22 May
2025
22 May
'25
10:46 a.m.
On Wed, May 21, 2025 at 07:29:51PM -0700, Len Ovens wrote:
I was thinking the input element would probably be a
FET
Unlikely for a mic input. As long as Zin is a few kOhm it
would be OK.
Some (much more expensive) mic preamps use a 1:5 or 1:10
transformer followed by a FET. That can work really well.
It says 101 which should be 100pf. Guitar pickup coils
could be anywhere from 5 to 20k
That would be DC resistance, which is not very relevant.
When the volume pot is fully up you have C11 + cable
capacitance in parallel with the *inductive* impedance of
the pickup. That will result in a resonance peak damped
only by the volume pot and preamp input impedance.
This is the main reason why different cables may have
there own 'sound'.
Ciao,
--
FA