unique audio designs
    the art and science of sound

headphone amplifiers - audio test equipment

The Audio Projects

Many of these are posted as DIY (do it yourself) audio projects on diyaudio.com.  I have bare PC boards available and, in several cases, offer the projects fully assembled.   Also below you will find some build tips on NwAvGuy's O2 headphone amplifier, O2 parts, and other audio goodies.

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OPA1688 Super CMOY

NOW SHIPPING! A mint-tin CMOY headphone amplifier using TI's brand new OP1688 headphone driver chip, plus two "9V" battteries with a real ground, not virtual, and a headphone relay.

Features: ultra high peformance with extremely low battery drain thanks to the new TI chip.  

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OPA1622 Multi-Use Board

COMING SOON!  A OPA1622 headphone driver chip breakout board.

Features: Configure for any amplifier type: non-inverting; inverting; unity gain buffer; differential; parallel stack, pin-to-pin breakout.  Large double-sided heat-sink foil area.  Just 15mm by 18mm and mates with 15.24 mm IC sockets.

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O2 Booster Board

An add-in board for NwAvGuy's O2 headphone amplifier that fits in the top slot of the B2-080 case.

Features: 50uV DC output offset vs. 3000uA for the O2; 250mA output buffers on each channel: headphone relay for zero turn-on & turn-off thumps; rail clamp diodes.

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ODA - O2 Desktop Amplifier

A desktop version of NwAvGuy's famous O2 Headphone Amplifier.

Features: dual-stage LDO power supply heat-sinked to the rear panel; 250mA of output current per channal; lower THD+N gain chips; 5K volume pot for lower Johnson noise.  RCA in, 1/4 out. Holds ODAC

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Inverting O2 Headamp

An inverting version of NwAvGuy's famous O2 headphone amplifier.

Features: invverting input and output stages for lower distortion.  +/-15.3Vdc power rails.  FET input gain and output stages.  3.5mm & 1/4" out, RCA out.  Holds ODAC..

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Victor Oscillator Power Supply

A power supply and case for Victor's ultra low THD oscilaltor boards.

Features: can be used on a tabletop or mounted in a Hammond 1598 case with up to 4 Victor baords.  Batteries, AC input, constant current sinks to the boards.

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Fliege notch filter

A work in progress. :) 

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NwAvGuy O2 Headphone Amp

Here you will find:
* O2 build mistakes to avoid
* Easy O2 headamp modifications
* O2 headamp parts

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ODAC carrier for ODA

A top-slot carrier board to add a NwAvGuy ODAC to your ODA.

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TPS3701 DIP-6 Adapter

An adapter board with the new SOT-23-6 sized TPS3701DDCT window comparator chp from TI that fits into a DIP-6 standard IC socket.  The board includes a 0.1uF bypass capacitor across the power supply, plus a place on the bottom for a 0805 sized capacitor in parallel.