Ed's Echoplex

[Ruben]

Ok, this is something else!!!

Anyone already tried a (Vintage) Dynacomp with Echoplex?

It DOES make sense!

Where to put the comp? Before delay I quess?

[Ruben]

Nice work. I guess now we'll need to invest in a soon-to-come EP Dyna-pre pedal....

[spaceace76]

you can get the CA3080 on a number of DIY sites. a bit expensive for an IC but not unreasonable:

http://www.smallbearelec.com/Detail.bok?no=219" onclick="window.open(this.href);return false;
http://www.mammothelectronics.com/CA308 ... 0-1093.htm" onclick="window.open(this.href);return false;

in case anyone is wondering the E suffix just stands for the chip in a plastic 8pin package (the IC's you're used to seeing)

i'm also wondering how the differences in the two designs affect the circuit's operation. another thing i find odd is that the schematic for the EP3CB shows a +22v input supply but then notes +9v after a 1k resistor... Would a 1k actually bring that voltage down to 9v?

the more i look at the two schematics the more i think a plain dynacomp might not do the trick. this is worth building into a standalone box, i think

[leadguy]

The 22 volt Echoplex rail gets knocked down to 9 volts by the Zener diode so the Dyna-Comp and the Echoplex compressor board are both powered by 9 volts..

Looks like the Dyna-Comp's first transistor Q1 gets replaced by the Echoplexes FET (preamp).

Looks like the compressor board in/out connections get installed onto the record level pot.

The 2 circuits are very similar.
A few different minor part values are used and the sensitivity is fixed on the Echoplex compressor board (to around halfway on the Dyna-Comp).
The output is taken from the collector on the Echoplex compressor board and the output is taken from the emitter on the MXR Dyna-Comp circuit.

[wjamflan]

Unfortunately, the finished unit was rushed into production without Dixon testing it. The compressor had been added to the entire signal – wet and dry – causing a furor from players. The units had to be recalled and the compressors removed, bringing an end to Dixon’s “improvement.”

I've been thinking about this since it was posted. Does this mean that every Echoplex bought new was recalled, like a car would be? Would the LA music store that Ed bought his from have contacted him and told him to bring them back so the compressors could be removed? If so, what if he did?

On a different note - Would the compressor have affected the signal even if the Echoplex was not switched on? And would running through 2 of them with compressors have squished the hell out of his signal, even if only one or none were actually engaged?

[spaceace76]

interesting point. how extensive was the recall? did they just pull them from stores? perhaps Ed had his boards removed to find out his tone had gone with it, and had them reinstalled? it would be great to find details on the recall, but looking around I don't see much info on the subject.

if it's hooked up the way the manual describes, the compressor is on the dry signal too. i think the preamp is as well. if you're plugged into the plex, your signal is going through that board

[JimiJames]

That's a viable angle. One of many ofcourse but, would have bearing

[leadguy]

The recall?

I don't know if it happened but if it did it didn't look to be too successful.

There are still EP-3's and EP-4's with the compressor board in them around today.

I have always thought that Ed ran his two Echoplexes on different amp lines and therefore not in series for live work.

The studio ATBL has 2 Echoplexes on it but the signal could be split to 2 Echoplexes with each Echoplex going into a different amp channel or each Echoplex going to 2 amps, like daisy chaining.

Also one Echoplex could have the compressor board and the other might not, unless we can see inside Ed's Echoplexes we will never really know.

Ed seemed to buy his EP-3 Echoplex(s) around the time when they were being sold with compressor boards.

I don't think it's really heavy compression anyway with the sensitivity being around halfway and there are a lot of other things in the signal chain and everything in the signal chain has some effect.

[ampSnob]

This got me curious so I opened up the two ep3s I have in my possession right now and neither one has the extra board although they both sound fantastic going straight into the amp input.

Not to get too far off topic but I have to note: the noisiness of the MXR 6 band eq gets oddly magically reduced a bit (to usable levels) when used in this order: guitar - (other pedals) - mxr eq- ep3 - plexi

[rgorke]

Not to get too far off topic but I have to note: the noisiness of the MXR 6 band eq gets oddly magically reduced a bit (to usable levels) when used in this order: guitar - (other pedals) - mxr eq- ep3 - plexi

I have noticed the same thing. My EP-3 cuts out a lot of hiss and extraneous noise when engaged.

[T.J.Fuller]

Leadguy, this is cool information ! I've researched this echoplex stuff for years and never have seen this compressor board info anywhere..very cool find !

My echoplex is around the same time period and has the same metal ID plate as evh but, I know I don't have the compressor board either.

but, there is another difference I noticed between the 2 types ...FWIW... may make a difference ...maybe not...

But, the ones without compressor board ( mine included ) all have those white +/- Mallory caps.

the compressor board model has a totally different brand of caps (black)....again just an observation.

I have tried to find those white Mallory caps on the internet, I can't find them at all.

I have a parts list of where to get every vintage echoplex part except the Brass flywheel and those Mallory Caps.

[Strat78]

I'll open mine up tonight. Who ever ells has an EP-3 here should do the same so we can find one of these boards and really see what's going on. Who's that guy who works on these things, is it Orbits or something, he probably has seen hundreds of these things. Perhaps with the numerous EP-3's on eBay, we could ask all the sellers to open theirs up as well. Great stuff!

[T.J.Fuller]

Tony at orbitelectronix

he would know something surely....

[dazzlindino]

My EP-3 dos not have the compressor board..wahhhh!!!! I WANT!!....wahhh!!
Mine also has never givin me any type of boosted siganal, slightly altered yes, boosted NO...Wahhh!!!

[rgorke]

No compressor on mine. Has chicken head knobs, serial number 14000ish.