electrog
Well-known member
ok- attenuater mystery solved - i started researching different attenuator configurations to figure this out (and to learn how they work in the process) and realized the mistake in my second drawing if you reverse the conections of the 2 680ohm resistors (mirror them top to bottom) you have an un-balanced bridged-T attenuator, like so:
which, when looking at the actual wiring, is indeed what is there. R3 and R4 are the two halves of the ganged 40k pot, R1 + R2 are the 680ohm resistors.
following through, i wired the input up unbalanced and presto: crazy attenuator hum gone!
thanks for proding me toward understanding this, everyone.
now, a question: i have the output wired balanced, which works great. in order to do the same for the input, would it simply mean replacing this attenuator with the same values in a balanced bridged-t configuration?
which, when looking at the actual wiring, is indeed what is there. R3 and R4 are the two halves of the ganged 40k pot, R1 + R2 are the 680ohm resistors.
following through, i wired the input up unbalanced and presto: crazy attenuator hum gone!
thanks for proding me toward understanding this, everyone.
now, a question: i have the output wired balanced, which works great. in order to do the same for the input, would it simply mean replacing this attenuator with the same values in a balanced bridged-t configuration?