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Old 16th August 2014, 04:09 PM   #1
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Default Which is worth burning or keeping

Well, something different has turned up..as part of a will I've been given a treasure trove of JAN GE 6550A (175 off) and Gold Lion KT88's (154 off) also a crate of two makes of 6SN7GT. Also mixed stillage of GE EL84's,Mullard EL84's, and 6SN7's. Each tube unused, and stored in dry conditions. No mice droppings.

Am I correct that the JAN 6550A GE green lettering is probably worth more than Gold Lion KT88's ? I cannot be sure if that version is a rebrand..despite the usual test cert that comes with these tubes. Is there a way of identifying ?
What would users do ? Use the power tubes in a circuit or keep as collectors items ? The 6SN7.. which version is better to use in a preamp.. Any experiences ?

richy
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File Type: jpg JAN6550A-KT88.jpg (286.2 KB, 287 views)
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Old 16th August 2014, 04:13 PM   #2
kevinkr is offline kevinkr  United States
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You lucky devil.. What you do with them is up to you, but I would keep a life time supply. I had a number of KT88 that looked as you described long ago, I believe they were genuine. These are both excellent tubes, the KT88 are probably the (slightly) better of the two.
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Old 16th August 2014, 04:20 PM   #3
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Obligatory "you better send them all to me just to be safe"!

I recall seeing a link to a detailed test on 6SN7 family tubes, and it turned out that the ones with the longest plates had best performance. In the picture they look quite similar though.
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Old 16th August 2014, 09:29 PM   #4
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The Brimars with the bright white printing and light grey boxed plates are almost certainly Soviet sourced 6N8S.
I have several examples of each here and they are identical in construction and performance.

Brimar, in the later 60's and 70's, sourced a lot of Eastern European tubes.
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Old 16th August 2014, 11:23 PM   #5
Sprags is offline Sprags  United States
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I'll take the KT88's if you don't want them.
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Old 17th August 2014, 12:28 AM   #6
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The GE 6550As are VERY tough customers, that happen to sound pretty darned good. The best runs of MOV made KT88s may sound a tad better, but I would not junk any of those big "beamies".

The 6550A was developed for bass guitar amp service, in which g2 is subjected to an atrocious beating.

Rich, you're an expert on Williamson style amps. What are you waiting for? Build a Williamson around some of those 6SN7s and the big "beamies". There's no good reason I can come up with why you can't "roll" tubes for quite some time.

BTW, give Jim McShane a holler. I'm pretty certain you and he can come to an understanding. In addition to HIFI service, some of Jim's Fender bass guitar amp customers would go to very great lengths to get decent 6550As. Even the very last production out of Owensboro, KY, is in high demand.
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Old 17th August 2014, 12:41 AM   #7
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I bought a quad of JAN GE 6550A's maybe 25 years ago from a reliable source. They look just like yours. They are, as stated, the best of the 6550 bunch. They cost so much these days that I only use them on rare occasions. Most of the time the EH 6550's are in the amp.
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Old 17th August 2014, 02:54 AM   #8
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Many years ago Uncle Sam unloaded a lot of stock from his underground storage facility somewhere in Utah. I was lucky enough to get a couple hundred before Richardson got the Lion's share. I'm down to my last hundred or so now. They are the best and were indeed designed as superior replacements for heavy duty service. I use them at 600 volts UL with Acrosound TO-600 outputs robbed from a UL-II. Also in my friend's HK Citation II.
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File Type: jpg amplifier1.jpg (140.0 KB, 181 views)
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Old 17th August 2014, 04:30 AM   #9
kmaier is offline kmaier  United States
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First, really nice to have something like that sent your way, congrats!

As noted, GE 6550A are mostly bullet-proof. I've fitted dozens into rebuilt amplifiers from the mid-80's to early 90's. Most (tubes) were dated from the 70's to early 80's. Only problems were one (JAN green label) went dead within an hour... no workie but got really hot trying, looks fine however. The second problem was with the first set ever fitted to a rebuilt pair of Dyna Mk-IIIs. After a few years the amps came back, tubes would barely light. Turns out the base pins were poorly soldered. I cleaned them all out, re-soldered and they worked as new again.

KT88s, I can't believe them to be original MOV made in England. While they physically look the part in overall shape, all markings are completely wrong, size, color orientation, style, etc. All original MOV ones that I have (and have seen) have brown micalex bases, not the black bases shown. There should also be a red inked label on the aluminum base collar with "Genalex" printed in white on it. Still, if they work properly and sound okay... why not?

Regards, KM
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Old 17th August 2014, 05:18 AM   #10
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Good for you, RW

You must have been a good enough guy that they
wanted you to have them. As Kevin said, keep your
own life time supply then do what you want.

(Shameless Plug): If you do get around to selling some I
would appreciate the opportunity to buy some for some
of my amps, not for resale. I've got a Citation II and two
Ampeg SVTs, for the 6550/KT88s. I've got some amps for the
smaller tubes also.

On the bright side, just be happy that the tubes are
old anachronisms and were common enough and
not valuable enough to subject you to a gift or
inheritance tax.

Cheers,
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