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On 4/18/2015 1:25 PM, Richard L. Hess wrote:
> On 2015-04-18 3:07 PM, Paul Stamler wrote:
>>
>> Well-designed tube circuits can have transient response as good as
>> transistor circuits, and incredibly low distortion as well (with the
>> application of negative feedback). I'm sorry, but the idea that
>> "euphonic distortion" is an inherent characteristic of tube circuits is
>> one that's been carefully nurtured by the purveyors of tube hi-fi gear.
>> I'll go on record as saying categorically that it ain't necessarily so.
>
> They key to this is circuit design/topology and paying attention to gain
> staging through the device as well as component selection.
>
> Tubes can handle rather large voltage swings and if the R/C rolloffs are
> properly controlled they may actually provide a cleaner representation
> of the transient--if the A-D converter can accept it without excessive
> noise. Again, gain-staging is of paramount concern.

It is, and it's important to pay close attention to load impedances. 
Most common tubes (high-mu) have trouble driving lower impedances like 
the common 10k without a transformer. Low-mu tubes like the 6SN7 can do 
it, but they're bigger, use more current, etc.

Peace,
Paul

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