MXR Distortion plus problems

Ghost Planet · May 24, 2013, 08:48:03 PM

I built a distortion plus from the schematic below, the schematic with the mods. It sounds good it just has a few problems. One problem is when the volume is all the way up it sqeals. When I lower the volume a little it quits. Also the tone knob at the end of the circuit has no effect for 90% of the sweep then suddenly it sounds like pedal is under water. Any ideas? Also the diodes at the end if the circuit, does the order of these have any effect on the sound? Thanks.

http://www.premierguitar.com/Magazine/Issue/2008/Dec/MXR_Distortion_Plus_Mods.aspx?isfullsite=true

pakrat · May 24, 2013, 08:59:49 PM

Do you have pictures of your build? How do you have the diodes oriented?

Ghost Planet · May 24, 2013, 09:08:05 PM

They go from signal to ground ln34a to ln4001, both sets. I hope that makes sense.

pakrat · May 24, 2013, 09:30:10 PM

It's difficult to help without pictures. Double check that all of the diodes face the way the schematic shows them.

Ghost Planet · May 25, 2013, 06:44:56 AM

I'll try to post a pic soon

psychedelicfish · May 25, 2013, 08:10:33 AM

about the squealing, how far away is the input wiring from the output wiring?

Electron Tornado · May 25, 2013, 04:56:05 PM

Quote from: Ghost Planet on May 24, 2013, 08:48:03 PM
I built a distortion plus from the schematic below, the schematic with the mods. It sounds good it just has a few problems. One problem is when the volume is all the way up it sqeals. When I lower the volume a little it quits. Also the tone knob at the end of the circuit has no effect for 90% of the sweep then suddenly it sounds like pedal is under water. Any ideas? Also the diodes at the end if the circuit, does the order of these have any effect on the sound? Thanks.

http://www.premierguitar.com/Magazine/Issue/2008/Dec/MXR_Distortion_Plus_Mods.aspx?isfullsite=true

Take a look at this for a simple tone control: http://www.muzique.com/lab/swtc.htm
For the tone control, are you using a 1M audio taper pot?

Regarding the volume pot - where is the volume set on your amp when the pedal squeals? It may not be the pedal squealing.

Ghost Planet · May 25, 2013, 10:46:45 PM

The input and output wires a on opposite ends of the circuit. I did use a 1M linear for the tone control.

pakrat · May 26, 2013, 10:02:39 AM

I've had a few recent builds squeal also, is yours boxed up yet? Maybe try using shielded wire for in/out?

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MXR Distortion plus problems