power supply advice

[Marco Pancaldi]

I need to build a mixer/fx send circuit to mix some line level signals (line out from a guitar POD with external delay returns).
The total circuit will have 4 5532 opamp.

The unit needs to be stompbox size, with external supply, unity gain. Less the components, the better.
But I will probably implement simple balanced input and impedance balanced outputs, and I'd wish good headroom.

I can build the internal power section as a guitar pedal, with 1/2 voltage used to bias the non-inverting inputs.
Or, I can implement a bridge double voltage circuit, using two diodes and caps. This version have the advantage to double the voltage (my regulated pedalboard adapter put out 9 or 12.5 volt), extending the headroom, but with lot more ripple...

Needs advice and maybe some schematic as reference.

Many thanks
m.

 

[PRR]

> bridge double voltage circuit, using two diodes and caps. ... (my regulated pedalboard adapter put out 9 or 12.5 volt

The regulated supply is probably _DC_. The simple voltage-doubler needs _AC_.

Unity-gain? Then just split the 9V for a bias reference. If truly unity-gain then nothing will ever hit 1V rms or 3V peak-peak. Most good opamps on 9V will cover this fine. Most levels will be under 1V peak to peak.

 

[Marco Pancaldi]

PRR,

sorry: the difference DC/AC is so basic... but I was so focused on the headroom that I lost any other point...

I agree that 9V is enough for a unity gain guitar circuit, but the PODs have large (even in complete bypass) gain: I haven't mesured exactly, but the output is in the range of +4dBm devices and outboards. So, while a 25-30 VDC source is not so easy to find, it is probably simpler to use a 12VAC transformer, but the ripple question remains.

thanks
m.