which tube using NonDirect heat with best-class sound ?

[calico88]

I wonder which tube is using non direct heat but in the top level of the class ?

anyone can type the list ? I know it's hard to tell but I have no Idea at all.

cal

[Giaime]

Best tube... for what?

There isn't "the best tube", nor exists a list of the "best ones".

For example a 300B may be great for single ended output stage with output transformer, but it can be very poor in phono preamps.

[calico88]

names one for Amp SE ?

[Eli Duttman]

There are so many variables. Triode, pentode, small signal, and power O/P.

You say you want to build a SE amp with IDH tubes. The electrical behavior of a triode strapped 6AV5 is quite close to that of the much loved 2A3 DHT. The 5965 is a very linear twin triode. A 5965 section driving a triode strapped 6AV5 will get you going nicely. Select a decent O/P trafo suitable for use with 2A3s.

[calico88]

well, I don;t think I can design that. with my limited knowledge.

are you saying 2A3 can be design to NDH ?
if I got it wrong, then which DNDH triode tube is good or best or commond for SE Amp ?
I know 300B or 2A3 is good fro me, but it's DH.

cal.

[lndm]

What about KT66, or 6V6GT.

If you want higher power, try 6550, KT88.

[hacknet]

apparently low voltage high current kt88s work like magic.

[calico88]

any schematic using 6550 KT88 ? how much power ? B+ ?

cal

[lndm]

Between 20 and 100W. Depends on how you use them. What sort of amp do you want? Maybe you could Google for the Williamson amp.

[Eli Duttman]

are you saying 2A3 can be design to NDH ?

Precisely. A triode strapped 6AV5 will substitute cleanly for a 2A3. Find a 2A3 circuit you like and use it. Obviously a hum balance pot. is not needed and you put 6.3 VAC on the 6AV5's heater.

Here is the schematic for the Morrison Micro, a Loftin-White style amp. Scrap the 2.5 VAC filament trafo and connect the 2.5 KOhm/47 muF. bias network directly to the 6AV5's cathode. Use a separate floating 6.3 VAC filament trafo for the 6AV5 heaters to avoid exceeding the heater to cathode potential limit. The Noval 5751 and the Locktal 7F7 are suitable substitutes for 6SL7s.

6AV5 data sheet here.


Edit: fixed typo