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Thread

UAP as DualVCA: bleedthru

2003-12-13 by jan-hinnerk.helms@t-online.de

Dear Smog,

done further patches with my [TKB] and Animal and having loads of great
fun with this enormously compact system. But this one thing puzzled me.

- Set the [UAP] to DualVCA
- [NTO] sine in [UAP] input 1
- [PCO] sine in [UAP] input 2
- [UAP] Pan/Fade to leftmost position
- [UAP] Gain to leftmost position
- 1/4" cables going from [UAP] output 1 and 2 to mixer

Result:
- [NTO] and [PCO] bleed thru to [UAP] output 1

Can anybody (un)confirm this?

On top of that, even with nothing patched but just the 1/4" cables
going from the [UAP] outs to mixer , I can still hear the [NTO] and
[PCO] bleeding thru to both outputs. If I patch the DTG's to oscillate
in the audio range, I can them going, too. John P., does this look like
the grounding issue you described on Egres/Wizardry intro?

Thanks in advance,
best regards,
Jan-Hinnerk

Re: UAP as DualVCA: bleedthru

2003-12-13 by John P

Yes, this is exactly the same grounding problem I wrote about on EGRES.
When the grounding problem is solved the bleed problem will go away.

I've run the grounding tab on my mixer to the ground on the Serge power
supply, and that's caused this bleed problem also. Disconnecting the
mixer ground fixes the problem. But I'm not sure where the ground is at
that point. If it's thru the common AC ground, then maybe... but
otherwise there's no signal ground (the shield on the 1/4" is peeled
back on one side).

These grounding problems make me feel like a novice every time they come
up... maybe I should take a class.

Show quoted textHide quoted text

>in the audio range, I can them going, too. John P., does this look like
>the grounding issue you described on Egres/Wizardry intro?
>
>
>

Re: UAP as DualVCA: bleedthru

2003-12-13 by john duval

not being an electrical engineer i can't help you much
on this one except that this has been a subject of
much discussion on the list in the past. The VCAs on
the UAP don't attenuate to 0db if memory serves. I
have also had this experience with the UAP in my
system...which is one of the reasons i went to Dual
Channel Stereo Mixers and the QVMs on my setup. I
believe there is a work around for this but i'm not
sure. In my tests on your patch i forgot to use a
UAP..i used a DSM instead. I'll go back and test it
again useing UAP later on today and let you know the
results..as i still have your patch (in modified form)
up and running. Just about anyone else on this list is
more technicaly savy than i and should be able to help
you out. I'm really surprized at the lack of response
so far... or have they all posted to you privatly??
Kind regards
John DuVal

Show quoted textHide quoted text

--- jan-hinnerk.helms@... wrote:

> Dear Smog,
>
> done further patches with my [TKB] and Animal and
> having loads of great
> fun with this enormously compact system. But this
> one thing puzzled me.
>
> - Set the [UAP] to DualVCA
> - [NTO] sine in [UAP] input 1
> - [PCO] sine in [UAP] input 2
> - [UAP] Pan/Fade to leftmost position
> - [UAP] Gain to leftmost position
> - 1/4" cables going from [UAP] output 1 and 2 to
> mixer
>
> Result:
> - [NTO] and [PCO] bleed thru to [UAP] output 1
>
> Can anybody (un)confirm this?
>
> On top of that, even with nothing patched but just
> the 1/4" cables
> going from the [UAP] outs to mixer , I can still
> hear the [NTO] and
> [PCO] bleeding thru to both outputs. If I patch the
> DTG's to oscillate
> in the audio range, I can them going, too. John P.,
> does this look like
> the grounding issue you described on Egres/Wizardry
> intro?
>
> Thanks in advance,
> best regards,
> Jan-Hinnerk
>
>

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Re: UAP as DualVCA: bleedthru

2003-12-13 by Peter Grenader

Is the faceplate of the panel with the UAP grounded?

Is there a wire connected to ground on any of the PCBs run to an eyelet that
fits behind on of the four standoffs that hold the panels in place on the
faceplate end?

jan-hinnerk.helms@... wrote:

Show quoted textHide quoted text

> Dear Smog,
>
> done further patches with my [TKB] and Animal and having loads of great
> fun with this enormously compact system. But this one thing puzzled me.
>
> - Set the [UAP] to DualVCA
> - [NTO] sine in [UAP] input 1
> - [PCO] sine in [UAP] input 2
> - [UAP] Pan/Fade to leftmost position
> - [UAP] Gain to leftmost position
> - 1/4" cables going from [UAP] output 1 and 2 to mixer
>
> Result:
> - [NTO] and [PCO] bleed thru to [UAP] output 1
>
> Can anybody (un)confirm this?
>
> On top of that, even with nothing patched but just the 1/4" cables
> going from the [UAP] outs to mixer , I can still hear the [NTO] and
> [PCO] bleeding thru to both outputs. If I patch the DTG's to oscillate
> in the audio range, I can them going, too. John P., does this look like
> the grounding issue you described on Egres/Wizardry intro?
>
> Thanks in advance,
> best regards,
> Jan-Hinnerk
>
>
>
> To unsubscribe from this group, send an email to:
> SergeModular-unsubscribe@yahoogroups.com
>
> Keep on Patchin'!
>
>
> Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
>
>

Re: UAP as DualVCA: bleedthru

2003-12-14 by jan-hinnerk.helms@t-online.de

Dear John,

thanks, I checked the archive. Cuari7 asked the same in 1881, John P.
answered that it is possible to cure the [UAP] 2VCA bleed thru by
adjusting internal trimpots - but no details found.

Hi John P., hi Cuari7,

do you mind giving me some more details on what exactly needs to be
adjust - and if you succeeded on that? And what exactly did you do to
solve your bleed thru issue?

Looks like these two can be solved. Ahhh…that only leaves this dreaded
TKB Clock/KP to [VCM] bleed thru to be solved. Hopefully someday…

Thanks much,
kind regards
Jan-Hinnerk

Show quoted textHide quoted text

> Date: Sat, 13 Dec 2003 08:41:37 -0800 (PST)
> From: john duval
> Subject: Re: UAP as DualVCA: bleedthru
>
> not being an electrical engineer i can't help you much
> on this one except that this has been a subject of
> much discussion on the list in the past. The VCAs on
> the UAP don't attenuate to 0db if memory serves. I
> have also had this experience with the UAP in my
> system...which is one of the reasons i went to Dual
> Channel Stereo Mixers and the QVMs on my setup. I
> believe there is a work around for this but i'm not
> sure. In my tests on your patch i forgot to use a
> UAP..i used a DSM instead. I'll go back and test it
> again useing UAP later on today and let you know the
> results..as i still have your patch (in modified form)
> up and running. Just about anyone else on this list is
> more technicaly savy than i and should be able to help
> you out. I'm really surprized at the lack of response
> so far... or have they all posted to you privatly??
> Kind regards
> John DuVal
>
>
>
> ---metafoetus2002 wrote:
>> Dear Smog,
>>
>> done further patches with my [TKB] and Animal and
>> having loads of great
>> fun with this enormously compact system. But this
>> one thing puzzled me.
>>
>> - Set the [UAP] to DualVCA
>> - [NTO] sine in [UAP] input 1
>> - [PCO] sine in [UAP] input 2
>> - [UAP] Pan/Fade to leftmost position
>> - [UAP] Gain to leftmost position
>> - 1/4" cables going from [UAP] output 1 and 2 to
>> mixer
>>
>> Result:
>> - [NTO] and [PCO] bleed thru to [UAP] output 1
>>
>> Can anybody (un)confirm this?
>>
>> On top of that, even with nothing patched but just
>> the 1/4" cables
>> going from the [UAP] outs to mixer , I can still
>> hear the [NTO] and
>> [PCO] bleeding thru to both outputs. If I patch the
>> DTG's to oscillate
>> in the audio range, I can them going, too. John P.,
>> does this look like
>> the grounding issue you described on Egres/Wizardry
>> intro?
>>
>> Thanks in advance,
>> best regards,
>> Jan-Hinnerk

Re: UAP as DualVCA: bleedthru

2003-12-15 by darreljohansen

All of the VCA modules are very susceptible to stray noise. On some
units, shielded wire was used for many of the inputs and outputs.
You might try just opening the panel and moving wires aside to see
if you can reduce the coupling between one input and the sensitive
high-gain circuitry of the other channel.

Darrel Johansen