DIY Sony VFET pt 1

Both channels up, it's alive... reporting for duty from pearl of orient.


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Late to the party and still can’t quite believe I have one of these! Finally got all the bits needed to complete the essentials kit I managed to snag online at BA22 and built it the next day.

Sounds wonderful into 93db floorstanders. Like others have commented, excellent bass and sometimes it can sound downright spooky!

Thanks Papa, this is special. And thanks to all who made getting it possible.


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I use it daily and I am very pleased. I am very curious what would happen with a "better" power supply than the included brick. I have thought about upgrading for a long time. Maybe the universal power supply from the diyaudio store will have nicer looking sinus waves, I don't know. The connector is somewhat confusing for novices with so many pins, and I don't know what precautions to take when building a new PSU.
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A relatively simple thing to try is adding a 1000 uF or 2200 uF, 50V cap between the power rails on each channel, right where the wiring is attached. The brick SMPS handles these values without any problem. If you like what you hear (give it a good 20 hours to settle in), consider whether you are willing to go further.
This mod has really good bang for the buck and is easy to back out if you are unconvinced about the improvement.
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I bought two Panasonic 1500uF caps to try just the above. And left enough cable protruding on the rails to easily add them. Going to listen to it as Papa intended for a few weeks then add the caps and see. No hurry. I quite like the connector and bought two matching male ends - in case I indulge the itch we all have, as proper diy’ers, to see if there’s any benefit to a different power supply 🙃!
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ZM - turned on the amp and fired up the multimeter's temp measurement. It said the ambient temp was 33 degrees C - it IS a hot day but that seemed about 3-4 degrees too hot but who knows....

After an hour playing music with the cover resting in place I removed the cover and measured the VFETs: 61 degrees each. MOSFETS were about 3-4 degrees less. Center between the TO3's was 50 degrees

Outside of heatsink - closest to T-Bar center (i.e, not on fins): 53 degrees C. Fins around 45 degrees. PS case 40 degrees.

Incidentally, the old Craftsman IR 'pistol' I have reads about 16 degrees lower. But was consistent. Those devices should come with a warning!

Rested cover back on and shall measure again when the music lets me remember....