MXR Distortion Plus Questions

[petemoore]

I tried this, and would again, if DIST +ing.
 I Found tones in diodes much better, plus it opened up the sound and helped add a touch of twang!
 WQhat a nice pot to plant in a Dist+ clipping diode arena.

[john1056]

I've used a 500K linear pot for gain... and i hear something only at maximum gain :/...  from 1% to 99% of the pot = *nothing*
The 100k log pot i've used for volume seems to work.. but at max the volume is veeery low... i have to turn drastically up amp volume to hear something...
please.. help me
when i bypass it.. it works perfectly.. so i think jacks wiring is right..

oh i've used DOD250 schematic with YJM308 variations..

Davide,

When I built this pedal, at one point I had exactly the behavior that you are seeing - I could hear a little sound if my amp was cranked.  The problem in my case was that I had blown out the OP Amp.  I'm not sure how I did it, but I had a few grounding problems with my input as well so I guess I could have fried it trying to troubleshooting that.  Anyway I would first short the board to make sure the problem is there (put a little peice of wire between the out and in pins of your bypass switch and see if it acts like the bypass is on), if so swap I different OP Amp if you have one.  Make sure your don't have your OP Amp in wrong, from what I've read that will fry it for sure.  Other than that I would double check the continuity of the components, and make sure something isn't wired wrong.

John

[Davide]

Thank you i'm going to try and tell ya

ah, if someone is interested for the malmsteen variation i've modified the dod250 pcb ('cause of the different IC with two op amps instead of one)



(thanks to ggg where i took the 250 pcb)

[petemoore]

Tha's what I use them for these days.
 Got some batches from RS, for early build stuff. Now I use them to test cct's before I put in something like a TL072 or a 4558.
 I usuallly wait till I'm about [hopefully] half the way through de-bugging before I put the 'nice one in. same thing with transistora, whenever possible I use a component I know works, but will probably not be the one I'll want in there.

[Davide]

so..
i've tried to bypass in and out pins of my switch when the effect is on... and it sounds as bypassed, clear and loud...
when i remove the bypass it sounds distorted but with a veeeery low volume :/...
and my gain pot (a 500k linear) works only at maximum gain...

[john1056]

Unfortunatly that means the problem is definitely on your board.  I don't know what to suggest other than just checking all the connections between components with a meter to make sure there isn't a bad joint somewhere.  I would try to swap a different Opamp in though, especially if you've socketed it.

[Davide]

everything on the board seems ok.. i think i've fried the ic.. i dont know how but probably i did .. i'll try with a new one.. and i'll substitute the lin gain pot with a reverse wired log pot..

[will]

Hi,

With this design, if you are only interested in the top 10% or 5% of the rotation of a 1 Meg gain pot. You could just use a 100K or 50K pot for gain. Where it is located in the circuit, maximun gain is when the pot is at zero.

Regards,
Will

[Davide]

mmm
i've replaced the IC with a new one.... but no improvements...

i still can hear the distorted sound but only at maximum amp volume...
i'll try with new pots...

[Jim Jones]

Hi Davide,

I know it sounds nasty, but I bet you anything there's a wiring error in your circuit.  They're frustrating as hell to find but when you do it's like you climbed Everest.  

Jim

[Davide]

i think you're completely right

but i've checked it many many and many times...

it was perfeclty working.. but i connected to ground ring's output jack instead of sleeve.. so i connected sleeves of both jacks with a wire to test... and it worked great... since i've corrected the mistake 'bout the output jack it does this trange joke.... and when bypassed there arent problems.. so i think jacks wiring is right.. and i havent changed anything else :/