DOD 250

[GVC]

I have made two of these now from GGG and both have this fizziness when playing through my Reverb Deluxe, I am starting to think this is no a fluke.  Anyone else hear this ?

My second build the Gain knob doubles as a level , any hints?

[gaussmarkov]

well, i am new at this, too. but i'd be happy to try to help.

must be quite frustrating.  you have two builds that look exactly the same and yet one has a gain pot that also affects the level.  have you have gone over that second build checking all of the resistor values and looking for accidental solder bridges from one pad to another?  do you know how to use your dmm to check for continuity?  i often check that everything that is supposed to be connected on the same net has continuity and things that are not on a particular net show no continuity with it.

if all that is fine, then i wonder whether there is a problem with one of your capacitors (c4 or c6).  i don't have a dmm that measure capacitance and i am not sure whether you can test your capacitors without a dmm that does.

[jimbob]

I recently bought a yjm308 and gutted it and placed a GGG home etched board inside and edded a boss style jack- took a little drilling too ..also added a blue led where the zero is on the YJM308. It ROCKS!   Anways,  try using the lm741. I thinlk thats the original. single opamp. The YJM uses a 4558. I messed with this circuit a lot and also found that changing out the input cap to something bigger and adding decent germ diodes help as well if you want to experiment. Maybe even added another 1n914 to it. It a nice little circuit to play around with. Dont get caught up with, "It has to be exact!" mentality. Go with what sounds good and use what you have.

Good luck

[Steben]

Yeah, try soldering sockets instead of the diodes and input caps and try different components. a double pair of 1N914 + 1N34 (or other germanium) for instance is very nice. Soft enough, but also loud enough.

Your gain pots are maybe of different values? Dou you have a multimetre?

DOD 250 / MXR dist+ is a very versatile distortion/OD circuit. It is the base form of most comercial distortion pedals. What you might like to add is a tone control.

[GVC]

Wow,

This is great, thank you all for the feedback!

I will check my connections and come back to post the results. 

To anyone that has tried different OPAMPS in this circuit (Liguid Drive): is there a noticable difference?  I would assume that with no trannys and low component count it would but I am not sure.  I have the 741 socketed right now, and to my ears it seems buzzy.

[gaussmarkov]

To anyone that has tried different OPAMPS in this circuit (Liguid Drive): is there a noticable difference?  I would assume that with no trannys and low component count it would but I am not sure.  I have the 741 socketed right now, and to my ears it seems buzzy.

maybe we should keep this thread focussed on your DOD 250? 

as far as the liquid drive gpes, i suggest that before you start a new thread you try reading previous threads about the liquid drive.  also, i see that fuzzcentral has some comments about the circuit--including the opamp choice and "stabilizing the ic."  have you already seen that?

[gaussmarkov]

if all that is fine, then i wonder whether there is a problem with one of your capacitors (c4 or c6).  i don't have a dmm that measure capacitance and i am not sure whether you can test your capacitors without a dmm that does.

FWIW, there i stumbled on a link in the DIY FAQ about testing capacitors without special DMM testing ability.

[GVC]

I made some of the suggested changes and I am happy with the one that I got:

added a switch for Clipping: SPST around the diode that creates assymetrical clipping, and a SPDT to switch between input capacitors. 

I was wondering if it is possible to put a dual opamp in the circuit by jumpering pins 6 and 7 and pin 5 to ground Like the liquid drive suggests:

http://fuzzcentral.tripod.com/liquid.html

but using the printed circuit board from GGG:

http://www.generalguitargadgets.com/diagrams/dist_plus_lo.gif

I noticed that the Liquid drive is more like a Dist plus than a 250 bu they use the same board.