Vox Distortion Booster

[Sparky]

The first version of this pedal has been around since 1965 and is a low-gain Tonebender circuit with lower value resistors for feedback, bias,  etc  [except it predates the Tonebender and Fuzz Face]. 
Seems to me that the higher gain trannies  [BC-108] would have more headroom and allow for some cleaner [louder ?] settings as well as more distortion [fuzz] at the extreme end of the volume and fuzz controls.
It also seems this topology is a good modding platform for different trannies and resistor values.    Has anybody put a pre-gain control at the front of the circuit [the Joe Gagan mod] ?   I'm curious as to the difference in distortion characteristics as compared to the stock fuzz control.

[PRR]

....would have more headroom and allow for some cleaner...

Why? And why would you want that?

The instantaneous "headroom" is the Q1 B-E junction, which will be "flavored" at 20mV peak input and be "flattopping" by 60mV peak input. *Same as* fuzzface or about anything feeing guitar direct to a grounded emitter.

[Sparky]

....would have more headroom and allow for some cleaner...

Why? And why would you want that?

The instantaneous "headroom" is the Q1 B-E junction, which will be "flavored" at 20mV peak input and be "flattopping" by 60mV peak input. *Same as* fuzzface or about anything feeing guitar direct to a grounded emitter.

With certain guitars I like to pre-set the volume and fuzz / gain  and leave the pedal engaged  so I can turn the guitar volume up and down as I need it.  With others I have the guitar volume wide open and turn the pedal off-and-on with the switch.  Depending on the situation I like a little more clean volume from the pedal. 

[antonis]

Has anybody put a pre-gain control at the front of the circuit [the Joe Gagan mod] ?   I'm curious as to the difference in distortion characteristics as compared to the stock fuzz control.

Joe Gagan's mod (actually a pot ala Fulltone 69 with its lug 1 gounded) should work more drastically (al least, in theory) due to "parallel" input equivalent resistance..
Of course, there are some factors to be taken into account, like its value AND its  taper in conjunction with guitar impedance..

[Sparky]

Has anybody put a pre-gain control at the front of the circuit [the Joe Gagan mod] ?   I'm curious as to the difference in distortion characteristics as compared to the stock fuzz control.

Joe Gagan's mod (actually a pot ala Fulltone 69 with its lug 1 gounded) should work more drastically (al least, in theory) due to "parallel" input equivalent resistance..
Of course, there are some factors to be taken into account, like its value AND its  taper in conjunction with guitar impedance..



I like being able to set the overall volume of the guitar with the pre-gain pot for some things.  Turning the guitars volume pot down makes things muddy.

[iainpunk]

if you want more output form a FF, move the output cap to the other side of the bias pot / connect it to the collector of the Q2

another Iain first pointed me to this solution.

cheers

[Sparky]

if you want more output form a FF, move the output cap to the other side of the bias pot / connect it to the collector of the Q2

another Iain first pointed me to this solution.

cheers

Thanx for reminding me about that.   I did that a few years ago for a volume boost but can't remember how it affected the fuzz.    Might be worth a shot to try it again.

[iainpunk]

it will be a bit brighter/fizzier, but still good. i like to combine this with clipping diodes for a more distortion-ish feel when the guitar's volume is turned down, instead of the overdrive vibes.

cheers

[Sparky]

it will be a bit brighter/fizzier, but still good. i like to combine this with clipping diodes for a more distortion-ish feel when the guitar's volume is turned down, instead of the overdrive vibes.

cheers

Yeah.... balancing the "fuzz" with volume and clarity is the deal.    There is also the issue of how something sounds at low volume in the apartment compared with how it sounds at gigging volume.   Since covid I haven't had much in the way of louder gigs with a real band so it adds to the frustration.

[iainpunk]

i feel the biggest difference when playing life is that you just need way more midrange, and not as much low end. i like a bass cut after the fuzz circuit to give it a less blown out sound that just sinks in to the mix, and a bit more apparent midrange.

there should be a fuzz face version with an active EQ for doing this.

cheers

[Sparky]

i feel the biggest difference when playing life is that you just need way more midrange, and not as much low end. i like a bass cut after the fuzz circuit to give it a less blown out sound that just sinks in to the mix, and a bit more apparent midrange.

there should be a fuzz face version with an active EQ for doing this.

cheers

I've been swapping input and output cap values with the basic  distortion booster / Fuzz Face / Tonebender  circuit.  My problem is I haven't had the opportunity to try anything out in a live band or club situation for the past 2 years due to all the covid rubbish.   I've also just built up a Mos Face  [Jack Orman] which has more volume and fuzz then a stock FF.   I'll post a new thread on it....