Anyone can help me here?
I have this schematic which is working but would be nice to add a high pass/bandpass function around 3khz to use as a boost only on this frequency.It would be on and off using a toggle.
I saw someone suggesting adding a parallel network around R3 and C3 on an old thread of freestompboxes.
I used Paint to edit the image and do a parallel out of the section and wanted to know if it's possible to do it.Perhaps the way I did is not the way to do it.Could anybody help!?
After all, how would I miix it back in, after (green), or before(red) the last opamp stage???.
Sorry for the bad drawing technique :P
Varying R3/C3 could give you a treble boost, for example with a parallel path (like in a Rat distortion).
The red and/or green lines are not needed (and wouldn't work, the red would disturb the SVF and the green would only add lows to the output).
In essence C determines the cutoff frequency and (TR1+R3)/R3 the gain for high frequencies.
(These are damped by the following lowpass, of course.)
Ei Kothoma, I've just realized the part of the circuit I've drawn it's wrong. The 47n cap is not connecting to ground and the line should come out from Rx, I believe.
I've made another one, let me know if like this it makes more sense.
If not, how could I add a treble boost(high pass) without changing anything else on the system?The idea is to do the pick attack that exists on the Wal basses.
I know that they either pull a high pass or a band pass tuned to arround 3khz and mix it with the rest of the signal through an on/off switch.
Can you help me here, is it a simple thing or would I need to duplicate the entire section?
No, this way you're still routing lows to the output (the highs all go to ground via Cx).
If you simply omit the red line then you get a treble boost, but that will be eliminated mostly by the lowpass.
If I understand you right you want a lowpass with fc anywhere well below 3 kHz and a highpass with fc = 3kHz and a gap between the two fcs?
Then the deluxe version would be to build a second SVF in parallel (everything twice from R4 to P4) but taking the highpass output (C6 connected to pin 7) and maybe a mixer opamp after the two level pots.
But maybe you could get away with a capacitor going from before R4 to lug 3 of P4. That C and P4 will form a RC highpass. Try a 4n7. Together with the 10k pot you should land somewhere around 3kHz, if my calculation is right.