6GH8 - A Little Off?

Vespasian · 28th October 2006, 02:46 AM

Having a great time bringing the old Scott lk72 back to life. Today I stuck in a bunch of Orange Drops and a couple new JJ7591's (they are bigger than the original, tight fit next to the output transformers) cranked things up adjusted the pots and found a hum in the left channel.

Switching the two 6gh8's and the hum followed, so hoping that a new tube will quiet things down nicely. - But now I'm looking at the tube and am a bit surprised - check out the bottom photo.

How common was that? (Early 60's)

The other thing that surprised me was the size of the new caps. The .25's are just going to clear the bottom cover.

Cheers, Ed

dhaen · 28th October 2006, 08:11 AM

I remember coming across several valves like that in the 60's, but can't recall any since. Mind you, at peak I was probably averaging 20 valve replacements in a day at work.

Cosmetics wasn't an issue then, when everything was enclosed. As long as it didn't interfere with a screening can or clip, there wasn't any practical disadvantage either.

SY · 28th October 2006, 11:12 AM

We refer to this as "bias."

28th October 2006, 02:46 AM	#1
Vespasian diyAudio Member Join Date: Sep 2006	6GH8 - A Little Off? Having a great time bringing the old Scott lk72 back to life. Today I stuck in a bunch of Orange Drops and a couple new JJ7591's (they are bigger than the original, tight fit next to the output transformers) cranked things up adjusted the pots and found a hum in the left channel. Switching the two 6gh8's and the hum followed, so hoping that a new tube will quiet things down nicely. - But now I'm looking at the tube and am a bit surprised - check out the bottom photo. How common was that? (Early 60's) The other thing that surprised me was the size of the new caps. The .25's are just going to clear the bottom cover. Cheers, Ed

28th October 2006, 11:12 AM	#3
SY diyAudio Moderator Join Date: Oct 2002 Location: Austin, TX Blog Entries: 1	We refer to this as "bias." __________________ “Listening to records is like ****ing a picture of Brigitte Bardot.” - Sergiu Celibidache

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28th October 2006, 08:11 AM	#2
dhaen diyAudio Moderator Emeritus Join Date: Jun 2002 Location: U.K.	I remember coming across several valves like that in the 60's, but can't recall any since. Mind you, at peak I was probably averaging 20 valve replacements in a day at work. Cosmetics wasn't an issue then, when everything was enclosed. As long as it didn't interfere with a screening can or clip, there wasn't any practical disadvantage either.

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