I don't understand why you wonders.
With choke/interstage you have about 30-40dB PSRR (for example at 100Hz), with CCS/gyrator 60-90dB. If you use R as anode load, all of PSU garbage (hum, noise) directly appears on the anode (0 dB PSRR), and interfere with signal!
You should understand the basics of electronics.
As you can see in the #3732 post (this is my #26 preamp schematic
) I also use SSHV2, but after it there a cascode (DN2540) CCS!The raw HT PSU is: 240V AC, AZ1 mesh, 5.4uF-10H-47uF-3H-220uF.
This is an old measuring (Spectrum__21.43.8.jpg).
50Hz component about 83-96dB, 100Hz component below 100dB!
DHT tubes are very sensitive things. If it's not well served, the result can be terrible.
Attachments
Standard cascode CCS.
I attached all schematics (in zip file).
I use common HT raw supply and separated SSHV2 units (with about 20mA CCS).
I use two box layout (about 2m umbilical).
PSU box contains LT raw supplies, HT raw supply and two SSHV2.
Preamp box contains large heatsinks, R. C regulators, tubes, CCSs, input connectors and (Elma 3x) switch, and in my case S&B TX-102 TVC transformers (also with Elma 24x switch).
Merlin, you once again lost in the details.
Look at the circuit solution.
As you can see this is my implementation of Salas shunt regulator. I use fix resistor for shunt's CCS, Salas (and its most common implementation TeaBag's PCB) use resistor paralleled trimmerpot.
The value of the resistor does not matter, because DN2540 Spice model not so accurate. It's sets in the real world -for example- 20mA current.
For your sake I measured in my (one of the many) TeaBags's type SSHV2 CCS bias resistor value: for 20mA it is 99 Ohm (300R paralleled -500R- trimmerpot).
The value of paralleling resistor is indifferent, it is only sets (with paralleled pot max. resistance) the minimum current of the CCS.
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Of course.....but what is the goal?
My implementation is parafeed circuit, cap coupling to the volume control TVC (and resonance reducing with resistors).
If you use (after the cap coupling) large inductivity, also will have resonance problems.