Wonderful content! Really enjoy the "cut and try" approach. It really points to the joy of discovery...Don't let the trolls get to you...Thick skin really is a virtue...Thanks again...
@Skunkie. I did find it interesting at how even the response curve was with the plate choke in place, but it seems to do so at the expense of distortion. Given how you had pretty good results with the last tube you put in the amp with a plate resistor, perhaps it would be better to go that route than have another massive piece of iron on the chassis. It certainly would make the amp construction that much cheaper as well. I was really impressed with the low frequency response on the amp, it goes down pretty far. For bass lovers, this might be an interesting project for those that have transmission line speakers.
To use a resistor in place of an anode feed chocke, you should consider impedance instead of resistance alone. Impedance consists of reactance plus resistance and is frequency dependant.
Always enjoy your content. Another possible explanation for the high distortion numbers is that the output valves are loaded to half expected impedance because using only half of the valve. In this possibility, the driver is operating linearly, and as expected, with its plate choke but is generating a complementary even-order distortion with the resistive plate load, which partially cancels the output valve's predominately even-order distortion. A definitive test would be to measure distortion after the driver and before the output valve. Anyway, keep up the great work.
right, and possibly removing the bypass cap would also help. I still think this power choke just isn't up to the task, but we will find out. I could also power up the other heater later and see what happens, well other than heating up the room lol.
Hello Steph , 266 volt on the plate of the 6C33 ( with the negative probe on the circuit mass ) Plate voltage is 266 volt minus the voltage ( 63 volt ) over the cathode resistor...equals +/- 200 volt plate.
Yes correct, I get that. Voltage across the tube (which is what matters) is not the same as the voltage measured at the plate. Both are important to know.
I’d look at the impedance of the choke vs the resistor. I use a de-5000 meter to measure impedance. That might help answer why it’s reacting the way it is.
Since you do not need the extra gain, get rid of the cathode bypass cap on the front end tube. You will get some degenerative feedback that will help lower the distortion. Dan
I've got some better quality Anode chokes on the way. I wanna see how they work. The solutions you suggested would work, a CSS would work etc but the goal here is to learn how anode chokes behave.
@SkunkieDesignsElectronics I made some anode feed chokes in the past using RDH4 design method. The thing with this type of chocke is that unlike PSU chokes they need to have low interwinding capacitance and low leakage inductance which both equal to very big size! So IMO use a mosfet gyrator and leave the choke idea alone.
That's why I am getting actual anode chokes instead of trying to repurpose this power supply choke. Like I said, I get I could do something else. I'm much more interested in exploring if this can work using good parts.
I think I did say it sounds pretty good just using the plate load resistor, but I feel like there is more to be had. I just need some time get back to playing with some better plate chokes. Thermionic labs is also sending me a choke to try.
were watching you learn as you go and learning from this journey.
Great video! THIS is development, and the challenges that we have to overcome make us grow!
Wonderful content! Really enjoy the "cut and try" approach. It really points to the joy of discovery...Don't let the trolls get to you...Thick skin really is a virtue...Thanks again...
@Skunkie. I did find it interesting at how even the response curve was with the plate choke in place, but it seems to do so at the expense of distortion. Given how you had pretty good results with the last tube you put in the amp with a plate resistor, perhaps it would be better to go that route than have another massive piece of iron on the chassis. It certainly would make the amp construction that much cheaper as well. I was really impressed with the low frequency response on the amp, it goes down pretty far. For bass lovers, this might be an interesting project for those that have transmission line speakers.
Love watching the development process. Great stuff.
Always cool to see a pro punching though the unknown to greatness!
To use a resistor in place of an anode feed chocke, you should consider impedance instead of resistance alone. Impedance consists of reactance plus resistance and is frequency dependant.
That's why I didn't just use a resistor that = the DCR.
Always enjoy your content. Another possible explanation for the high distortion numbers is that the output valves are loaded to half expected impedance because using only half of the valve. In this possibility, the driver is operating linearly, and as expected, with its plate choke but is generating a complementary even-order distortion with the resistive plate load, which partially cancels the output valve's predominately even-order distortion. A definitive test would be to measure distortion after the driver and before the output valve. Anyway, keep up the great work.
right, and possibly removing the bypass cap would also help. I still think this power choke just isn't up to the task, but we will find out. I could also power up the other heater later and see what happens, well other than heating up the room lol.
It is the Loch Ness of America!
Lovely work.
Hello Steph , 266 volt on the plate of the 6C33 ( with the negative probe on the circuit mass )
Plate voltage is 266 volt minus the voltage ( 63 volt ) over the cathode resistor...equals +/- 200 volt plate.
Yes correct, I get that. Voltage across the tube (which is what matters) is not the same as the voltage measured at the plate. Both are important to know.
I’d look at the impedance of the choke vs the resistor. I use a de-5000 meter to measure impedance. That might help answer why it’s reacting the way it is.
That's prototyping.....🙂 First build, then tune.... :-) Hope it works out...
Oh it will I'm sure!
Disappointing , but interesting, thanks. I am looking forward to your upcoming reel to reel videos!
I am not giving up, a lot to learn here!
Since you do not need the extra gain, get rid of the cathode bypass cap on the front end tube. You will get some degenerative feedback that will help lower the distortion.
Dan
That's on the table too.
Hope it turns out great as it looks too cool to be a dud.
It will, even in the plate load resistor form it sounds good. I just know there is more here.
It's an interesting build and I wondered where you ended up with your power supply? Is it 33uf-4H-220uf-50ohm-220uf?
yes
Hello, will you please try CCS using 10M45 supplying 20mA plate current.
I plan on trying several things like this.
Use gyrator instead of that choke, another option is to use a low distortion cascaded driver like the one used in 6336 amp by Cascadetube.
I've got some better quality Anode chokes on the way. I wanna see how they work. The solutions you suggested would work, a CSS would work etc but the goal here is to learn how anode chokes behave.
@SkunkieDesignsElectronics I made some anode feed chokes in the past using RDH4 design method. The thing with this type of chocke is that unlike PSU chokes they need to have low interwinding capacitance and low leakage inductance which both equal to very big size! So IMO use a mosfet gyrator and leave the choke idea alone.
That's why I am getting actual anode chokes instead of trying to repurpose this power supply choke. Like I said, I get I could do something else. I'm much more interested in exploring if this can work using good parts.
Enjoying this series, thanks for your work.
I'm sorry, Skunkie fans. I ordered one of those phono stages and she accepted my order. I certainly don't need this amp's extra heat here in Phoenix!
I think they may have used that tube, as a template for Chernobyl Nuclear Plant!😂
It feels like I should be wearing a lead suit being near it lol
wonder how this would work as a headphone amp..its bass should be great..
well, being mono, itll blow the drivers out of one side of your headphones
Would only be a good headphone amp if you also need a space heater.
@@SkunkieDesignsElectronics haw haw haw!
🔊💜🎶🦨
At the least can't you listen to it and make a report on what it sounds like as is?
I think I did say it sounds pretty good just using the plate load resistor, but I feel like there is more to be had. I just need some time get back to playing with some better plate chokes. Thermionic labs is also sending me a choke to try.