Bottlehead Forum

General Category => General Discussion => Topic started by: JamieMcC on February 12, 2014, 03:58:28 AM

Title: Tube questions
Post by: JamieMcC on February 12, 2014, 03:58:28 AM

Hi guys a quick question on tube purchasing, if you would be so kind.

When looking to purchase tubes for my BHCrack how important is having balanced triode values?
How much of an imbalance might still be considered acceptable?

Thanks

Jamie
 

Title: Re: Tube questions
Post by: Doc B. on February 12, 2014, 05:10:18 AM

Luckily it's not too important for the 6080 since it is used as a cathode follower with slightly negative gain. I say luckily because balance was not really a quality criterion for these tubes and they can be rather grossly mismatched. I recall Svetlana having a devil of a time getting tubes with even a 25% difference between halves of the 6AS7 they sold. The 12AU7s will benefit from having balanced sections. But 25% difference in transconductance from side to side is probably fine. That is just an off the top of my head number, please don't use it to judge some tube vendor's credentials.

Title: Re: Tube questions
Post by: JamieMcC on February 12, 2014, 05:25:22 AM

Dan thanks, that is just the sort of general guidance I was after.