Can I build a headphone amp with NE5532 or TL047CN

[travis]

I found a bunch of both of these chips in a drawer and I don't remember what I bought them for.

I have AKG K220M headphones. I think they are 35 Ohm.

I did a quick search here and with google and didn't find anything I liked.

[Iain McNeill]

I don't think so. IIRC, both these op-amps have highish output impedance (~100ohms I think) which would make it hard to get enough level into 32ohm headphones. You might just get enough level if you run them at max supply voltage but distortion would be compromised.

There's a few tricks like adding a complementary pair of emitter follower transistors inside the feedback loop to get more output.

You could go old school and use an output transformer (if you got two lying around )


Whats the application? Audiophile or mp3?

[DigitalJunkie]

Give the Cmoy headphone amp a try..I built one and used it with my 32ohm phones,sounded fine to me.

http://headwize.com/projects/showfil...=cmoy2_prj.htm

[travis]

MP3

I've seen that chu moy amp. Are either of these chips compatible with whatever burr-brown he's using? Oh man, I should just look.

[kuldeepsingh]

check out AD8397 ARDZ. high current opamp. It is used on quite a number of portable headphone amps available online (eg, Mini3)

[sangram]

I added (for fun) a 5532 on the output of a PCM2702 DAC to provide a bit of gain. The chip drives my (very basic) earbuds and open-air Panasonic headphones just fine. I don't listen at all to phones, and the distortion is probably a bit higher than I would like, but the fact is that they work. I needed to whole thing to fit into the case that comes with the Alien DAC and the supply is provided by a small regulated supply.

I'm running off +/- 12V regulated rails from a 78xx/79xx series reg. The 'amp' is able to crank a surprising amount of volume into the 32 ohm Pannys, and the Nokia earbuds as well. I cannot turn it up more than halfway without busting my ears. Output offset is about 2mV, so no output cap is required or used. The amp is simple, non-inverting with 6dB gain.

There are obviously much better options, but for almost free, the 5532 works. Not sure about the TL074. I was expecting the chip to self-destruct when presented with a 32 ohm load, but it did not. It probably produces copious amounts of distortion, though. The opamp distortion papers I saw last (Groner) showed the 5532 in distress at 600ohm loads, let alone 32 ohms. A current booster would surely help.

[travis]

Cool, thanks!

I wonder what I bought these for... Filters?

[travis]

Oooh. I see Elliot Sound uses two of them in parallel at the output of one of his headphone amps. Maybe that was it...

http://sound.westhost.com/project109.htm

[Minion]

You could also paralell the output of 2 opamps to drive lower impedance loads , or add a discrete output stage to an opamp useing low power transistors like BD139 ....

Cheers