audio-talk

I guess the unbypassed cathode resistors affects Rp and therefore drive Z will be higher compromising performance.

Yes, allowing the two cathodes to have their own resistor will allow a voltage to develop on the cathode, so Rp will be increased. Coupling the two cathodes together will remove that ...

Push-pull?
I’m talking signal current?


How is that any different?

Just because you can draw a loop in the circuit, the signal is carried by current.

You could go valve1 -> cathode1 -> 0v -> power supply cap -> top CCS -> valve2. But the CCS will interrupt any signal current. Same starting ...

through valve 1, cathode r1, cathode r2, valve 2, winding 2, the cap, winding 1

In at least half of this you are going the wrong way through a valve.

Yes, a capacitor is a short at AC and a open circuit at DC. Its in series with an inductor which is a short at DC and a open circuit at AC.

But I may not be understanding the point you are making.

I think that the anode ccs’s don’t keep the cathode current constant because signal current flows through the load?
If you have a single shared cathode resistor then the current through that might be constant?


I thought that at first, but that's not the case. 34mA is locked in down each leg ...

Belt and braces tbh. Just use the two 270 and try connecting the cathodes and see if there is any difference.

Any reason you are not using a shared cathode resistor for the second stage?

The major advantage of chokes over resistors or CCS as loads is they will swing above as well as below B+. So you need to have more B+ for resistors. In that circuit you may have enough B+ as you are dropping some of it in the 5k resistor. The other advantage is the added balancing action of the ...

I am sure it was a rhetorical question but

Resistors and coupling caps; Who said they need fixing

I think almost entirely you.

Those ccs. as sold by Kevin, I thought that too so I didn't, but later maybe. In other similar applications a ccs on the anode or cathode added great sound quality, so perhaps they are ( always) better!? I'll never get round to it.


That sounds a bit like a version of:

No one I think is in my ...

So remove the center tapped choke and use to resistors. Ok, standard PP driver stage. Not sure where the CCS's come into it?

Nick, so actually I could use a two power resistors of the value required and b+ to centre tap? Or just use the ccs and have a horizontal. Loadline?

I would have to see a schematic to know what exactly you are suggesting.

I may be getting confused here, but if you are using a choke load, then the inductance not the impedance is what matters. Impedance only makes sense if there is a load on the secondary that is reflected to the primary. When you have a choke load only, then there is no load line as you would have ...

Can we just be clear here:

But when I was measuring distortion

You are not measuring anything, all you are doing is using some curves to estimate what might happen. Its just a very (very) simplified version of what spice does.

andrew Ivimey wrote: Wed Dec 11, 2024 10:01 am Think what Jimi did with distortion!!!!

True, but unhelpful