EH Deluxe Memory Man: a cool mod and a question

[filterazonatie]

Cool mod for EH DMM, almost embarassingly simple, but it took some thinking on my part.

I wanted to come up with a way to "ride" the feedback pot, and thought I'd hook up the leads from it to a NC stereo jack, that could break the connectio nto the pot and send it to an expression pedal. Two problems: 1. I don't have a TRS NC 1/4" jack, and they look very expensive on Mouser (and minimum of 10 on order...) 2. The pot is only 10k, and I don't know of any 10k expression pedals.

Trying to come up with simpler solutions, I decided that shorting the wiper to the high-side would produce something similar. Now, as I discovered, it's not exactly the same, since doing so doesn't raise the resistance to ground up to the full 10k, effectively shanging the overall value of the pot to, say, 5k or whatever, depending on where the pot was initially. Surprisingly, this ended up having a benefit.

When the Feedback pot is typically turned all the way up, the self-oscillation produced gets "boomier" and muddier as it feeds back on itself. It can be cool but is pretty bombastic, and not really useful for anything except giving the audience a proud middle finger.
:twisted:

On the other hand, when the pot is set for somewhere in the middle, say 3 repeats and around 5k or so, and the wiper is then shorted to full-potential, the result is lower resistance to ground, so the signal starts self-oscillating, but without the low signals building to a crescendo. The repeats get more and more atmospheric, and the lows slightly attenuate, creating a kind of "dub" effect. It's IMHO much more useable.

The other cool thing is that this can be hooked up in parallel to the pot and wired to a momentary switch. I used the "Direct Out" Jack which I never use anyway. The only thing is that the jack has to be insulated from the enclosure, or the repeats will short to ground through the box. I used some careful dressing of rubber tape, trimmed with an exacto knife to look nice. I suppose plastic washers could also for the trick.

Very cool trick, worth trying!


Now, an unrelated QUESTION: The modulation stage on my DMM has been acting up lately. Vibrato is greatly reduced in effect, and Chorus is greatly exaggerated. Also, and more annoyingly, the Chorus setting is producing a ticking in sync with the LFO. It gets slower the more you turn it up, but it's pretty pronounced at all settings. It literally sounds like a clock going tick-tock. :cry:

Any thoughts on why this might be coming through? How to fix?