Simplistic MosFET HV Shunt Regs

I am about to finish a SSHV reg with one of the boards of DVB project...
I am using a single cooler for both the semis with a sort of adapter piece in between. Both IRF's have their respective mica pad and insulation washer (see picture)
But measuring across the tabs I am having continuity which puzzles me a bit...
is this harmful to the Mosfets?
And yes, I checked washers and everything...
 

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diyAudio Chief Moderator
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Check the schematic again. The tabs are drains, and they connect. You still don't want HV on a large metal mass that you may touch or it will be fixed to a chassis. So you make sure there is no continuity between tabs and cooler, and that's it.
 
Follow up on the SSHV I built for the C3G-SE amp...

It fired up with no problems (into dummy load at first, then into the circuit).
Rset is 33R, about 2.1V across it so around 64mA CCS, 30ish mA into the load.
Rset is socketed so will probably change to 39R to cut down on dissipation.

Directupload.net - Dacfesgtg.jpg

Sound is gorgeous... very open, dynamic and extremely detailed. I also have no
signs of harshness anymore... Rzobel is a 5R6 with spendy MKP caps, but it seems
to pay. Maybe the harshness was the standard Polyprop caps that I used before...
Dissipation into the cooler seems to be okay running the numbers and both Mosfets
connected to one cooler. Might have to connect it to the bottom plate once it goes
in the chassis... (see preview :wave:)

So was it an improvement...? Yes sir!

Otoons - Political Jokes :: Bush & Condoeeza



.
 

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Follow up on the SSHV I built for the C3G-SE amp...

It fired up with no problems (into dummy load at first, then into the circuit).
Rset is 33R, about 2.1V across it so around 64mA CCS, 30ish mA into the load.
Rset is socketed so will probably change to 39R to cut down on dissipation.

Directupload.net - Dacfesgtg.jpg

Sound is gorgeous... very open, dynamic and extremely detailed. I also have no
signs of harshness anymore... Rzobel is a 5R6 with spendy MKP caps, but it seems
to pay. Maybe the harshness was the standard Polyprop caps that I used before...
Dissipation into the cooler seems to be okay running the numbers and both Mosfets
connected to one cooler. Might have to connect it to the bottom plate once it goes
in the chassis... (see preview :wave:)

So was it an improvement...? Yes sir!

Otoons - Political Jokes :: Bush & Condoeeza



.


Looks like a headamp? Have a similiar SSHV spud WE417 SE OPT (wonderful sound , a few minor bugs I'm working on), what OPT's are you using?

Last night I found that moving my OPT's 3 ft away from the power supply transformers dropped a bump at 60hz from -80db to -100dB

As far as Rzobel caps I also found a huge improvement upgrading these, went with K75's bypassed with the russian teflons (good bang for the buck.) I believe it is really the only cap in the signal path. If you look at pimms website, he shows a shunt supplied ccsload-parafeed here the only cap would be the parafeed cap.
 
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Looks like a headamp? Have a similiar SSHV spud WE417 SE OPT (wonderful sound , a few minor bugs I'm working on), what OPT's are you using?

Last night I found that moving my OPT's 3 ft away from the power supply transformers dropped a bump at 60hz from -80db to -100dB

As far as Rzobel caps I also found a huge improvement upgrading these, went with K75's bypassed with the russian teflons (good bang for the buck.) I believe it is really the only cap in the signal path. If you look at pimms website, he shows a shunt supplied ccsload-parafeed here the only cap would be the parafeed cap.

regal,

yes, it's a headamp. Seems as if I am only building headamps...(this one being Nr.7 ;))
OPT's are custom made from Reinhoefer (quite a well known winder around here) and are 7.5k : 300 ohm. They have taps for other combinations as well.
My amp (although still on the breadboard) is dead quiet despite the proximity of the OPT's to the psu... I am happy about that 'cause 3 ft makes for a large headamp. :D

Guess you are right on the caps but it plain looks better to have both caps the same kind... when I have some room left under my chassis I will try the russian teflons
though listening most of the day the tonal balance now leaves nothing to be desired.
Unless that urge to try someting starts itching again...