audiomixer
Well-known member
I don't think you can mix / match 0V from the bipolar supply with this circuit.
the first objective was ( I believe) to tinker... second to see weather you can make it work in a 500-ish environment.
for the first:
think of the split power supply as a 0V / 15V / 30V supply, where 15V is what you would call ground in a bipolar setup. you can reference the original schematics ground to the negative rail and should be able to get the circuit to work as long as you don't connect anything really 'grounded' to it. with grounded I chassis, power supply, ground connected shield / return lead, the microphone grill you are singing into and so on. you can directly plug a guitar into the input, and might use a line transformer on the output so that you can get away with the pre sitting at -15V. get the component values right and of you go. in this example the 15V tab is not connected, and you do need to regulate the 30V down to 24V.
for the second:
really better of using a fet pre designed for bipolar operation, really. otherwise you will have to decouple in and outs with transformers, that just does not make sense with this design, I believe. and having to regulate one of the two supplies down so htat you get 24V to accommodate the preamps requirements is even more weird...
- Michael
the first objective was ( I believe) to tinker... second to see weather you can make it work in a 500-ish environment.
for the first:
think of the split power supply as a 0V / 15V / 30V supply, where 15V is what you would call ground in a bipolar setup. you can reference the original schematics ground to the negative rail and should be able to get the circuit to work as long as you don't connect anything really 'grounded' to it. with grounded I chassis, power supply, ground connected shield / return lead, the microphone grill you are singing into and so on. you can directly plug a guitar into the input, and might use a line transformer on the output so that you can get away with the pre sitting at -15V. get the component values right and of you go. in this example the 15V tab is not connected, and you do need to regulate the 30V down to 24V.
for the second:
really better of using a fet pre designed for bipolar operation, really. otherwise you will have to decouple in and outs with transformers, that just does not make sense with this design, I believe. and having to regulate one of the two supplies down so htat you get 24V to accommodate the preamps requirements is even more weird...
- Michael
