Does anyone have the original build doc? OR, even better... a link to the old thread that included the mods?
Thanks!
...do you mean Black Horse's Duplex Drive?
https://www.dropbox.com/s/kmv9fcw4bv2dhx1/DUPLEXDRIVE.pdf?dl=0
See if that link works.
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If link don't work, I can send you a pdf
I found the build doc! It was buried in my files ::)
Does anyone happen to have the info regarding the mods to the circuit? In particular, the value mods that allow for different diodes in the G-2 section (using diodes other than the 1N60s)
From page 5 here: http://www.madbeanpedals.com/forum/index.php?topic=18614.60 (http://www.madbeanpedals.com/forum/index.php?topic=18614.60)
Socket these components, and try these subs:
R10- 18k (was 15k)
R11- 100R (was 680R)
C5- 100pF (was 1nF, fixes the dark tone issue)
I think that fixes the diode dependence issue. You may find other diode references in that thread though. It's a good read. I had a chance to play a real G2 a couple months ago. As you would suspect it is much brighter than all the clones. I find that you can use the Black Horse Duplex Drive SS2 side to EQ the G2 to sound almost identical to a real one. No gain, adjust volume and treble to taste.
Aion just released a G2 PCB project and the documentation (if memory serves) has some mod info with respect to bass response. Worth checking out.
https://aionelectronics.com/project/cygnus-distortion-sustainer-cornish-g-2/ (https://aionelectronics.com/project/cygnus-distortion-sustainer-cornish-g-2/)
https://www.dropbox.com/s/miogjh7i0t42j30/cygnus_documentation.pdf?dl=1 (https://www.dropbox.com/s/miogjh7i0t42j30/cygnus_documentation.pdf?dl=1)
I have a set of mods for the SS2 and G2 written on my build docs. They are at home. I'll post them, tonight. It makes a big difference, especially with the G2.
Can someone explain the 'diode dependence' issue a bit? Also, what exactly are the resistor changes accomplishing?
I have SBE generic 1n34a's with Vf around .26 in mine and that seems to work well. Also, I've build mine to stock specs and it doesn't seem terribly dark (the tone sweep is rather useable through the whole turn rather than getting 'ice picky'). My go to muff variant is a green Russian, though—so I might just like things a tad darker. Some new diodes are en route and I plan on trying some others out to see if there's any beneficial differences. Germs are rather finicky after all.
Cheers!
I'm not sure if anyone ever figured out what brand/style of GE diodes were used in the original. It appears there was an error in the value of that one cap in the initial tracing attempt (100pF vs. 1n). The result was a very dark sounding effect which does not at all sound like the genuine box if played side by side. It is as if the tone control has a range of 1-2 rather than 1-10, there is a ton of top end missing in the clones. Also vf of .26 seemed to be the target for sourcing germs for the circuit. Apparently with the mods done, you are not locked in to such a tight tolerance with the diodes.
I found my Duplex Drive notes. The changes I made where C5 100pf, C9 470pf, c23 470pf. I changed all the diodes: D1 1n695, D2 1N695, D3 1N5817, D5 1N695, D6 1N695, D7 1N34A, D8 1N34A. I, also, found that using the LM1458 is key to the SS2 sounding good. A faster opamp sounds too bright. I guess if you wanted to use a different opamp, you could change a couple caps but it does sound good with the LM1458. I've seen other mods that help the G2 side but haven't tried them. The combination of caps and diodes really opened up the G2. With the default values, it really is muddy.
Thanks for the insight here. I probably should've gone about socketing from the beginning, but these changes aren't too major. I'll see if the base-collector caps make an improvement for me along with swapping out diodes.
I found a link that has some different mods. http://www.madbeanpedals.com/forum/index.php?topic=24354.msg237590#msg237590 (http://www.madbeanpedals.com/forum/index.php?topic=24354.msg237590#msg237590) Those changes look good and the build is amazing. I would still probably change C9 and C23 to 470pf. I'm going to try the resistor mod, next time I make a G2. Adding some more gain at that stage wouldn't hurt.
Nice find. That thread has some good info.
At this point, I think I'm going to end up building another. I like the stock tone, but the changes seem to change the pedal enough that it's a different beast.
Has anyone had experience changing the volume pot?