In article ,
Don Pearce wrote:
In tube power amps, the difference between wide
band and "A" weighted was often found to be 12dB,
and this was, IIRC something of a rule of thumb.

Iain

Such a difference would suggest a great deal of 1/f noise.

Fairly typical of AF valve circuits. Hum.

--
*Ever stop to think and forget to start again?

Dave Plowman London SW
To e-mail, change noise into sound.