'Vacuum Tube Valley' is such a good resource for tube-related info that I'm surprised more people don't read it. http://www.vacuumtube.com/
Issue #19 contains LOTS of info on 6550s/KT88s/KT90s. With new tubes costing $40 - $80/pr. and NOS tubes going for far more, #19's $22 purchase price is well worth it IMO.
I assume you have read the Vacuum Tube Valley shoot out - in a recent issue.
Metralla, no I haven't read that article, although I'd like to, and I'll order the back issue tomorrow. In the meantime, any highlights would be appreciated, especially as related to Tung Sol 6550 and Genelex KT88.
VTV 6550/KT88 Shoot Out for Hi-Fi
Genalex KT88 Gold Lion 1969 - 4.87
Tung-Sol 6550 1963 Solid Grey Plate - 4.77
JJ KT88 2002 - 4.63
Ei KT90 1999 - 4.52
EH KT88 Reflektor 2002 - 4.16
Sveltana 6550 2001 - 4.13
Svetlana SVKT88 2002 - 4.09
Svetlana SV6550C Reflektor 2002 - 3.98
Philips Sylvania 1970s - 3.98
Chinese 6550 Valve Art 2002 - 3.89
GE 6550A 1970s - 3.78
The Tung-Sol was voted the best 6550. The Genalex was voted the best KT88 and the best tube in the shoot out. The Ei KT90 was voted the Best Value - it was liked by all reviewers. The JJ KT88 was voted the best new KT88 and also a KT88 best buy.
You will enjoy the article.
Metralla, thanks for the list. It's interesting that the only other tubes I've rolled in my amp were GE 6550As, and I wasn't impressed. Now, I know my ears weren't deceiving me. Now, I'm especially curious about the Tung Sol or Gold Lions and how much better 1.5+ points is on the scale?
Also, interesting that the JJ tubes ranked so high. I went to the VTV website and they seem to feature JJ tubes for sale. Coincidence?
Makes you wonder, doesn't it?
I am a novice, so can you explain whether the 6550 and the KT88 are electrically equivalent or not?
I know you can usually use them in the same amp (swapping one type for another as a set...not individually). They are not electrically the same. They require different biasing.
FYI - I have the Audiopax amp driving Avantgarde Duo speakers and recently brought in the NOS Genelex Gold Lion tubes, replacing the Svetlana that is put in by the manfacturer. What an awesome improvement in sound - just outstanding results! Highly recommended.
I also upgraded to NOS Amperex (Holland) 12AT7's and they were yet another level of improvement.
I took the plunge and bought a set of NOS Genelex Gold Monarchs to replace my the stock Chinese KT88 tubes that cam with my VAC amp. I should have them the week of Dec. 5th and I will report back after some listening.
In response to the "VTV 6550/KT88 Shoot Out
I read a article in VTV Issue #6 (VTV6) titled "KT88&6550 The Power Kings" by Eric Barber. It is a interesting article giving some history about development of these tubes. The above 'shoot out' reminded me of a part of the aricle as follows; "By the 1960's these tubes had set the standard for power amplification. So it was inevitable that other makers would introduce their own versions. GE came out with the straight sided 6550A in 1971. It was called the 6550A, because of the introduction of a exotic 5-ply metal plate material manufactured by Texas Instruments. This metal, produced by cladding a copper and iron core with aluminum outer layers using explosives, made for a more reliable tube with greater bias stability. The clad metal was better a dissipating plate heat, and thus it lessened plate and grid emission and reduced hot spots on the plate.
I am not making a judgement as to which tube is better, but the statement that I posted seems to say that the GE tube had some improvements over the Tung Sol.
I myself am currently using Svetalna's manufactured prior to the selling of the Svetlana name and they sound good. In looking for improvements I may try GE6550A's. One reason for using the GE's is they seem to be a bit more reasonably priced than the Tung Sol's.
I tried GE6550a tubes in my VAC amp, and there was not enough difference to warrant the $250 expense. Frankly, I preferred the stock Chinese KT88s...they had more extension and tighter bass.
Tvad, what do you think of the Gold monarchs, I love myh genelex.
711Smilin, this hobby (or addiction) is filled with components and tweaks that are insanely expensive, and add just a little more greatness to a system. This is what the Genelex Gold Monarchs do. With the Gold Monarchs in the VAC amp, there is a little more "magic" to the mids and sweetness to the highs. I don't find it romantic, or bloomy, but just more "real". Bass is still deep. Soundstage is very open.
Honestly, I could live with the stock VAC tubes if I had to, but the Genelex Gold Monarchs are better, and worth the expense.
Does anyone have an opinion on the EH 6550 tubes? I bought a couple of matched quads for what seems like a great price shipped form the Audio Pimp. Then I got the VTV issue, and they didn't even test them. I'm still waiting for my amp to come back from repair to try them, but wondered if anyone has prior experience with them. They're the fat bottle versions.
i have 1960 Gold monarchs kT88 IN MY pA100/100are they are so Great!
I "lucked" across a brand-new quad of the original GEC MO Gold Monarchs a year ago. I play them every day and they continue to astound. I'm hoping by the time they're worn completely out, the Chinese, who are getting close, will have achieved a similarly sweet-sounding and long-lived KT88.
@deepee99 GEC Marconi Osram KT88s are magic with lovely holographic midband.
@tvad Make sure you try a different 6SN7 too. You might be amazed the difference rolling them will have on how the power tubes sound.
@lizardzkingI guess we belong to a rather exclusive club. I'm angling for another quad of the GEC Marconis with a guy right now but I fear the days of the $750 NOS quad are over, unless you're willing to take your chances on counterfeits.
I echo tvad's sentiments on drivers. I use a total of 7 of them (3 in the driver section of the amp; four in the line pre-amp -- all 6SN7s. A lame driver array will make even the best output tubes sound like yesterday's oats. The beauty of 6SN7s is they're plentiful and cheap to come by. I probably have enough chrome-dome Sylvanias to decorate the Christmas tree. Here is where the Chinese really shine, and I think are competitive with the best of the American and European NOS offerings. Currently I am using Shuggie CV-181-ts to great effect but PSVanes churn out some good 6SN7-types as well. I dislike rolling output tubes, but tube-rolling drivers is (relatively) inexpensive good sport. The Russians have, IMHO, yet to turn out a good 6SN7. This is prolly worthy of another thread, but who likes what in your volt-amp holes?
FWIW, I use Psvane 6SN7
Globes and they are very good. Most detailed and finely grained version I've heard. A little bright for the first 20 hours but then they settle in.