Echoplex EP3 Preamp Based Circuit Layout by Ulysses

[amz-fx]

I quickly searched for the Echoplex EP-3 schematic and on first inspection, it appears that the jfet input circuit is powered by 20v to 22v.

I would definitely power this with at least 18v to get more of the original vibe.

regards, Jack

[pinkjimiphoton]

man..

what happened to you guys? whole lot of dick measuring going on here..

1m 10m 100m who gives a @#$%?

i stated on the layout this is based on the original circuit, i added a pull down and changed the tranny to one i thought "sounds really nice" (stating i had changed the tranny AND listed the tranny the circuit originally had)

i even called it a "BASED" circuit ffs.

so if you want to try it.. go on and try it.. i think it sounds really nice. it'll only take you 20mins to give it a go and if you think its sh*t - desolder it.

cheers

sorry brother ulysses, no disrespect intended.... i know stuff can come off harsh sometimes, especially from me.
my beef is the whole "echoplex secret preamp" myth bullshit.

i have no doubt the boosts sound great. but do they really model an echoplex?

not even close. that's my point. maybe i'm jaded, maybe i'm an arsehole, but i read so much BULLSHIT in the marketing of circuits it makes me cringe.

from wampler with his "class a " distortion (bullshit) to the "ep3 preamp" (ultimate bullshit) i wonder why people are afraid to be honest, and just say...

hey!! i came up with a cool circuit!!!


ya know?

again, my apologies.

i queried about the input impedance cuz to my ear there's no noticeable difference.

pretty much anything higher than about 20k seems to work for a pulldown. as long as it's higher than the source feeding it.

but .... that said... i am a hack, and far from an EE.

no dis intended to anyone in this thread...but  the bozos marketing this style circuit as being related to an echoplex are so full of shit ibet their @#$%ing eyes are brown.

peace.

i am seriously gonna a/b my echoplex ep3 with a true bypass box. i'm betting it doesnt' even hit unity gain, and it's never bypassed. and you can't "crank it up"... there is one trimmer on an echoplex for the recording level of the tape, and that's it. you can crank it up to where the tape saturates, but that has ZERO effect on the dry signal.

[ulysses]

i am seriously gonna a/b my echoplex ep3 with a true bypass box. i'm betting it doesnt' even hit unity gain, and it's never bypassed. and you can't "crank it up"... there is one trimmer on an echoplex for the recording level of the tape, and that's it. you can crank it up to where the tape saturates, but that has ZERO effect on the dry signal.

hey pinkjimiphoton

if you look at the schem in the original echoplex manual, you will see the the output from the buffer splits off in two ways -
1. it goes through a decent amount of resistors to get to the dry output (volume reduced)
2. it goes to the record level (500K) pot to set the record level.

in my layout the circuit takes the output from the record out pot (500k), which is why you get some boost.

cheers

[pinkjimiphoton]

i am seriously gonna a/b my echoplex ep3 with a true bypass box. i'm betting it doesnt' even hit unity gain, and it's never bypassed. and you can't "crank it up"... there is one trimmer on an echoplex for the recording level of the tape, and that's it. you can crank it up to where the tape saturates, but that has ZERO effect on the dry signal.

hey pinkjimiphoton

if you look at the schem in the original echoplex manual, you will see the the output from the buffer splits off in two ways -
1. it goes through a decent amount of resistors to get to the dry output (volume reduced)
2. it goes to the record level (500K) pot to set the record level.

in my layout the circuit takes the output from the record out pot (500k), which is why you get some boost.

cheers

i get that, bro.

my point is, the actual echoplex does not boost the signal like the guys who started pimping this circuit claim.

not YOUR circuit.

my beef is witht he guys misleading people into believing the hype that "the pros knew about this secret ep3 preamp and the boost it gave them"....that it not only didn't, but couldn't.

peace

[ulysses]

i get that, bro.

my point is, the actual echoplex does not boost the signal like the guys who started pimping this circuit claim.

not YOUR circuit.

my beef is witht he guys misleading people into believing the hype that "the pros knew about this secret ep3 preamp and the boost it gave them"....that it not only didn't, but couldn't.

peace

oh yeah i see what youre saying

i forgot about the mojo factor

for me i build sh*t and use my ears - if it sounds good, it flies, if it doesnt it gets desoldered.

there is some truth to the mojo though, insofar as our brains actually trick us into thinking something sounds better if we believe in the mojo. sounds crazy, but my wife (a psychologist) tells me it's true.

i would also say that sometimes those "engineer secrets" do turn out to actually sound really good. just chance? illusion? or something that filtered through the years of sweating over the console?

cheers

EDIT: just had a quick look at it does seem that some boutique builders have been making ep3 based circuits. i only had a cursory glance, but from the looks of them they are even further from the original circuit than mine. again, at the end of the day, if it sounds good.. but it is frustrating to think you are "buying" an original circuit when you are not. ie, when jim dunlop released an opamp wah and called it the Jimi Hendrix wah.
i just saw an advert for the EP3 dunlop pedal on the last page of guitar world july 2014 and figured i'd build my own to see if it was any good - to my surprise it did sound pretty good.

[pinkjimiphoton]

i get that, bro.

my point is, the actual echoplex does not boost the signal like the guys who started pimping this circuit claim.

not YOUR circuit.

my beef is witht he guys misleading people into believing the hype that "the pros knew about this secret ep3 preamp and the boost it gave them"....that it not only didn't, but couldn't.

peace

oh yeah i see what youre saying

i forgot about the mojo factor

for me i build sh*t and use my ears - if it sounds good, it flies, if it doesnt it gets desoldered.

there is some truth to the mojo though, insofar as our brains actually trick us into thinking something sounds better if we believe in the mojo. sounds crazy, but my wife (a psychologist) tells me it's true.

i would also say that sometimes those "engineer secrets" do turn out to actually sound really good. just chance? illusion? or something that filtered through the years of sweating over the console?

cheers

EDIT: just had a quick look at it does seem that some boutique builders have been making ep3 based circuits. i only had a cursory glance, but from the looks of them they are even further from the original circuit than mine. again, at the end of the day, if it sounds good.. but it is frustrating to think you are "buying" an original circuit when you are not. ie, when jim dunlop released an opamp wah and called it the Jimi Hendrix wah.
i just saw an advert for the EP3 dunlop pedal on the last page of guitar world july 2014 and figured i'd build my own to see if it was any good - to my surprise it did sound pretty good.

well, think about it. an echoplex is buffered. and it rolls off a little high end.

so yeah, it will make many amps sound a bit smoother. but it's not "boosting".

thanks for understanding why i get nuts about this. i've overdriven the circuit in my plex myself and it sounds great. if ya like that sound. and ya got the delay time slider all the way to the left..... ya can get a pretty cool double.

but how a circuit that cuts gain is a booster.... (and the snake yomps back on it's tail...)


you can make a fuzzbox outta damn near anything.

any preamp will tend to sound good if it's pushing an amp to distortion. some better than others. if it sounds good, i agree, it IS good.

[Gus]

Did you miss what makes this circuit a little different?   
The source RC values note take the collector C away or make it a big value the peak at 4KHz is reduced
Also the 100K and 220pf are a lowpass

So you have a lowpass input filter to a gain stage that has a high pass bump
I am guessing this was done to reduce RF into the EP and then boosting the highs for recording to the tape.