Marshall ED-1 compressor

[whiskeytown]

I need schematic of Marshall ED-1 compressor pedal. Is it similar to Mxr Dynacomp?

[Mark Hammer]

I need schematic of Marshall ED-1 compressor pedal. Is it similar to Mxr Dynacomp?
It is somewhat similar to the Dynacomp, but the extra control allows the user to select whether it is equally responsive to the entire audio spectrum, or more sensitive to bass content ior treble content. It's kindof like the Big Muff Pi tone control, but placed between the gain cell and the envelope-follower/rectifier. Someone posted the schematic but I don't have the link or file on me at the moment.

[Enzo]

There is no schematic for it on my dealer site, it is a "replace only" unit.

[Mark Hammer]

Why do you need the schem? For a repair? clone? intellectual stimulation?

Not challenging you, just trying to figure out what the best recommendation is. I have the schem at home but it is practically drawn so as to prevent comprehension. If there is something more useful I can provide, it would help to know the goal you have in mind.

[whiskeytown]

Thnx people, especialy Mark, well I need the schematic for building clone, but also cause Ross/Dyna comp is my favorite comp, and just wanna to compare it with Ross (and by that I mean is it use same CA3080 ?!).

Thanks Mark your posts are always very clear and helpfull.

[Mark Hammer]

You're welcome. Glad to be of service.

I'll tell you right now, the schematic is a very poorly drawn one. Not that the physical document is grainy or fuzzy. It is a very clear factory-issued PDF from what I understand. It is just ridiculously difficult to follow because of how it is drawn.

In many respects, you could duplicate what the ED-1 does simply by cutting some of the bass or treble being fed to the sidechain, so that it responds more to high-end, more to low-end, or responds equivalently to everything. Apart from that, I can assure you it doesn't really do anything that a Ross/MXR doesn't do.

I'll see if I can locate it over the next few days.

[Mark Hammer]

OK, I have the schems. Where can I mail them to?

[whiskeytown]

acahool@yahoo.co.uk


thanks Mark

[JJGross]

OK, I have the schems. Where can I mail them to?

I have an Ed-1 that somebody poured what looks like beer into it. It doesn't work - big surprise.

I'd also like the schem for this if I could.

jeff at jeffgross dot com will get it to me

Cheers

[ste454]

hi, I own an ED1 too and with my fender stratocaster and deville amp it crunches, does anybody knows why, or colud send me the schematic so I could try to solve the problem by myself?
thanks

[Mark Hammer]

Here you go, gents.

http://img.photobucket.com/albums/v474/mhammer/ed.gif

[Enzo]

Did you redrawn that yourself?

The factory has it online now, I posted a pdf of the original on www.ampix.org in the Enzo gallery, just for reference. it really is a chopped up pain in the ass.

For lack of a better term, I call those engineering drawings instead of schematics.

[Steve Conner]

Hey, thanks for sharing that! I have one of these pedals too, and I've always wondered what in heck the "Emphasis" knob did (but not nearly enough to dismantle it and trace the circuit...) So it's basically a Big Muff-style tone control in the sidechain?

[Mark Hammer]

I've always wondered what in heck the "Emphasis" knob did (but not nearly enough to dismantle it and trace the circuit...) So it's basically a Big Muff-style tone control in the sidechain?
As near as I can gather, that is what it does. That is it changes how sensitive the sidechain is to different parts of the frequency spectrum. In principle, you could tweak it to be a de-esser by positioning the treble end of the emphasis control to emphasize the sibilant frequencies.

Enzo,
Someone else at the diystompbox forum redrew it. All I did was save it and post it. And yes, the Marshall schems are an absolute bugger to interpret. Almost as bad as the Boscorelli drawings! ;)

[Ben N]

Those drawings should still be helpful to someone trying to TBP mod this pedal, by teasing out what the heck is going on on the jack-pcb. IMHO, tone-sucking is its only shortfall. I assume those beads are to get rid of RF? In a TBP iteration, would they be necessary, or could they all be inside the bypass, along with the effect?

[David Schwab]

Someone else at the diystompbox forum redrew it. All I did was save it and post it.

I was wondering.. I looked at it and thought "that doesn't look so bad" lol

[Mark Hammer]

Yeah, all of those Marshall pedal schematics are enough to give you a migraine. There is very little about them that permits an easy understanding of the circuit. Maybe they were meant that way. On the other hand, if you've ever seen any of the circuits from Nicholas Boscorelli's stuff, whether the Stompbox Cookbook or the Stompboxology newsletters, you'll see schematics that were deliberately intended to be instructive (or at least accompany instruction) but are every bit as hard to follow as the Marshall drawings. I guess some folks have a good head for drawing things, and others not so much.

I don't know about you, but my capacity to recognize functional relationships or elements in a circuit can very much depend on the manner in which it is drawn. Sometimes, all it takes is a simple 90-degree rotation of a pot and all of a sudden the lights go on...or off.

[Steve Conner]

Me too. The way that I visualize how circuits work needs things to be arranged on the page roughly according to their voltage, so in a tube amp you have B+ at the top, ground near the bottom, and bias voltage under that. Current flows from the top of the page to the bottom.

And yes, when I try to visualize the AC operation of a circuit, I can't help but see things fly up and down the schematic according to their instantaneous voltage, with diodes flipping head over heels and resistors getting squeezed and stretched like accordions.

As a consequence of this mental model, when I first saw those old Fender schematics that draw one tube of the push-pull pair upside-down, I wondered where in heck they got PNP tubes from. :eek: To make sense of the push-pull pair, I have to draw the output transformer horizontally, so the primary is like a see-saw or pair of scales, with the power tubes yanking on the ends to make it "swing".

I actually worried that I might have been one of those "special" kids, till I read an article in an electronics book by a designer who visualized things in just the same way. (The book was edited by Jim Williams, so everything in it must have been right.)