All about Tubes, Tube Circuits, Tube Gear

Wednesday, June 13, 2012

Ju-Jutsu: Ultimate Monoblock (Pt 6) PSRR

 Lets rearrange the Top Tubes in our amp, and put them on a separate Power-Supply Chassis, with the HV B+.

For SE operation, we have to do a little extra isolating of HV power supply to the top tubes,
using additional Cap/Resistor legs. (top of diagram).

Also, we install the signal caps on the PS chassis, so that at least two of the connecting lines
have no High Voltage DC (this is blocked by the caps.
Even the two lines with DC only have half the full B+ voltage,
since it is divided ('dropped') across the Top Tubes.

You can use ordinary 600 volt insulation wire (shielded) between PS and Amp Chassis.
Make sure you orient any connectors safely (males on receiving circuits, females on power sources).

Although there are now two tubes (a 12AX7 and a 5998 for instance) on the PS chassis,
it really isn't any more than you'd find on almost any regulated HV powersupply.
What has happened is that we have simply made more intelligent use of similar tubes,
with much more spectacular results.
Why have a mere 'regulated' supply, when you can have a 'feedback-controlled' CSS supply?
Don't forget to add a good heavy gauge ground line between the two chassis.

"Nazaroo, I'm not seeing what is the advantage of relocating the upper tubes of the Mu-Follower to the P.S. chasiss. Please clarify. Thanks."
(1) It helps isolate the real dangerous high voltage and keep it contained in the powersupply.

(2) Teaching purposes, so that people can understand the true meaning of the Mu-Follower.

(3) The separate heater supply for the top tubes (with HV offset) is also isolated.

The heater supply is perhaps the most dangerous, because even seasoned technicians
forget that it can have lethal HV riding on it.

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