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-   -   Discrete simple headphone amp (http://www.diyaudio.com/forums/headphone-systems/107976-discrete-simple-headphone-amp.html)

kubeek 4th September 2007 10:47 AM

Discrete simple headphone amp
 
I already posted it in the chip amps section, but I didnīt have too many helpful answers.
So could someone please comment on this circuit?
here

+-9V, 16-600ohm load

thanks

djk 4th September 2007 12:21 PM

Looks like it needs a bit of work.

You should probably have a zobel on the output.

Don't forget to use compensation on the NE5534, I would use the NE5532 instead.

You don't need driver transistors.

Here is a headphone amp from an older top-of-the-line McIntosh preamp.

http://i56.photobucket.com/albums/g1...eitsch/C32.jpg

It looks a bit like the AKSA power amp without the outputs.

kubeek 4th September 2007 01:20 PM

I don' t need too good amp, I need only something cheap (I will make 4 stereo drivers) with enough power and voltage for wide range of loads, and not as bad as LM386.
Driver transistors are the 2N..? I simulated distortion, and it came out better with them.

The choose of transistors is because I have enough of them from some recent project, but will BCxx and BD139/140 make a difference?
And what about TL072 instead of the NE5534/2?

What values of zobel do you suggest for headphones?

Gordy 4th September 2007 02:09 PM

For reference...

A project something like your project:
http://headwize.com/projects/showfil...=eaton_prj.htm

The circuit diagram from that project:
http://www.headwize.com/images/eaton2.gif

Other interesting reference projects:
http://headwize.com/projects/index.htm

kubeek 4th September 2007 03:08 PM

I just found out that my behringer mixer uses two 4580s + 100ohms paralleled for headphone out, so I guess almost anything will be better than that.

djk 5th September 2007 04:40 AM

"The choose of transistors is because I have enough of them from some recent project, but will BCxx and BD139/140 make a difference?
And what about TL072 instead of the NE5534/2?"

The 5534/32 sounds quite a bit better in the mids and bass than the TL07X opamp in this circuit.

"What values of zobel do you suggest for headphones?"

It has nothing to do with the headphones, it is for amplifier stability. I generally use 0.1uF and 10 ohms.

The Eaton2 looks like a good project. The MJE243/253 are much better devices for outputs than the MJE340/350.

Bonsai 5th September 2007 07:06 AM

Suggestion: use an off the shelf buffer like an LT10 or similar if you want something simple with good performance.

Take a look at the LT website.

kubeek 5th September 2007 10:09 AM

No LT10 or mje243/253 in here :(

djk 5th September 2007 10:30 AM

Use what you can get, the MJE340/350 are good up to about 100mA when warm.

Should be good for over 120dB on most headphones.

Leolabs 6th September 2007 02:59 AM

Try 2SB647/2SD667 too.


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