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

Showing 4 responses by trelja

This is just my opinion, but I see no reason whatsoever to use the 6550 tube. The Legend Starlet integrated amplifier, a fabulous sounding product, designed around this tube(run pedal to the metal) excepted.

My complaints are basically everything you outlined Zaikesman. I'm not sure I wouldn't investigate a nice solid state amp over something running 6550. My money would be on the KT90 or KT88 every day of the week.

If I was after neutral sound, the Ei KT90 would be my choice, which is what I use in my Jadis. This tube is rugged, reliable, and very long lasting. Still going strong after 4 years. It is not a sweet tube, but offers a nice tone. It betters the 6550 in every area one would ever opt for that tube - bass, power, longevity, extension, neutrality.

As for the KT88, it is a sweeter sound, and sounds more like what most people consider classic tube. Will probably give them a go next in the Jadis. It's midrange is great, with a nice punch in the bass. And, I can't complain about the treble.

The JJ KT88 are my favorite, by far. After that, I guess I like the Svetlana. The JJ tubes, badged Teslovak, had a bad production run and ruined many a person's day a few years back, but recently a good friend of mine had a bad Svetlana do some serious damage to his Rogue amplifier/ Coincident speaker. So, who knows?
Zaikesman, if you ever travel up the road to Philadelphi, you are welcome to give my 4 KT90 tubes a spin,
Joe
Zaikesman, it's commendable of you to keep us up to speed. Thank you so much.

Yes, Russ sure is a prince. Heck of a guy!

I'm happy to hear your impressions on the tubes. I have never given KT88EH tubes a listen, but in my experience, the JJ(Tela/Teslovak) KT88 are easily much sweeter than any 6500 I have been around.

It's so wonderful to hear that you are getting the best sound you have ever had!
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.