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The end-all SVT Tube post..Opinions required.

Ok my fellow lowenders. I have read post after post about what tubes are best for SVT power and pre section with no real answer. Before someone says it; I know this is a subjective thing. With that in mind there are good and bad tubes and the reasions for them. So I propose we end this debate now! Post here with opinions on your favorite tubes and please go into detail, experiences live or otherwise, pic's, sound clips, places to get the best deal on tubes, 6550 vs KT88, NOS vs New, all that good stuff that us "tube heads" thirst for...tube knowledge!! So let her fly... I will start things off by asking the question: Has anyone tryed Ruby Tubes KT88 in a SVT? And, like I said, please go into detail. And away we go!
 
Cant help on the Rubies.

Only tried two sets of pre tubes and two sets of power tubes in my SVT.

original pre tubes were "china" labelled 12AX7s and Amperage 12AU7s, swapped them for JJ's, which gave a much clearer sound.

original power tubes were Philips ECG 6550A (Sylvanias), now ive got Svetlana 6500Bs.

Not a huge fan of the 6550Bs, they are just missing something that those Sylvanias had. But, if you find the price on six NOS sylvania 6550s, you'll see it isnt too viable an option :(
 
My tech says that if you just select the best built tubes out of a batch (by excessive testing) you will not hear any difference between different brands of tubes because the amps characteristics will overshadow those of the tubes. Besides it's pretty obvious you will hear a difference between used and new tubes anyway.

It's just that not all tube selling companies do those tests... most of the time companies who give you the best price are the ones that are selling tubes that more expensive tube retailers have labelled not good enough to sell under their name.

In conclusion he just said if you buy the tubes which are sold with the longest waranty, you will hear how your amp is supposed to sound.
 
I like the Tungsol 6550/ OLD Sovtek KT88. JJ KT88's will work, but they may run too hot if you drive them hard. New Chinese 6550's or KT88's are also great tubes. The biggest problem with modern tubes is consistency, so you should always buy them from a dealer who will warrant them. I use Triode Electronics Across the board, 6550 offerings of today are MUCH better overall quality than they have been in 20 years.
 
Well upon the advice of PBG and Mr. James Hart, I have Sovtek KT88's (new ones) and TungSol 6550's. I like the TungSols better.

They are a very musical tube with an excellent break up, good tight low end and controllable highs (I'm not much into highs) but the excellent mid range characteristics are what makes this tube for me.........like I said very, very musical and well balanced when pushed, did I mention I like em alot??

For Preamp tubes I have both NOS GE and a spare set of JJ's to be absolutley honest with you - I can't tell the difference.

I also run TungSol and Electro Harmonix (preamp tubes) in my Peavey - the preamp tubes seem to make much more difference in this head (Peavey CL 400).
 
From an electronics standpoint, KT88 and 6550 are the same part. I can't believe there would be such a difference in sound? Guess so!

Historically, yes and no. KT88's specs call for slightly higher heater current as well as more robust screen grid disappation. In modern practice, few KT88's actually differ from 6550's, which are all clones of the the 6550A, which mirrors a true KT88 except in heater current.

Do you have any experience with TAD (Tube Amp Doctor) tubes psycho ?

They're specially produced and selected Chinese tubes. I have never encountered any of their 6550's or KT88's, but I'd expect them to be great tubes. TAD's have a good rep among people I trust.
 
You can expect slight differences between tube makers. Each has a slight difference in mechanical construction, even for direct replacement tubes, and that is reflected in gain, etc, etc. In turn those factors make for the sound.

Since the SVT was intended (after the original version) for the classic US made 6550, it should be best with them, or a close equivalent.

The 6550 / KT88 differences are far less than the differences between other "pairs", for instance, the 6CA7 and the european similar tube EL34. The KT 88 and the 6550 are "both-way substituteable", but the 6CA7 subs for the EL34, not the reverse.

These days, there are tubes made similarly, tubes that just happen to be close, tubes that would sub but the bottles are too fat and prevent it........ lots of choices. Most of the really bad subs and alternate manufacturers have dropped out, so most choices are OK.

But, everyone seems to have bad runs, so a "good" maker now may be "bad" 6 months later.
 
Great reviews guys! I am ordering a replacement/backup set of Tung-sol's now. Just fyi: I found that Ruby Tubes has a 6550 Tung-Sol and they warranty them for 6mths. I'm calling on prices now. Someone chime in on things to look for when tubes are going out. And again, lets headoff the obvious...the amp won't work post. :rollno: But some of you guys that have experenced tube failure let us new-tubies know what you experenced and what to expect. This is an important issue to me and others with new(to us) vintage SVT's. Especially since the vintage SVT will run on 5 tubes and this is, I'm assuming, not good for it at all. So PSB and Jerrold, keep those opinions comming on anything you can think of with pertinance to the SVT. I think I can speak for all that own one when I say we love'em and don't want to fk em up making a "rookie" mistake or something we could have prevented with a little of your knowledge. Thanks again guys, your help here has already been invaluable.
 
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