2. tech-talk
  3. 1107569647

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
cjfrbw
148 posts
 
I currently use the tung sol 5687's and like them for their warmth and punch. I think tube rolling is going to depend on your system. I have tried the raytheon triple mica 7044's, and they are also better than the stock GE 7044, which can sound soft and bland. You should try some of these, they don't cost that much, and for the 6922
I don't think there are any bad or best choices, but most decent NOS tubes will sound better than the stock soviet 6922's and some improvement is also possible by changing the 7044's. I would like to try the bendix tubes, but have generally heard that they do better in circuits that bring them closer to their higher 600v rating than in circuits that keep them at 250v or 300v, and they are very expensive. Amperex, Mullard and Ediswan tubes are all good choices for the 6922 slot.
klinerm OP
80 posts
 
More updates - keep in mind Cjfrbw's admonition that most of this is probably system dependent, so it may not work for you.

STEELHEAD

1) I've decided I prefer Mullard E88cc's in the 6922 position over grey-plate Siemens CCa's. A little less accurate, perhaps, but more "musical". Go figure.

2) The jury is still out in my mind on whether Bendix 6900's are better (in absolute terms) in the 7044 position than the TungSol 5687's. For the money, it's a "no-brainer"; the TungSols blow them away.

ARC REF 300 Mk II

1) I have decided Tung Sol 6550's have far too much bass, relative to Gold Lions, for my taste. I have gone back to all Gold Lions.

On another note, I have amassed quite a collection of Gold Lion KT88's, ranging from the older "large lion" brown-based ones complete with rotting boxes (which I think are unequivocally real), to slightly smaller "small lion" tubes with black bases and newer-style boxes. Some of the latter have solid plates, and some have holes. I recently saw a thread on Tube Asylum in which the latter, newer style were described as "unequivocal Chinese fakes", identical to current "Shuagang" (or something like that) tubes.

I don't pretend to know much about this, but I understand that MOV did begin manufacturing in China towards the end of their production. I have been conducting A/B tests (not blinded) between the older "unequivocally real" Gold Lions, and the newer "maybe fake" ones. Guess what? If anything, the newer ones sound BETTER, at least in the above system. If the newer-looking Gold Lions are actually current "Shuagangs", then I think there is a real bargain to be had. I have also wondered that if the Chinese companies kept making tubes after MOV went under, then it may not be so surprising if their current tubes look like later Gold Lions. I'm pretty much content to believe what my own ears tell me, but if anyone is really an "expert" in this area, I'd like to hear their 2 cents' worth.
nguyenson123's avatar
nguyenson123
12 posts
 
Just got my Manley Steelhead with Telefunken 6922 and Phillips 5687, it sounds beautiful.
mmrkaic
33 posts
 
@klinerm 

1. Did you discover the differences between tubes in blind testing?
2. Do you have a background in electrical engineering?
randy-11
1,913 posts
 
I agree with the above post - for my own ARC Ref 2 Mk II preamp, I let the engineers at ARC carefully select individual tubes from their already carefully spec'd lots.
More to discover