Noise Cancelling Headphoneamp design.

[Garbz]

Hi all

Before i get into it just to let you know i'm not genious when it comes to opamp based headphone amps. This is has been cobbeled together from my knowledge of electronics and a few other designs.

http://users.bigpond.net.au/decane/noisecancel.gif
big image but only 22k. linked for thoes people not running 1600x1200 :

Anyway the design was based on a design i found on www.headwize.com with a few minor changes:

- Opamps changed to opa234
- Output of the inverted stage has a buffer
- To turn noise cancelling off the switch cuts the power to the preamp for the microphone instead of switching to an aditional unity gain inverting opamp. (the original design allowed noise to be amplified this way).
- DC input protection can be bypassed
- Gain switch for low-Z and high-Z headphones.

Also the power supply will probably change to 8 1.5v batteries centre tapped to get rid of the rail splitter.

What do people think? Will it work? Will i damage something? I'm not to sure about the microphone stage (that's one of the things i've copied).