headamp with pre-out [3pic]

[digi01]

hi guys,thread killer digi01 come back again







This amp is an opamp + discrete design.The idea of the discrete output is from EATON amp.
With slight modification, the amp uses AD823 opamp to drive a pair of matched B647/D667 audio grade transistors, running in AB mode. Input stage using ERO caps and dale resistors; Elna 220uF BP non-polar caps are used as output; PSU with Telecom. Grade Siemens Caps and FC; Alps potentiometer; Gold plated RCA jack, and pre-out ( can serve as dedicated preamp.the amp voltage gain setting in 11) as requested.
in fact,the amp style can drive a wide range of headphones with different impedance.it certainly can drive HD650, it can even drive AKG K1000 with PSU upgrade.
this is a europe diyer work:
http://www.justchords.com/docs/eaton.htmlhe use the amp to drive K1000 headphone.

enjoys

[carlmart]

The project looks quite good: congratulations!

Just one question: why pick that particular headphone design?

Personally I have an aversion to using large capacitors in the signal path, and this project uses a big one (4700uF).

The Eton project seems to be based on Jung's headphone amp, but that project had no output cap. So why not try that same project?

Sheldon Stokes proposed a variation of Jung's circuit at Headwize, that used an OPA2132 chip and MOSFET drivers and no output cap.

In any case I am saying this but I don't see a large cap on your project that might be the output one. So what circuit are you using?


Carlos

[digi01]

Hi Carlos,
Thanks for the compliment
here is my output stage sch pic.


I use a couple of bp caps for output,indeed the caps can be bypassed.
I like class AB mode,high output carrent and very fast respond.

digi