DIY Sony VFET pt 2 (N-Channel Build)

Vfet 153, up and running
 

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N-VFet 183 warming a bit before hook-up.
At idle the vfets are running at about 71C and the mosfets at about 58C.
A fun build, and I think that the case is a work of art.
I'll share some impressions when I have listened for a while.
Many thanks again to all involved for this outstanding
amplifier.
 

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🙂

I double checked, the top of the case is is indeed around 41C. The "valley" of the fins, where the T-Bracket mounts are at 48.5C.

I'm using a Raytech Laser thermometer

And I agree, counter intuitive for sure.

You need to put a piece of black electrical tape on the vfet case,let it heat up and re measure.Your emissivity may not be set right (if it can even be adjusted) as you are measuring a shiny surface.41C is way low,should be around 70C.Maybe your thermo is even defective?
 
I just put together and biased #138 but I'm getting what I think is a 120 Hz hum when I attach interconnects. If I touch the metal of the amp the hum goes away. Also there is no hum when no interconnects are attached or I short the inputs.

I attached a lead to the DC input jack shell to ground to the chassis but it doesn't seem to make any difference whether it's attached or not. If I touch that lead when unattached, the hum goes away.

The behavior is the same in both channels. Any help would be appreciated.
 

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