6CJ3, 6DN3, 6CM3, 6CH3 and 6DW4B damper tubes

6CJ3 damper tube produced by Lindal. NOS (New Old Stock) + NIB (New in box).
6CJ3 damper tube produced by Lindal. NOS (New Old Stock) + NIB (New in box).

When going through the photos in my blog post on my Leben amplifier, I noticed that the damper tube in this photo:

6CDN3 damper tube in a Leben CS-600 tube amplifier.
6DN3 damper tube next to a cathode switch, a 6CS7 and an EL34 tube.

was marked 6DN3, which I, funnily enough, hadn’t noticed before. I was of the impression that the CS-600 uses 6CJ3 tubes, which is stated on Leben’s official site.

In the folder that came with my amplifier, the CS-600 produced around 2007 the tubes are listed as: 4 X 6L6GC (5881) tubes + 4 X 6CS7 tubes + 1 X 6CM3 damper tube (6CJ3), which adds to the confusion as the 6CM3 is equivalent to the 6DN3, and not the 6CJ3.

I’ve looked up both tube types (or rather all four) on Radiomuseum and see slight differences in the specs.

Box of four 6CJ3 tubes from General Electric - marked 6CJ3/6DW4B.
Box of four 6CJ3 tubes from General Electric – marked 6CJ3/6DW4B.

6CM3 (6DN3) versus 6CJ3 (6CH3)

Four 6CS7 tubes & one 6CJ3 tube from General Electric.
Four 6CS7 tubes & one 6CJ3 tube from General Electric.

Tubes that can be used confirmed by Leben

Yoshi Hontani from Leben has kindly confirmed by mail that the following damper tubes can be used in both the CS-600 & CS-600X amplifiers: 6DN3, 6CJ3, 6CM3, 6CH3 and 6DW4B.

That’s good news, I think, as supplies of the 6DN3 seem to be drying up.

Four General Electric 6CJ3 tubes

6CJ3 NOS tubes from General Electric. The Leben CS-600 design uses one of these for a damper tube function.
6CJ3 NOS tubes from General Electric. The Leben CS-600 uses one of these for a damper tube function. Nikon D3 & Carl Zeiss Milvus 50mm.

Also see:

An Introduction to 6CS7 driver tubes
The Leben RS-30EQ RIAA
Sunbuck Audio Note preamplifier “clone” from AliExpress