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Pair of fully populated USSA 5 25w Class A board


Paid Member
2018-03-17 6:45 pm
Assembled by Fab, the designer.

Mosfets 2SJ313/K2013
output Mosfets ALF16P16W/16N16W
Everything is matched.


£300 the pair + P&P. If I can find them I'll also throw in a new pair of 24v SMPS that can be used to testing.

Specifications of USSA-5 (obtained on 1 channel) (updated 2019-11-24)
 Gain: 20dB (or x10)
 Input sensitivity: 1.8 V-peak for output (20W rms)
 Damping Factor (100 Hz , 8 Ohms): [35 – 45]
 Output impedance: about 0.2 Ohm
 Input Impedance: 22K Ohms
 Max power into 8 Ohms before clipping: <25Wrms (at Supply voltage of +/-24Vdc, 1.2A Bias current)
 Power in Class A (8 Ohms): depending of bias current
 DC offset: trimmable to < 3mV
 Rise time (10 to 90%) < 1.3us


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Paid Member
2018-03-17 6:45 pm
Can also throw in some panel mount RCA inputs for free, and I also have some brand new Jensen input transformers as well that I would sell alongside at a good price. A good way to have XLR input to a single ended amplifier.


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