EHX - Polychorus

lofibrian · Post by **lofibrian** » 04 Sep 2009, 20:51

I think alot of people would love a modernized polychorus. More true to the original circuit. I bought my RI hoping to dial in Nirvana's RFUS tones from kurts hand written settings...But the RI is very different.

sfx · Post by **sfx** » 05 Sep 2009, 03:24

soulsonic wrote:Hey! I've been repairing alot of these lately for a customer who collects them. I've worked on two Echoflangers, and now I'm working on a couple PolyFlangers. They really are incredible sounding effects.
I can provide some more photos if any are needed, though Nelson's pdf pretty much gives all you need, and I've found it a very useful reference while doing my repairs because his layout matches the original's very closely.

I've found that when fixing them up, replacing all the electrolytic caps will go a long way towards helping it to sound new again. Most of the chips seem to hold up ok, but sometimes you'll get a bad SAD1024... and that can be a problem to replace. One of the ones I'm working on right now appears to have a bad switching chip, but those are cheap and easy to replace.

I'd love to design a modern version that uses commonly available BBD chips.

Yes, I was thinking of giving that a shot myself. Convert the Reticon chips to MN3007's or 3207's for sure. Add a blend knob for good measure and you'd have one dynamite chorus/flanger/noisemaker.

Soulsonic, do you know if that specific rotary switch is still available?

SonOfChaos · Post by **SonOfChaos** » 05 Sep 2009, 07:33

I'm REALLY broke and out of work now, but assuming I get the job next week I can kick someone some cash for parts so they can build 2

borislavgajic · Post by **borislavgajic** » 05 Sep 2009, 11:36

I'd love to design a modern version that uses commonly available BBD chips.

that is nice.....

soulsonic · Post by **soulsonic** » 05 Sep 2009, 20:17

sfx wrote:Soulsonic, do you know if that specific rotary switch is still available?

I've seen a couple different ones used in different units I've worked on. Any DP4T rotary should work fine. Small Bear sells one that's intended as a replacement, but I think it's for the newer ones because the pins don't match up with the layout on the board and the shaft is knurled instead of D style. But even with that being the case, you could still use that one with a little extra work.

sfx · Post by **sfx** » 07 Sep 2009, 18:10

Yeah, I have used one of the Small Bear ones as to fix a RI Stereo Poly. Its a drop in replacement on that one.

echiurco · Post by **echiurco** » 08 Sep 2009, 00:11

Sorry for the offtopic guys, but, wha power supply should I use for this pedal??

Thanks!!

PmCimini · Post by **PmCimini** » 29 Sep 2009, 00:06

EH has a version of this pedal. What kind of BBD circuitry do they use?

Any gutshots?

http://www.ehx.com/products/stereo-polychorus

sfx · Post by **sfx** » 02 Oct 2009, 02:36

The stereo reissue has a MN3008 and a MN3009 in it.

analogkid · Post by **analogkid** » 02 Oct 2009, 03:51

Hey all, it's real cool to see a thread devoted to talk about the Echoflanger, uhmm Polyflanger , uhmm I mean Polychorus

Not to mention a whole corner devoted to vintage pedals!! I've never posted on this site before as I don't do the forums much anymore but since this device is very sentimental to me I thought I'd holler out. I am actually the guy who cloned the EF a few years back...at least at that time there was no others to be found who'd done it. It took a couple months of lots of research into all the versions schems/b.t.p's/pics for component markings, alot of data sheet reference etc.. but it's just a wonderful thing and the only way I apparently was ever going to own one. Dirk who I seen here "might" have been one of the one's whom had an original gut shot that really allowed it to get done iirc not sure. So anyway at least used to know a great deal about this bad boy. maybe if I get around to it I throw up pics of it if anyone wants. I actually showed it a my booth at the southern ohio guitar show a couple weeks ago , it usually gets a few people's eyes(ears)
I'll have to come back more often for the vintage fx thread, next up the incomparable PolyPHASE (which I did the same thing with but have done many of those for others too) Sort of sucks to me at least the Mathews(EH) reissued these things (and more) pretty much right after I had pulled off 'cloning' them to the 'T'. But it's sort of odd too that far as I know none are real reissues! Espec. the PPhase it's nothing really like the original.
Later on

SonOfChaos · Post by **SonOfChaos** » 02 Oct 2009, 04:15

Way too go man! Cloning the Polychorus looks like an absolute biatch of a project. Just curious, after you figured that sucker out how long did it take you to build one?

analogkid · Post by **analogkid** » 02 Oct 2009, 04:32

Oh btw should point out now that Paul(great dude by the way) who I just noticed mentioned here, who used the gut shots to draw the pcb that I used (pretty much replica of the orignal with nicer tight race track traces and I scoured up all the technical data on it that I could and he and I went back and forth quite alot during the time I was building and tweaking that monster. WOuldn't have done it without him. I didn't know if that pdf was a public known one or not so I didn't mention it. BTW not sure if anyone has tried to make one using off of that document , by know probably, but there are a few things not in there and or not correct I'd be happy to help with if someone ever needs be. Mine is True bypass rather than ic switching btw.
well after figuring it out (so to say) there was ALOT of tweaking especially around that bitch of a companding section during the process of building it actually. As such complex crkt designs should be done in sections IMHO, and I'm not even talking about the tweaking of the trimmers obviously yet , which as those who have worked on alot of them know can be a bit of a 'back and forth' in a couple of spots. There's a very precise way to adjust those 7 trimmmers(iirc) which I doubt I'll ever forget as many times as I ran through that process

PmCimini · Post by **PmCimini** » 02 Oct 2009, 04:47

analogkid wrote:Oh btw should point out now that Paul(great dude by the way) who I just noticed mentioned here, who used the gut shots to draw the pcb that I used (pretty much replica of the orignal with nicer tight race track traces and I scoured up all the technical data on it that I could and he and I went back and forth quite alot during the time I was building and tweaking that monster. WOuldn't have done it without him. I didn't know if that pdf was a public known one or not so I didn't mention it. BTW not sure if anyone has tried to make one using off of that document , by know probably, but there are a few things not in there and or not correct I'd be happy to help with if someone ever needs be. Mine is True bypass rather than ic switching btw.
well after figuring it out (so to say) there was ALOT of tweaking especially around that bitch of a companding section during the process of building it actually. As such complex crkt designs should be done in sections IMHO, and I'm not even talking about the tweaking of the trimmers obviously yet , which as those who have worked on alot of them know can be a bit of a 'back and forth' in a couple of spots. There's a very precise way to adjust those 7 trimmmers(iirc) which I doubt I'll ever forget as many times as I ran through that process

Whoa, really good to see people that are really into EH's old designs. I am a very big fan of all of them too. Have a couple of projects to start when I get a break from college (breadboarding the rackmount EH synth!), but I have a couple of questions about the PolyFlange.

Are all of the circuits the same? I mean, as sfx said, I took a look at the reissue schematic and it has indeed a MN3008 and a MN3009 (which is funny, because this isn't an easy-to-acquire BBD), and Electroconducive has the factory schematics (and a nice project) on the old version, the EchoFlanger, that has two SAD1024, but I only counted 4 trimpots. Which version are you talking about? The controls are the same in all versions, but I wish I could see gutshots of the original device.

Welcome at freestompboxes.org

PmCimini · Post by **PmCimini** » 02 Oct 2009, 05:06

Now that I checked, the reissue apparently has 7 trimpots.

Ry · Post by Ry » 02 Oct 2009, 22:18

I assume everyone has seen this page (with echoflanger and polyphase projects among others):

http://electroconducive.googlepages.com ... veprojects

chicago_mike · Post by **chicago_mike** » 09 Oct 2009, 05:54

Can we design a drop in board for replacing the 1024 and use a 3007 or similar?

cap10random · Post by **cap10random** » 22 Nov 2009, 14:17

Ry wrote:I assume everyone has seen this page (with echoflanger and polyphase projects among others):

http://electroconducive.googlepages.com ... veprojects

has anyone tried this? i really want a polychorus.

bumblebee · Post by **bumblebee** » 25 Dec 2009, 11:11

lofibrian wrote:I think alot of people would love a modernized polychorus. More true to the original circuit. I bought my RI hoping to dial in Nirvana's RFUS tones from kurts hand written settings...But the RI is very different.

Its not different (well it is but it sounds almost identical) and you can dial in the RFUS intro noise 100% perfectly. Its the knob locations that have changed hence kurts hand drawn notes dont line up with the knobs on the new PC. You need to convert the notes to the new current knob locations,thats all it is!

See this is kurts polychours:

And this is the current one. Notice the controls are in different places,once you convert his notes you will get RFUS sounds!!!

kmoore · Post by **kmoore** » 22 Feb 2010, 16:45

I've got a Polychorus open on my desk right now, issue is that when switched off, gain is lost. switches on fine. I'm thinking the problem lies with the switch.

Anyone know the model # of the switch?

bumblebee · Post by **bumblebee** » 23 Feb 2010, 09:19

Its just a standard alpha DPDT slide switch like this:
http://www.smallbearelec.com/Detail.bok?no=37

Google "switchcraft dpdt slide switch" for the switchcraft/mouser part numbers. I have them somewhere but cant be fucked looking through tons of bookmark folders for them.

Or unless you mean the stompswitch then its just a regular 3PDT like this:
http://www.smallbearelec.com/Detail.bok?no=20

EHX - Polychorus [schematic]