Doepfer

After doing some investigating yesterday, I noticed that my A-132-3 is noticeably louder than either the A-133 or A-135-1 when set to exponential. Is this right? I know the response is different but had assumed that voltage levels would still be similar. Is there info on all of the Doepfer VCAs and their respective amplification?

Thanks,

Neil

Sent from my iPhone

> After doing some investigating yesterday, I noticed that my A-132-3 is noticeably louder than either the A-133 or A-135-1
> when set to exponential. Is this right? I know the response is different but had assumed that voltage levels would still
> be similar. Is there info on all of the Doepfer VCAs and their respective amplification?
>
> Thanks,
>
> Neil

As a rule all A-100 VCAs have about amplification 1 (0dB) with +5V CV. But it's more complicated as some VCAs are equipped with
initial gain controls and attenuators for CV and audio signals. So it's difficult to give an overview as it also depends upon the
control settings - provided that controls are available.

And the behaviour is totally different for linear and exponential VCAs. For example the A-132-4 has a control scale of 12dB/V and is
adjusted in the factory for amplification 1@+5V CV. With 0V CV one obtains about -60dB (-5*12), with +6V CV about +12dB which is
already about 4 times the input level and may already cause clipping as the output range is limited to about +/-12V. With a linear
VCA (whith an amplification 1@+5V CV) +6V CV corresponds to amplification 1.2 only ! That's why an exponential VCA seems to be much
"louder" compared to a linear VCA as the control voltage goes beyond the 0dB (amplification 1) point. In addition there is no
standard for the exponential scale of VCAs (like the 1V/Oct scale of VCOs) which makes things more complicated because each
exponential VCA may behave different.

Hope this helps.

Best wishes
Dieter Doepfer

Ah right thanks Dieter that makes sense!

Regards,

Neil

Sent from my iPhone

> On 7 Jan 2015, at 10:32, yahoo@doepfer.de [Doepfer_a100] <Doepfer_a100@yahoogroups.com> wrote:
> 
> > After doing some investigating yesterday, I noticed that my A-132-3 is noticeably louder than either the A-133 or A-135-1
> > when set to exponential. Is this right? I know the response is different but had assumed that voltage levels would still
> > be similar. Is there info on all of the Doepfer VCAs and their respective amplification?
> >
> > Thanks,
> >
> > Neil
> 
> As a rule all A-100 VCAs have about amplification 1 (0dB) with +5V CV. But it's more complicated as some VCAs are equipped with
> initial gain controls and attenuators for CV and audio signals. So it's difficult to give an overview as it also depends upon the
> control settings - provided that controls are available.
> 
> And the behaviour is totally different for linear and exponential VCAs. For example the A-132-4 has a control scale of 12dB/V and is
> adjusted in the factory for amplification 1@+5V CV. With 0V CV one obtains about -60dB (-5*12), with +6V CV about +12dB which is
> already about 4 times the input level and may already cause clipping as the output range is limited to about +/-12V. With a linear
> VCA (whith an amplification 1@+5V CV) +6V CV corresponds to amplification 1.2 only ! That's why an exponential VCA seems to be much
> "louder" compared to a linear VCA as the control voltage goes beyond the 0dB (amplification 1) point. In addition there is no
> standard for the exponential scale of VCAs (like the 1V/Oct scale of VCOs) which makes things more complicated because each
> exponential VCA may behave different.
> 
> Hope this helps.
> 
> Best wishes
> Dieter Doepfer
> 
>