What are the best 6550/KT88 tubes for 2011?

[MstrB]

I am looking to buy an octet of power tubes for my bass amp. I have not been using any of these recently and was wondering which ones were the most reliable and which seemed to have the best sound. Thanks, B.

[AXEnGEAR4J]

I've been doing a lot of research on new KT88 & 6550's and I believe you may want to go with KT88's.
Many long time, old time and hard time users running them in high plate voltage amps have provided great input and it's come down to either Winged C's or JJ's for sound and durability.
I planned to buy several quartets in the near future for my Marshall Majors and Model T.

[Steve Conner]

6550s and KT88s are not quite the same. The 6550 has more "outer mu" and so likes to run with a lower screen voltage. It may not be as happy as a KT88 in an ultralinear circuit like the Major.

That was historically the case, anyway. The reissue 6550s and KT88s might share the same innards.

I personally liked the Russian "Tung-Sol" 6550 reissues, but you won't go far wrong with the JJ or Winged C tubes.

[AXEnGEAR4J]

I do like the Russian Tung-Sol 6550 RI's which are in one of my Majors and I've also tried them in my 1st gen Model T, not quite like the original GE Tung Sol but very close I will say...

[MstrB]

Thank you, I am putting these in my Peavey Classic 400 bass head.

[MstrB]

Does any one know what the differences are between the RI Tung-Sol and the regular Sovtek?

[lilsugar]

Replacing tubes in my 1969 SVT

I'm also in the market for replacing the 6 power tubes in my amp. Are there any other vintage SVT users out there that have feedback on this subject? Mine has been modded to use the 6550's. I've been leaning toward JJ's because I have heard they sound great but are not consistant/dependable...?

[defaced]

I have read the same, but my experience has not matched that. I buy my JJ tubes from Bob at eurotubes.com. I have had no problems with the pre or power tubes I've purchased from him, but I'm admittedly not a high volume user, so take that for what it's worth.

[Steve Conner]

Does any one know what the differences are between the RI Tung-Sol and the regular Sovtek?

I've got a few of each. Different shape bottle (the Tung-Sol is coke bottle shaped, the regular Sovtek 6550WE is a plain cylinder) and better quality construction (Tung-Sols feel nicer, thicker glass, more getters, no rattles) as far as I can see. The guts look the same apart from that.

If you want different guts, the only other choice is the Winged C or JJ, I guess.

[jrfrond]

I've had few issues with the EH 6550 or KT88. They sound good and have lasted, so I continue to use them, rather than going "uptown" with another pricier New Sensor reissue from Tung-Sol, Gold Lion, etc.

[pdf64]

'If you want different guts, the only other choice is the Winged C or JJ, I guess.'
I think that chinese made 6550 and KT88 are available, branded Gold Lion and Valve Arts. Pete.

[lilsugar]

Winged C's vs JJ's

A friend recently put these two to the test and mentioned the Winged C's (SED?) did not hold up when higher voltages were applied? Maybe for 100w users that is ok. Since I'm looking specifically for my SVT , I'm guessing JJ KT88 would be best unless I hear more opposition? Also..... are the blue and red glass just for looks and function the same? Does JJ make gold pin kt 88 and are those better as well?

[km6xz]

How was the amp set up that failed with Svetlana Electron Device 6550's? From my experience they are the most rugged of the tubes sold as 6550 but also most expensive. Their wholesale prices just went up again.
There is so little data on any of these tubes, just opinion and rumor that flipping a coin will likely be as useful as asking how a brand of tubes are since most brands are different labels, and prices, not different tubes. There are only a few plants making 6550 style tubes a couple in China, 2 in Russia and 1 in Slovak Republic, and 100 brands sold for vastly differing prices of those same 5 plants. There has been no new developments in 40 years in glass tubes so don't expect any breakthroughs with any. The companies selling tubes are marketing, not R&D facilities. Buzz words, claims of magic mojo and killer tone are all hollow, backed by nothing but marketing hype, particularly the reviews of tubes by sound. How a tube performs in your SVT will be determined more by the way the amp was serviced than by the tubes selected. When you hear of people needing tubes often in them, the tech is more responsible than the factory that made the tubes. If not set up well, it will go through tubes of any brand.

[Pedro Vecino]

I've tried many SVTs (Classic, Vr, II pro, etc.) with different tubes. With 6550 Svetlana sounds more musical than with 6550 Sovtek (deeper and wider. With more dimension and better overall balance). Matching is important, and Groove tubes and TAD offer better matching than original Ampeg equipment (6550 Sovtek).
The JJ KT88 through Groove Tubes sound more solid/rocky but it is a matter of taste. They are also mechanically stronger and more stable electrically.
Even with small differences in plate current between them, itīs desirable to measure and distribute them as symmetrically between sides.
A good selection of preamp tubes is also important. I always use in the driver circuit good ECC83/82īs. Philips, Mullard, RT or other NOS tubes. You'll get more musicality/dimension and without the premature compression of 12AX7A Sovtek and 12AU7EH or similar.
Regards

[km6xz]

I might be a little dense but what measurable trait(s) of a vacuum tube result in "deeper and wider. With more dimension and better overall balance" of sound?
The comment is doubling troublesome due to the range of circuits it is made about, which they all have one element in common: they are intended to be distortion generators.
What test set up did you use, and what methodology was employed to ensure objective tests? After 50 years of dealing with tubes and other active devices, I have never been able to reproduce test results similar to yours. What am I missing?