headphone on Pass A40

[rwagter]

As a newbie I was wondering how to make a connection for a headphone on the A40 power amp, is there a quick fix?

It doesn't need to be an audiophile solution as long as I can keep listening.

 

[Zappa]

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...

 

[rwagter]

I do want to use it for normal speaker (dynaudio diy) but I also want a headphone connection just to use when my girlfriend is watching telly or something

 

[Zappa]

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]

You really choose your speakers well to make DIY ones...

 

[rwagter]

Thank you for the complement, it's to bad dynaudio is not into diy anymore.

The SDS amp. looks like a fine and cheap amp, am already ordering the parts, did you make your own print or can you buy one already made.

Ralph

 

[paulb]

Resistors in series with the speaker outputs is all you need. Value depends on your headphone impedance. Try 100 ohms to start if you have low-impedance (32 ohm) cans.
Using a dedicated headphone amplifier may get you better sound, but it is not necessary.

 

[Zappa]

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!