I have owned and used this wonderful Nelson Pass creation for over 30 years. It is one of the latter S/200 models that have the British Cotswold Electronics transformer fitted so it was easy to connect to the 240volt windings and avoid having to use a step-up transformer
I managed to contact Mr Pass a few years ago and asked what he would recommend in the way of servicing the amp and he said to just change the capacitors. All the smaller ones were replaced. I then contacted Jon Soderberg of vintageamprepair.net who specialises in updating old Threshold amps. He supplied me with a pair of 30,000 mf input capacitors (Double the standard size) and a set of 4 Cardas CCGRS speaker binding posts that I had fitted.
Go forward 5 years and the amp is still wonderfully transparent, airy and powerful. The only reason that I am changing now is because I am going to use a balanced system and will use a much small amplifier as a replacement.
It is heavy and needs a strong platform to stand on – as can be seen from the photos it is designed for rack mount.
Power output: 100 watts per channel into 8Ω (stereo)
Frequency response: 7Hz to 100kHz
Total harmonic distortion: 0.1%
Gain: 26.6 dB
Signal to noise ratio: 100dB
Semiconductors: 8 x transistors per channel (output)
£800 plus postage