New to me paraglow monoblocks

[Paul Joppa]

Notes interspersed

I. Component Value Changes
Driver Cathode: Changed from 274 ohm to 180 ohm (Increases 5965 current to ~10mA).

That's for 150v at the 5965 plate, a compromise when direct-coupled. To use the Stereomour upgrade kit, you'll want more like ~200v, which alters the resistors.

C4S Board R1: Changed from 237 ohm to 150 ohm (Sets C4S current to match 10mA target
2A3 Cathode: Fixed at 3k ohm (Two 1.5k ohm Mills MRA-12 in series).

Depends on which circuit you choose - that's not clear yet.

Main Dropper Resistor: Changed from 1k ohm to 2.2k ohm Mills MRA-12.

Why?

C4S Protection (New): Added 15k ohm 12W Mills resistor between supply rail and C4S input to pre-drop voltage.

Depends.

Grid Stopper: Changed from 1k ohm to 681 ohm.

OK

II. Topological & Wiring Changes
Driver Power Feed: Driver stage is fed directly from the power supply rail (after 2.2k dropper) rather than being tapped from the 2A3 cathode.

For SRC4S?

Standby Implementation: SPST toggle switch breaking the High-Voltage Center Tap to Ground. A 100k ohm 2W resistor is wired across the switch lugs.

Power Supply Filter: CLC configuration using DC Link Capacitors. Each cap is bypassed with a 0.1uF high-quality film capacitor.

AC Input Snubber: 1 ohm 10W Mills MRA-12 + 0.1uF X2-rated Safety Capacitor at the IEC inlet.

Rectification: Solid-state Schottky diode bridge

A full bridge would double the voltage, to 900vDC - you don't want that. Just use two diodes.

-PJ

 

[superchunk]

OK, here's your reminder :^)

I'll post again shortly with notes on the changes.

Yes, thank you. I'll never scan it but a few pics of schematic and whatnot is good enough, msg me your address and I'll get it out next week.

 

[Paul Joppa]

ok so, I ordered 4 x 100uf wima dc link caps, and am ordering some new resistors to increase the voltage to the 2a3 and drivers a bit.

Just want to run it by the experts before buying. I will then rewire everything, new caps etc...

New resistors:
- cathode resistor to 900ohm - 10w ww - use 4x 910 10w I. series/parallel to get 910 40w

- drop resistor b - 1.2k 10w ww

The proper cathode resistor is 750 ohms and the B+ supply is 300v, at least if you do not keep it direct-coupled. You might get that if you use a choke-input power supply topology.

 

[superchunk]

Notes interspersed

I. Component Value Changes
Driver Cathode: Changed from 274 ohm to 180 ohm (Increases 5965 current to ~10mA).

That's for 150v at the 5965 plate, a compromise when direct-coupled. To use the Stereomour upgrade kit, you'll want more like ~200v, which alters the resistors.

C4S Board R1: Changed from 237 ohm to 150 ohm (Sets C4S current to match 10mA target
2A3 Cathode: Fixed at 3k ohm (Two 1.5k ohm Mills MRA-12 in series).

Depends on which circuit you choose - that's not clear yet.

Main Dropper Resistor: Changed from 1k ohm to 2.2k ohm Mills MRA-12.

Why?

C4S Protection (New): Added 15k ohm 12W Mills resistor between supply rail and C4S input to pre-drop voltage.

Depends.

Grid Stopper: Changed from 1k ohm to 681 ohm.

OK

II. Topological & Wiring Changes
Driver Power Feed: Driver stage is fed directly from the power supply rail (after 2.2k dropper) rather than being tapped from the 2A3 cathode.

For SRC4S?

Standby Implementation: SPST toggle switch breaking the High-Voltage Center Tap to Ground. A 100k ohm 2W resistor is wired across the switch lugs.

Power Supply Filter: CLC configuration using DC Link Capacitors. Each cap is bypassed with a 0.1uF high-quality film capacitor.

AC Input Snubber: 1 ohm 10W Mills MRA-12 + 0.1uF X2-rated Safety Capacitor at the IEC inlet.

Rectification: Solid-state Schottky diode bridge

A full bridge would double the voltage, to 900vDC - you don't want that. Just use two diodes.

-PJ

Yeah so, I see where the mistakes are, I let the llm convince me of some things based on the rectifier which I know isn't a full wave bridge.

Either way, it looks like I should reevaluate based on the shunt regulator kit - that will work for me, yes?

Once I fully understand how that fits in I will go over everything again. I understand it, then I get jumbled then I understand again....

 

[Doc B]

The schematic is fine. DC current flows thru the plate choke to the tube and out thru the cathode. It cannot flow thru the output transformer because the capacitor blocks DC thru it. That is how parallel feed works. Though the cap is most often positioned between the tube and the output transformer it doesn't matter which side of the transformer the cap is on for it to block DC and only pass AC.

 

[superchunk]

The schematic is fine. DC current flows thru the plate choke to the tube and out thru the cathode. It cannot flow thru the output transformer because the capacitor blocks DC thru it. That is how parallel feed works. Though the cap is most often positioned between the tube and the output transformer it doesn't matter which side of the transformer the cap is on for it to block DC and only pass AC.

Sorry I deleted my post to clarify without noticing yours.

Yes I wasn't questioning the schematic but the current wiring which has the choke and pin 2 meeting at the exo36, which perhaps doesn't matter but it seemed a bit odd to me, seeing the choke soldered directly to the transformer. And yes, I thought of the cap wasn't between the tube and the opt it wouldn't block the dc, but I hear you that it doesn't matter if it's between the tube and the opt or the opt and ground?

Either way, I'll do it as in the original schematic...

 

[Doc B]

With the images gone I'm not sure of the configuration you are describing. But yes, one leg of the plate choke (the "low" side), the plate pin of the tube (pin2) and one leg of the output transformer primary would be connected together as in the schematic. The other leg of the output transformer primary goes to the parallel feed cap. The parafeed cap then connects to ground at its other end. The only difference from the more usual approach would be that the primary of the output transformer floats at B+ DC potential in this case, while in the usual case of the cap between the tube and the OT the OT primary would be at DC ground potential. IIRC we listened to both configurations and preferred the setup in the schematic.

I would suggest looking up some basic electronics texts regarding how capacitors work regarding direct current (blocks) vs. alternating current (allows passage of AC frequencies dependent upon the capacitor value and its interaction with other circuit components). This is a fundamental bit of knowledge that is very useful for working with audio circuits.

 

[superchunk]

Ok that all makes sense. My issue is actually that I find it super difficult to think in terms of a loop and not a linear path. So when I see tube - opt - cap configuration it explodes my brain because I always revert back to linear thinking. In theory I understand the loop but when I look component by component I lose that theory again.

Appreciate the help.