Author Topic: EHX Big Box PolyChorus Clock Setting  (Read 479 times)

GrindCustoms

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EHX Big Box PolyChorus Clock Setting
« on: November 29, 2023, 11:14:02 PM »
Hello there! A while ago i acquired a "vintage" Polychorus that was in perfect working order, at the same time i was fooling around with my OG Aquapuss and i pulled out the BBD from the PC to verify some stuff. Got the Aquapuss to work correctly, slapped in a known to work BBD in the Polychorus and never been able to get that thing to work again.

My BBD based effects tuning skills are not up to par right now and i'd need a refresh/guidelines on how to clock that effect properly.

If anyone have pointers, i'd be very grateful!

Cheers!
« Last Edit: November 30, 2023, 03:39:19 PM by GrindCustoms »
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Thewintersoldier

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Re: EHX Big Box PolyChorus MN3005 Clock Setting
« Reply #1 on: November 30, 2023, 11:44:16 AM »
poly chorus is the same circuit as the echo flanger. Follow the bias procedure in the lectric-fx dandy horse and you should be able to get it working, assuming your poly chorus uses the mn3005. Having built the dandy horse myself, it's not too bad.
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GrindCustoms

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Re: EHX Big Box PolyChorus MN3005 Clock Setting
« Reply #2 on: November 30, 2023, 01:16:50 PM »
poly chorus is the same circuit as the echo flanger. Follow the bias procedure in the lectric-fx dandy horse and you should be able to get it working, assuming your poly chorus uses the mn3005. Having built the dandy horse myself, it's not too bad.

Fantastic, i have built BBD effects before and had great results, for some reason this one just didn't want to cooperate.

Thank you!
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Bio77

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Re: EHX Big Box PolyChorus MN3005 Clock Setting
« Reply #3 on: November 30, 2023, 02:24:33 PM »
Are you sure it was a 3005?  I believe the original had a SAD1024 and later a MN3008 or MN3009.  If you have the right chips in there you should really only have to adjust the bias trims (2) to get it working.

GrindCustoms

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Re: EHX Big Box PolyChorus MN3005 Clock Setting
« Reply #4 on: November 30, 2023, 03:32:13 PM »
Are you sure it was a 3005?  I believe the original had a SAD1024 and later a MN3008 or MN3009.  If you have the right chips in there you should really only have to adjust the bias trims (2) to get it working.

I might have had it all wrong all along and that would certainly explain why i never got it to work back again. The operation mentioned in OP didn't happen in a single sitting but well spaced in between, I'll have to go back through both effects to clean up my self made dysfunction. Last time i played around it is 6-7 years ago.

Thank you for clearing up those details, i would have been chasing my tail for eternity... ...now i'm doubting myself that i used the BBD for the Aquapuss....

I'll grab some pictures and update, will likely help to clear up the mistakes!
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GrindCustoms

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Re: EHX Big Box PolyChorus Clock Setting
« Reply #5 on: November 30, 2023, 04:09:05 PM »
Quick update, MN3008 it is, printed on the PCB.... ...i'm feeling fabulous right now! HAHAHA!

Now to find one of those.....
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Bio77

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Re: EHX Big Box PolyChorus Clock Setting
« Reply #6 on: December 01, 2023, 12:42:52 AM »
Just looked up the data sheets: 3009 has 256 stages (it's small also), so, definitely not that one.  3008 has 2048 and 3005 has 4096.  I think the 3005 should be in the Aquapuss and the 3008 in the PC.  3008 seems long for a chorus but I know the VFE Choral Reef has one.

GrindCustoms

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Re: EHX Big Box PolyChorus Clock Setting
« Reply #7 on: December 01, 2023, 05:57:34 AM »
Just looked up the data sheets: 3009 has 256 stages (it's small also), so, definitely not that one.  3008 has 2048 and 3005 has 4096.  I think the 3005 should be in the Aquapuss and the 3008 in the PC.  3008 seems long for a chorus but I know the VFE Choral Reef has one.

Yep, and also why the 3008 that was originally in the PC would have worked in the AP and be able to set the clock correctly, just a shorter Delay time overall... ...but the way i used the AP was mostly for the fast slap back type of delay so shorter time wouldn't affect it's sound enough for to find it unusable. I think that is what I did.
I'm now going through my stash of pedal that i had stored to retrieve those chip and use actual 3005 in the AP and maybe load it off the collection.
The two analog delays i've been using for years now are the Maxon AD999 that is constantly ON in the loop of my Boogie MKIV, there's something very nice about the buffer/opamp section of that circuit that acts as a "mastering" in my loop, just have a minimum of delay dialed in to add a bit more depth. Ibanez AD-9 is what i use for the long repeats on my clean signal.

Although, like everything i might completely change my mind about the AP once i get it back in the loop and find something fun to do with it! lol
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LaceSensor

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Re: EHX Big Box PolyChorus Clock Setting
« Reply #8 on: December 01, 2023, 04:47:52 PM »
the reissue 1999 stereo big box polychorus uses two BBD lines for the different effects

There is indeed MN3008 for the chorus and double track (slapback delay) effect

If you struggle to find any legit chips let me know Rej, I can square you away

GrindCustoms

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Re: EHX Big Box PolyChorus Clock Setting
« Reply #9 on: December 01, 2023, 07:35:50 PM »
the reissue 1999 stereo big box polychorus uses two BBD lines for the different effects

There is indeed MN3008 for the chorus and double track (slapback delay) effect

If you struggle to find any legit chips let me know Rej, I can square you away

Ok, i think mine is a reissue EC-7000 RevD, appears to have been made in 2004. Second BBD is a MN3009.

I still have to unpack most of my electronic stash but i sure do appreciate the offer if can't find a MN3008 in there or in the AP, i'll let you know, much thanks mate!
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