Frequency analisys until V2a's grid in Soldano's SLO100

[roberto]

Hi all,
I'm interested about the real frequency shaping until the second OD triode.
Slo100 just because it has the most complete and complex coupling stage in universally known schematics.

- due to Rk//Ck: 145Hz Shelving Filter (SH) between Unbypassed 47x gain and bypassed 77x gain.

the the cut-off frequency of the coupling cap depends on clean/crunch channel switch, but the 22nF CC has always a cut-off frequency that is below the guitar fundamentals (eg 14Hz with 470kOhm load).

Then the whole R5//C3 and C100//VR1 should be something like a:
- 4200Hz Low Pass Filter (LP) due to C3 and VR1
- 154Hz SH due to C3, VR1 and C5
- variable SH filter due to C100 and variable VR1
- 2200Hz LP due to grid resistor.

Do I forget something? Is there any error?

Thanks!

[David Root]

Your LF cutoff is correct, I ran V1 thru TubeCad and I get F -3dB 13.3 Hz into a 500k pot load. I can't model the HF cutoff in Tubecad because it doesn't include the 470k resistors and the 100pF cap.

[roberto]

Thanks David.
My interest is focused on a claim I've found on an Aiken's pdf:
bypass caps are often used to compensate high series resitance frequency roll-off. So.. if I lower triodes load.. ..and also thermal noise should.. Am I wrong?