a silicon Tonebender MK 2 and the thing has a loud oscillation coming from somewhere so time to "de-bug".

[35L6]

Does it put out a good sine wave ? In my current facebender adventue , I've tried a couple things . I put in a 47K series resister and low value cap on the input to raise the input impedance and not load down the source and lose highs . It cut the input level to much and seemed to raise the Miller capacitance and create the very problem it was supposed to cure . I paralleled the cap and jumpered the resistor . The other thing I did was add a tilt control to the output ( aka BMP ) . That worked out better but I think it could be improved . I used Duncans tone stack calculator to model it which was only so accurate since I don't know the output impedance or just what corner frequency I want anyway . I wonder if choosing just the right input and output caps would work as good or better than more complicated solutions .

[Brian W.]

Does it put out a good sine wave ? In my current facebender adventue , I've tried a couple things . I put in a 47K series resister and low value cap on the input to raise the input impedance and not load down the source and lose highs . It cut the input level to much and seemed to raise the Miller capacitance and create the very problem it was supposed to cure . I paralleled the cap and jumpered the resistor . The other thing I did was add a tilt control to the output ( aka BMP ) . That worked out better but I think it could be improved . I used Duncans tone stack calculator to model it which was only so accurate since I don't know the output impedance or just what corner frequency I want anyway . I wonder if choosing just the right input and output caps would work as good or better than more complicated solutions .

I used much thinner hook-up wire then I normally use........wonder if that created the howling ?? Underneath the oscillation it sounds like the circuit is "working" [volume and distortion] and voltage readings looked o.k.

[35L6]

There is not a lot of current or voltage so thin wire should be OK . Try moving wires around .