Oddball Tube - Useful for Audio??

[FlaCharlie]

A couple weeks back I visited the local tube emporium to pick up a couple of voltage regulator tubes. They were scurrying around, as usual, putting together a huge order (190,000 tubes!) which was going to China. It seems the Chinese are buying some NOS American tubes because they are cheaper to buy than to make them themselves.

Anyway, the tubes they were readying for shipment were the 15KY8 and the word was they intended to use them to build amps. I looked them up - see the .pdf file on Pete Millet's site linked below. They are a combo beam power tube and high mu triode in a single bottle. Small quantities of these are listed at $1 each.

Has anyone heard of or used these? Any comments on their possible usefulness in audio? Are the Chinese on to something or crazy??

TDSL Tube data [15KY8]

. . . Charlie

[mashaffer]

http://scottbecker.net/tube/sheets/049/1/15KY8.pdf

Looks useful to me.

[Miles Prower]

I'd say they're onto something. You could use two to make an LTP splitter/voltage amp + PP finals amp. The weird heater voltage wouldn't be a problem for that.

There are a lot of audio "sleepers" out there you can pick up for cheap. I wouldn't expect these to stay that way for much longer, given this development.

[smoking-amp]

Walmart tube amps coming soon. With "made in USA" tubes prominantly on display.
(--SWAG--)

The datasheet curves look very linear for both devices . It is a TV vertical amp, so not too surprising. Looks better than the 6LU8. Too bad there aren't any of them left now.

[tubelab.com]

The "local tube emporium" to Gainesville would be Radio Electric Supply (vacuumtubes.net). Stan at ESRC still has the 15KY8 on the dollar menu. I don't know If he has any left. I bought a few when they first showed up.

The datasheet curves look very linear for both devices . It is a TV vertical amp, so not too surprising. Looks better than the 6LU8.

I tried to crank them in SE, but the 6LU8 kicked their butt. You can get 20 watts from a pair in P-P but I can't remember just how I did that. If the Chinese can buy our tubes, they can read our forums too. Never mind these tubes suck.....they will fry your transformers and blow your speakers!

[smoking-amp]

"If the Chinese can buy our tubes, they can read our forums too. Never mind these tubes suck.....they will fry your transformers and blow your speakers! "

Yeah, and they're radioactive too! 180 milliSieverts.
Says right on the datasheet in the very fine print.

[FlaCharlie]

I tried to crank them in SE, but the 6LU8 kicked their butt. You can get 20 watts from a pair in P-P but I can't remember just how I did that.

Was your evaluation only based on power output or did you listen to them? Any comments on the sound?

If the Chinese can buy our tubes, they can read our forums too.

No problem. Let's just have a few discussions about Democracy, throw in some references to Jasmine Revolution and suggest that the Chinese take to the streets and overthrow the Communist regime. That ought to get the forum blocked pretty quickly!

. . . Charlie

[Matt.B.H.]

Had the same thing on this side of the pond with the 5B255M, the Taiwanese bought a whole load of em. I havnt seen anything with them though. I have seen them on ebay for silly prices from Taiwan.

Perhaps if the Chinese read this thread they will see "Taiwan" and steer clear;-)

[smoking-amp]

The 6/15KY8 has the same base as the 6LR8 (which is the same tube as the 6LU8, which has been liked and used a-plenty), so if you don't like it, just plug a 6LR8 in and re-bias.

And you can even put a 6GF7 (11 Watt power triode, with 2nd 1.5 W triode Mu 64) in the same socket. Section #1 6GF7 triode is identical to the 6/15/KY8 triode even.

Gotta be one of the most flexible amplifiers around.

[tubelab.com]

The 6/15KY8 has the same base as the 6LR8....And you can even put a 6GF7.....Was your evaluation only based on power output or did you listen to them? Any comments on the sound?

I built a spud amp several years ago. It was made for the 6LR8, but I also ran it with the 6GF7 since I had a bunch of them. I found some 6KY8's plugged them in and I remember liking the 6GF7 better. All testing was in SE triode mode. The 6KY8's that I tried seemed to start to sound good as the plate started to glow. I didn't take the time to optimize the bias / load impedance / supply voltage, so my initial observation could be off. The 6LR8 is twice as big and can often be found cheaper than the 6KY8. It ROCKS too.

I briefly wired some 15KY8's into a Simple P-P board using clip leads and saw nearly 20 WPC. Sounded good, but not good enough to prompt me to buy a bunch of tubes and design a PC board. No one is buying the Simple P-P board, so I'm not going down that road again. I currently have a pair of 6BQ6's wired into that same Simple P-P board. Now that combination got my attention.