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

 

[calico88]

Eli,
wow wait a second, I did not know that DH can be "convert" to NDH.
I already built 300B SE w 6sn7, I wonder if this is the same situation with 2A3 ?

trying to understand the circuite mod to NDH.

cal

 

[Eli Duttman]

wow wait a second, I did not know that DH can be "convert" to NDH.

It just happens to work for 2A3 designs. The 6B4G is electrically equivalent to the 2A3, except for the 6.3 V filament. Some tubes sold as 6B4Gs were in fact 6AV5s that were triode strapped internally, including connecting the cathode to the heater. Taking advantage of the facts given allows a 2A3 circuit to be used with an indirectly heated 6AV5.

 

[calico88]

just 1 problem.
I only have 1 source, which is car battery. (12VDC)

yes it's for car.
there is no AC involve on this thing

cal

 

[Tweeker]

Except for space charge tubes the only ways your going to run a tube amp in a car is by a switching or inverter power supply to up voltage or alternator hacking to provide 3 phase (~400hzish) power to step up with transformers.

 

[lndm]

I once read of a compromise from older automotive days that a hybrid system was useful. Maybe it's not what you want to hear but I believe you can make quite a neat package with mosfets in the output in class A on a low supply rail, for example.

 

[calico88]

low voltage rail... all I know is from Computer PSU.

oh... smps again, I hate that... can't do the 400Hz here, no iren, and winding experience.

now I'm stuck.

cal

 

[lndm]

12V battery = low voltage rail.

 

[Jeb-D.]

I think the design of the amp and output transformer is most important for sound. But from the tubes I've messed with, I like the 6c33c. Although it's hard to find output transformers for. I know a guy that sells excellent quality, inexpensive OPT's for the 6c33c. If anyone is interested I can give you his e-mail address.

 

[mashaffer]

I think there is some confusion here (or else I am confused and thus there is still confusion). I think the original poster has gotten the idea that you can take a DHT and convert that tube to make it an indirect heated tube while I think the responders are saying that you can take an indirect heated pentode and modify a cricuit designed for a DHT so that the circuit can use the indirect heated tube. Right?

mike

 

[calico88]

now you get me confuse.
all I want is modify DH to NDH triode such 300B.

if there is any "300B" (or higher class) NDH, I will use that tube. but none telling me which tube is NDH.

cal