ARC VT100 with KT-120 tubes ?

I talked to ARC today 3/9/11, sorry I forgot the name, but ARC is now strongly recomending that even current products like my Ref 210s be sent back for some power supply adjustments before going with the K120 tubes. He said they have learned more about the K120.

BTW I did not go into any detail since I was calling about another 6550 tube issue and I have 650 hours on my set so I will not be making the jump soon. My issue is a 6550 driver tube that will not hold bias.

I am looking forward to the K120 for hopefully both sonic improvements and reliability improvements over the SED 6550 - but its not like they dont sound good IMO.
Terry

Both the Ref210 and Ref610 require changes to one of the regulated power supplies in those two amps. I will probably be able to update the Ref210 at my office, the Ref610 on the other hand requires a more extensive update and therefore Ref610's will need to go back to the factory.

Thanks Tdaudio for the power supply info. That's good to know.

Hifigeek, do you know anything about the power supply adjustments that Tdaudio mentioned in the post above? Also, just curious about the VS115 you have for repair. What's the problem? I'm interested because I own a VS115.

Tdaudio and Hifigeek: spoke with Chris at ARC today. Was told that REF210 and REF610 will require mods, as mentioned by Hifigeek above. However, the VS115 and many others are ok as is. Until something comes out in writing, I would still call to double check for yourselves.

Chris also said that ARC is not in a position to say that the KT120 will have extended life over the 6550C because there is not enough history behind the new tube and a lot of variables are in play that can affect tube life. However, ARC does believe that the new KT120 sounds better than the 6550C.

In my case, as I get closer to the 2000 hour mark for my current set of 6550C tubes, I will probably consider dropping in the KT120s. I'm very curious to hear how they sound. FWIW.

Hi All. Did talk to Chris O. this week as well about dropping those KT120 into a pair of Classic 120. His response was that ARC have not "tested" those in a pair of 120's and will not until they get a pair in for service. He told me that electronically speaking there should be no issues using KT120 in the 120's except that there may not be enough range on the pot to adjust the bias up or down. A resistor may have to be changed. Physically speaking, they may not fit within the cage enclosure as they are taller. However, i operate my 120's with the cages off so that is not an issue. He said to me just drop them in and report back to us. Otherwise, it may be a while before they are tested in my 120's and the many, many other amps ARC has designed in the last 40 years. I am not quite willing to send my amps down to the Factory from Canada just to see if they are a fit or not. However, Chris appears to be very confident that they should work just fine in those 120's.
Long story short, i have to make a decision soon as i have 2000 hrs on my SED 6550C now.
Sly