NAD 3020 project, strip down and upgrade.

I'll give it some thought. The big problem might be mounting the transistors. They would have to be flat pack outline (so like slightly bigger TIP3055/2955) and wired with very short leads to the original E,C and B points.
Well if it's one thing I do well it's practical adaption I'm sure I could work out something NP
 
so after a long hard look i couldnt work out what was wrong with the amp i was modifying, and it was the speaker terminals, they were not gold

so with another 'A' version i have here ive today repaired it, cleaned it up, put gold RCA'S on it but i have stripped off the old grab terminals, made up a new base plate out of black 5mm perspex and installed gold plug ins

i think it looks ok but it would be good to know what others think

this is one thing the 'A' version was missing(later installed on the 'B' version
 

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Mooly

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2007-09-15 8:14 am
The end of life means they are out of or going out of production and so not recommended for new designs but they are not Lateral type FET.s. Only Profusion are making these. All the IRF parts are HEXFET's.

The Laterals were made purely for audio use (back in the late 1970's) and are very different to all the other types. Only Hitachi made them back in the day and that then got taken over by Renesas but they are long since obsolete.

The two big differences of Laterals that stand out are that the gate/source transfer characteristic is very linear and the FET begins to conduct with a very low gate/source voltage. A HEXFET only begins to conduct at around 4 volts on the gate. The other stand out feature to identify them is Rds or Drain to Source resistance when fully on. Modern HEXFET's achieve values lower than 0.1 ohm, sometimes lower than 0.01 ohm which makes them absolutely perfect for high current power switching such as power supplies and solid state relays. The laterals have a much higher Rds, typically around 7 ohms.