GE 6L6GC for ODS build

[gary sanders]

This could be a Technical Discussion topic BUT since Im talking of running them through a 101/124 build I put it here.SO.....

I know they arent the magical mystical RCA blackplates but how are they and what is a good price for a good pair?

[bepone]

fantastic and rich tubes/ experience from soldano hot rod 50

[bluesfendermanblues]

Have used them in a 6G6 Bassman head and a RI 59 Bassmann. They sound very neutral with a nice chimey top end.

I find them very similar to NEW Tungsol 5881/6L6

Have tried them in Dumble clones, but prefer "Winged C" in D amps. Winged C's are supposed to be very similar to STR Sylvanias as used by Fender in SF amps in the 70s and by Boogie in the 80s.

I would save the GE's for a fender Tweed or 60s amp.

[brentm]

I haven't tried them either, but KCA sells them for 100 bucks a pop (NOS) with no matched pairs available. He has some used for 50 per tube that he claims are almost NOS. Might be an interesting gamble on a used pair.

How about the JAN Philips 6L6WGBs? How are those in the D-style amps?

[jelle]

Awesome tube. The TAD 6L6WGC gets very close imho. The Tung Sol one does sound different to me.

Jelle

[gary sanders]

Im just a little shaky with these ebay guys with 50 year old tube tester saying they are good.Just how good is their WW 1 tube tester? Ive seen some go for less than $100 for a "matched pair".I guess I could make sure they will guarantee their specs and check them myself.

I know GE was one of the pioneers so I figured they would be good,you just dont hear much talk of them as you do the RCA brand.I may snag a pair today

[David Root]

Gary wrote: "Im just a little shaky with these ebay guys with 50 year old tube tester saying they are good.Just how good is their WW 1 tube tester?"

Almost all of these old testers test Gm, transconductance. Gm by itself is absolutely worthless as a measure of what a used power tube will produce in terms of current draw at a given Va and bias voltage. I have bought a lot of used RCA blackplate 6L6GC and EL34 Xf* on Ebay and elsewhere and I know what I'm talking about.

With preamp tubes there is some indication that as the Gm goes up the current draw does too, but it is far from the perfect guide that it's touted as.

Just recently I got an alleged matched quad of 1960 long tube double D getter RCA blackplate 6L6GC. I put them on my (modern) Maximatcher which is a digital tester all these Ebay sellers should use. At 400 Va and minus 48V bias, two tubes were within 1 mA or so around 20-21 mA. One was a bit lighter at 17 mA, the fourth drew 47 mA! All matched on a rickety old tester on Gm only.

Fortunately I had another used long tube that measured close to 20 mA so I used that to make up a real matched quad. I have some other high ones so maybe I can do something with it, but.....if you go this route with used tubes prepare to buy at least twice to three times as many tubes as you need to get what you are looking for in a quad, and probably more than that for a close pair. You will end up with quite a few "bonus pairs" if you're lucky!

To come back to the main topic of this thread, I haven't used GE 6L6GC but most folks rate them a close second to the RCA blackplate, not quite as warm but otherwise real close. I have tried Sylvanias in my 100W #124 and did not like them at all, despite the fact that Dumble used them a lot at one time. Very lean, no meat, sort of like the difference between Twiggy and Marilyn Monroe. (That dates me, doesn't it!).

[Teleguy61]

I am using the set of GE 7581As that came stock in my 64
BFTR in my 100 watt ODS HRM, built with 68 Twin iron.
They absolutely rock. Sound way better than in the original Twin!

[bepone]

also to be noted that GM from old tubes don't decrease linear with use, many tubes hold GM at maximum values until the end of life...i measured
(visible, very used) EL34, which were used maybe 30 years in guitar amp, GM was on max..
new ones (modern production ) dont have this behaviour (JJ EL34 after 1 year of using, shows significant degradation of GM value)

so, we buying used tubes which are measured at 100% or 200%, but clearly , means what? maybe visual inspection of clear glass and nice getter, without vapor, with GM measured should give working life estimation..

[gary sanders]

so you can visually inspect an old tube to some extent,like the getter?

[jelle]

Sure you can! The getter is burned onto the glass when the tube is finalized. During its life it disappears and gets thinner. The getter gets thin and this is noticable at the edges of the getter in the beginning of the process, and later on you can see through the getter. I usually try to look to a lightsource through the getter. If dark...then the getter is quite thick...*MAYBE* good....if I see the lightsource...not so good.

However, for me as a scientist, I like to know, and I do not like to guess or trust that it will work. I like the gm test combined with the LIFE test and the SHORT tests of my Hickok better as I care about performance more than looks, or as a friend architect regularly says: 'Function over form'. And engineers like to measure stuff just to be sure.

Hope this helps,

Jelle