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Post by videoguy on Jun 3, 2014 16:21:08 GMT
I purchased the printed circuit board from Wiliams-Hart & supplied my own components. It works flawlessly & it's sound quality is very transparent. Many have listened to music through the amp. & cannot tell whether it is tube or solid state design. The opamp is an AD823. I have modified the output stage to drive pair of AKG K340 headphones, with no problem. The K340's were introduced in the mid 1980's & have a dynamic driver for the lower frequencies & an electrostatic tweeter for the highs. They have been considered hard to drive by many head fiers.
The regulated power supply is external to the amplifier, in its own enclosure with a 3 foot umbilical cable. Instead of a standard volume control I chose to use a 23 position switched attenuator. The headphone jack is on the front panel, with the attenuator. I chose not to implement a balance control, in order to keep the signal path as clean as possible. There is no hum or circuit noise, just dead quiet until the music starts.
It is in a black enclosure from Lansing Manufacturing. NOTE: The power transformer is for 120 volts ac only; for use on 220vac the power transformer would need to be changed. The schematic diagram is included. Pictures can be supplied to interested parties.
Price: $195- USD; $116.45 pounds.
Buyer is responsible for shipping charges & any duty or tarrif.
SOLD AS OF JULY 26, 2014
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