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VTL Siegfried Monoblock Power tube rolling- Calling all VTL owners

Hey all.  Have been enjoying my VTL Siegfrieds and currently have them populated with GL KT88s.  They're coming up on 3000 hours and while still very engaging, they are probably going to need to be rotated out at some point in the not-so-distant future.  I'm looking at some current production TungSol 6550s to try on something new and see how it goes.  I'll order some spares just in case a few go gassy or outright cook off.  I only had 2 KT88s fail to bias correctly over the life of the amps and just popped them out with a few spares I have of those.

I have already rotated out the signal tubes and run some wonderful NOS 1959 Valvo 6201s and mid-60s RCA 6350 and really smoothed it all out.  Wondering what you all have done in the past, and also to verify that these are indeed 100% compatible after I reset the tube bias after swapping these out and letting the autobias do it's thing.  

I'd be interested to know what you found after they settled in after a few hundred hours.  Also would like to know if anyone has used other alternatives and to what affect the presentation has/had changed.  My musical tastes are all over the board from small chamber music, to large scale orchestra and jazz, to rock, and everything in between.

If it doesn't work out, I'll just switch back to a new set of KT88s.  Thanks in advance for any input or feedback.  
73cuttysupreme
2 responses Add your response
folkfreak's avatar
folkfreak
1,349 posts
 
I love my MB-450 III with the stock 6550s (although I do have some nice NOS (I think Mullard) 12AT7 in them). 

The bigger difference in my mind is whichever way you go looking into Herbies tube dampers for all of the tubes (I specked the HAL-O models to be over sensitive to the high temps) and even more importantly working on footers and platform

My 450s sit on a pretty complex rig of (from the ground)

  1. Grand Prix Audio (GPA) Apex footers with SiNi balls
  2. GPA Monaco Stands (perspex shelves)
  3. Marigo Composite shelf (sitting on some small Marigo pucks on top of the GPA shelf)
  4. Marigo Composite puck
  5. Marigo F8 Mystery Feet

Every step in this is completely audible and beneficial and if you haven't looked into what your Siegfrieds are sitting on it's well worth exploring
vegasears
1,173 posts
 
I've been using VTL amp's for 15 years+.  First 300 Deluxe MB then I upgraded to my current 450MKII.  Over the years I've used SED Svetlana Winged "C" 6550 and still have a set w/spares, Shuguang KT-88's and GL-KT-88's. 

I currently use GL-KT-88, they sound the best with my related equipment and have been pretty reliable.  I really liked the Shuguang KT-88's but they were very unreliable and any cost savings went in the trash with the multiple tube failures.  I use the 6550's when I switch my other speakers, which I don't do often.

Good Luck


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