Different values of C7 (CE) in Alephs

[Josep]

Hello all

I am making an Aleph 30 with Kristijan PCBs for Aleph 5.
It is easy to adapt but my doubt is about C7.
The only difference in my A30 is that C7 is from the collector to emitter instead collector to base in original A30.
BrianGT ask to Mr. Pass about similar problem and he say :
"The value of the npn compensation cap pretty much depends on the placment. .001 for CB or .01 for CE."
I see different schematics with 0.047 or 0.01 for collector to emitter placement. What it is the correct value in this case?
Thank you

Josep

Note : Sorry for my bad English.

 

[uli]

try and error

hi,
this cap is either nfb (CB) or output to gnd (CE).
It forms a lo pass with R18 in the CE config.
in CB it forms a fb loop thus "slowing down" the npn
to avoid oszillation.
I would put either .001 in CB or .047 in CE.
Try it!
Uli

 

[vpharris]

I would trust Mr. Pass!

 

[Nelson Pass]

Lots of times it works fine without a cap, but not
always.