Need help with Sonic Distortion

[ethniccheese]

I've been working on the Sonic Distortion from J.D. Sleep's GGG site for some time now.  I finally found a capacitor on the parts layout, C6, that was backwards from the schematic.  Before that I barely got any sound out of the pedal.  Now I get a good strong signal, however, the signal isn't changed from the original.  The tone section works, but the drive pot doesn't do anything.  The diodes aren't clipping.

I have replaced almost every part on this board (some 4-5 times!!).  I'm getting good voltages on my transistor and my opamp.  The diodes are oriented the correct way.  I have checked for cold solder joints and have come up empty handed.  I built the audio probe from Geo and probed my little heart out and the signal never clips.  I even used my oscilloscope and found nothing clipping.  I am at the limit of my knowledge and resources and don't know what to try next.

Anyone have any experience with this pedal?  Any suggestions?

[Joep]

Hi,

I build one myself, I did it one perfboard but I used the GGG layout as a guide.

With my humbucker guitar the distortion is quite high, even at low drive settings and there is indeed not a big diiference between the lowest and highest drive settings. With my single coil guitar it works fine.

The minimum gain is set by R5 (470) and R7 (33k) so the minimum gain is 33k/470 = 70x The maximum drive is (250k+33k)/470 = 600
You can lower the 33k resistor to a lower value to lower the gain on the lowest drive (dist.) setting.

Maybe some other people can post there experience with this pedal. Aron, didn't you liked this pedal much?

Hope this helps.

Joep

[Jay Doyle]

There is something wrong with the wiring around the opamp. The gain pot must be mis-wired somehow, did you check the wiring of the pot? is the 220pf cap shorted?

Something with the opamp circuit is worng, even with the pot at it's lowest resistance the gain would be a little over 60, plenty to clip.

Check that cap and make sure the leads don't short together, this would keep the gain at one.

Also post the opamp voltages just in case...

[Joep]

ah, sorry. I misunderstood, I though you had a lot of gain.

I thing Jay is right, have a real good look. An overnight sleep might be a good idea. I've speed many night debugging finding nothing, and when you look at it the next morning, you just see your mistake......

Bye,

Joep

[petemoore]

Good enough I entered mention of it in the DIst+ threads.
 Bout the same trouble to get going IIRC as a New Clipper or DOD250, the Sonic D I buiilt is the OA Diode Clipper of my choice...YRMV...