RE: strange behavior of Belvu and S&H 5751 tubes in my EICO ST84 preamp

Tubes Asylum

Questions about tubes and gear that glows. FAQ

The tube that hums, when you tested, did you test for shorts? Filament to cathode or grid?

5751 gain is considerably less than 12ax7, but I encountered a no sound situation with 5751's where 12ax7's sounded fine and it was a power supply problem causing the tubes to be biased off the chart for either tube. Suggest you measure DC voltage on cathode, grid and anode on both sections (pins 3,2,1 and 8,7,6) and take a look at the curves for both 5751 and 12ax7.

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Follow Ups Full Thread

Topic - strange behavior of Belvu and S&H 5751 tubes in my EICO ST84 preamp - DAK 14:36:40 07/03/17 (9)

RE: strange behavior of Belvu and S&H 5751 tubes in my EICO ST84 preamp - fredtr 17:12:55 07/04/17 (2)

I have not done any voltage measurements with the bad tubes - DAK 02:23:25 07/05/17 (1)

RE: I have not done any voltage measurements with the bad tubes - fredtr 05:11:18 07/05/17 (0)

RE: strange behavior of Belvu and S&H 5751 tubes in my EICO ST84 preamp - Triode_Kingdom 06:11:11 07/04/17 (1)

I was set to do that but changed my mind - DAK 11:22:18 07/04/17 (0)

RE: strange behavior of Belvu and S&H 5751 tubes in my EICO ST84 preamp - FenderLover 18:14:18 07/03/17 (3)

Even stranger it worked good in a SE EL84 amp - DAK 23:23:33 07/03/17 (2)

RE: Even stranger it worked good in a SE EL84 amp - Mechans 11:45:57 07/04/17 (1)

Yeah, lots of them - DAK 12:32:19 07/04/17 (0)

Follow Ups

RE: strange behavior of Belvu and S&H 5751 tubes in my EICO ST84 preamp - fredtr 17:12:55 07/04/17 (2)

I have not done any voltage measurements with the bad tubes - DAK 02:23:25 07/05/17 (1)

RE: I have not done any voltage measurements with the bad tubes - fredtr 05:11:18 07/05/17 (0)

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