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Doepfer A132-3 Dual VC Bleed

2019-04-08 by neal@neallayton.co.uk

Hello all.

I’ve just noticed an unusual behaviour on my A132-3 Dual VCA

With no gain and 0 cv the bottom channel is letting bleed through.

It seems to be on linear mode only, and it is easily audible. Top channel is fine.

Looking at the pcb my module is a v2 revision with two TL074CN IC’s and and one V2146D IC.

https://www.dropbox.com/s/0kgmlmhitb21ix8/A132-3.JPEG?dl=0

If anyone can advise it would be really helpful as I need to use the module to gate two channels of samples at a theatre event soon. The sample material suits a linear response, so I really need both channels to open and close at a similar rate, and to close to silence!

Many thanks,

Neal

BTW It’s a small LC1 rack, though I’ve tried it in my LC 3 and LC 6. I’m also using a recently purchased Doepfer A140-2 which I completely love. It pairs with the A132-3 really well and is so compact and useful, especially for stereo signals and twin voices. Would recommend it to anyone wanting to save HP.

Re: [Doepfer_a100] Doepfer A132-3 Dual VC Bleed

2019-04-08 by Diego Ragnini

I firstly thought that it could also depend by the gate or the envelope generator you’re using (if any), then I recall that some VCA are used not to close completely, finally I read that your VCA is mounted on a low cost case so I am afraid it might depend on the floating ground. I had similar issue and users here had helped me. That kind of case need to be grounded. But wait for further advice coming from other users. Best, dxx

Show quoted textHide quoted text

> Il giorno 08 apr 2019, alle ore 18:37, neal@neallayton.co.uk [Doepfer_a100] <Doepfer_a100@yahoogroups.com> ha scritto:
> 
> 
> Hello all.
> 
> I’ve just noticed an unusual behaviour on my A132-3 Dual VCA
> 
> With no gain and 0 cv the bottom channel is letting bleed through.
> 
> It seems to be on linear mode only, and it is easily audible. Top channel is fine.
> 
> Looking at the pcb my module is a v2 revision with two TL074CN IC’s and  and one V2146D IC.
> 
> https://www.dropbox.com/s/0kgmlmhitb21ix8/A132-3.JPEG?dl=0 <https://www.dropbox.com/s/0kgmlmhitb21ix8/A132-3.JPEG?dl=0>
> 
> If anyone can advise it would be really helpful as I need to use the module to gate two channels of samples at a theatre event soon. The sample material suits a linear response, so I really need both channels to open and close at a similar rate, and to close to silence!
> 
> Many thanks,
> 
> Neal
> 
> 
> BTW  It’s a small LC1 rack, though I’ve tried it in my LC 3 and LC 6. I’m also using a recently purchased Doepfer A140-2 which I completely love. It pairs with the A132-3 really well and is so compact and useful, especially for stereo signals and twin voices. Would recommend it to anyone wanting to save HP.
> 
> 
>

AW: [Doepfer_a100] Doepfer A132-3 Dual VC Bleed

2019-04-09 by yahoo@doepfer.de

Hello,

V2 is an older version from 2010. Due to tolerances of the V2164D sometimes
the VCA does not close with CV=0. To avoid this a high value resistor (e.g.
4M7) has to be added between pin 4 (upper VCA) or pin 5 (lower VCA) of the
V2164 and -12V. This adds a small negative voltage to the CV summing
node. -12V is available e.g. at pin 9 of the V2164 or the wire bridge "J1"
below the V2164.

In V3 and V4 of the module the 4M7 resistors have been added.

Hope this helps
Dieter Doepfer

Show quoted textHide quoted text

> Hello all.
>
>
> I’ve just noticed an unusual behaviour on my A132-3 Dual VCA
>
>
> With no gain and 0 cv the bottom channel is letting bleed through.
>
>
> It seems to be on linear mode only, and it is easily audible. Top
> channel is fine.
>
>
> Looking at the pcb my module is a v2 revision with two TL074CN
> IC’s and  and one V2146D IC.
>
>
> https://www.dropbox.com/s/0kgmlmhitb21ix8/A132-3.JPEG?dl=0
>
>
> If anyone can advise it would be really helpful as I need to use
> the module to gate two channels of samples at a theatre event
> soon. The sample material suits a linear response, so I really
> need both channels to open and close at a similar rate, and to
> close to silence!
>
>
> Many thanks,
>
>
> Neal
>
>
> BTW  It’s a small LC1 rack, though I’ve tried it in my LC 3 and
> LC 6. I’m also using a recently purchased Doepfer A140-2 which I
> completely love. It pairs with the A132-3 really well and is so
> compact and useful, especially for stereo signals and twin
> voices. Would recommend it to anyone wanting to save HP.
>
>
>
>
>
>

Re: [Doepfer_a100] Doepfer A132-3 Dual VC Bleed

2019-04-10 by Neal Layton

Dear Dieter,

Amazing- thank you. I will solder a couple of hefty 4M7 R’s in those places.

Thank you for taking the time to reply personally, and for creating this wonderful world of sound for us to explore.

Best wishes,

Neal

Show quoted textHide quoted text

> On 9 Apr 2019, at 12:07, yahoo@doepfer.de [Doepfer_a100] <Doepfer_a100@yahoogroups.com> wrote:
> 
> Hello,
> 
> V2 is an older version from 2010. Due to tolerances of the V2164D sometimes
> the VCA does not close with CV=0. To avoid this a high value resistor (e.g.
> 4M7) has to be added between pin 4 (upper VCA) or pin 5 (lower VCA) of the
> V2164 and -12V. This adds a small negative voltage to the CV summing
> node. -12V is available e.g. at pin 9 of the V2164 or the wire bridge "J1"
> below the V2164.
> 
> In V3 and V4 of the module the 4M7 resistors have been added.
> 
> Hope this helps
> Dieter Doepfer
> 
> 
>> Hello all.
>> 
>> 
>> I’ve just noticed an unusual behaviour on my A132-3 Dual VCA
>> 
>> 
>> With no gain and 0 cv the bottom channel is letting bleed through.
>> 
>> 
>> It seems to be on linear mode only, and it is easily audible. Top
>> channel is fine.
>> 
>> 
>> Looking at the pcb my module is a v2 revision with two TL074CN
>> IC’s and  and one V2146D IC.
>> 
>> 
>> https://www.dropbox.com/s/0kgmlmhitb21ix8/A132-3.JPEG?dl=0
>> 
>> 
>> If anyone can advise it would be really helpful as I need to use
>> the module to gate two channels of samples at a theatre event
>> soon. The sample material suits a linear response, so I really
>> need both channels to open and close at a similar rate, and to
>> close to silence!
>> 
>> 
>> Many thanks,
>> 
>> 
>> Neal
>> 
>> 
>> BTW  It’s a small LC1 rack, though I’ve tried it in my LC 3 and
>> LC 6. I’m also using a recently purchased Doepfer A140-2 which I
>> completely love. It pairs with the A132-3 really well and is so
>> compact and useful, especially for stereo signals and twin
>> voices. Would recommend it to anyone wanting to save HP.
>> 
>> 
>> 
>> 
>> 
>> 
> 
> 
> 
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