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    Building, troubleshooting and testing of these amplifiers should only be
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Best sounding tube for low power?

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This thread has inspired me to put together a 46 stage. I want to avoid a cathode bypass cap so I'll start with a 200R resistor. I may try filament bias as well. It's up against my 10Y stage which is a big ask. A couple of draft ideas.......
 

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I might have a box full of Teflon / Silver stranded wire from a Korean war era US fighter jet. It's too heavy for signal wiring but makes for some good heater wire since it is all twisted pair. I used most of it to wire up a car.

I helped a friend strip out all the avionics and other electronics from the plane and in the process acquired a box full of wire that probably cost the US taxpayers $50 per foot.

#1 son, now a pilot, used to cut grass at one of the larger FPO's in NJ -- a regular tip-diver he would pull out the avionics out of the dumpster every week == when some of the big companies were "doing over" -- he made a nice piece of change.

I have a 20' piece of high velocity teflon cable when the avionics on his work plane was redone a couple years ago. Too short for ham radio use.

George -- how did you do under the knife?
 
The surgery went relatively good. The doc took a good size chunk of something "like he had never seen before" out of my back.

I was pretty sore and immobile for a few days, but I am taking a break from mowing the yard right now.

The stitches come out on Tuesday, and hopefully he will have a biopsy report from the chunk.
 
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I ran the 45's at about 25 mA to 30 mA and the B+ is 320 volts which is slightly over spec. This does not seem to be an issue since the amp still uses the same pair of used 45's that I got on Ebay over 17 years ago when you could find them for under $10 each.

I don't have anything to add that you wouldn't know , ' just writing to thank you for taking the time.
Partial to near horizontal load lines anyway, you've talked me into having another go at the 45 . I have a pair of transformers with a secondary of 16KΩ. Oddly enough the 10Y they were designed for (used on a compression driver) sounded better to me with about half that and Vp <250V, Ip = 30 - 35mA.

Thanks George!
 
The surgery went relatively good. The doc took a good size chunk of something "like he had never seen before" out of my back.

I was pretty sore and immobile for a few days, but I am taking a break from mowing the yard right now.

The stitches come out on Tuesday, and hopefully he will have a biopsy report from the chunk.


Sounds ominous, sure hope your results are positive. Best of luck, John L Stewart.:)
 
1P24B rod pentode not bad either.
1 K screen-to-plate resistor, 150 v, 25 mA, 8 K load. Can get whopping 700 mW SET power. But 3D6 is a bit more refined to my taste.

I have some 1P24B that I may use for a small SET amp/headphone amp.

If they are half as good as the 1J24B and 1P29B I have used to good effect (up to about 60mW) then I expect they perform very nicely indeed.
 
I have only heard one type of sound from any type of tube: braking glas when it falls on the ground.

Tubes don't make any sound!

It's the complete circuitry that matters.

Well yes, that's always the case. But tubes do have a distinctive sound. If you optimise the circuit you're never going to get a 6L6 to sound like a 300b, or a 12AU7 to sound like a 01A.

Yes you can, it's all about frequency response, the spectrum and amplitude of the harmonics, plus the spectrum and amplitude of the noise.
A good designer can achieve any of that, with any technology.
 
13fm7 set, low power....best sounding build so far...imho, even this lowly tube can sound very good....
 

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