Valve Itch phono

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#721
If you think of it as 3 different supplies:

1 x 300V
1 x 6.3
1 x 6.3

The 300V gnd and the 6.3 gnd are connected together.

The elevated heater GND is not connected to the same GND as the other 2, but rather to a point on the HV supply so that it actually floats at ~1/3 the B+. This point is made by the 2 resistors on the bottom of the PSU sch (220K, 470K). So even without the heater connected, testing voltage at this point should give you 1/3 B+. The bypass cap in parallel with the 220K stops hum.

Post a pic maybe too?


Fran
 
#727
Yes, connect the GND of the heaters for V3 and V4 to the 150V point on the HV supply. Those heaters do not connect to "normal" or circuit GND at all but that heater then "floats" above ground.

If this is done correctly, then using the DMM, measure:

Circuit GND to elevated heater GND = ~150V
Circuit GND to elevated heater POS = ~156.3V
 
#731
Capacitor & shunt regulator question for new build

Hi all

I have just spent some time reading most of this thread and deciding I will build the itch phono, I have nearly everything I need. I have some questions.

I have a lot of stock of gas regulators, VR150, VR105 etc, how about a shunt regulator for the HV from an Ixys 10M45S CCS feeding two series VR150 running at 30mA?

I have used this method with gas regulators quite a bit, in a phono stage, and in driver stages for single ended amplifiers with much success. The CCS isolates the rest of the power supply very nicely.

I am having problems finding 1% film caps for the RIAA section. I have used polystyrene capacitors in phono stages before to good affect. Has anyone used polystyrene caps in the RIAA for the itch?

Thanks

Martin
 
#733
Any good -quiet- supply is acceptable, the system has some PSRR also due to the upper deck tubes in the schema working as CCS. The solid state shunt reg is an optional peripheral that has some own merit.
 
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