[CBMC]

I am working on getting all of the parts together for building this headphone amp. My question involves the r3-r6 resitor values. I am not sure how to decide which values are right for me. My musical preference is quite varied. Anywhere from jazz to rock to classical to rap. Anyway, the main use for this will be when I am working outside(gardener/landscaper), so I will be using it with some sort of portable device. I am not sure of the headphones I will be getting, I have heard good things about the ER-4S from Etymotic Research. I am looking at the 2 OPA637AP op amps. I have heard to use an inner loop gain of about 200 and a outerloop gain of 5, does this sound good. What percent tolerance would I need? Any input is appreciated.

 

[CBMC]

Forgot to ask, does anyone know the independence value at the output of the meta42 would be with the above configuration?

 

[phaedrus]

cbmc,

tangent has a calculator page that will provide resistor combinations for a given gain and another that will calculate total gain for a multi-loop arrangement. the calculators can be found at:
http://www.tangentsoft.net/audio/calc.html

he also provides some advice on selecting values for the R3-R6 resistors in the multiloop topology section of:

http://www.tangentsoft.net/audio/meta42/assy.html