Another 6550 vs. KT88, 90, et. al.?


Recent listening after having the tetrode/triode switches in my VTL 185's restored by the factory to functioning status (a previous owner removed them) has me reassessing the amps' tonal balance as presently configured (with Svet 6550C's, new last fall). While the tetrode setting I was confined to before the repair holds most of the 'high fidelity' aces (dynamics, space, separation, resolution, articulation, detail, extension, bass definition), my newfound ability to access the triode option has confirmed, and strengthened, my previous suspicions about the overall balance: A little spotlit in the lower treble, a little tight from the lower mid's down through the mid-bass.

The result is a tad hard and lean (for a tube amp), with a bit of glare above and a lack of plushness and body below. Triode corrects this balance toward the warm side, more neutral overall IMO (except at the frequency extremes), and also gives a smoother textural presentation with lowered grain, but at a cost in the other areas mentioned above. In general, the amps pass more info and get better speaker control in tetrode, but are purer and more natural through the heart of the audioband in triode, if also less present and more homogenized.

I know none of this is revolutionary news to many, and obviously questions of tonal balance will be highly system-dependent as well.* And in the big picture the 185's are the most revealing and least colored and distorting amps I've owned. But before plunking down for 12 more power tubes to experiment, and after having read through the archives, I wanted to bring this question back to the forum, especially in the hope that some VTL owners might shed more light on their power tube experiences.

*[Thiel CS2.2's/AZ Satori/VTL MB-185 Signatures (with 60's NOS Sylvania gold pin 6201/12AT7 inputs)/HT Magic Link One/Levinson 380S/HT ProSil/Theta Basic IIIa and Pearl/Shunyata Sidewinders on the amps, HT AC11's on the digital separates/API Power Wedge Ultra 116 on all]
zaikesman
While we're commiserating, you guys know I'm from Philly.

The Sixers won the last title in this town - in 1983!!!

We haven't ever won a Super Bowl(makes you feel small when your neighbors are DC, Baltimore, and NYC), and the last NFL Championship was in 1960.

Ed Snider and Comcast run the Flyers, and Ed no longer is Ed, but "Mr. Snider". He returned to the team to snatch it away from his son, who Ed thought was doing a poor job, with the statement, "This is all BS, my goal has never been to get to the playoffs. That's chicken%$#^! My only definition of a sucessful season is the Stanley Cup!!!!" Nowadays, he berates the media at every turn, telling them, "What the hell do guys want? We make the playoffs every single year..."

The Phillies ARE THE ALL TIME MOST LOSING TEAM IN ANY SPORT.

Then they wonder why we're hooligans...

Honestly, Zaikesman, please don't worry about disrupting my system. While audiophilia is the antithesis of a team sport, cooperation and sharing definitely broadens my experience, enjoyment, and my low level of knowledge. Feel free to use the KT90s. My only requirement will be that I label them with a marker so I don't have to rebias the Jadis.
Zaikes, et al , let me alert you to a different KT88 than the usual suspects that I read about on the "Gon. This is the "Ruby" brand out of China.I was sceptical when a friend who works for the US distributor gave me a pair to try out in my ASL integrated but I was very pleased. They clearly beat out JJ/Tesla and EH in clarity without sounding etched. Plus he tells me they're cheap.check out rubytubes.com John
Trelja, thanks for your kind offer. Russ is sending me six each of his spare KT-90's and MO KT-88's to try out in one monoblock against my 6550C's, and this should greatly help me get the way pointed right.

At least with the KT-90's, there's only one kind of the tube currently produced. As Jkaway notes, there are choices when it comes to 88's. I actually found that I preferred the Chinese Ruby 6SN7's over the Sovteks for the driver stage of my CJ MV-55 amp, but have never tried any Chinese power tubes, and generally haven't liked any Chinese 9-pin miniature dual triodes, so I was pleasantly surprised. I'll take a look at the website.
HEY GUY'S...(Zaik and RCP)....I'd be interested in the audition of the 88's vs the 6550's....
Please keep us posted!!
Jkaway, I've heard nothing but bad things about the Ruby KT-88's. Their EL-34's are junky, cheaply made tubes with thin glass, and the general consensus is that the Svetlana EL-34 blows it away. I find it very hard to believe the Ruby KT-88 beats the JJ-Tesla KT-88, which, along with the Svetlana KT-88, is the top contender for KT-88, in my opinion.