[ECM]

i'm in the process of building another amp. i plan on biasing the opamps into class a and then buffering them. very similar to the PIMETA with different component values and such.

i'll be using an opa2132 and buffering it with buf634's.

for biasing, i will use the 2 jfet method with the 2n5484 and 2n5486 pair.

how do i figure the total current draw for this amp? i'll be using it with 32 ohm phones and i need to determine if i'll run off batteries or a walwart.

 

[Excalibur]

Your amp should run fine on a coulple of 9 Volts. Biasing the opamps for Class A does not take a lot of current. In fact, you can have both channels drawing less than 1 mA in some instances.
The only thing that will draw too much current for battery operation is if you sett those BUF634's in wide-band mode (connecting pin 1 to V-).
Tangent has this information at his website:

http://tangentsoft.net/audio/opamp-bias.html

 

[tangent]

Quote:

how do i figure the total current draw for this amp?

If you intend on using random JFETs and no source resistor, you don't.

I'd add a trim pot for a source resistor, like we do in PPA v1.1. Then you can set the bias point anywhere you like, within the range of your JFETs.

 

[ECM]

thanks a lot for the info. i'll try to draw it up soon. my main concern was the battery life.