Tube rolling ARC amps & Steelhead


A while back I decided to try tubes. I have had an ARC Ref 2 Mk II preamp for about 2 years, a pair of ARC Ref 300 Mk II monoblocks for about 1 year, and a Manley Steelhead for 3 months. They sounded great, but it never occurred to me until recently that they could sound better - I always assumed that the manufacturers knew best when they put the stock tubes in.

My speakers are Acoustat Spectra 66 full-range electrostats, and, of course, I wanted more bass. After some investigation, I replaced the stock Sovtek 6550's in the monoblocks (8 per channel) with CryoValve 6550C's (from TubeDepot). The improvement in bass was nothing short of dramatic, and I much preferred them to the stock tubes. Nonetheless, the midrange and treble seemed to be lagging behind. After some more investigation into tube replacement options, I replaced the stock 5AR4 rectifier in the Ref 2 Mk II with a Genalex Gold Lion 5AR4, let the amps warm up a couple of hours, and then listened. I was dumbfounded at the change in sound. There was no "good bass" or "good midrange", everything just fell together with remarkable imaging and coherence, and that was with CD's and the tuner! All from changing ONE tube! I then replaced the stock 6922's in the Manly Steelhead with Mullard E88C's (following the advice of another A-gon member), put on an album, and and watched the bar further raised beyond my wildest expectations. All the sound was in beautiful coherence, rock-stable imaging, perfect balance of frequencies, not a touch of harshness, enjoyable at every volume level, like Neil Young was sitting there in the room pouring out his heart to anyone who would listen. I had a friend with me who has heard my system many times before, and he independently remarked "I can't believe it, everything sounds PERFECT!"

My question is - is this a unique experience, or have others found NOS or other tubes to make such an significant difference? I can certainly see why manufacturers don't include scarce tubes with their products, but it still amazes me that the choice of tube can affect the sound so profoundly. I would be interested to hear if others have had similar experiences.

Other equipment:
VPI Scout / Benz Ruby
Levinson 390S
Luxman T12
klinerm
Most people who have rolled tubes know there's certainly different and possibly better sounds. I've had such bad luck with NOS that I gave up and then my favorite was the current Ei Elite 6dj8's til after a couple of weeks a tube shorted out so I stick with EH 6922's. Be aware many NOS tubes can have a shorter lifespan and/or become microphonic but indeed the sound can be much better.
I have tried rolling several different brands of 6dj8 and 6922 variants. The Steelhead can be improved a lot with a good NOS tube. My current favorite is the Amperex orange globe 6dj8 (with splatter shield).
Because the 7044 tubes are cathode follower buffer, I didn't think that they would make much difference. I was disturbed by reports on Audio Asylum that the GE 7044 were extremely microphonic. I tried some D getter 5867 black plate tung sol tubes. Wonder of wonders, it did improve things even more. Better drive, slam and detail, better audibility of lyrics. The steelhead went from being very quiet to dead quiet. I don't like to gush because that gets old, the same old terminology used to death, but it is surprising to hear improvements like this in something that is already so darned good.
Makes me wonder what the Bendix 6900's might sound like, but I don't know if I want to spend $400 or $500 to find out. Some opinions think the tung sol's sound better than the expensive Bendix tubes.
Thanks for your post, Cjfrbw.

I'm going to try upgrading the 7044's, per your suggestion. The Steelhead is a wonderful piece of equipment, as you point out, and it deserves to be "maxed out."

With my ARC gear, I've also replaced the Russian 6L6GC in the Ref 2 Mk II preamp with an RCA Black Plate, with overall improved "liquidity" and "listenability." I'm still a novice at this, but I think this is about as far as I can go with this piece.

I have purchased, but not yet installed, RCA Black Plate 6AS7G's to replace the Russian equivalents in my Ref 300 Mk II mono amps, and have purchased GE 6550A's to replace the the Cryo-Valved Svetlana's in the same amps. From what I read, TungSol 6550's may be better, and Gold Lion KT88's would almost certainly be better, but it could take many months and a big wad of cash to try that experiment.

The only saving grace to this madness is that this seems to me to be a sort of "final frontier" in upgrading. There appears often to be fairly good agreement on what constitutes the best tubes of a given type ever made, so there's (thankfully) nowhere to go after that.