Wednesday, September 30, 2009

YAHA Headphone Amplifier

I created hybrid headphone amp using op-amp & electron tube. (quite unique!)
see for details.
Most of parts are bought from and
Capacitor: Nichicon Muse KZ
Op-amp: TI OPA2134P
Resistors: Dale
Case: Hammond Steel Instrument (1454 Series)

The schematic. I changed some parameters from the original.

The board.

I bought 2 electron tubes from, electro-harmonix 6922 and Sylvania Jan 6922 (deadstock made in 1972). electro-harmnix tube is less noisy. People say this amp produces a lot of distortion but I think this amp creates better sound than the original iPod touch. Especially the low sound is much better than iPod touch.

Im sartisfied with this headphone amp. It sounds nicely! Also the orange light from the tube makes me relaxed!

Tuesday, June 02, 2009

iPod Line Out Dock Adapter

Got iPod Connector ("iPod Connector Male Style 1" sku: DEV-00633) from

Cut Universal board, make it U-shaped, and put it in the iPod connector.

This is Kobiconn 3.5MM Stereo Jack 161-7300-EX ordered from File it and make the diameter a little shorter to put it in the iPod Connector.

Attach the stereo jack to the U-shaped board with bus wire or magnet wire.

Put it in the iPod connector.

Wire and solder the pins between iPod connector and the stereo jack. pin2 is connected to GND (white line), pin3 is connected to Right (Green line), pin4 is connected to Left (Orange line). See for details. Took those lead lines from 10Base-T cable. Also, if you are using iPod touch (2nd) or iPhone (2nd), connect pin11 and pin15.