EP-3 Echoplex preamp circuit in pedal UPDATE/CLIPS!

[Ruben]

Guys, the EP+ is just awesome....

[harddriver]

Here's Pete Thorn demoing the Clinch EP-PRE. You can really hear the pedals' affect on the tone a feel in his demo. There are couple different echoplex pedals out there now, but I feel Mr. Clinch got it right down to the minute details. I'm still very happy with mine and we as Mr. Pete Thorn.

http://www.youtube.com/watch?v=LderEFqb ... r_embedded" onclick="window.open(this.href);return false;

[bmf5150]

I never did jive with that ep pre,reallY didn't color sound like my echoplex I had!it just sounded different! miss that echoplex i had!!!I'm looking for another ep3 if anyone has one they want to sell!

[Xplorer]

hello !
well, i never noticed the effect of the echoplex on the tone, cause i probably don't have the right speakers : actualy i don't have speakers. until i can get some, i'm playing on an spl transducer, put into cubase with some IR's of speakers, and altiverb, it gives a great result, but i want some celestions one day. the reason is that i can't afford these for now, and i can't play loud. neighbours ..
and i'd have to unplug the jack from the ep3 , and plug it directly into the amp, and try to hear a difference, but i didn't notice anything yet.

but i have a second echoplex, which came with 6 heads, fixed, in line, and a total of 5 preamp boards ! i'm thinking of using some of them ( cause i'll restore this echoplex to standard specs if i can find a bridge for the sliding , and the sliding block for the writing head. got any from a damaged ep 3 or ep 4 ? ) to build some kind of ep pre.
i'd like to ask to peter if that's simple to do, and what should i do ? there are two knobs on the ep pre if i remember, and i don't really know what kind of current should be sent , and what mod should be done to these original ep3 preamp boards.
but i didn't read entirely the thread yet, so there might be some answers there i guess.
thanks.

[clinchfx]

but i have a second echoplex, which came with 6 heads, fixed, in line, and a total of 5 preamp boards ! i'm thinking of using some of them ( cause i'll restore this echoplex to standard specs if i can find a bridge for the sliding , and the sliding block for the writing head. got any from a damaged ep 3 or ep 4 ? ) to build some kind of ep pre.

Wow, that Echoplex sure has been chopped about I suspect that the five preamp boards are head preamps, not input preamps. The head preamps are completely different from the input preamp. It looks as if there may be only one input preamp.

i'd like to ask to peter if that's simple to do, and what should i do ? there are two knobs on the ep pre if i remember, and i don't really know what kind of current should be sent , and what mod should be done to these original ep3 preamp boards.
but i didn't read entirely the thread yet, so there might be some answers there i guess.
thanks.

There is only one knob on the EP-PRE. It has the same function as the echo volume pot on the EP-3. If the input preamp and the echo volume pot and output circuitry in this unit has not been modified, you should not have to make any modifications. However, it the circuit has been modified like the rest of the unit, I have no way of knowing what else you may need to do to get the preamp working.

Peter.

[Xplorer]

Hi peter ! Thanks for your help. Indeed, my bad, I forgot, these are head preamps. Once i'll find a bridge and a slide block, i'll know what to do. But no much changes on this unit , on the boards. Just out of specs electrolytics. It needs a work.
I have to try your ep pre !
Thanks again.

[Xplorer]

... Now i'm thinking that i should use this rp3 as an ep pre, but modded a bit. I suppose that to get rid of the echoplex noises that occur, i should run this preamp directly with 2x 9 volts batterys or something, well : the right voltage, and disconnect the heads. So no motor running, no ground problems with a bigger circuit, just the preamp. Does that sound reasonnable ? Then if it works i'd like to mod my other echoplex to make it a switchable ep pre or classic echoplex.it already has a cool mod and i like the idea that it's like a secret weapon
may i ask you then if i just need to do that, to have this preamp working nicely and then a/b the difference ? For now, i can use the volume of the echoplex at 3 max, or noise comes ... I don't understand how eddy used two echoplex for his sound, without noise ( ??? )

[clinchfx]

... Now i'm thinking that i should use this rp3 as an ep pre, but modded a bit. I suppose that to get rid of the echoplex noises that occur, i should run this preamp directly with 2x 9 volts batterys or something, well : the right voltage, and disconnect the heads. So no motor running, no ground problems with a bigger circuit, just the preamp. Does that sound reasonnable ? Then if it works i'd like to mod my other echoplex to make it a switchable ep pre or classic echoplex.it already has a cool mod and i like the idea that it's like a secret weapon
may i ask you then if i just need to do that, to have this preamp working nicely and then a/b the difference ? For now, i can use the volume of the echoplex at 3 max, or noise comes ... I don't understand how eddy used two echoplex for his sound, without noise ( ??? )

Xplorer, I don't believe you would need to do much to quieten the preamp, assuming that there hasn't been too much butchery.

Yes, disconnect the motor, ensuring that you terminate and insulate any wiring that carries mains voltage.

I would replace all the Electrolytic Capacitors in the power supply, including the 35µF 25V cap near Q5, and connect a 0.1µF ceramic cap in parallel with this Electro. I would also connect a .01µF ceramic in parallel with the Zener, D1.

There is no need to disconnect the heads - disconnecting the heads will very likely cause the head amps to pick up and amplify other noise. Just plug a shorted plug into the Echo Off jack and disconnect the orange wire that connects terminal 12 to terminal 7 (as shown on the schematic). This connection has probably been extended to the extra head preamp boards and may have to be disconnected in a number of places.

Peter.

[Xplorer]

thanks peter !

would these mods have to be removed if i use it again as a working echoplex ? i mean : is it useable as a way to remove the noise of an echoplex ?
And if i remove the preamp board out of the echoplex, is it easy to make it an ep pre ?
on my other echoplex, i changed all the electrolytic caps, checked every resistors and changed all of them twice ( the modern small 1% resistors didn't sound good to my ears, and i just used some Carbon comps, but i should use some pihers in there )
finaly, swapping the Q5 legs connections provided some help into reducing some bassy hum. it seems that it was wrong, stock ! or i don't know ..
.. what is a shorted plug, for the echo off ? i'm not sure to understand what you meant.

to be more simple, we can simply imagine that i rebuilt this echoplex like the other, like stock specs. then, i guess i could perhaps have a mod that would make this echoplex silent and disconnected with some switchs , from all the unuseful sources
like the heasd amp ? the power supply,.... the motor being disconnected too,.... and finaly, this preamp board working simply with some 9 v batterys, like an ep pre. does that sound good to you ?
and with the switchs, it could go back to a stock echoplex circuit, running as tape echo. the mod involved would simply make it quiet, clean ... and reversible. cause i have no real good way to make this echoplex quiet as much as i'd like to.

but if VH used two echoplex for their preamps : what do you think he did on these units ? disconnecting the motor as you said ?
it would be impossible with mine. too noisy.
and something i don't understand : if i increase the volume, well it'll make the delayed signal stronger, but it'll make the immediate signal going to zero, right ? so the ep pre makes the immediate signal going from zero to ten ? ( without delayed signal )
cause at 3, the immediate signal and the delayed signal are balanced, equal, but if i'm going up, it's only about the delayed signal, and the immediate signal disapears. when you talk about this coloration with the ep pre, is it about this level, at 3 ? max ? or is it about anything between 0 and ten ? i'm not sure to be very clear, but let me know if you don't see what i mean

there certainly something i'm missing, not understanding.
thanks !

[harddriver]

Bump for a great product.

[harddriver]

Bumparoo and not just because Peter is in Australia either.

My original EP-PRE's are still alive and well and they pretty much stay on all the time when I play!

Hope you have a Merry Christmas and Happy New Year!

[clinchfx]

Bumparoo and not just because Peter is in Australia either.

My original EP-PRE's are still alive and well and they pretty much stay on all the time when I play!

Hope you have a Merry Christmas and Happy New Year!

Thanks hd, it's great to hear that your EP-PREs are surviving the test of time

"Bumparoo" 'Roos have a bad habit of jumping out in front of your car on outback roads, but we managed to drive about 50,000Km (31,000 miles) in some very remote areas without hitting one. Most of them are not very large, but they can completely disable a car if you hit one

Mandy and I hope that you and everyone here at MetroAmp have a happy and safe Christmas, and the very best for 2013.

Peter.

[harddriver]

No Roo's here Peter but plenty of white tail deer that do just as much damage.

I did manage to take my Toyota Rockcrawler off road truck out to California and drove the Famous 25 mile long Rubicon trail for my 2012 holiday. We were supposed to do some other off road trails Colorado but they had alot of mountain wildfires burning (right were we needed to go )this year since most of our country is in a nationwide drought.

It was great and was one of those Bucket List trips that you only do once since I live 2000 miles away.

I wish the best to you and Mandy as well!

[harddriver]

Here's Pete Thorn's demo of the EP-PRE from last year.

[youtube]http://www.youtube.com/watch?v=LderEFqby4A[/youtube]

Here's another good video of the EP-PRE in action

[youtube]http://www.youtube.com/watch?v=2U7jdzTH7Vg[/youtube]

[clinchfx]

I did manage to take my Toyota Rockcrawler off road truck out to California and drove the Famous 25 mile long Rubicon trail for my 2012 holiday.

Wow, that makes our little off road excursions look tame, although bogging our Toyota on a beach with an incoming tide didn't seem tame at the time

After spending 16 months touring Australia, we still haven't touched the far north. We are hoping to do that in a couple of years time.

Peter.