Author Topic: Need help adding a gain control to first fuzz pedal  (Read 1213 times)

Isg1315122

Re: Need help adding a gain control to first fuzz pedal
« Reply #20 on: February 25, 2018, 07:12:05 PM »
Lol I have lower ohm pots. The reason I said the 250k was because I thought, based on the video the guy made he used/ suggested a 1m pot. I'm thinking he had a different circuit built which he was referencing.

The lowest I have is 5k at the moment. I'm going to put a 5k resistor parallel and kick it down to 2.5k with a cap to ground and see where that gets me.

Thanks for all the input.

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So I just finished the build on the bread board. I tried the parallel resistor with the 5k pot and 2, 10uf caps in parallel because I don't have a 20. It seems to work both ways with or without the other resistor. It seems to sound brighter without the ground hooked up.

On a different note the high E string notes don't seem to sustain very well. It's like an unnatural decay. Any thoughts?

pinkjimiphoton

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Re: Need help adding a gain control to first fuzz pedal
« Reply #21 on: February 25, 2018, 07:15:58 PM »
biasing
digi2t:
"Fuzz, distortion, and wah, are plenty abound. Mutron Flanger, not so much.  8)"
#FuzzyGoodness

nocentelli

Re: Need help adding a gain control to first fuzz pedal
« Reply #22 on: February 27, 2018, 03:26:30 PM »
On a different note the high E string notes don't seem to sustain very well. It's like an unnatural decay. Any thoughts?

I think that's part of the bazz fuss sound
Quote from: kaycee
squeeze on the back and never open it up again

Isg1315122

Re: Need help adding a gain control to first fuzz pedal
« Reply #23 on: February 27, 2018, 06:25:29 PM »
I'm not really familiar with biasing. If I understand it correctly its adjusting voltage or current at the base to be at a value that turns on the transistor but without fully saturating it. When looking at the data sheet for the 2n5088 it looks like at about 25-30mA that the gain drops significantly. If it's pushing the threshold for mA would that cause a clip of some sort, that would drop the signal or cause the cut off?

Since I'm running two transistors in a Darlington fashion is it possible the 2nd transistor is amplifying too much current and hitting a clip point?

PRR

Re: Need help adding a gain control to first fuzz pedal
« Reply #24 on: February 28, 2018, 08:21:56 PM »
> base to be at a value that turns on the transistor but without fully saturating it. When looking at the data sheet for the 2n5088 it looks like at about 25-30mA that the gain drops significantly.

Your plan in post #5 shows a 10K resistor with a 9V supply.

The MOST you can suck this way is 9V/10K which is 0.9mA.

You don't "bias" for the transistor, but for the circuit.

You could bias at zero mA, the collector would sit at 9V. Or you could bias for 0.9mA and the collector would sit at zero Volts.

Audio swings both ways. As a first-guess, in simple circuits like this, for "good" sound, you aim to set the collector "halfway", 4V or 5V, 0.4mA or 0.5mA.

But this is a FUZZ. Not supposed to be "good". In fact, with the plan in post #5, if the collector comes above 1.2V the diode turns-on the transistor and pulls-down. The collector will set near 1.2V. (And current will be like 0.78mA, which is safely below the small fall-off above 20mA of the transistor you cite.)

> I'm running two transistors in a Darlington

Yes, that is different. Diode leakage may matter in ways hard to predict.

Keep it simple. Don't Darlington until you know why and what it will do. (It is not necessarily "more gain!")

Use the right parts. (250K is MUCH too big for emitter with 10K in collector.)

Post your voltages.

Isg1315122

Re: Need help adding a gain control to first fuzz pedal
« Reply #25 on: March 07, 2018, 09:46:25 AM »
I'm gonna level with you guys, I didn't take the voltage readings. I stuck a 10k pot where that resistor sits on the collector. I fiddled with it for about 5 min, got it to a point where I liked the sustain and level of distortion and then switched off the circuit. I then tested the resistance of the pot at the position that I liked. It tested 6.8 K so I put a 6.8k resistor in it and haven't looked back. I put it all on Verboard and soldered away. I still need to mess with 3pst switches and test it with the switch but I'm satisfied with the overall sound and sustain.

Picture of finished vero:
« Last Edit: March 07, 2018, 09:48:14 AM by Isg1315122 »

Dares

Re: Need help adding a gain control to first fuzz pedal
« Reply #26 on: April 15, 2018, 12:27:54 PM »
The video says a 1000k might be best for cleaner tones.

Hello,
I think the video says 1000omhs resitor which is 1k (not 1000k)
https://m.youtube.com/watch?v=yX7iQANBAI8
At 145 there are explanations and right after some tests with a resistance box.