Dear people,
I am busy with an effects loop recovery stage into an ltp. After wiring it up as A, I noticed the longish wire is very sensitive to crosstalk and hum. Since I thought this must be current based ( electric field), I thought lowering the lpt input impedance might help. In my infinite wisdom I wired it up as B, thinking the cathode followers output impedance must be in parallel with the lpt input, lowering everything including the wire to 680r.
I did not notice much improvement. What do I need to learn and how can I make this wire more immune to noise and crosstalk?
Kind regards!
I am busy with an effects loop recovery stage into an ltp. After wiring it up as A, I noticed the longish wire is very sensitive to crosstalk and hum. Since I thought this must be current based ( electric field), I thought lowering the lpt input impedance might help. In my infinite wisdom I wired it up as B, thinking the cathode followers output impedance must be in parallel with the lpt input, lowering everything including the wire to 680r.
I did not notice much improvement. What do I need to learn and how can I make this wire more immune to noise and crosstalk?
Kind regards!
A high impedance node must be compact and kept away from other circuitry to avoid capacitive noise coupling.
Locate those two endpoints close together, so the coupling capacitor bridges the distance with short leads.
Don't use a long wire. Keep the capacitor away from other circuitry as well.
Locate those two endpoints close together, so the coupling capacitor bridges the distance with short leads.
Don't use a long wire. Keep the capacitor away from other circuitry as well.
Or just use a small coax cable with the shield just attached to the circuit common at the source end.
Is there a way to lower the high impedance node? Resistor before coupling cap to ground or lowering the 1MEG grid resistors?
There would be high voltage on a coax and I havent found one that is rated for that.
There would be high voltage on a coax and I havent found one that is rated for that.
Locate the coupling capacitor at the first tube, so the long wire has only the second tube's lower DC cathode voltage on it.
That is possible, although the capacitor is a very sensitive point itself too.
From a theoretic standpoint, was I correct that lowering the send impedance into the wire also lowers the receiving high lpt input and thus lowers capacitive noise coupling in the wire?
From a theoretic standpoint, was I correct that lowering the send impedance into the wire also lowers the receiving high lpt input and thus lowers capacitive noise coupling in the wire?