Tubes gone wild

Tubes Asylum

Questions about tubes and gear that glows. FAQ

I have a pair of Tenor 300 watt Hybrid amps and it is coming close to the time to re-tube them (tube input stage, solid state output). This is straighforward except for one tube, designated "V3". This is one of four (per amp) Russian 6H6P tubes. According to one of the original Tenor engineers whose opinion I respect, this tube must "swing negative" between -3 and -10 volts when tested in the amplifier. Apparently most 6H6P tubes "swing positive" with only about one in ten or twelve "swinging negative". This can only be tested for in situ in the amplifier. The danger in running tubes that swing positive is that the positive tubes could "run away" and blow a soldered pico fuse on the board, plus they apparently can sound "hard" with some odd order distortion. The guys at the Tubestore.com have never heard of anything like this and can't imagine the issue. Can anyone explain this to me and in particular a way to identify these negative tubes or whether I am really going to much things up by running the positive tubes? These are fabulous amps and with the Tenor Company now coming back, are well worth the effort to keep them.

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K&K Audio / Lundahl Transformers

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Topic - Tubes gone wild - Bud 11:28:04 02/26/07 (2)

You only need a bit more info - Russ57 16:19:53 02/26/07 (1)

Thank you - Bud 16:39:12 03/01/07 (0)

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