mxr distortion 2 mod

[scaesic]

http://www.diystompboxes.com/pedals/dist2.GIF

id like to mod this to work on 9v, i think if i cut out the logic switching and use a 3pdt this should be possible.
am i right?

[Mark Hammer]

Yeah, that should work at 9v.  If you want to use a 3-pole stompswitch, you can omit all that stuff in the upper and lower right hand corner (once you rotate the GIF properly) for the clean output and electronic switching, and can also scrap everything after the Output pot.  Of course whether it runs happily from a battery for hours on end is another thing.

[scaesic]

is there anyway i can host a pic on here to show the re-drawn schem for checking?
doesnt matter about battery life, im using the godlyke power-all wallwart.

[scaesic]

is this right?

[Mark Hammer]

Close.  You've eliminated the appropriate parts but show the switch inappropriately connected.  I'm assuming your plan is to benefit from the input buffer of the Dist-II and leave it in circuit even during bypass.  In which case, the stompswitch needs to select beteen that tap point at pin 7 of U2 and the wiper of the output level pot.  The way you've drawn it, pin 7 simply does or doesn't connect to the ouput jack and the level pot is hardwired there.

If you don't need to take advantage of the input buffer, then consider using a DPDT or 3PDT switch for full bypassing of the circuit.  Should you do so, the path between pin 7 of U2 and the output jack becomes moot, and you will need a 1-2meg terminating resistor between C1 and ground to eliminate popping.

[scaesic]

howabout this?
yes??
i could do this with a dpdt.

i've made up the original pcb's, but im assuming itl be much easier to perf board this with these changes.

i was also wondering if anyone could tell me what some of the eliminated parts of the circuit are for, namely, the tlo72 (u4) and the rc/diode configuration just before the output jack, it looks almost like a second buffer, but i dont really know.

[smank]

I've just realized a Distortion II clone with some mods.
With a 9V supply I suggest you to insert a capacitor between R20 (10K) and ground: this help you to obtain a better headroom (prevent distortion on last opamp stage), else the circuit amplifies also the DC voltage in input to the pin 5 of U3 by twice... After this mod you can increase also the gain of this stage: it's enough to increase a bit R21 (to 15K or 22K, for example). In this way you can obtain a large output level.

[scaesic]

r20 connects to Vs and leg4 of the ic, which leg of r20 should be connected to ground via the cap, and is it a case of experimentation for the value?

[smank]

I've used a 2,2uF electrolitic cap, but from 1uF to 4,7uF it's not so critical.

[Mercury Mad]

Hi,

I have been doing basic repairs and have found that the switch in my MXR micro amp has been stomped to death.  I checked the board and everything works except the switch.  Can anyone tell me where I may purchase one online?  If there is a stronger replacement that would work then that would be cool too.

Thank you it will be a big help to get this up and running.


M.

[smank]

I buy regurarly from www.effectsconnection.com
John Lewman offers good quality 3PDT switches at a good price. I recommend you.