Help with a tone control in a Delay Guitar Pedal

[eduardo_gj1]

Hello, I would like to know if what I did in a schematic is well designed or bad. the schematic is the same as the original only I added a tone control for the repetitions of the delay

Thank you all so much for your help

 

[RadioRon]

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?

 

[eduardo_gj1]

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?

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

 

[eduardo_gj1]

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?

the original schematic had a switch to control the hi/low repeat, check and tell me what do you think pls

 

[dr pepper]

Looking at the datasheet that concept should work, although they suggest 100n, the vlues you show will allow digital noise through, unless you have a short delay time.

 

[RadioRon]

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

To correct your circuit to become like the Leviathan circuit do these things:
- disconnect C1 (+ side) from pin 14 of U2. Re-attach C1 (+ side) to the junction of C40 and TONE control
- change R10 to 2K7, change C28 to 10nF

Also, but not related to the other issue, there seems to be a fault in your schematic. There is a green line drawn directly above C16. This line should be removed.

 

[eduardo_gj1]

Thank you all so much for your help, I always come here and I never go home without your help hahahahaha,
I fix some things, check it out and let me know if I am missing any other modifications

ahh i almost forget about the comment, i really dont follow the idea

Looking at the datasheet that concept should work, although they suggest 100n, the vlues you show will allow digital noise through, unless you have a short delay time.

 

[dr pepper]

Just tack a capacitor across the terminals and try it, if you get digital noise increase the capacitance till it sounds as good as you can get it.