NS Genelex Gold Lion KT66 owners: BEWARE!!

Good evening gents

Now that I have your attention, here is something that seems to be a problem with the New Sensor Corporation's KT66 Gold Lion reproduction tubes. Purely COSMETIC issues, but it is still an issue for me at least:

I have about 400 or 500 hours of usage on my set of KT66 tubes in my ST-70. The glass surfaces of tubes tend to become dull after extended usage (deposits / dust or whatever), and in the past I have always cleaned it by washing it with a mild soapy solution (non-ammoniac!) and leaving it for at least 2 hours to dry. I know for a fact that the gold insignia and lettering has never had a problembefore, but yesterday I did the same thing and all of a sudden, the gold lettering and lion insignia literrally came off like decals on an old cheap plastic model plane.

So... I checked the next tube and seems I can easily scratch off the lettering with my thumbnail - something I know I could not do a year ago at all (I know, I tried to get rid of the prominent "Made in Russia" lettering when the tubes were new, and could not budge it at all)

So... seems extended exposure to heat destroys the gold lettering on these tubes. Sonically these tubes still sound as good as new (actually better) but if cosmetics are important to you, be forewarned!

Best Regards to all
-- 'Jan

I'm also guilty of enjoying the fancy decals on my Electro Harmonix 6CA7's that I'm currently running in my ST70. They have a large label showing the EH face logo (what is that thing, anyway?)in gold displayed prominently on the tubes. http://www.tubedepot.com/eh-6ca7.html
After only 200 or so hours, the decals have all but turned to dust and fallen away. None of this effects the sound, but if you're gonna bother putting it on there, wouldn't the manufacturer consider the fact that the decal needs to stand up to some serious temperature? For many of us part of the allure of a tube amplifier is the cosmetic appeal of the tubes glowing brightly in our listening rooms. The vacuum tube is much more to us than just another electronic component. Nobody buys resistors based on their color or shape, do they? Really just a silly complaint, but tubes aren't cheap. In the 60's when tubes were standard in all electronics they were hidden in the backs of amplifiers. Today, the tube is itself is an object of desire, and new manufacturers obviously take that into account by adding fancy graphics to their glass. It's a shame they can't find a way to keep them there.

Hi Kevco,

That makes two of us - graphics are important. I wonder if the "Into tubes since the days of Steam Radio" folks on this forum woul tell us if the tubes back in the day (General Electric etc) also lost its graphics as easily - or did they etch the glass back then?

BTW 1) I think that "face" on the EH tubes are the head of a Gryphon or some mythical creature, and 2) my thing for graphics even extend to resistors - I still have the idea in the back of my head that the better quality resistors specced at 1% tolerance are blue, whereas it can probably be any colour - one should REALLY go read the tolerance specifier on the resistor itself.

-- J

I received a matched quad of these as a Christmas present from my bride (what's better than building a christmas list with specific internet links?.....)
I'm running my St-70 with the VTA board, and an upgraded cap can. What is the correct bias setting for this config? I thought I saw it here, some days ago, but now I'm looking to install these kids......

Thanks-

4markny

Bob Latino wrote:

4MarkNY wrote:I received a matched quad of these as a Christmas present from my bride (what's better than building a christmas list with specific internet links?.....)
I'm running my St-70 with the VTA board, and an upgraded cap can. What is the correct bias setting for this config? I thought I saw it here, some days ago, but now I'm looking to install these kids......

Thanks-

4markny

[b]Hi Mark,

You can run these a little hotter than the EL34's. I run mine at .450 VDC per each KT66.

Bob

Bob, just to be specific: across what value cathode resistor, and are you using separate ones?

Better, in my opinion, to specify CURRENT and let users figure out the required VOLTAGE by Ohm's Law!

4MarkNY wrote:I received a matched quad of these as a Christmas present from my bride (what's better than building a christmas list with specific internet links?.....)

Thanks-

4markny

Kind of funny that my xmas spoils followed the same arc:)
Gold Lion KT66's from the Mrs. and some different 12AT7's from my bro.

After pulling a Mullard and putting in an RCA black plate, then dropping in the KT66's I had to stop experimenting because it sounded too damn good! I really wasn't sure how much of a difference these "xmas tubes" were going to make, but I'm actually a bit stunned at the difference. I need to listen to it for awhile again to get used to the sound!

I've done a pretty serious run of 12AT7 rolling since my system uses them in three spots. If anyone is interested, I'm using a Dared SL-2000A preamp with a pair Tele ECC801S. RCA Black Plate 12AT7WA in the middle position on the VTA ST-70 and Siemens ECC801S Triple Mica's on the sides.
I still have to try out a pair of Mazda's, but I'm having a hard time believing I can get a sweeter sound out of this stuff!

Not that I'd actually know any better for sure, but the Dared preamp seems to be a nice match especially since it uses 12AT7's so you can do a lot of swapping and experimenting between the VTA ST70 and the preamp.

I'm really just listening to these KT-66s now for the first time. I installed them initially back after Bob answered my bias question. When I went to bias the new tubes, I was getting higher numbers and couldn't get it to stabilize much under .86 or so. Back to the EL-34 set and still a problem running hot. I finally had time to tinker with it tonight and changed out the month-old rectifier tube. Once I changed that out I could get the bias spot-on.
Black Joe Lewis and the Honeybears are entertaining me at the moment. Thanks all for your input.
Happy New Year !

Mark

I have a pair of Genelex KT66 original in my W-5-M Heathkit, The graphics and decals on these disintegrated, fell off or whatever not too long after the kit was put into service back in the early 60's. I'm pretty sure the printing, decals ect oxidize from the intense heat. I have a lot of tubes that only have the etched markings left. It's just the way it is. The heathkit still sounds the same, markings or no, they are great tubes.

Can't say that I've had any decals problems after 3 to 4 months of use, however the color is now closer to copper rather than gold.