A great sounding amp from an unlikely source!
Sep 15, 2009 at 3:34 AM Thread Starter Post #1 of 4


Headphoneus Supremus
Dec 4, 2007
A while back I found a pair of Dell speakers at a rummage sale for a few dollars. It's one of those sets that goes underneath a monitor.

So I did what any kid would do with a new (and functioning) piece of technology. I ripped it apart into a dozen pieces.

What I found inside was a small amplifier board with a Texas Instruments Class D chip amplifier and four op-amps. After trying the speakers out, I knew the potentiometer was much too small of a value. When I checked it, I was right. It was a rather nice looking alps potentiometer with integrated on/off switch, but a mere 5k ohms.

I replaced the pot with a Noble 50k ohm stepped attenuator, wired up to a source and plugged my headphones in to the headphone port.

It sounds great! To my ears, better than my portable amps and at least as good as my SS millett. It has a warmer feel to it. Lots of energy. Works great with all my full size headphones including Grados. It definitely gives my Grados the low-end that they are often missing.

It actually draws less than 500ma @ 12vdc. No heat at all. Very impressive if you ask me.

Anyhow, I boxed it up in a nice enclosure and added an on/off switch and input jack. Pretty good for under $50 including misc parts.

This looks exactly like the one I used. I can grab the part # off the casing of mine if you want. NEW Dell AS500 Flat Panel Sound Bar Speaker 4Y463 - eBay (item 370260340628 end time Sep-15-09 10:23:09 PDT)
Sep 15, 2009 at 3:42 AM Post #2 of 4

Pricklely Peete

Franken modder
Feb 17, 2008
Cool...great job of recycling and modding !

Sep 15, 2009 at 6:24 AM Post #4 of 4


500+ Head-Fier
Oct 17, 2008
Actually I've been a little curious why there are so few Class D (Tripath or other chip) headphone amps. They have poor THD numbers at enough wattage to run speakers but the THD is decent at low wattage for headphones. Maybe there's something about impedance of headphones that makes it arder or more expensive to do.

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