Dear all,
I am working on a project building a stereo audio delay. The project is basically two rebote 2.5 delays in an expensive 19" rack enclosure.
I am nearly finished, I etched two identical boards and everything works as it should. except for the fact that the PT2399 chip was a bad decision for a stereo project. The IC is a very cheap one and the delay-time (length) is adjusted by changing the frequency the chip operates at. this is done by setting a potmeter configured as rheostat which is connected to the internal RC network.
When i first tested the two board in parallel i noticed how the two chips operated at different speeds while connected to the same stereo-potmeter (obviously). While anyone (including myself) could have told me this at the beginning I did not foresee this issue.
Since I already invested quite alot in the project I decided not to give up. I solved one part of the issue by ordering 25 PT2399's and found two which are practically identical (<0.1% difference in delay time).
The other issue still remains, the setting of two identical resistances with one knob. I bought a relatively expensive stereo-potmeter but it still has like a 1% discrepancy between the two outputs.
So finally my question: is there a good solution (possibly digital?) to set two resistances (up to 47k) nearly identical with one knob, which is preferably cheap and easy?
I'm looking forward to hear all your brilliant solutions!
I am working on a project building a stereo audio delay. The project is basically two rebote 2.5 delays in an expensive 19" rack enclosure.
I am nearly finished, I etched two identical boards and everything works as it should. except for the fact that the PT2399 chip was a bad decision for a stereo project. The IC is a very cheap one and the delay-time (length) is adjusted by changing the frequency the chip operates at. this is done by setting a potmeter configured as rheostat which is connected to the internal RC network.
When i first tested the two board in parallel i noticed how the two chips operated at different speeds while connected to the same stereo-potmeter (obviously). While anyone (including myself) could have told me this at the beginning I did not foresee this issue.
Since I already invested quite alot in the project I decided not to give up. I solved one part of the issue by ordering 25 PT2399's and found two which are practically identical (<0.1% difference in delay time).
The other issue still remains, the setting of two identical resistances with one knob. I bought a relatively expensive stereo-potmeter but it still has like a 1% discrepancy between the two outputs.
So finally my question: is there a good solution (possibly digital?) to set two resistances (up to 47k) nearly identical with one knob, which is preferably cheap and easy?
I'm looking forward to hear all your brilliant solutions!