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Old 02-12-2018, 10:09 PM
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benman94 benman94 is offline
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Join Date: Jun 2011
Location: Detroit, MI
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Quote:
Originally Posted by maxhifi View Post
The main advantage of ultralinear, so far as I can tell, aside from damping factor, is that you can use a screen voltage the same as the plate voltage, and avoid complexity in the power supply. Beam power tubes really work better when Vg2<Vp, but this of course asks for a more complex and expensive power supply, regulated screens being best.

I don't really like it either, but it does offer a lot of value for money, in terms of performance versus cost and complexity.
There's a paper from Williamson in which he rips into the so-called ultralinear design and proves mathematically that under certain sets of conditions, it affords more distortion than a properly built beam power tube output stage with regulated screens, or a comparable output stage with triodes or triode strapped tubes.

You're 100% right, the UL connection was a cheap way to handle the problem of the screen grids. It also ignores the fact that a great number of output valves simply can't have the screen at the same voltage at the plate. About the craziest example I can think of is the 6146. 200 volts max on the screen, and 600 or 750 volts IIRC on the plate. Yikes! Good for 100 watts, so the entire neighbourhood can hear what you're listening to
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