Help with a tone control in a Delay Guitar Pedal

RadioRon said:

I had a quick look at the details of the PT2399 in this website:

ElectroSmash - PT2399 Analysis

Circuit analysis of the PT2399, a CMOS echo/delay/reverb processor by Princeton Technology.

www.electrosmash.com

In this, I learned that your IC2 pin 14 is an output from an opamp. Assuming that this op amp is operating in its linear range (ie. output is not saturated), then pin 14 will have a low impedance output. This means that the output will be unaffected by R10, C28, C40, TONE control, and C18. "Unaffected" means that the tone control will not function. Both R10 and C28 are supposed to be a low pass filter in series with the output, which tells me that your circuit has bypassed this filter and ignored it.
I'm not sure what to suggest to better implement a tone control, but this circuit is perhaps not it. It would be useful if you could define exactly what you are trying to do, or in other words, what exactly do you want your tone control to do? Do you want it to vary the corner frequency of a low pass filter, or of a high pass filter, or something else?

Click to expand...

RadioRon said:

I had a quick look at the details of the PT2399 in this website:

ElectroSmash - PT2399 Analysis

Circuit analysis of the PT2399, a CMOS echo/delay/reverb processor by Princeton Technology.

www.electrosmash.com

In this, I learned that your IC2 pin 14 is an output from an opamp. Assuming that this op amp is operating in its linear range (ie. output is not saturated), then pin 14 will have a low impedance output. This means that the output will be unaffected by R10, C28, C40, TONE control, and C18. "Unaffected" means that the tone control will not function. Both R10 and C28 are supposed to be a low pass filter in series with the output, which tells me that your circuit has bypassed this filter and ignored it.
I'm not sure what to suggest to better implement a tone control, but this circuit is perhaps not it. It would be useful if you could define exactly what you are trying to do, or in other words, what exactly do you want your tone control to do? Do you want it to vary the corner frequency of a low pass filter, or of a high pass filter, or something else?

Click to expand...

eduardo_gj1 said:

hello, thanks for your reply, I want to control the high pass filter, I had the idea of another pedal, which has the same tone control, uses the same PT2399, I already built this model and the tone control filters the hihg signal Repeat the delay, not dry signal and works fine. But I guess they are different and I have to fix some things. if you can help me it will be great

Click to expand...