EHX - Soulpreacher

phibes · Post by **phibes** » 05 Jan 2012, 05:15

Bernardduur posted a schematic of the OTA SP in question above. Isn't the Low Frequency Compressor the same as the Black Finger?

pedalgrinder · Post by **pedalgrinder** » 05 Jan 2012, 05:56

The low frequency compressor uses and 10k resistor and and a 1uf cap to ground as a low pass filter there was two versions of it one was an ota the other which i like better used a transistor for attenuation. The blackfinger only came out in a out please correct me if iam wrong. as far as i understand and doesn't employ a low pass filter as the output of the ota heads straight in to the tone control. Hope that helps anyways.

R O Tiree · Post by **R O Tiree** » 01 Oct 2012, 17:45

trad3mark wrote:Hey all,

Searched for this, but there doesn't seem to be a thread. Apologies if there is!! Just wondering if anyone has one of these or has built one? I'm looking at building a compressor with the parts that i have and this one seems mighty nice. The schematic is all over the web, and there's two drawings of it:

Drawing 1:
http://www.montagar.com/~patj/soulprch.gif

Drawing 2:
http://www.schematics.ca/modules/PDdown ... 67&lid=473

It seems that Drawing 2 at schematics.ca has been removed. Has anyone got a copy handy, perchance?

Thanks

DrNomis · Post by **DrNomis** » 17 Oct 2012, 17:12

I've actually built a Soul Preacher compressor using schematics I found on the internet, one thing I did notice is that although my build worked well when first built, it had a couple of issues, firstly the sensitivity would slowly reduce till I couldn't tell whether it was doing any compressing, secondly the circuit had a nasty habit of suddenly saturating with gain and distorting, I also found that my build was very picky with the type of FET used, some FETs worked reasonably well while others didn't....

All in all, I think that the Soul Preacher is a bit of a finicky circuit to build and get going right.....

mrelwood · Post by **mrelwood** » 28 Oct 2012, 20:16

The schematics in this thread seemed to be all for the bigger Soul Preacher Vintage. I bought the Soul Preacher Nano (SMC board), and I would really love to get to see the schematic. Any hints?

The Nano is actually very good on the bass. There is a trimmer inside that can be adjusted to ease on the squish somewhat, and it made the pedal from overboard to very usable. Had my first gig with it last night. It's a keeper.

One peculiar issue is that if I power it from a splitter cable, whenever I connect the same power to another pedal that connects the power minus to signal ground, the signal output of the Soul Preacher Nano increases significantly. I think the compressor also squishes more that way. What I did as a quick fix was to connect the power minus connector to ground internally, and adjust the trimmer again.

If the schematic would allow, I would like to try a pot for the attack settings, and increase the range to even longer attack. I only use the long setting.

Sendy CZ · Post by **Sendy CZ** » 02 Dec 2017, 20:55

Pleas have anybody Soul Preacher with LM3080 - "PC4501" PCB?

I have one SP to repair, unfortunately somebody has exchanged some parts and some parts are missing.

borislavgajic · Post by **borislavgajic** » 21 Jul 2018, 20:36

Sendy CZ wrote:Pleas have anybody Soul Preacher with LM3080 - "PC4501" PCB?

I have one SP to repair, unfortunately somebody has exchanged some parts and some parts are missing.

this?
https://www.freestompboxes.org/download/ ... &mode=view
https://www.freestompboxes.org/download/ ... &mode=view

Manfred · Post by **Manfred** » 14 Aug 2018, 20:46

I love these old PCBs with the curvy conductor strips, so I made this PCB clone.

EXH_SoulPreacherSolderSide.pdf: (12.77 KiB) Downloaded 241 times

SprintLayout6-file:

EXH_SoulpreacherLay6.zip: (31.13 KiB) Downloaded 233 times

Manfred · Post by **Manfred** » 17 Aug 2018, 08:10

Here the meanings of the abbreviations on the wire symbols.
9V - +9 volts
BSNC - bypass switch normaly closed terminal
GND - ground
INP - input
OUT - output
Tr1 - threshold potentiometer terminal 1
Tr2 - threshold potentiometer terminal 2
TSCO - treble boost switch common terminal
TSNC - treble boost switch normaly closed terminal
Tr3 - threshold potentiometer terminal 3
VOL2 - volume potentiometer terminal 2
VOL3 - volume potentiometer terminal 3

graeme · Post by **graeme** » 15 Oct 2018, 08:51

Hi Folks,

I noticed that one of these schematics has some glaring mistakes in it. It is the one called "electroharmonix soul preacher.gif"
Specifically it shows the cathodes of the two rectifier diodes connected together (which they aren't) and also it shows the second opamp (the one associated with the rectifiers) being fed from the ac side of the 10uF dc blocking cap at the output of the first opamp. It should be connected directly to the output (pin 1) of the first opamp, so that it can get the dc bias from the first opamp.

Hope that all makes sense!!!!

Cheers

mictester · Post by **mictester** » 05 Apr 2025, 21:11

mictester wrote: ↑30 Nov 2011, 20:53
RnFR wrote:there are clippers on the output?
There have to be! They don't clip very much at all - they're there to handle the "overshoot" of the compressor. The compressor has a fairly slow attack, so the initial peaks can get chopped off by the diodes.

The other thing those diodes are doing is rectifying the output of the gain cell to provide a DC input to the sidechain circuit. It's a horrible way to do it!

mictester · Post by **mictester** » 23 Apr 2025, 14:14

trad3mark wrote: ↑29 Jan 2010, 13:09
Drawing 1:

One small improvement: I added a 47n capacitor in series with a 1MΩ resistor between drain and gate of the FET. This has the effect of reducing the 2nd harmonic distortion that you get as it starts to compress. If you like the slight distortion, don't fit my mod, but if you want cleanliness, it helps!

mictester · Post by **mictester** » 25 Apr 2025, 00:28

You can use 100n too:

The improvement is minor, but noticeable. Any value from 33n to 100n works OK.

EHX - Soulpreacher [schematic]