Particle Accelerator mods: any filter values recommended?

[cris_mas]

Well, since i,ve got the Fractal Ax8 i've became aware of two things:
-i don't understand how people is so trapped in digital. I mean, is convenient and all, but it just doesn't sound like tubes. It just sounds "nice".
- The frequency response of the clean channel modeling is way more clearer in the digi world. I've started to play again with the Particle Accelerator (Bliss) but i've noticed how boomy is.

The first thing i thought was checking the filters in the circuit, the tonestack, and all seems to be the right values, except for this:




And most Fender guitar schematics are like this:



What happens if i swap those caps to those "fender" values? Will it change the frequency response in some way?
please forgive my ignorance, been a while since i don't analyze circuits this deep.

To wrap things up, i need (i think) the preamp to cut higher the frequencies, it's too much bass, to the point i have to crank all the way up the treble to equate to the response of fender amp models in the same settings. I know Fender are naturally "bass open" designs, but i've found that the PA is a bit too much, almost not usable ( this in headphones context, in live wasn't able to cut through mix ).
BTW i'm using a JJ ecc83s, i know they can be "warmer" than other tubes, but i've swaped with others and it was much the same.

Thanks in advance!

 

[vigilante398]

Particle Accelerator is based on the Alembic F-2B, which is particularly popular with the bass crowd due in part to the extended low-end frequency response. Reducing the value of the cathode bypass cap will absolutely shift the cutoff frequency of the low-end of the circuit. You can see visually how it affects it here and can try out some values in the calculator before you try swapping them on the board.

Cathode Bypass Capacitor Calculator

ampbooks.com

 

[cris_mas]

Particle Accelerator is based on the Alembic F-2B, which is particularly popular with the bass crowd due in part to the extended low-end frequency response. Reducing the value of the cathode bypass cap will absolutely shift the cutoff frequency of the low-end of the circuit. You can see visually how it affects it here and can try out some values in the calculator before you try swapping them on the board.

Cathode Bypass Capacitor Calculator

ampbooks.com

Thanks @vigilante398, as usual helping .
I’ve changed the caps and gives a bit better response, still on the warm, dark side of things but it improved. I’ve also changed the speaker IR. I’ve remembered some reissue Fenders are carrying Celestion V types so that’s what I’m trying to deal with that natural smoothness from this circuit design.

 

[Tassieviking]

You could go a lot lower as well, on Marshall JCM800's the lead input would use a 0.68uF capacitor in a similar position.
I think I ran 2 wires to a switch on mine so I could select different capacitors to give me more tones, I can't remember what values I used.

 

[Tassieviking]

I couldn't help myself but to check the different values so here are the pics, C9 different values.
I am also considering using a different mid pot on my next build, using a 20k would give you a small gain boost.
I might try a B20k pot for Mid next time

EDIT: The flat tone stack response is with the Bass and Treble at minimum (0) and Mid at maximum (10)

 

[cris_mas]

I couldn't help myself but to check the different values so here are the pics, C9 different values.
I am also considering using a different mid pot on my next build, using a 20k would give you a small gain boost.
I might try a B20k pot for Mid next time

EDIT: The flat tone stack response is with the Bass and Treble at minimum (0) and Mid at maximum (10)

nice one, thanks! I will check, at the end i've modified both sides of the tube (c9 and c18 of C2C) maybe i've made a mistake, but I’ve followed Fender schematic, so I did that. Will see if I have more caps to try out