6SL7 tube question

Farfetched · #1 07-13-2010, 09:11 PM

are 6sl7GT the same as 6sl7? can they be used interchangably?

projectMalamute · #2 07-13-2010, 09:43 PM

Looks like it to me:

http://tdsl.duncanamps.com/show.php?des=6SL7GT
http://tdsl.duncanamps.com/show.php?des=6SL7

BassmanPaul · #3 07-14-2010, 12:04 PM

GT stands for Glass Tubular. Most if not all 6SL7s available today are GT.

Paul

Lo-E · #4 07-14-2010, 12:06 PM

Yes, they're interchangeable.

poorbassist15 · #5 07-14-2010, 12:20 PM

They are the same thing. One is metal and the other isn't.

BassmanPaul · #6 07-14-2010, 12:44 PM

Don't use a metal tube. The vacuum in them is not as hard as a glass envelope and they do get gassy.

Paul

KramerBassFan · #7 07-14-2010, 12:51 PM

Quote:

Originally Posted by BassmanPaul

Don't use a metal tube. The vacuum in them is not as hard as a glass envelope and they do get gassy.

Paul

Arent they also more likely to be microphonic?

Farfetched · #8 07-14-2010, 01:22 PM

thanks guys

BassmanPaul · #9 07-14-2010, 01:48 PM

Quote:

Originally Posted by KramerBassFan

Arent they also more likely to be microphonic?

Sometimes yes.

okcrum · #10 07-14-2010, 02:04 PM

Quote:

Originally Posted by BassmanPaul

Don't use a metal tube. The vacuum in them is not as hard as a glass envelope and they do get gassy.

Paul

Inside the metal envelope (at least on the US tubes I've used in restorations) is a glass envelope to hold vacuum. I'm not sure if there are reissue metal tubes; I haven't looked and I don't know if they are made the same. The G or GT suffix was used for a number of tubes when they switched to glass-only envelope. 6L6 for example was originally a metal outside envelope.

BassmanPaul · #11 07-14-2010, 02:29 PM

Indeed it was with not much more plate dissipation than a 6V6. The G was the "coke" bottle shape.

Paul

okcrum · #12 07-14-2010, 02:38 PM

Quote:

Originally Posted by BassmanPaul

Indeed it was with not much more plate dissipation than a 6V6. The G was the "coke" bottle shape.

Paul

+1. I actually found some metal mil-spec 6V6s to use in an old radio restoration. They sound great.

BTW, OP please note: 6SL7s were common in 1940s/1950s Hallicrafters receivers, for one. Check around the local ham radio swap meets or gear lists; you might just find some nice ones cheaply. Some old TV sets used them too, if I remember correctly.