Doepfer

Can I use A-133 as a 2-quadrant multiplier without adding an offset to 
the VC? Obviously this is no problem for all + signals like most 
envelopes, but how about for LFOs?  For example, to get a good vibrato, 
I would have to run a sine into A138c and use the offset function to 
get 0 amplitude at the maximum negative portion of the sine. Is there 
any other module that does offsets like this?

-nicholas

> Can I use A-133 as a 2-quadrant multiplier without adding an offset to
> the VC? Obviously this is no problem for all + signals like most
> envelopes, but how about for LFOs? For example, to get a good vibrato,
> I would have to run a sine into A138c and use the offset function to
> get 0 amplitude at the maximum negative portion of the sine. Is there
> any other module that does offsets like this?
>
> -nicholas

The A-133 has a manual offset control. If you e.g. turn this control to ~ +3
you can add an LFO signal with adjustable level to the CV input.

In general nearly all A-100 modules have an offset control for each voltage
controlled parameter. There are only a few exceptions like the low-cost dual
VCA A-132-1 or the dual crossfader A-134-2 with small 4 HP front panels
(only sockets, no controls).

Best wishes
Dieter Doepfer

So the man knob controls not only amount of multiplication (-2.5x at 
knob setting of -5 to +2.5x at knob setting of +5) but also 
adds/subtracts an offset?

-nicholas

Quoting hardware@doepfer.de:

>> Can I use A-133 as a 2-quadrant multiplier without adding an offset to
>> the VC? Obviously this is no problem for all + signals like most
>> envelopes, but how about for LFOs? For example, to get a good vibrato,
>> I would have to run a sine into A138c and use the offset function to
>> get 0 amplitude at the maximum negative portion of the sine. Is there
>> any other module that does offsets like this?
>>
>> -nicholas
>
> The A-133 has a manual offset control. If you e.g. turn this control to ~ +3
> you can add an LFO signal with adjustable level to the CV input.
>
> In general nearly all A-100 modules have an offset control for each voltage
> controlled parameter. There are only a few exceptions like the low-cost dual
> VCA A-132-1 or the dual crossfader A-134-2 with small 4 HP front panels
> (only sockets, no controls).
>
> Best wishes
> Dieter Doepfer
>
>

> So the man knob controls not only amount of multiplication (-2.5x at
> knob setting of -5 to +2.5x at knob setting of +5) but also
> adds/subtracts an offset?
>
> -nicholas

That's the same - unless you speak about a DC offset voltage appearing at
the output.

Best wishes
Dieter Doepfer

I'm not in the office from January 14-27,2008 as we exhibit at the NAMM show
in Anaheim/USA. During this time I cannot respond to emails. In case of
urgent technical questions please contact software@doepfer.de or
keyboards@doepfer.de.