[sdiy] Quick query about 2164 VCAs

Erik Dower electronicpresskit at gmail.com
Sun Mar 17 14:32:55 CET 2019


Hi Tom,

Yes I’m sure it wasn’t the log db/V response. The curves were more like log for rising voltages and exponential for falling voltages for what I remember from the first time I tried it. The most recent time (a couple weeks ago), was an integrator configuration and the rise and fall times were different, yet the cv was constant in both cases.

Thanks,

Erik

> On Mar 16, 2019, at 10:58 PM, Tom Wiltshire <tom at electricdruid.net> wrote:
> 
> Hi Eric,
> 
> Are you sure you weren’t seeing an effect of the log dB/V response?
> 
> I’ll have a look and see what schematics I’ve got that show this clearly, but no, I’ve not had trouble.
> 
> Regards,
> Tom
> 
> ==================
>       Electric Druid
> Synth & Stompbox DIY
> ==================
> 
>> On 16 Mar 2019, at 20:59, Erik Dower <electronicpresskit at gmail.com> wrote:
>> 
>> Interesting. I’ve tried serially configured gain cells without I to V stage between them on a couple of occasions years apart and the results were not good…i.e linear waveforms suddenly had curves that shouldn’t be there.
>> 
>> Can you provide an example where this is working normally?
>> 
>> Thanks,
>> 
>> epk
>> 
>>> On Mar 16, 2019, at 7:15 PM, Tom Wiltshire <tom at electricdruid.net> wrote:
>>> 
>>> Hi all,
>>> 
>>> I know you can mix together the outputs of several 2164 VCAs direct into the input of another one, but can you mix together the outputs of several VCAs into the inputs of several VCAs simultaneously?
>>> 
>>> The situation I’ve got is this: I have a wet and dry level controlled by a VCA each. These are brought back together at a single point (which will need to be a virtual ground node). I then have Main and Phones outputs, both controlled by a VCA each too. Can I connect the inputs of the two output VCAs together and mix the outputs of both the Wet and Dry VCAs into that same single point? Will the current divide equally between the two output VCAs? Will I need to adjust the output I-to-V stage resistors to compensate for the fact that each VCA only gets half the current?
>>> 
>>> I love the fact that often with the 2164 VCA you can omit the following I-to-V stage and just feed the current direct into the next stage somewhere. There’s often no need to go back to a voltage before turning things into currents again. I’m hoping that’s the case here too! ;)
>>> 
>>> Thanks,
>>> Tom
>>> 
>>> ==================
>>>     Electric Druid
>>> Synth & Stompbox DIY
>>> ==================
>>> 
>>> 
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>> 
> 




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