FF volume drop

[shay1510]

Hey there FF gurus,
I've built the GGG Si NPN Fuzz, without any mods.
I've put both knobs on 12 and found out there is a serious volume drop when the pedal is on.
Checked all the parts, their values and soldering, made sure the transistors' legs are in place. everything looks fine.
I've changed the two transistors from 2N2222  to 2N3904 , and also tried to play a little with the trimpot but nothing's changed.
I can turn the volume knob all the way up but it sounds realy muddy.

* I'm picking some rf signals when using it at home (doesn't happen in the studio).

Does anyone got a solution in mind?

Thanks.

[Heemis]

Are you able to reach unity volume at any point in the volume knob's travel?  Lots of pedals are below unity volume at 12 o clock, you should be able to get above unity gain at some point, but it might be closer to 2 or 3 o clock.

[pinkjimiphoton]

imho, do the following...
make the input cap between .47 and 1u ....this will let less bass thru, clear up any muddyness, and give a bit more focus.
change the 500k output pot to 100k. this should give you plenty more output.
change the 8.2k resistor to a 10k trimmer, adjust by ear.

you want this to be set so you can sweep from clean to scream with your guitar knob. somewhere between 4.5-6 volts usually does it.

hope that helps. there's other stuff you can do to make it louder still if need be. 

[Kesh]

Hey there FF gurus,
I've built the GGG Si NPN Fuzz, without any mods.
I've put both knobs on 12 and found out there is a serious volume drop when the pedal is on.
Checked all the parts, their values and soldering, made sure the transistors' legs are in place. everything looks fine.
I've changed the two transistors from 2N2222  to 2N3904 , and also tried to play a little with the trimpot but nothing's changed.
I can turn the volume knob all the way up but it sounds realy muddy.

* I'm picking some rf signals when using it at home (doesn't happen in the studio).

Does anyone got a solution in mind?

Thanks.

3904s are fairly highish gain for a ff, even if ggg recommends them. not sure if that is causing the problems though. (edit, i just checked spec sheets, and it seems to say 100-300 hfe at 10mA Ic/1 Vce, but every 3904 i have ever tested has been at the very top of this at 300)

are the electrolytes in the right way?

for the radio you can try puting an RC circuit at the input, 470 resistor in line and a 47p cap after that between input and ground. also make sure the case is grounded (including the base plate), and maybe use screened cable from input jack to pcb. but even this doesn't always work. my first ff picked up "do the hustle".

telling us transistor voltages might help.

[LucifersTrip]

it all boils down the the last thing Kesh wrote...

There's pretty much no use diagnosing problems until you know that you're in the ballpark with your voltages

Here're the voltages from the actual GGG instructions:

Q1 Collector 1.4v
Base 0.6v
Emitter 0.0v
Q2 Collector 4.5v (if you use a trimmer,
you can set the voltage)
Base 1.4v
Emitter 0.8v

...and remember to always post the schematic and note any changes you made

good luck...

[pinkjimiphoton]

often with RFI issues, a small cap...say, 56-100pf between b and c can help some.

or is it e and b?

[shay1510]

here are the measured values for the transistors: (very similar to the GGG specs)

Q1 Collector 1.3v
Base 0.6v
Emitter 0.0v
Q2 Collector 4v
Base 1.3v
Emitter 0.7v

Here is a link to the schematic http://www.generalguitargadgets.com/pdf/ggg_ff5_sc_npn.pdf?phpMyAdmin=78482479fd7e7fc3768044a841b3e85a

Will test the pedal again at the studio and report/demo the results. Thank you everyone.

[Electric Warrior]

What kind of pickups are you using?

[shay1510]

stock fender american standard 2010 pickups.
(btw I've built a ts808, p45, and a reverb and they all sound great).

[bluesdevil]

Oooops!! Needed to edit this:

I would just fiddle with the 330 ohm resistor with higher values to increase volume. If you can, replace it with a 1k pot wired as a variable resistor to get it where you like, take out and measure for the resistor value. Also a good idea to replace the 8.2k bias resistor with a 10k trimpot to dial it in better for closer to 4.5.
A 100k volume pot will increase brightness more than volume, I think..... but you may prefer it if the tone is a bit too muffled to your ears (I like 250k in most of my FF builds).
  As for the radio signal:
       Try tacking on a small cap between input and ground until it goes away..... start with 100pf and try up to .001uf.
                    Good luck!