EHX Deluxe Electric Mistress Vintage MODS

[Quadra]

I just got one of those vintage green DEM. I'm pretty sure it's not true bypass and i also want to add a LED to it when it's on. Can somebody help me with a link or something to pull out those mods?... cause i can't find any mod on internet about this particular pedal.

What other mods can get done to this pedal?

btw is just like this.

[jacobyjd]

You'd probably be better off building one yourself...it'd be a shame to hack it up for the sake of TB if it's in decent condition.

Also...is it not doing something you want it to do? Will modding improve it? BUMS is a dangerous syndrome.

[Mark Hammer]

The schematic can be found here:  http://www.generalguitargadgets.com/diagrams/dmistsc.gif

With some older effects, adding true bypass can be more trouble than it's worth, and not necessarily improve tone.  True, the input impedance of the pedal is kind of low, but if you are generally always feeding it with the output of another effect or some buffered source (as opposed to going straight from a guitar to the DEM), the low impedance should not suck too much tone.

A "full-featured" flanger would offer essentially 5 controls.  The DEM offers three via panel controls.  The two "missing" controls would be a dry/wet mix that could provide subtler flange sounds and dry-only vibrato sounds, and a manual offset (sometimes called "Initial") that could position the sweep in different ranges.

To some extent, the 10k trimpot labelled as "gain adjust" in the schematic can accomplish some of the functions of a wet/dry mix control. Playing around with it a bit might give you a sense of whether it would be useful to transform it into a panel-mount control.  If you are not able to identify which of the two 10k trimpots it is, however, then I would recommend steering clear of such a mod since that would suggest your chops aren't up to it yet.

The manual offset can be simulated to some extent by the 100k trimmer labelled "clock adjust" .  That trimpot sets the range of the clock generator in a manner functionally similar to what the suggested panel control would do.  My sense is that really only a portion of the full range of that trimpot is actually usable.  Ultimately, if it were amenable to a panel-mount control, my guess is that it would only be a 25k-50k pot with an additional fixed resistor in series.  Again, if you are not able to figure out how to determine that, then steer clear of the mod.

A status light is a useful addition, but I have to caution you that those folded steel chassis are an absolute bugger to machine.  So, "popping a hole" in them is going to require a) a very sturdy and sharp drill bit, b) a drill press, c) disassembly of the unit so that there is nothing inside the box to be damaged in case the drill bit goes a little further than you planned.  You also need to figure out where the hole can go first.

Actually, a lot of this is outlined here:  http://hammer.ampage.org/files/Device1-5.PDF

Note that two of the illustrations are in error.  You'll need to look at this document to straighten the whole thing out. http://hammer.ampage.org/files/Device1-6.PDF

[Ed G.]

This is what I'd do: Build a true bypass looper with an LED function. There's a bunch of plans and how-tos on the web somewhere if you look.
That way you keep the pedal stock, get true bypass and LED.
BTW, the DEM is the one vintage pedal that I wish I'd kept. I didn't have the green one, I had a silver one. But it had zillions of sounds in it. It had that "Barracuda" sound and it had the "Spirit of Radio" sound and believe it or not, I could do "Bridge of Sighs" with it (I read that Robin Trower once used these instead of the Uni-Vibe at some point of his career) and it also nails the "Hey You" from Pink Floyd. I've never heard a more musical flanger than the DEM.

[george]

status leds ... sigh.   If you can't hear when it's on it's not worth having IMO.   

[jacobyjd]

status leds ... sigh.   If you can't hear when it's on it's not worth having IMO.   

I've found that peoples' opinions on status LEDs differ widely by what styles they play. A big part of the last band I played in involved making a drastic gain change--so, from light and airy to all out distortion. Additionally, it was an agreement in the group to avoid unprofessional 'signal testing' between songs. Sometimes this is necessary, but it was mainly a 'play the song, then mute your signal' kind of thing.

For a situation like that, LEDs are necessary, even if you can hear it when it's on.

[Mark Hammer]

+1

I too tend to allocate my 3PDTs to things that are difficult to identify as "on" by sound alone, using my DPDTs for fuzzes and auto-wahs, and providing a status LED for a compressor or clean booster.....or for something I think I might later sell.

That being said, in the heat of the moment, in a gigging situation, people need feedback about whether an intended change is an achieved change.  If you can afford to be slower and deliberate, the satisfying "click" can sometimes be enough, but in many instances it isn't.  It's also the case that with things like loop selectors, people will set up multi-pedal configurations in advance to be able to dip into for a solo and then get out of.  In those instances status LEDs can be useful for simply verifying that something will be ready when you need it.

[StephenGiles]

I have an even older silver DEM, the best mod I ever did is disconnect the power supply and use 2 large 9v batteries - much quieter.

My Craig Anterton AMS 100 Flanger uses the clock & LFO from the DEM together with the bounce circuit from the Eventide Instant Flanger - thus the Andertide Flanger!

[tsatterca]

Did anyone ever find a diagram on how to install a 3 PDT switch to add a on/off light

thanks!

[Mark Hammer]

It's in the FAQ.  Oh, and welcome first-timer.