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-   -   OP Amp based headphone amplifier. (http://www.diyaudio.com/forums/headphone-systems/128487-op-amp-based-headphone-amplifier.html)

zebra100 21st August 2008 09:13 PM

OP Amp based headphone amplifier.
 
I am exploring the possibilities of making a headphone amp based around an op amp. The amp only needs to have one set of analogue. I have a couple of Phillips NE5532's sat in my spares box which I would like to use if possible (salvaged from my NAD C520). The 5532 has an output impedance of 600ohms. I haven't settled on a decent pair of cans yet, so the amp should be capable of a wide range of loads. I quite fancy a pair of Grado GS1000's ;-) No, just kidding, SR60's are more in my league. Does anyone know of anywhere I can get my hands on a fairly simple circuit design, or a supplier of ready made PCB's for this purpose? I don't mind mains or battery supply either.

Regards,

Chris

CJ900RR 21st August 2008 09:29 PM

Search for C-moy or cmoy or c-moy or any spelled version of what I just wrote :clown:

lineup 21st August 2008 09:36 PM

Rod Elliotts headphone amp projects
http://sound.westhost.com/projects-1a.htm

big website for headphone amplifiers projects articles & stuff
http://www.headwize.com/projects/

big DIY headphone discussion forum, with member projects
http://www.head-fi.org/forums/f6/

wakibaki 21st August 2008 09:47 PM

A well-documented headphone amp: -

http://www.johncon.com/john/amp/

w

error401 21st August 2008 10:08 PM

See: http://tangentsoft.net/audio/cmoy-tutorial/

Nice boards are available http://jseaber.com/cMoy/diy.htm and I don't know if he has any left, but joshatdot over at Head-Fi was selling some nice ones too. See http://www.head-fi.org/forums/f42/fs...boards-253920/

pikkujöpö 21st August 2008 10:15 PM

Quote:

Originally posted by CJ900RR
Search for C-moy or cmoy or c-moy or any spelled version of what I just wrote :clown:

Grado SR60 he's interested in, has 32Ohm impedance,so Cmoy without an output buffer may not be the best...

error401 21st August 2008 10:20 PM

Quote:

Originally posted by pikkujöpö



Grado SR60 he's interested in, has 32Ohm impedance,so Cmoy without an output buffer may not be the best...

He wants to use an opamp based topology with a relatively weak opamp. I agree, but that's what he wants...

zebra: pikkujöpö is right. This design, especially with NE5532 probably won't satisfy into Grados. A simple design that would probably work well for you is the Szekeres driver, just a single MOSFET and some passives.

lineup 21st August 2008 11:19 PM

NE5532 dual op-apm
has got a pretty good level of output current.
As has the OPA2134, too.
In my opinion both these have current output enough
to drive Grados 32 ohm Hi-Fi phones.

This has also been told & confirmed by several members at this forum.

Now, NE5534 is even a better choice.
Besides having better data, this is a single op-amp.
Two NE5534 can dissipate like two times of one OPA2134/NE5532.
When 2-channels in same IC, the IC will have to handle power heat from left+right.

The usual limit of safe operation area ( SOA ) for 8-pin Plastic DIP chips is like 500-600 mW.
Because plastic melts down and destroys at some temperature.

About the same power level, 500 mW, is for one ordinary small signal transistor.
For example BC547, BC550 or 2N5551 and similiar 'audio transistors'.
TO-92.

Lineup

SpittinLLama 22nd August 2008 04:16 AM

Use one of the new National LME op amps. Many if not all of them are designed to drive 600 ohms at full supply voltage. If not enough current then use the LM49600 buffer to give you up to 250mA of drive current. Look up AN-1768 to see a headphone circuit using the buffer part.

-SL

pikkujöpö 22nd August 2008 08:53 AM

Quote:

Originally posted by lineup
NE5532 dual op-apm
has got a pretty good level of output current.
As has the OPA2134, too.
In my opinion both these have current output enough
to drive Grados 32 ohm Hi-Fi phones.

This has also been told & confirmed by several members at this forum.


Lineup

Well I'm listening to one with OPA2134(or was it opa2132).With 16 Ohm headplugs:bigeyes: .
The sound quite hasn't got the bunch I'm used to, suprisingly good anyway.

P.S. I bet several members of this forum would confirm this as well,or am I mistaken ?
:)

Edit: I will hopefully soon try it with a buffer and report back.


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