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DIY Stompboxes => Building your own stompbox => Topic started by: foozertone on July 27, 2007, 05:52:29 PM

Title: GGG Distortion plus C5 mod
Post by: foozertone on July 27, 2007, 05:52:29 PM
Can anyone tell me about the C5 (10pf cap) mod(?)   What effect will taking this out or leaving it in do?

Jeff
Title: Re: GGG Distortion plus C5 mod
Post by: wampcat1 on July 28, 2007, 12:21:28 AM
Quote from: foozertone on July 27, 2007, 05:52:29 PM
Can anyone tell me about the C5 (10pf cap) mod(?)   What effect will taking this out or leaving it in do?

Jeff

schematic please?
Title: Re: GGG Distortion plus C5 mod
Post by: Krinor on July 28, 2007, 03:13:22 AM
Distortion+ schematic:

http://web.archive.org/web/20070329032312/www.generalguitargadgets.com/diagrams/dist_plus_sc.gif
Title: Re: GGG Distortion plus C5 mod
Post by: hellwood on July 28, 2007, 04:17:24 AM
i think it prevents oscillation?
Title: Re: GGG Distortion plus C5 mod
Post by: oskar on July 28, 2007, 04:20:20 AM
At higher gains amplifiers gets unstable. Having a small cap in the feedback path like this prevents the
amp from oscillating. It is a lowpass rolloff thing but you'll hardly notice if it's in or not... unless off course
the thing freaks out because you left the cap out...
Title: Re: GGG Distortion plus C5 mod
Post by: foozertone on July 29, 2007, 02:51:18 PM
I'm working from a PCB acquired from GGG. If I leave out the C5 do I have to put a jumper in it's place? Sorry if this is stupid.

Jeff
Title: Re: GGG Distortion plus C5 mod
Post by: fixr1984 on July 29, 2007, 02:53:32 PM
No jumper
Title: Re: GGG Distortion plus C5 mod
Post by: foozertone on July 29, 2007, 04:06:23 PM
As I lookcloser it says that the following components are optional: R1, D3, D4 and R11. What happens if i leave these out or in. I really have no idea what is best for me.
Thanks for all your help.

Jeff
Title: Re: GGG Distortion plus C5 mod
Post by: hellwood on July 29, 2007, 04:18:46 PM
D3 is for a different clipping diode configuration. i hear the sound change is minimal but worth investigating. D4 is your light (LED) if you want to know if your pedal is on or off (as if?) R11 keeps your light(LED) from burning out and i couldnt tell you what R1 is for. maybe it helps keep it from popping w/ true bypass w/ LED?
Title: Re: GGG Distortion plus C5 mod
Post by: foozertone on July 29, 2007, 04:54:59 PM
I ended up finding this out for myself. Sorry to waste your time, but I just love the sense of community here. Makes my first tentative steps more sure.

Thank you.

Jeff