Echoplex Restoration Story

[Xplorer]

some more

[Xplorer]

mh ... too bad.. I thought that increasing the resistance value of the trimer on the nortronic board would increase the level of ustain too ... but it's the opposite, measuring a piher trimpot aside, it decreases the presence of the sustain, and when on zero ohms, it's at its max.
i still don't understand why the sustain pot doesn't work as early as the one of the other ep3.
everything is maxed out, except the volume pot which seems to work as it should, but maybe very early in his reaction.
so .. bug ? transistors not working as they should ?
i didn't touch the tis58 installed.

letting a 1M resistor to touch the pins 1 and 3 of the 1M sustain pot, making it a 500k pot didn't change anything, but i didn't solder it. well, a 1M pot works there ...

i'm wondering which components to play with, for their values, affecting different stuffs.

the variable cap seems to be a nice spot to try, increasing the capacitance. it affects the echo presence, so it may perhaps affect the sustain presence ...

did you guys seen some differences, when playing with some values ?

[Xplorer]

... I noted the transistor's voltages, they seem not bad.

Q1 : e = 0,6485 v versus 0,6v in the schematic
b = 1,2824 v ....... 1,2v
c = 3,09 v ....... 3v

Q2 : e = 2,459 v ....... 2,4v
b = 3,085 v ....... 3v
c = 13,366 v ....... 15v

Q3 : e = 0,3758 v ....... 0,4v
b = 0,987 v ....... 1v
c = 11,654 v ....... 12,2v

Q4 : e = 1,16 v to 1,23 v ( varies a bit ) ....... 2,2v
b = 1,7 v verus ... not sure what it's written ... 10v ? 1,4v ? 14v ?
c = 13,53 v ....... 14,3v

Q5 : G = 0 v ....... 0v
S = 1,26 v ....... 1,1v
D = 11,56 v ..............................................

this is where i'm confused with the schematic, may i ask you what's your voltage guys please ?
between D and one side of C12, i have 11,56 v. the schematic says nothing there. on the other side of C12, the schematic says 14,4 v, and i measured zero volts !!!! this point is just between this side of the orange C12, and one side of the record level pot, connected by this little yellow wire.

[Tazin]

For Q4 the schematic says:
Q4: e = 2.2v
b = 1.6v
c = 14.3v

The other side of C12 (junction of C12 and record level pot) should probably read zero volts since C12 is blocking the dc voltage like it should to only allow the ac voltage to pass. I think they only placed that reference voltage (14.4v) there on the schematic since it wouldn't fit on the other side.

[rgorke]

Here's what I did to improve sustain. Have you set the trimmers on the Nortronics board and the Q1/Q2 boards? I noticed having to balance these trimmers to maximize the sustain. I did not use a scope on it, I did it by ear and got it good results.

[Xplorer]

Well, the trimmer on the q1/q2 board seems to have no effect, bit i think that it's dedicatef to the sos circuit ( ? )

[Xplorer]

oh, sorry, i didn't see your answer first, thanks Tazin.
Yes, so it seems to work as it should ...

i'll take some measurments on my ep3 I, and eventualy swap some boards, to locate some different effects on the way the ep3 works ...and see why. it could be interesting.

the voltages on the nortronic board, from what i remember, weren't so right, on these two transistors.

i which the heads could be oriented more easyly... it's tough to move them right. The tape's center is maybe too far from the center of the playback head ... it may affect everything. I should work on the bridge's chassis, to have the mounting hole wider, so this way i could place the head more on the bottom, meeting the tape in a better way perhaps.
The sos head didn't work at first, i moved it a bit and finaly it works.

For Q4 the schematic says:
Q4: e = 2.2v
b = 1.6v
c = 14.3v

The other side of C12 (junction of C12 and record level pot) should probably read zero volts since C12 is blocking the dc voltage like it should to only allow the ac voltage to pass. I think they only placed that reference voltage (14.4v) there on the schematic since it wouldn't fit on the other side.

[Xplorer]

So ... today i worked on the ep3 I ...
i changed the wrong 0,1uf electrolytic for a1uf tantalum, and swapped the other 1ug of the preamp board, by another tantalum.
i also added in parrallel a 330pf ceramic cap, to the 150pf ( max ) variable cap, so it offers more range, ( 150 variable + 315 pf ), under the board. ( there was previously a 270pf in parrallel, on the top of the variable cap ) but anyway, changing the values doesn't seem to affect anything on this ep3, while it does a lot, on the ep3 II ( ?? )

i cleaned this ep3 I, changed the tape, demagnetized it. It works perfectly, very beautiful sound, and should i tell again how much i love my jtm 45/100 ?
with the vintage electric mistress it's heaven. i really have to do several clips about ep3's, fuzz etc ... didn't yet.

i think i'll start to swap some boards between the two ep3's, to see where it may bug.

the ep3 I has some mps8098 i think, and the ep3 II has some tis98, 240hfe. i think that it may affect the definition of the echo ... maybe too gainy, not sure.
if i had some nice stuffs just to clips some transistors and swap them easyly, this would be nice ... i think i tried once but it wasn't the best model of connector for this.

i'll add a little ceramic disc 100 pf, to the 380pf ( max ) variable cap, on the ep3 II. it should help. the ceramic disc there seems to be good for the tone, although i'm not sure yet.

what resistors values, or caps values, or transistors , and in which spots may improve the echoplex ? what do you think ?

[Xplorer]

Endly did a little clip, playing arround with the Echoplex I, not II that i restored. I think this one sounds better than the other one but i didn't have time to figure this out. i just replaced three 1uf caps by some tantalums, correcting one 0,1uf by a 1uf basicaly.
recorded on a 1x12 celestion pre rola G12H30 75hz, JTM 45/100 ( attenuated ) , strat into an early electric mistress then in the echoplex. and also without the electric mistress. Recorded with a pair of nice Ribbon mics, but the result isn't so much professional, i didn't spend much time on it, and it's in my room.

http://soundcloud.com/xplorer80/130416-ep3-one-jtm" onclick="window.open(this.href);return false;

[rgorke]

That sounds fantastic. So organic. That is what I love about the Echoplex, so natural, nothing sterile.

Well done! And, now get that other one up and sounding like this one.

[Xplorer]

thanks man. Yes, very organic.
the echoes aren't copys of the original signal. if you listen carefuly, you'll notice some tape saturation, some specific frequencys ... at 4:22 it ays a lot.
it really transforms the signal. i don't really care about the preamp hype.
anyway, it brings things that make you comfortable to play, it's like it allways sounds good whatever you do.

i forgot to show the self oscillation. sorry it's been compressed and it's clipping a bit sometimes.
sustain pot at noon only ! ( ep3 II needs the sustain pot at max, and doesn't even really self oscillate ! )
i don't know why this one sounds great. one thing though is that after about an hour of playing, the echoe starts to do some wow, warble ... i don't know if it's about the motor getting hot, not working with a linear response , or anything else ..
it's doing some quick vibratos.

past 10 -11 o' clock on the echo volume, it starts to get unuseable, the echo is too loud and the background noise starts to be too present. at 5 pm, it's so loud. maybe something wrong with my ep3 as allways,k but i prefer to set the recording level pot at max, so i don't need to cranck the volume pot and get some unwanted background noise. it gives quite a nice ratio of echo volume - signal - background noise, this way, with the echo volume at 9 o'clock.

the ep3II needs the echo volume close to max ! big difference in their behaviors. still didn't have the time to swap some boards and see if it's about some mechanics, or some electronic, and then on which board, or which ensemble of reasons.

ep3 I has some carbon comp resistors, "new". ep3 II has some piher carbon film resistors "new"

quantegy 478 for the tape, it works perfectly.

[rgorke]

On my #2 unit, I also need to crank the echo volume and sustain to get the oscillations. When I do that, the hiss becomes really noticeable. I am convinced it is a trim pot adjustment. My #1 unit will do endless "nearly" perfect repeats.

I also had on of my tape cartridges malfunction. I am guessing my splice came undone. The tape wound it self around the capstan, nearly freezing the motor.

[garbeaj]

Endly did a little clip, playing arround with the Echoplex I, not II that i restored. I think this one sounds better than the other one but i didn't have time to figure this out. i just replaced three 1uf caps by some tantalums, correcting one 0,1uf by a 1uf basicaly.
recorded on a 1x12 celestion pre rola G12H30 75hz, JTM 45/100 ( attenuated ) , strat into an early electric mistress then in the echoplex. and also without the electric mistress. Recorded with a pair of nice Ribbon mics, but the result isn't so much professional, i didn't spend much time on it, and it's in my room.

http://soundcloud.com/xplorer80/130416-ep3-one-jtm" onclick="window.open(this.href);return false;

Great Caesar's Ghost! That sounds amazing...the Electric Mistress is the shit! Is that the one with the green lettering? The echo is unbelievable of course...putting that with the Echoplex sounds almost exactly like Mike Rutherford's "Follow You, Follow Me" tone, especially when you are trying the Gilmour "Another Brick In The Wall (Part 1)" licks. Jesus I could play with that sound for days!

[Xplorer]

Wow, thanks man ! i appreciate.
i'm sure that it could be improved.
the electric mistress, especialy when placed in front of the echoplex sounds the best to my ears, but unfortunately some kind of wierd oscillation "bump" occurs too if you listen carefully. and you can't really cranck some of the electric mistress settings. My friends who have such setup told me they had the same thing happening. But ... anyway it's a lot of fun to play anyway.
the electric mistress, the vintage one, yes, early one from the 70's and with the Reticon SAD 1024 .... that's the best ......

if you play the clip loud, you'll maybe notice , on some parts, that it sounds quite natural, that's thanks to my beloved ribbon mics ^^ .

that's just it :

[vanhalen5150]

Sounds great. Pass the bong.