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EHX - Electric Mistress 18v Version 2 1976

PostPosted: 06 Jun 2018, 13:27
by bettsaj
I'm planning my next pedal build, and this is going to be a biggy.

I want to build as accurately as possible a version 2 18v Electric Mistress. I've started researching this pedal as much as possible, apart from correcting the notorious volume drop i want to make it as authentic as I can..... Pretty much as I did with my Colorsound Powerboost and Violet Rams Head clones. if need be i'll print and etch my own board ideally cloning from an original, and build it using as many vintage correct parts as possible.

around Christmas time i was lucky enough to post something on the Farnell forum regarding this, and a kind gentleman in Holland contacted me and said he had 2 or 3 SAD1024 IC's that he didn't want. All are NOS and surplus to requirements. Long story short he sent them to me for free and I just paid the postage. With that in mind I've started to assemble the components required for the build, but i'm still having issues with a PCB. This is where you guys come in...... Has anyone here got a PCB trace of a 18v EM board, or can you point me towards one. I've looked everywhere and have hit brick wall upon brick wall.

Secondly, looking at the schematic, does anyone know what the workaround is for correcting the volume drop on these pedals. If i can alter slightly the PCB layout (when I eventually get one) to accommodate the modification I can do that at design stage.

1976-electric-mistress-v2-schematic.gif

Re: Electric Mistress 18v Version 2 1976

PostPosted: 07 Jun 2018, 23:40
by AuditoryDriving
Adjust the IC1b resistors for more gain or replace them with trimpots! I cannot take credit for this, i think it was Skreddy who first proposed it,there s a post of his about it somewhere. I've done the same on my dem and it worked like a charm :)

Good luck!!

Re: Electric Mistress 18v Version 2 1976

PostPosted: 11 Jun 2018, 09:16
by MetalPose
I guess increasing the gain before SAD1024 will cause clipping.
I increased the two 47nF capacitors (after the SAD1024 and for the dry path) and decreased the 13K and 10K resistors to the same ratio in my V2 18V Electric Mistress. I could scan the pcb of my pedal if that helps.

Re: Electric Mistress 18v Version 2 1976

PostPosted: 11 Jun 2018, 11:33
by bettsaj
MetalPose wrote:I guess increasing the gain before SAD1024 will cause clipping.
I increased the two 47nF capacitors (after the SAD1024 and for the dry path) and decreased the 13K and 10K resistors to the same ratio in my V2 18V Electric Mistress. I could scan the pcb of my pedal if that helps.


A scan would be great! I already have a few that I got off the net but they're not all that clear to be honest.... it's the trace side i'm interested in, and also the PCB dimensions

Re: EHX - Electric Mistress 18v Version 2 1976

PostPosted: 12 Jun 2018, 10:18
by MetalPose
I scanned it but it's blurry, i hope it works for you.
If you create the pcb, could you share it here?

Re: EHX - Electric Mistress 18v Version 2 1976

PostPosted: 12 Jun 2018, 10:19
by MetalPose
I forgot to add dimensions,
11.5 cm x 10.3 cm

Re: EHX - Electric Mistress 18v Version 2 1976

PostPosted: 13 Jun 2018, 12:53
by DrAlx
I spent a long time reworking that circuit and fixing all its problems. In particular the noise and volume drop.
Search for "18V Electric Mistress with reworked LFO & VCO" and you'll find all the details on one of the other sites.

Re: EHX - Electric Mistress 18v Version 2 1976

PostPosted: 13 Jun 2018, 18:47
by MetalPose
DrAlx wrote:I spent a long time reworking that circuit and fixing all its problems. In particular the noise and volume drop.
Search for "18V Electric Mistress with reworked LFO & VCO" and you'll find all the details on one of the other sites.

With shielded cables and TL072, mine is pretty silent and with the mod that i’ve done in addition to the blondegraemey’s mod, it’s unity.