Topic: tube rolling suggestions kt88/6550

[dave w]

 I just picked up a Rogue Audio Stereo 90, and was looking for some suggestions on tube rolling.  The amp with the stock tubes have more low end drive  than any tube amp I've found in the price range, while maintaining a tube feel, but I'd like to up the 'warmth' factor a bit.
Here's what the stock tubes are:
Output: 4 EH 6550s (also can be KT88s)
 also has 2 6SN7 and 2 12AX7, but I haven't tracked down what they are yet
  One suggestion I've heard is JJ KT88s.  Any suggestions or thoughts?  Good places to buy tubes?
-Dave

[Brian Skalinder]

Formatting went all screwy after the latest TS.com update, but a bunch of online sources:

http://taperssection.com/index.php?topic=49078.msg635383#msg635383

I suspect most really hot-shit tube recommendations and purchases are made by telephone, though.  With whom?  No idea.

[EScott]

I just picked up a Rogue Audio Stereo 90, and was looking for some suggestions on tube rolling.  The amp with the stock tubes have more low end drive  than any tube amp I've found in the price range, while maintaining a tube feel, but I'd like to up the 'warmth' factor a bit.
Here's what the stock tubes are:
Output: 4 EH 6550s (also can be KT88s)
 also has 2 6SN7 and 2 12AX7, but I haven't tracked down what they are yet
  One suggestion I've heard is JJ KT88s.  Any suggestions or thoughts?  Good places to buy tubes?
-Dave

I used to run the EH KT88s, a pair of Pope 6Sn7s, and a pair of Siemens 12AX7s in my Cary integrated when I had it.  This combination was very pleasing to my ears - a nice boost in the low and midrange with plenty of warmth.

There are plenty of tube retailers out there.  I bought my NOS tubes from Kevin at Upscale.  You could probably beat his pricing if you shopped around, but he has a large selection of old stock and will talk tubes with you for hours.

[BobW]

Again, my vote for the EH KT-90s
More durable, longer life, and nice mid-range .
Possibly a tiny bit down on the top-end, may depend on the amp.

[Lil Kim Jong-Il]

I'm currently using TS6550 reissues.  They seem more detailed than the Svetlana 6550s but a bit dry.  The Svetlanas have sweeter mids.

I have run Ei KT-90s.  The KT-90s had a bit more low end but definitely did not have the sparkle on top of the 6550s.  When I went back to the 6550s, the additional top end extension was not subtle.

Possibly the Svet 6550s and Ei KT90s are worn and I have no tester.  But the TS6550s have only about 350 hours on them, and they are very much like the Svets and dissimilar to the KT-90 so I think the traits follow the tube type.


Edit:

Dave, are you anywhere near DC?

[Nick Culbreth]

I have no experience with the KT88/6550 tube family but with my Primaluna amp rolling the signal tubes made a more profound impact than the power tubes.  Amperex and Mullard manufactured 12AX7s are known for their warmth and musicality, they might be exactly what you are looking for.

[dave w]

Thanks for all the suggestions!  After some rolling in my pre (a hybrid solid state/tube Sonic Frontiers SFL-1) I settled on a Mullard 12AT7, so may well follow Nick's suggestion and try a Mullard 12AX7 signal tube, as well as try out some of the suggested KT88/6550s. 
 I love new toys.
-Dave

[Nick Culbreth]

Another option you might look into is swapping in some NOS 5751s in place of the the 12AX7s.