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-   -   Headphone amp chips (http://www.diyaudio.com/forums/headphone-systems/107478-headphone-amp-chips.html)

kubeek 25th August 2007 12:15 PM

Headphone amp chips
 
Could someone please recommend me some good chips for headphone amps?

I would like to build a 4x stereo headphone amp for my studio, and would like to use some more power- and voltage-capable chips because sometimes the headphones need to be loud as hell.

thanks everyone!

ashok 25th August 2007 02:13 PM

".........headphones need to be loud as hell...."


:hot:

You need to check out

http://www.headwize.com/articles/hearing_art.htm

Next ....you can use any of several opamps at the input stage ( OPA2134, LM4562 , NE5532 ,AD826, NJM4580 etc) and follow it with a buffer chip like BUF634 . That can easily drive headphones of all impedances. A few opamps can drive 600 ohms directly . However the BUF634 solves that problem.
Or you can go fully discrete !
I assume you are looking for a good sounding easy implementation. In that case the chips are the easiest and sound very good and can kill your hearing pretty fast ....if you are not careful.
You could stick to +/- 9 volt supplies to limit output but even that might be too much. Some opamps sound better at higher supply voltages ( like +/-12 to 15 volts). I'm not sure how good the BUF634 is at +/- 9 volts.

Check the headwize forum for circuit details or do a search on this forum.
Cheers.

head_spaz 25th August 2007 06:12 PM

kubeek,

You could use any chip you like, and then build a simple transistor output stage. Seems relatively easy enough.

Or, there is the AD815 High Ouput Differential Driver which seems to be well capable of driving low impedance loads. I seem to recall some projects here using this chip. A search of this site might reveal some useful information.
If you don't like the SMT version of this chip, BG-Micro still stocks an older 15-lead through hole SIP version for only $1.95 USD. This package is nearly identical to the LM3886, so it shouldn't be too difficult to work with. This chip was designed as an ADSL line driver, so it has good bandwidth and plenty of umph behind it.

Texas Instruments also offers their TPA6120 High Fidelity Stereo Headphone Driver, which is considered by some to be the best headphone amp on the planet right now.
Veteran has played with this, and may even have some PCBs available.
Rod Elliott at ESP has a write-up in his technical articles about this new TI headphone amp chip, and he details the prototype he built. He seems very well pleased with the final result. See THS6012 CFB Pre-Amplifier (about halfway down the page).
Notice two different TI numbers. IIRC, they seem to be nearly identical chips. Unfortunately, these chips use the new SMD PowerPAD heatsink config. which can make DIY a tad more difficult trying to solder the bug's belly to the PCB.

Headwize is a good resource for headphone stuff.

Hope this helps.
David

kubeek 26th August 2007 04:09 PM

The BUF634 is not available here, could you suggest some other buffers?

ashok 27th August 2007 02:46 AM

How about a discrete output stage ? That must be easy to get.
Say BD139/140 !
Can you tell me what your requirements are ?

1. Does it need an on board power supply ? ( say 12-0-12 v ac input to the board )
2. Does it need an onboard headphone socket.
3. Does it need an on board volume control ?
4. Any restrictions on the board size ? ( 4x4 inches ? )

There might be ready made boards available .
Cheers,
Ashok.

kubeek 27th August 2007 08:09 PM

It will be probably 4 stereo amps on one board.
Power supply is not yer decided, I would prefer single railed because you can use cheap wall wart as power source instead of a costly new transformer. So tha t means caps on output, can the on-thump destroy headphones?

I can do the board design and manufacture by myself, I only need help with choosing cheap and simple output stage.

I never designed discrete amp by myself, so I would appreciate your help with that.

So my requirements could be 12v supply, 1-2W per channel.

Thanks

btw what about LM386? is it usable? I used it a looong ago for some experimenting and it wasnt too great..

kubeek 27th August 2007 08:14 PM

And I could also use some adjustable limiter to prevent ear damage. Anyone seen some schematic independent on the amp itself?

KP11520 28th August 2007 01:20 PM

Try this web-site for ideas. If you drill down far enough , somewhere in this web-site he compares many op amps. This might give you some ideas. Good luck!

http://tangentsoft.net/audio/

Regards//Keith

jarthel 29th August 2007 01:56 PM

headwize.com (projects section)

lots of headphone amps using opamps

kubeek 30th August 2007 02:52 PM

2 Attachment(s)
So what do you think about this? Transistors will probably be 2n5551/5401 and MJE340/350, with NE5534 as opamp.


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