the old (first) version A130 and A131 were ac-coupled, so, if you pass the A106-6 output from one of these vca's, your offset will be removed without sound coloration. i think some doepfer filters are ac-coupled too, but they will probably colour the sound a bit (depending on the filter)...
any other solution Dieter


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--- On Sun, 2/22/09, mirror_saw7778 < haven1@... > wrote:
From: mirror_saw7778 < haven1@... >
Subject: 1 Re: my 132-3 VCA goes "thump"
To: Doepfer_a100@yahoogroups.com
Date: Sunday, February 22, 2009, 12:12 AM












Another way to get rid of the "thump" is to use offset. If I patch the

output of the A106-6 into my Plan B M14 and use the offset knob, a

tiny bit of offset removes the thump sounds. If I look at a recording

of the sound witout the offset I can see negative DC offset in the

waveform and a small amount of negative DC that is being amplified by

the VCA. this transition from negative CV to positive CV makes a small

bump, that I hear as a "thump" or "pop" sound.



So mystery solved - the A106-6 introduces DC offset - is there a

module that can AC couple a signal with changing the sound noticeably

The Asol SY02 is coloring the sound, so I only use it when I dont want

a clean VCA. I guess I could just use offset - but it would be nice to

have something cheaper and smaller that the M14 doing this.



I am NOT talking about the click that happens with a fast envelope

controlling a fast VCA - this is caused by abruptly changing the

volume of a constantly running waveform - which creates a variable

click sound since the wave is suddenly going from zero to whatever

voltage it is presently at. This is what Argitoth is talking about,

and can be dealt with by slowing down the amplitude change of the VCA

or having the VCA and waveform start at a zero crossing at the same time.



thanks for your help everyone.



--- In Doepfer_a100@ yahoogroups. com, "mirror_saw7778" <haven1@...> wrote:

>

> I did some simple patches and found out it is not the 132-3 VCAs

> making the "thump" it is in fact my new 106-6 filter. Sorry about not

> being absolutely sure before I posted.

>

> I did find some interesting differences between the Asol SY02 and

> 132-3 which might be of interest to some. the 132-3 reacts much faster

> to CV as I cannot get the Asol SY02 VCA to click on a fast attack or

> release.

>

> If I use not filter, no "thump" if I use either of the other two

> filters I have (A108 and M12 Vactrol Filter) no "thump". As soon as I

> use the A106-6 "thump thump thump". The A106-6 into A132-3 with

> nothing going into the A106-6 input makes thumps.

>

> This brings me to someones suggestion of using a buffer, which I am

> not sure I understood so I patched the M31 between the A106-6 and

> A132-3, still "thump". I can really big thumps if I patch just the

> output of a M31 buffered mult into the A132-3.

>

> I can rid of the thump by slowing down the ADSR attack and release as

> I said. however I think the issues lies in the A106-6 creating a DC

> offset. Is there a trimmer inside that I could adjust

>

> My audio path post modular is a MOTU 828mk2 with Black Lion mods

> (analog and clock). I am monitoring it on ATH-M50 headphones.

>

> -Argitoth-

> I do not have web space - is there a free site I can post audio files

>































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