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RoadToNever 1st January 2012 07:39 PM

First amp project
Hi everyone!

I'm looking around for a simple first amp project for desktop use with high measured signal quality and gain control. The headphones I want to drive are between 16 and 250Ohms respectively.
So far I've had my eye on a modified Cmoy: NwAvGuy: Cmoy With Gain

ethanolson 2nd January 2012 05:04 AM

That should be a great place to start. That particular amp is a very good Cmoy design, and should have no trouble driving your headphones. My only serious reservation is the DC voltage offset.

RoadToNever 2nd January 2012 06:18 AM

Thanks, ethanolson. Good to know that it's a good Cmoy design. Regarding DC offset, I plan to use DC wall power exclusively and If it's good(not great) to NwAvGuy's standards it's fine for now. I can't seem to find a PCB or perfboard/stripboard layout for that particular circuit. You wouldn't happen to know?

FREDtheDOG 2nd January 2012 09:55 AM

Sorry that circuit wont work with wall power, it depends on having 2 batteries to genertate the virtual ground

If you use a wall wart you'll need a voltage divider type circuit

Davey 2nd January 2012 03:00 PM

Well, you can buy "wall-warts" that provide +/- DC power......


The modified Cmoy is a nice, simple project but why don't you consider building the O2 amp sans batteries? It's simple too and thanks to RS and terrific group of DIY suppliers the parts/pieces/pcb are easily available.



Willakan 2nd January 2012 04:42 PM

Indeed, someone who was new to DIY electronics reported it was easier than building a CMOY, mainly thanks to the incredibly detailed documentation and that it uses a PCB, unlike most CMOY amps, which must be built on a breadboard.

RoadToNever 10th February 2012 02:45 AM

Anyone have an idea about a good design for for more than one set of headphones? I'm thinking about building something similar to this, except 2 or 3 outputs: PreSonus

RoadToNever 11th February 2012 02:33 AM

Found this: PAiA - 9206KP Headphone Distribution Amp Kit (International version - ships without 110V power supply), Headphone Distribution Amplifier, 9206KP Looks perfect (low output impedance) except that it has twice more outputs then I need right now. Still looking....

ddietz 11th February 2012 03:19 PM

For the headphone distribution, check out the schematic. It is incredibly simple. Inverting voltage amp with gain of 10 for each channel. Uses a standard virtual ground split by resistors with smoothing capacitors. All channels are identical so you can easily duplicate Channel 1 however many times you need, 2, 6, 12, whatever.

Probably costs about $2 a channel if you use nice opamps. The dual audio log pots for level is the most expensive part. Cheap ones can be a couple bucks each. They also don't have to be 100K either, afaik, 10K-20K is fine.

Tajzmaj 11th February 2012 03:34 PM

If you really want to drive load low as 16E than just an op amp probably won't do the job. Try something with discrete output stage. Gyraf HP amp or SDS headphone amp are good ,,ready made,, projects. Check.
Regards, Taj

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