Pete Cornish - G2 Guts, Schematic, Layout (from Tracer's Fund)

soulsonic · Post by **soulsonic** » 21 Apr 2010, 01:54

culturejam wrote: Eh, I think I get that.

So maybe we should all be doing that to help reduce ground loop issues?

I dunno... have you ever had a ground loop in a pedal? I haven't. I think this is why some people don't attach a ground wire to the output jack and instead let it get the connection through the chassis. Personally, I try to return everything to the input jack ground, or if it's an isolated jack, use a chassis star ground point.

Duckman · Post by **Duckman** » 21 Apr 2010, 02:08

John Lyons wrote:C24 is 4.7uf . Where are you seeing the .01, am I blind?

this explain the "missing cap"

My fault

"My" C24 is in the layout that Dirk_Hendrik posted before in this thread (page 3 - post 18) Any way, you can see the cap in this picture https://www.freestompboxes.org/download/ ... &mode=view (If it's wrong to repost the layout, please moderators do your job and forgive me)

John Lyons · Post by **John Lyons** » 21 Apr 2010, 04:02

Ah! Ok, I see now. I didn't think to look at dirk's as well.

Thanks

John

Visualdistortion · Post by **Visualdistortion** » 23 Apr 2010, 10:30

Thanks a lot for make this!!! You rock guys!

Any PCB(S) (buffer and effect) has been made for test this awesome pedal?

sinner · Post by **sinner** » 23 Apr 2010, 11:12

Visualdistortion wrote:Thanks a lot for make this!!! You rock guys!

Any PCB(S) (buffer and effect) has been made for test this awesome pedal?

http://www.madbeanpedals.com/projects/index.html

#9 Darkside

Cheers
Pawel

Visualdistortion · Post by **Visualdistortion** » 23 Apr 2010, 11:50

Thanks

So the only change is 47KA -> to 470KA?

Visualdistortion · Post by **Visualdistortion** » 23 Apr 2010, 12:28

I can't edit so:
Few capacitors don't have been listed on the DH pdf: C14, C17, C19, C23 and C3 is listed 2 times

Tube2stomp · Post by **Tube2stomp** » 25 Apr 2010, 13:45

Sound wise I never had any interest in any Cornish pedal, let alone a BM.
But still you guys deserve respect and thumbs up for the effort, so in the words J. Peterman:

"Kudos, Elaine, on a job... done."

Btw, bootstrapping the input impedance does work, but it depends a lot on the feedback drive level (need to have a gain as close as posible to 1) and the cap size (because it makes the impedance gradual).

joelap · Post by **joelap** » 01 May 2010, 15:12

Great job guys. Noticed the board says "P2/G2" on it. Obviously their topologies must be the same between those two pedals, any idea where the main sonic differences could lie? Big fan of Gilmour's tone with the P2.

mictester · Post by **mictester** » 01 May 2010, 21:54

soulsonic wrote: Personally, I try to return everything to the input jack ground, or if it's an isolated jack, use a chassis star ground point.

I always go for a star point because I almost always use insulated sockets. I often find that a convenient star point is a ring tag around the threads of the footswitch. I have only ever used screened lead inside an effect when there were highly amplified signals that I needed to keep apart - never to try to prevent hum pickup.

ryanuk · Post by **ryanuk** » 03 May 2010, 11:15

Visualdistortion wrote:Thanks So the only change is 47KA -> to 470KA?

Madbean answered earlier in the thread - 47KA

However, Dirk H's schem - who degooped the pedal - says 470KA.

Can this be clarified please?

RyUK

MWichni · Post by **MWichni** » 03 May 2010, 13:19

ryanuk wrote:
Visualdistortion wrote:Thanks So the only change is 47KA -> to 470KA?
Madbean answered earlier in the thread - 47KA
However, Dirk H's schem - who degooped the pedal - says 470KA.
Can this be clarified please?
RyUK

Hi guys, the correct value of the sustain pot is 47kA. Dirk's schematic has there an error. He changed that in another pdf but I don't know why it isn't uploaded in this thread. If you want to build one you can use madbean document which is 100% correct.

Regards,
Mariusz.

Dirk_Hendrik · Post by **Dirk_Hendrik** » 03 May 2010, 17:03

MWichni wrote:Hi guys, the correct value of the sustain pot is 47kA. Dirk's schematic has there an error. He changed that in another pdf but I don't know why it isn't uploaded in this thread. If you want to build one you can use madbean document which is 100% correct.

Regards,
Mariusz.

47k indeed. Thanks Mariusz

MWichni · Post by **MWichni** » 03 May 2010, 17:32

Dirk_Hendrik wrote:
MWichni wrote:Hi guys, the correct value of the sustain pot is 47kA. Dirk's schematic has there an error. He changed that in another pdf but I don't know why it isn't uploaded in this thread. If you want to build one you can use madbean document which is 100% correct.

Regards,
Mariusz.
47k indeed. Thanks Mariusz

No problem. Thank you for the tracing and degooping!

Regards.

Oliphaunt · Post by **Oliphaunt** » 04 May 2010, 00:07

I breadboarded the input buffer section of the G2 today and really like it. I can't claim to understand how it works though and would love if anyone wants to chime in with information about it.

TheLemon · Post by **TheLemon** » 04 May 2010, 18:52

Oliphaunt wrote:I breadboarded the input buffer section of the G2 today and really like it. I can't claim to understand how it works though and would love if anyone wants to chime in with information about it.

I'm in the same situation. I would like to know this as well.

soulsonic · Post by **soulsonic** » 05 May 2010, 03:43

Look up "Bootstrap Follower". That's what the buffer is. It's just a standard simple emitter follower. The input is bootstrapped, which gives it a higher input impedance than you'd normally get with the values used. Nothing special about it. A simple opamp buffer would have better performance.

mictester · Post by **mictester** » 05 May 2010, 04:55

soulsonic wrote: A simple opamp buffer would have better performance.

A simple op-amp buffer would have much better performance!

Dirk_Hendrik · Post by **Dirk_Hendrik** » 05 May 2010, 17:39

mictester wrote:
soulsonic wrote: A simple opamp buffer would have better performance.
A simple op-amp buffer would have much better performance!

True.
But that density of PCB layouting, combined with the high level of the technology used in an opamp, might be too much for mr Cornish.

bear in mind the PCB layouts from the G2 are routed in a style I do know only from early 1970's elektor magazine. Some here call that style artwork by the way. I prefer to call it lack of progress. Thank the programmers for CAD. (not to be mixed with autorouting!)

Duckman · Post by **Duckman** » 05 May 2010, 20:55

Maybe he's not looking for a better perfomance... just that performance, or... just don't wanna trace a new board!

Pete Cornish - G2 Guts, Schematic, Layout (from Tracer's Fund) [traced]