headphone on Pass A40

Zappa

Member
2002-07-03 7:00 am
Québec
Hi,

I built an A-40 and use it every day on speakers of my own and I'm happy with it.

the point is:

1) Do you need 40W per channel on headphones ???

2) Don't forget you will get the noise associated with the PSU requied to feed a 40W class-A amp. In my sense, maybe too much noise to be a good thing.

Why don't try the nice SDS Labs Headphone amp. I drive a pair of 32 Ohms Grados with it. Sounds very good and dead quiet at idle...
 

Zappa

Member
2002-07-03 7:00 am
Québec
Same answer,

the A-40 is a power amp and you barely need 1X or 2X line level (ie 2-4V RMS). A well buffered opamp based design should cut mustard like a purpose built mustard cutter for you. If I was you, I may be looking elsewhere that modifing the A-40, at least for the purpose. :)
 

Zappa

Member
2002-07-03 7:00 am
Québec
paulb answer seems to be something really acceptable but I wonder if you really get rid of the noise in this case.

For the SDS Labs little amp, I have had the print made for me for this project. Just check if the pcb transformer holes are at the right distance from each other. I remember I've had some problems with that... IRF610 and 9610 could be a better pick from their lower gate capacitance but IRF620 and 9620 are making great music in mine.

Good luck!