Low Distortion on new GGG DOD 250 build

Started by Major Sparky, December 29, 2020, 10:34:01 AM

Previous topic - Next topic

Major Sparky

Hi all, I just finished building a grey spec DOD 250 using a General Guitar Gadgets Kit and following this layout, http://www.generalguitargadgets.com/pdf/ggg_dist2_g250_lo.pdf. I actually really like the sound of the pedal, but comparing it to youtube demos of the reissue and original units, it doesn't seem like it has nearly as much distortion as it should. From what I can tell my builds distortion tops out at about half of what it seems like these other units produce. I've been through the circuit triple-checking part values/solder joints/component placements/etc. And the voltage readings from the IC match what is listed at the bottom of this build doc from GGG, http://www.generalguitargadgets.com/pdf/ggg_dist_instruct.pdf. So I'm at a bit of a loss as to what the issue is.

I have made two deviations from the layout posted above, one is swapping the 4k7 resistor for 47k, which he recommends in the build instructions, and the other was moving the jumper connecting V3 to the anode of D3, which seems to be just connecting it to ground, to the pad just below it connecting it to the cathode. The way that jumper is placed in the layout seems like a mistake to me. When I had it wired up the way the layout shows it, I got no sound when the pedal was engaged.

Any ideas as to what I could be missing? Any other voltages I should check? I know there are mods to increase the gain, but it seems like the stock pedal should have much more gain than it does, so I want to make sure I haven't missed something before moving straight to mods.  The only other relevant piece of info for this build is that it's actually a two in one, one side is this 250, the other is a blues breaker KOT type drive, which sounds like it's working fine. They are separate boards though, each true bypassed, wired up according to this diagram from GGG, http://www.generalguitargadgets.com/pdf/ggg_sw_2in1a_lo.pdf. The only difference is I omitted the battery clip since I'm only using a power supply.

iainpunk

that 4k7 resistor is for the gain, replacing it with a 47k lessens the amount of gain, place a 4k7 there and it works as it should. the max gain is devided by nearly 10 here, giving you 22x instead of 213x
cheers, Iain
friendly reminder: all holes are positive and have negative weight, despite not being there.

cheers

ElectricDruid

+1 agree with Iain. I don't know why they recommend increasing the 4K7 to 47K.

Major Sparky

Thanks yall, that worked perfectly. Really confused why they would recommend the other value unless I'm misunderstanding the build doc. The pedal sounds great and now has plenty of drive, even with my low output strat pickups.

Govmnt_Lacky

Quote from: Major Sparky on December 29, 2020, 12:14:26 PM
Really confused why they would recommend the other value unless I'm misunderstanding the build doc.

My guess is that JD had a moment of juxtaposition when he wrote that doc.

Try sending him an email and let him know. Be the savior  ;D
A Veteran is someone who, at one point in his or her life, wrote a blank check made payable to The United States of America
for an amount of 'up to and including my life.'

willienillie


ElectricDruid