6L6 replacements

[TD_Madden]

Anybody tried these? I bought a few and think they are pretty good...

http://www.vacuumtubes.com/6BG6.html

[Arthur B.]

I don't think they are intended 6l6GC replacements. Sweep tubes tend to have their own characteristics.

[TD_Madden]

Well, I have some Sylvania 6L6GCs I took out of a Bassman 135.....and they sound the same......

[Rob Mercure]

Check out the old Ampage archives that Steve has recently provided. We "cussed and discussed" this one to death and the owner of the site mentioned even responded. To "nutshell" it the result still came down to his assertions as no Ampager seemed to have tested the tubes in a controlled manner. Who knows?

But to respond to Arthur's comments: The first sweep tubes were variants of 6L6s tweaked for higher plate voltages and with a plate cap and the 6BG6 is a 6L6 variant. The HO frequency for TVs is a bit less than 16 kHz well within the audio band and many well known amplifier designers, such as Macintosh, used sweep tubes at one time or another.

[TD_Madden]

well, if I knew how to test them in a "controlled manner", I would.

They sound good and are inexpensive....and being made by Sylvania in the US, well, I'm sure ready to take the chance. Eyeballing the innards and comparing them to the Sylvania STR's they sure LOOK the same (except for the plate cap, of course.)

Anybody else trying 'em????

[TD_Madden]

sorry for sounding annoyed....I was just trying to get some other folks to try something that is inexpensive and apparently easily available.

The major drawback is the inclusive length with the adapter.

[Rob Mercure]

Well, I for one, didn't notice your "annoyance." And I suppose that I was a bit vague about "controlled manner." What I was hoping to relate was that no Ampager at that time seemed to have bought these bottles/adapters and used them in a circuit that stressed them as highly as a 6L6GC or a 7027A. On the good side the price doesn't seem to have gone up in 7-8 years. Almost cheap enough for TTD ("test {un}til destruction"). I dunno, I wish I had a "dud" as I've got a collection of "innards" from dead output tubes going back a few years and I know I've got a 7027A with a vacuum leak - white getter - that I would readily dissect to compare plate structure thickness, etc.

And, just because a bottle shares a common plate doesn't mean that the cathode can provide sufficient electrons nor that the screen dissipation is as high as the tubes these claim to sub for. The North American 6CA7 has a plate that is claimed to be identical, at least in GE tubes, to that of the 6550 (I've got a 6CA7 in parts but no 6550 to directly compare it to) but I've never seen any claim that the 6CA7 would dissipate as much power.

So, who knows, "someone" just has to buy a few and play "guinea pig" for the rest of us. Any volunteers?

Rob

[TD_Madden]

Rob,

How do I find that old Ampage discussion...is it still available?

I don't have a chassis that could really push these things....just a couple 30-40 watters. I think I'd have to upgrade the OT in these things to truly check 'em.

[TD_Madden]

This is interesting....

http://cgi.ebay.com/Ampeg-Vintage-6B...QQcmdZViewItem

[Rob Mercure]

Way cool - and I wasn't aware that there were any "New York" Ampegs - somehow I thought that the company started in Linden, NJ - and I wonder if the Celestion is original - I'm not much of an expert on English speakers.

As far at the archive Tboy/Steve had them listed on the main page - here's the link I copied from there:

http://archive.ampage.org/

[Steve Conner]

I'd be very surprised if the Celestion speaker was original. That looks like a 70s vintage of Celestion with a ceramic magnet.

Those 6BG6 tubes might not be exact replacements for 6L6s, but I'm sure they work fine. If none of the American Ampagers bites, I guess I might get a pair to test. If I'm going to play with top cap tubes, I have some 6146s to try too, and some big old STC something-or-other beam tetrodes that look like KT88s with top caps.

[steve]

Rob,

How do I find that old Ampage discussion...is it still available?

I don't have a chassis that could really push these things....just a couple 30-40 watters. I think I'd have to upgrade the OT in these things to truly check 'em.

Here's what a Google search turned up:

http://www.google.com/search?q=6bg6+...icrosoft:en-us

HTH,

steve

[soundmasterg]

I got some of the 6BG6's from that same site and made up some adaptors, but haven't tried them in anything yet. Which thread was the archive discussion on?

[Arthur B.]

But to respond to Arthur's comments: The first sweep tubes were variants of 6L6s tweaked for higher plate voltages and with a plate cap and the 6BG6 is a 6L6 variant. The HO frequency for TVs is a bit less than 16 kHz well within the audio band and many well known amplifier designers, such as Macintosh, used sweep tubes at one time or another.

Sorry; I was thinking of the European frame grid pentodes.