Mxr distortion+ diodes

[Mann]

I'm building the mxr distortion+ kit (www.musikding.de) and wondering about the diodes which came with the kit. The parts list says: "1N4148 or 1N914 or germanium diodes
". How do I know which ones came with the kit? And which ones would you recommend? (I'm going to solder ic-sockets for the diodes and I have some germanium diodes.)

[George Giblet]

1n914's etc tend to be small and copper colored,

http://www.solarbotics.com/assets/images/d1/d1_ps.jpg

Whereas germaniums tend to look be the clear glass types,

http://www.mtmscientific.com/diomix.jpg

The small black one is a probably a 1N34A.

[by the way the original MXR used germaniums.  The DOD Overdrive was similar and that used silicons like the 1N914]

[Mark Hammer]

The original used 1N270 diodes.  I know because the one I traced in 1978 had them and I had precious little knowledge of diodes in those days, so I only wrote down what I saw, not what I assumed was there.  1N270 diodes are germanium, which have a lower clipping threshold. This will yield more distortion, but lower maximum output level from the pedal.  The DOD250 used/uses 1N914/1N4148-type silicon diodes.  These have a higher clipping threshold, which will result in somewhat less clipping, but noticeably hotter maximum output signal, which will help to push the amp into clipping more easily.  Your choice where you want the clipping to come from most.

[Krinor]

As always (and even though you probably want to finish your kit and fire it up asap), you should put in sockets for the diodes. It is both fun and rewarding to try lots of different things in there for clippers. You can experiment and find the type of distortion you like best.  Personally I ended up with some A119 gremanium diodes in asymetric setup in mine.

[drewl]

I always found the level of the D+ to be a tad low (must be them germs) so i swapped a few different 741's until I found one with a higher output.

[petemoore]

  GE across Si works for quick sPsT switcheroo, and whwn-if the switch fails you still have clipping on that side.
  Same trick works say across a Ge diode, hook-dehooking the wire to hear different sounds [wire soldered to one end, then bent perfect with a hook to touch the other side when I want to hear the difference between SI+Ge compared to just SI, little wire goes across the ge bypassing it out of the clipping circuit..
  Once I decided on the diode configuration i think I did pretty good with that and the gain knob to adjust gain/clipping amount, my Rats' 3 way diode switch ends up in one position all the time...
  >Si> 
  <Si/Ge<
  AMZ 'Warp control's a good one for adjusting clipping amount.
  I like to have a knob on the cap that goes across the diodes, HF's seem to need adjusted from time to time, level changes etc., a pretty good place to do it.

[mac]

I have a switch to change from ge to si diodes, and 50k volume pot. It is more like a ross than a D+.

The ge diodes I used are those new 1n60 that are very similar to 1n4148. They also sound brighter than the old ge diodes I have, so my guess is that they are schottky si diodes, not really ge. I should have to replace them .

mac

[Mark Hammer]

1N60 are germanium diodes and frequently used interchangeably with 1N34 and 1N270.  Having said that, there ARE part-to-part variations in the actual forward voltage and clipping threshold.  My best advice would be to select your diodes based on measurement of the forward voltage with a DMM.  Most cheap meters will permit/provide this.  Using my cheap Radio Shack meter, I find ge diodes of the same number-type can exhibit variation between 180mv and 260mv.  Given that this results in a difference of 520mv p-p vs 360mv p-p, that is an audible difference in terms of both the volume and clipping quality.

Do try to use a volume pot of 50k or even 100k as a means of retaining as much of the signal amplitude as possible.  Finally, don't be afraid to increase the value of the 1M feedback resistor to a higher value (either a single resistor or two in series, like 1M+220k), so as to permit greater maximum gain.  With gain increased, you can then switch to diodes with a higher forward voltage, like 1N914 or several Ge diodes in series, and expect to get the same distortion quality at a higher output level.

[mac]

I forgot to say that my new "1N60" are immune to temperature changes... strange.
I'm not saying that all the new 1n60 are fake, just be careful.

mac