Let's show go on: Building Monster SE!

[Wavebourn]

I am going to design and build a stereo SE amp using monstrous tubes, with 100W plate dissipation each.

Looking at curves, I think 8K output transformers, 1 KV B+ would be optimal for it, what do you think?

[tomchr]

SE tends to like operation at about the max plate dissipation. If Pmax is 100 W, then 1 kV, 100 mA would work. But it seems something along the lines of 700 V, 140 mA might be more linear. I'd have to plot the anode dissipation curve and play with the load lines to reach any form of conclusion, though.

~Tom

[Wavebourn]

I have already 1200V rectified for this project, so dropping 200V on something like IGBT would give 1KV stable, with 40W loss on regulation (20W per channel). Should cover ripples and instability in power outlet well.

Also, I will need up to 400V P-P drive, with 10-20 mA peak. Here Semisouth JFETs would be nice, of course, or some tube in cathode follower configuration, but it has to be most probably some TV compactron for high cathode to filament rating.

[Wavebourn]

I am thinking about something like this. Comments/suggestions?

Edit: Semisouth device looks like overkill... Which 600V MOSFET has low capacitances, to dissipate something like 200V*20MA?

[jjman]

Is it ok to have no grid leak resistor on G1 of V1 ? I'm not very familiar with transformer coupling.

[Wavebourn]

This one looks nice:

http://www.datasheetcatalog.org/data...e8h097wwfy.pdf

270/38/5 pF

Originally Posted by jjman

Is it ok to have no grid leak resistor on G1 of V1 ? I'm not very familiar with transformer coupling.

It is not significant yet. Let's discuss major issues before starting to draw such details. Transformer will need matching loading as well, and so on.

[SpreadSpectrum]

I have used FQPF2N90 as a follower with good results. 900V with low capacitance.

In case you are interested, here is a spectrum of 200Vrms out with new production 6SN7s (CCS loaded and driving a source follower), something to compare to as you get going.

[Wavebourn]

Thanks a lot!

What current did you use?

Edit: hmmm... Looks like 4P1L in triode mode is the best driver tube I can find.

Now, I need to find the best pentode for the 1'st stage...

[astouffer]

Originally Posted by Wavebourn

Thanks a lot!

What current did you use?

Edit: hmmm... Looks like 4P1L in triode mode is the best driver tube I can find.

Now, I need to find the best pentode for the 1'st stage...

7KY6, 6EJ7, EF86?

[Wavebourn]

Originally Posted by astouffer

7KY6, 6EJ7, EF86?

Thanks, let's see...