Best Of 6550/KT88 Tubes Under $100/pair

Hi, I am an owner of a pair of VTL MB-300 amps and I am very pleased on their performance until I changed the tubes 6550x16 to the new reissue tung-sol tubes so far in the 5 houres of operation at 25 milliamps (meter on front of unit) I currently have 3 failed tubes These tubes start with an unpredictible flash and a very loud pop in the speakers The last (third tube) blew the B+ fuse and caused speaker damage. These TUBES ARE NOT RECOMENDED!!

Just got the chance to listen to KT100 Valve Art. Very Powerful sounding. A DIY P-P Mono 2 each side 60 watts driving a pair of big AR9 to a very satisfying level. Bass is tigh and rounded, may not be as low as SS amp but very enjoyable. Highs seems like there no row off, to some it may be a little too emphasized but I think it sounds extented and very dynamic(Tested by Time from Darkside of the moon-Pink Floyd)Intro of this track kicks in with alarm clocks and bells. Only a very slight hint of sharp edges which I think can be trimmed by some tuning, if you are familiar with this song you know this is quite good already. Mids may not be as smooth as EL34 but the richness, gutsiness and liveliness make it forgiveable. Downside, may not be the choice for SET lovers, KT100 is a typical all rounder tube. Tubey sounding? of course. Reliability? I don't know but VA claims that KT100s are their highest quality and higher workrate selected bunch of KT88. I hope it live up to this claim.

Thanks Bombaywalla and Psam.

One thing about Prima Luna is that it's auto bias, to many this could be a selling point but to me, I still prefer to have better control over the amp especially in the area of bias. Cayin is more what I like.

Winged C-6550 should be more preferred over their KT88.
If you still searching and uncertain, go for EH KT88. If you have a choice in mind, compare it with the EH first before you spend your hard earned money. KT100? I like this tube. What I heard in Asia about TungSol RI 6550 is a mixbag, some say it sounds like Sovtek and some say that it sounds 70% of the Org Tungsol. Abstract isn't it?

My audio philosophy is simple and may sounds stupid. "Always let your amp bully your speakers, never let you speakers bully your amp". So power is important, anything can give me a satisfying top to bottom passed the first audition.

Thanks for the info Rainchild.
You are correct that this info is very amp specific. I own a JoLida 502A which has been heavily modified component-wise. I also use used old-stock input & driver tubes.
I have not heard the PrimaLuna nor this particular Cayin.
However, in stock form the JoLida 502A is a dark sounding amp. It also sounds a bit closed-in. The bass is a bit loose as well.
Post modifications, it is a much better amp - more open sounding & much tighter bass (I'm using the winged-C Svet 6550 that came w/ the amp). However, compared to amps priced higher (say 2-3X it's retail price), this amp is still dark sounding. It uses a heck of a lot of global feeback (I was a bit horrified after one look at the schematic! But I got what was coming to me as I paid very little attention to the words "ultra-linear operation").

They say that the winged-C Svet KT88 works the best w/ this amp followed by the EH KT88. The opinion could vary wildly, of course! I'm getting ready to try a new quad & am wondering which one to get - winged-C Svet KT88 OR EH KT88 or Tung-Sol 6550 re-issue. So, your post provides some info in this direction.
I do agree with you that the winged-C Svet 6550 is warm & smooth. Good for Jazz & maybe even classical but lacks "growl" for other genres such as rock & blues. I'm looking for some "growl" in my next set of tubes. Looks like the EH KT88 might be it?
People have commented that the winged-C Svet KT88 has quality issues. Am I mistaken?

Hello Rainchild,
The gain of the EHs is higher than the Tungsols, but with my speakers (94db sensitivity) I have no problem, even listening to AC-DC and such.

The amp is a great piece! I have listened to the PrimaLunas as well, and they sounded very good too. With the same power tubes, the Cayin sounded more authoritative than the PrimaLuna two.
The Cayin also has the remote control and the possibility to play in triode mode, which gives a sweeter sound, better for classical etc.
Another issue is that the Cayin is much heavier than the PrimaLuna, and this is a quality indication for me.
The Jolida I have not heard at all.
Hope this helps!

Hi Psam,

Tell me more about your amp, it's a very beautiful baby. Have you compared it to Jolida JD502B or the Prima Luna Prologue Two? My next amp could be any of these three.

"They are not as loud as the EH KT88". Do you mean the "POP" or the gain?

Hi Psam,

Tell me more about your amp, it's a very beautiful baby. Have you compared it to Jolida JD502B or the Prima Luna Prologue Two? My next amp could be any of these three.

Tung Sol Reissue with some relaiblity concerns.

Mine are some 100 hours old and sometimes (twice) I heard a "pop" from the speakers...I hope they were random effects.

They are not as loud as the EH KT88, but they are much more balanced in tonality. The VAs are definitely inferior - and cheaper.
Amp is a Cayin A88-T