[sdiy] Dumb mixer circuit question

[Seb Francis]

No, it will vary from full gain down to 0.  Gain is equal to 
-Rfeedback/Rinput so is proportional to Rfeedback for a fixed Rinput.


Scott Gravenhorst wrote:
> Also, I think that it attenuates down to a gain of unity instead of the usual full
> amplitude down to zero amplitude.
>
> Seb Francis <seb at burnit.co.uk> wrote:
>   
>> Tim Parkhurst wrote:
>>     
>>> Use one op amp per input and put the variable resistor in the feedback 
>>> loop?
>>>
>>>       
>> It's kind of neat because you don't get the gain non-linearity (but then 
>> again when using log pots as you would for a mixer, how close to ideal 
>> log are they - and does it really matter anyway).
>>
>> The disadvantage I can think of is that the tolerance between different 
>> pots is likely a lot worse than 1% when using a resistor.  So each input 
>> channel would need trimming to get matching gain.
>>
>> Seb
>>
>>
>>
>>     
>
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