O2 Desktop Amplifier (ODA)
NwAvGuy mentioned creating a desktop version of his famous O2 Headphone Amplifier in his blog and forum postings, but never did. My version of an O2 Desktop Amplifier is my attempt to imagine what that ODA might have been.
The ODA offers several benefits over the O2 for desktop use, including:
- Three times the output current capability at 420mA per channel
- Headphone relay for absolutely no turn-on or turn-off thumps
- Super quiet 2-stage power supply with voltage regulators heat sinked to the case
- Input power CRC filter, snubber, and transorb to remove power line noise
- Lower THD+N LME49990 (optional FET OPA827) gain stage chips
- Clipping detect circuit and front panel LED
- 1K volume control and 4.99K ground return resistors for lower Johnson noise, given that the new LME49990 (or OPA827) chips are rated for a 600R load vs. just 2K with the NJM2068
- Lower distortion and higher S/N ratio with 6 paralleled op amps per channel
- Rear panel RCA jack input, front panel 3.5mm jack input, input select switch, 4 position gain switch, front panel 3.5mm & 1/4" out, front panel pre-amp out, damping factor adjust option.
- Rear panel AC input and power switch, vs. front panel for the O2
- The case has room or an optional top-slot PC board
The ODA project is a do-it-yourself project I've posted out at DIYAudio.com in the headphone forum. All the project files are at the Google Drive link below including schematic, layout, bill of materials (BOM) for purchasing parts from Mouser or Digikey on the internet, build instructions, photos, and part ID diagram. In the DIY Audio forum I've posted a full photo build guide - see the first post in the forum ODA thread.
Google Drive link for the ODA V2.1 do-it yourself files
An ODA FAQ can be found here.
Bare PC boards, PC boards with all the parts soldered on, and entire ODA Headphone Amplifiers are available. If Mouser and Digikey are out of stock of any part for the ODA I probably have that too, although I don't sell complete parts kits.
For prices and ordering information see here.
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