2 watt zen amp for headphones

I would like to build a small zen amp of 2 watts to drive a pair of 8 ohm headphones. I will use it to drive the tweeters in my biamped system at school for my desk. But I have a few questions. What would be the rail supply voltage and what size transformer. Also how large of a heatsink would I need?

Thanks in advance,



2001-06-01 4:53 pm
Are you sure your headphones are 8 ohms? Most are 32 ohms or higher. You don't need anywhere near 2 watts to drive headphones.
Assuming they are at least 32 ohms, the "Szekeres" amplifier at www.headwize.com (under Library/Projects) is a Zen-type amp. Single gain stage, no feedback. Sounds great. Nelson Pass has recommended this (conceptually speaking).
I'm not to sure if you have your application right but I'll try and answer your question anyway.

2W into 8-ohms will will need pwr=V*V/R => sqrt( 16 ) Volts = 4 Volts peak so 8-volts P-P.

So, given that you'll want some headroom, you can go with, say a 12-volt rail voltage.

At that voltage level, you would also be able to increase your bias current up to double what most zens run at, so 5-amps or even 6. Or you could run it at a lower bias and have less heat as well.