ARC VS-115 Amp with new KT-120 Tubes

Cmalak, bias is still at 65mV -- at least in the VS-115. As an aside, in the VS-115, each tube pair has only one set bias tube, the other being a slave. So, in total, bias is set on only four tubes and checked on the others --in contrast to the VS-110, in which each tube's bias had to be set. I note that in the case of the KT-120s, the bias in the slave tube was much closer to the bias in the set tube than with the 6550s. Who knows, maybe it's all in my head, but that's what it seems to be.

I'm 9 hours in and the sound continues to improve. Maybe I'm just imagining things, but it seems that the sound stage is getting larger and moving back behind the speakers. Again, maybe it's all in my head??? Bass continues to improve -- one helluva lot of kick-slam. I may have been bleeding out of my ears from listening to Linda Ronstadt, Prisoner in Disguise LP. Lotta bass.

Then my wife start chasing me around the dining room table with a rolling pin because she was yelling something about the bass thumping from the stereo making a challah she was baking for the Jewish sabbath fall? How can bread fall when it's baking on an oven grill?? Where's it gonna fall to?? Any Rabbis out there in A'gon-land??

Byfwnne, I just replaced the 6550's in my arc VS-110 with KT-120's from Upscale Audio as well.  I only have 20 hrs on the tubes so far I am impressed. 

I had the unit checked by my dealer with the new tubes and he recommends running them at a lower bias around 60mv, which is a little lower than the arc recommendation.

Listening to classical music gives me a wider soundstage and sounds smoother and more effortless.  Listening to jazz the sound was more 3 dimensional.  I did not experience the sound to move further back but it is wider.  But the again you have a better amp than I do.

When I was using the amp in home theater watching blue ray movies, the transients and slam was immediately more noticeable.

I am looking forward to listening to more music to see how these tubes continue to sound.  Hope your experience is good as well.  

Ps I am not a Rabbi, but I am not sure that extra bass will make the challa to fall.  Good Shabbos!

Sdgron, good shabbos to you as well.

I'm not sure how much more the KT-120 tubes will break in after 20 hours. Just curious about your amp, why did you have your dealer check the VS-110 with the new tubes? Were you concerned about something? Also, any reason he suggested biasing the tubes at 60mV?? Will it result in extended tube life or better sound??

Hifigeek is an ARC repair tech. If he picks up this thread, perhaps he can weigh in on the questions on break in time and recommended bias.

BTW, I used to own the VS-110. I think it's a very nice piece of equipment. I hope you enjoy it. What are you using for a pre?

Bifwynne, I spoke to Audio Research before I purchased the KT-120's to see if it was ok to drop them into the VS-110. They said that they had not tested it with older equipment so I decided to buy them and have my dealer make sure everything was ok. I also took the opportunity to demo a pair of Vandersteen 5A's with my amp as a potential upgrade from my Quattro's.

My dealer recommends 60mv for sound first and some longer tube life. I am using an ARC Ref 3 as my pre.

Just a few quick comments with another brand amp. Chris at Parts Connection was doing his SE+ mod to my Sonic Frontiers Power 2 amp which he originally designed last November. He suggested using the KT120's. I had run 6550's an KT88's and preferred the 88's so the KT120's seemed a reasonable option.

BREAK IN: There was some break in and 20 hours would be a good guess as to when it ended. Early on, they had settled in and (as had I) and have remained consistant since. My experience was a slight but consistant early improvement that I think was equally the tubes and me getting aquainted with their sound. Than again, my amp had been upgraded which made a significant improvement and the new parts were getting burned in. As in most discussions about "sound" user experience will vary.

SOUND: I agree with all the above stated impressions but will highlight two rather dramatic areas. I run Wilson WP7's which can be a difficult load. I have a spare ML 23.5 that I was using while the Power 2 was modded. The 23.5 is known to have the bass balls of a charging rhino. I actually like the bass with the KT 120's every bit as much as the ML. Great deal of fun to have a tube amp that does bass with the best of the ss.

My guess is that we listen to tube stuff because we are drawn to the "more musical" sounds that tubes bring as against the "more accurate" sound of ss. I think in terms of a painting vs a photograph. Some of the golden ears have used the term "organic" which best describes the sound I currently enjoy. The ability to close my eyes and get lost in the experience is what floats my boat. Is it real? Not quite but more real than any other listening experience I've had in 30+ years of trying. At the risk of offending the more conservative folks... For most of us there was an experience where pot and music first came together. I imagine most of us remember it well. The "oh my higher power" moment. Music became alive and we were part of the experience. Real? Who cares because the music was an emotional and personal event that captured our awareness and demanded our attention. The music limited our exposure to the rest of the world. Kind of like being at a concert where the event has a life of its own and we are grateful to ge involved. So in a sense the KT120's plus the amp mods plus the phases of the moon and God knows what else has made it easier to get stoned tot he music without the dope. Many of you will understand emotionally what I have just described. For the rest, go find a friend who has smoked some dope to translate for you.

I really like the KT120. They seem to like and enbrace music. What more is there?

Enjoy the music