On Apr 2, 6:53�am, "Ed Engelken" wrote:
Googling the term, I see that the 52 tube seems to be an example where
both grids are brought out to individual terminals.

=======================================
The #46 is another. The 46 was popular in a number of A****er Kent
radios circa 1932-33. *Class B Push-Pull output stages in high-end
radios had a brief run in the early 1930s, then faded into history. *--
Ed

Hi RATs!

I have a huge P-P 46 vintage amp. It is not yet functioning. It is
clearly very well built

Grow up, Class "A" does not mean good, it means simple ... which,
despite some journalists' daydreams, is not exactly the same
thing ...

Happy Ears!
Al

On Apr 2, 12:14 pm, "tubegarden" wrote:
On Apr 2, 6:53?am, "Ed Engelken" wrote:

Googling the term, I see that the 52 tube seems to be an example where
both grids are brought out to individual terminals.

=======================================
The #46 is another. The 46 was popular in a number of A****er Kent
radios circa 1932-33. ?Class B Push-Pull output stages in high-end
radios had a brief run in the early 1930s, then faded into history. ?--
Ed

Hi RATs!

I have a huge P-P 46 vintage amp. It is not yet functioning. It is
clearly very well built

Grow up, Class "A" does not mean good, it means simple ... which,
despite some journalists' daydreams, is not exactly the same
thing ...

A push-pull pair of zero-bias class B triodes is even more remarkably
simple.

When I first saw the schematic of a 811A P-P audio amp, I was
astonished to find not a single resistor or capacitor in the circuit.
Two tubes, input and output transformers, and connections to a
filament supply and a plate supply. That's all there is, folks!

Tim.

This is very true and interesting. RCA figured out you could strap
the control and screen grids of certain power pentodes and use them as
low or zero bias triodes, and a couple of RCA theater amps do this.
This is also seen in AM era editions of the W6SAI Radio Handbook for
modulators. It is simple. It works. Based on long time experiments it
was concluded it doesn't sound very good at all.

I have never tried it, on the theoryu if it worked very well it would
be popular.

The 811 is certainly an attractive tube economically. It has a mu of
160 as I remember. The Altec 1570B used them as did the Gotham Audio
cutter head amp using a GR toroid for output.

On Apr 2, 6:27 pm, "Bret Ludwig" wrote:
This is very true and interesting. RCA figured out you could strap
the control and screen grids of certain power pentodes and use them as
low or zero bias triodes, and a couple of RCA theater amps do this.
This is also seen in AM era editions of the W6SAI Radio Handbook for
modulators. It is simple. It works. Based on long time experiments it
was concluded it doesn't sound very good at all.

Several of the last of the RCA MI-series cinema amps did this with
6L6s and I believe 6146s. None are desireable to the audiophile in
stock form.

I have never tried it, on the theory if it worked very well it would
be popular.

The 811 is certainly an attractive tube economically. It has a mu of
160 as I remember. The Altec 1570B used them as did the Gotham Audio
cutter head amp using a GR toroid for output.

They showed why toroids are a bad idea for opt's very well, although
there are still a lot of people not listening. With a conventional or
C-core transformer and a revised feedback loop the basic design is
well worth study, though.

The 811 can be substituted in the MI200 McIntosh if the proper
intermediate transformer is put in so as to get the filament voltage
at the 6.3 rather than the 10 volts of the, I think, 8005s. Although
the amplification factor of the 811 is way too high it works anyway.
Distortion still meets Mc specs. We wound one, in fact, where I worked
on a toroid, because we had plenty of scrap surplus transformers we
could dewind (and take the copper home.) And a Gorman winder, which
makes winding toroids pretty fast and simple. The 811s pull more
current but the Mc filament transformers never even got hot.

Bugger... HTML.

Al said:
....
Grow up, Class "A" does not mean good, it means simple ... which,
despite some journalists' daydreams, is not exactly the same
thing

*Saxophones are really complicated.

cheers, Ian.