If you idiots are done laughing at your own jokes, I'd like to add that I'm planning on using a grid choke anyway - I just didn't modify the drawing.
Oh, and please don't take that the wrong way.
Oh, and please don't take that the wrong way.
I have no first-hand experience with grid chokes.
It should, however give tight control of "any grid current that might flow"😉
My question is: would you then need the 1k stoppers?
Presumably they're there to stop parasitics? Would the choke change things enough?
Pay attention John, I said choke in the cathode circuit. See the schematic scott nixon linked to. They use a 600mH choke in parallel with the cathode bias resistor (pot).... and I was wondering why you would do that, since having a high (AC) resistance would seem to me not a good choice for a cathode follower, where Ro' would increase then. But I'm not sure.
It will also almost double the potential output voltage.🙂
A slight😎 increase in power one thinks😉
A slight😎 increase in power one thinks😉
choke time
Fot Joel.. The choke specified is a high current design, so the total resistance is likely small. Example: Hammond has a 300mh 1A choke as a standard part, don't remember the number - duh - but it's 6 ohm series r. Perhaps two in series would make up a useable inductor for a SE OTL. If you'll note, the japanese '52 SEOTL also has a 20 ohm in series with the inductor as well as what I'm guessin' is a 1mh inductor that may be there to tune either resistance or inductance. On your amp ( IMO ) you need more than 20db of gain, much lower Z drive, a tiny bit of feedback and perhaps take the front end B+ to 250v or close to double the output supply. Think about a 6SL7, k-bypassed into a cathode follower to drive the output. Your cathodyne will get the pase right, but output Z will be 20k+, as a cf you can drive with ~500ohms. Just one view of it 😀
Fot Joel.. The choke specified is a high current design, so the total resistance is likely small. Example: Hammond has a 300mh 1A choke as a standard part, don't remember the number - duh - but it's 6 ohm series r. Perhaps two in series would make up a useable inductor for a SE OTL. If you'll note, the japanese '52 SEOTL also has a 20 ohm in series with the inductor as well as what I'm guessin' is a 1mh inductor that may be there to tune either resistance or inductance. On your amp ( IMO ) you need more than 20db of gain, much lower Z drive, a tiny bit of feedback and perhaps take the front end B+ to 250v or close to double the output supply. Think about a 6SL7, k-bypassed into a cathode follower to drive the output. Your cathodyne will get the pase right, but output Z will be 20k+, as a cf you can drive with ~500ohms. Just one view of it 😀
Thanks Scott. But I was referring to the AC impedence of the choke. I know the DCR is low - otherwise there would be no point in using one.
Let me simplify - what happens when the AC impedence in the cathode circuit rises to large levels at the higher frequencies?
A 1H choke will have a resistance of 62,832ohms at 10kHz.😕
Let me simplify - what happens when the AC impedence in the cathode circuit rises to large levels at the higher frequencies?
A 1H choke will have a resistance of 62,832ohms at 10kHz.😕
Mmm, let me guess....
....More power into the speaker?Possibly so, I haven't checked. What you do want, is an impedance that is high enough at the lowest frequency we intend. Say 10Hz.
Also, think of the DC current that choke will pass. Do you think a gapped 1H choke at that current will fit on your chassis?
Stop whingeing, and try it for yourself (on a small signal stage for starters), so you can get a feel for what's going on.😉
Correction:
What you want is an inductance that has a high enough impedance at the lowest frequency we intend.
I meant to say:
What you want is an inductance that has a high enough impedance at the lowest frequency we intend.
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