[Firefart]

Hi all!

I'm currently trying to come up with a portable headphone amp and I'm looking for some information on op-amps.

is it possible that a low power op-amp could sound good ?

I need to keep the quiescent current in control ( less than 1mA from each op-amp) in order to have a really portable unit.

I was looking at the TS931 for example... is it good for audio?

which parameters should I care about when selecting the op-amp?
(being the quiescent current the one I need to me really low...)
slew rate? bandwidth?

thanks in advance!

 

[semisight]

The problem is two-fold: a) amps by definition put out a certain amount of power and b) the type of amplifier chip you're using will have a huge impact on both SQ and power consumption.

Assuming you want to keep your amp decently powerful but want to keep wasted power to a minimum, a Class A topology is not your friend. Class A amps have a theoretical max of a 1:1 ratio of power out to power wasted (although without inductors you'll only get 1:3 at best). Class A generally has little distortion so SQ will be very good.

The next I'd consider would be some variant of class D. The advantage of class D is high efficiency, although it uses some tricks to do so, so it may not be quite on par with class A (the good ones certainly are). Efficiency might be 4:1.

And of course you have to consider slew rate, bandwidth and other constants that may affect audio performance. Slew rate is ideally as fast as possible, and bandwidth should be large (? - this is where my knowledge gets a bit fuzzy) but it can also lead to oscillation problems.

 

[Firefart]

Thanks for the help! but I missed one point...

these op-amps are not for the headphone drive. the output section will be the one with power hungry.. the EQ must not "waste" power...

 

[Firefart]

anyone?

 

[boomana]

There is an opamp thread in the DIY forum. Maybe ask there?

 

[Firefart]

Quote:

Originally Posted by boomana /img/forum/go_quote.gif There is an opamp thread in the DIY forum. Maybe ask there?

I'll try out