C14 on Arachnid too high?

[mstrat]

Is there a good reason to keep C14 at 220pF? Is that going to cut too much highs at a max volume?

Would 100pF be a better choice?

 

[Betty Wont]

I would assume it was designed with the best choice value.

 

[mstrat]

Can you elaborate?

At max volume, if I'm not missing anything, the 220pF puts the LPF shelf at about 7kHz. This is within audible range.

At 100pF it'd boost it to about 15k, which seems more "transparent".

Assuming I'm not miscalculating or misunderstanding, I guess a more direct question is: "Is there any unforeseen problem in making that change?" e.g. thermal noise?

 

[zgrav]

easy enough to try it and see if you like it. it won't cause any harm to the chip, the board or your ears.

 

[mstrat]

Sure of course. And I did. Sorry I guess my question wasn't well stated.

I'm not looking for permission, but for reasoning.

i.e. why was 220 chosen? Was there concern over high frequencies at high volume? Issues with lower value caps in the feedback? etc

 

[zgrav]

Sure of course. And I did. Sorry I guess my question wasn't well stated.

I'm not looking for permission, but for reasoning.

i.e. why was 220 chosen? Was there concern over high frequencies at high volume? Issues with lower value caps in the feedback? etc

I don't know why 220pf was used there, but presumably to reduce higher frequencies. If you used 100pf instead, what do you think about the output and noise level?

 

[manfesto]

Can you elaborate?

At max volume, if I'm not missing anything, the 220pF puts the LPF shelf at about 7kHz. This is within audible range.

At 100pF it'd boost it to about 15k, which seems more "transparent".

Assuming I'm not miscalculating or misunderstanding, I guess a more direct question is: "Is there any unforeseen problem in making that change?" e.g. thermal noise?

It's within the audible range of human hearing, but it's pretty far out of range of what the electric guitar and amp can produce, which really starts to fall off well before then (5KHz to 6KHz usually).

 

[mstrat]

It's within the audible range of human hearing, but it's pretty far out of range of what the electric guitar and amp can produce, which really starts to fall off well before then (5KHz to 6KHz usually).

Aha! Thank you. I had assumed harmonics went well above that but never really validated that. And I so frequently see filters in the 15kish range it just further solidified that assumption. Seems so obvious now in retrospect, but I guess that's how it goes.

Thanks so much!

 

[zgrav]

Good question. Certainly could be an issue for folks using the effect for sound mixes.