ARC Ref 110 with KT 150 tubes

I am currently running a Ref 100 with KT 120 tubes, no probs, net gains on the old 6550s. But has anybody gone a stage further and used KT 150s? Any potential problems, you think?

Many thanks for advice.
ARC has just pronounced on the latest Reference amps, 75/150/250/600, approving a straight swap of KT120's and 150's and the 150's are a big improvement for my reference 75. That did not include the Ref 110, as far as I can remember. I suggest you ask your dealer or ARC. If you ask ARC, don't hold your breath, they took over a year to decide on the models I listed above
David12..... If I may inquire, have you been advised on this point , Verbatum, by your own dealer/distributer ? Absolute Sounds I would assume, or are you referring to the unpublished internal comm sent out by ARC some time ago, to distribution network ?

Jasper and David, ... other than double secret hearsay comments that have been published here and on another website, I have *NOT* read or heard directly out of ARC's metaphorical mouth that the KT-150s are approved for use in other models, be they current amps or older models. If either of you gents can point me and the others to a direct *OFFICIAL* source, the collective "we" would be grateful.

(@Jasper, you are the official A'gon grammarian, should I say "the us'es" as in "us" plural instead of saying the "collective we"?? I want to come off as an erudite.)

David, ... having said all of that, until and unless ARC blesses the KT-150s for use in the ARC Ref 110, I would be very cautious about dropping in the KT-150s. As an "fyi" the current Ref series amps (i.e., Refs 75, 150, 250 and 750) were designed to run with KT-120s. The KT-120 is a more robust tube and draws considerably more current than its predecessor, the SED 6550 "winged C."

Stated differently, the marginal difference in power draw between the 6550 and the KT-120 is much greater than then the marginal increase in power draw between the KT-120 and the KT-150. Check the web yourself to confirm what I am saying.

Nevertheless, it would not surprise me that ARC, if and when it gets off its royal corporate arse, may ultimately bless the KT-150s for use in the Ref 110. ARC amps are very robust and can take a "lickin' and keep on tickin'" so to say.

In the meantime ... we wait for its royal majesty to get off the can. And as the official A'gon audiophillic (sp?) erudite Wolfman would say, it's time to can it sweet prince. Say goodnight Gracey. LOL :)
Bifwynne..... I rather suspect that we, the Loyal ARC customer, may not see any such public proclamation until ARC have stockpiled sufficient KT150's to meet demand.

In the absence of any such affirmation from the horse's mouth, or should that read Ass?!!! and Were your Ref150 to have any factory warranty left on the clock, then I would suggest that the most pertinent source of any such confirmation would be your own Dealer, responsible, for honouring and facilitating the practicalities of that warranty, who presumably, will have seen, or at least be aware of, this mythical ARC memorandum.
@Jasper ... not sure I concur with the practical take of your last response. It would be a pure greed play by ARC to withhold the KT-150s approval if they otherwise would not damage the current ref line of amps. Sh*t, who is to say that even if ARC approves the KT-150 that I would buy from ARC .... for $200 a tube. I think not.

Next, my amp was purchased pre-owned from a dealer. Upshot is still no factory warranty. I am dubious that a dealer would go crosswise with ARC.

Having said that, one dealer did in fact post on anther A'gon thread double secret hearsay information sourced back to ARC that the KT-150 was approved for use in current ARC amps. When I spoke to ARC a week or so later, the tech folks denied the bona fides of the report because it came from a marketing guy ... not the tech department.

Go figure.

I'm a big boy. I'll make a decision shortly. If I opt for KT-150s, I'll take my chances.
I'm a big boy. I'll make a decision shortly. If I opt for KT-150s, I'll take my chances.
Please do it NOW!!! Beating a dead horse ... stuck in repeat wining with the SAME monologue.
It's spelled whining .. not wining. If you're going to chide me, at least spell it correctly! LOL
I'm sorta with Joecasey, only because I want Bifwynne and Jasper to turn their attentions to the 6550 tube in the ARC preamp. Now that the SED 6550 winged C's are out of production, and apparently nothing else is as good, some have questioned if a KT88 can substitute. Imagine Gold Lions, Shuguang Treasures, Penta Labs or Psvanes...hmmmmmm
Jasper, If I may answer your question. I have had a thread running for about a year, on this subject. If you look towards the last few posts on

"New KT150 tubes?"
There is indeed a recent ARC pronouncement referred to, to the effect that KT150's are approved now, in the amps I mentioned. I suggest you look at that thread
I used to own the ARC VS-115 amp which came stock with Svetlana SED 6550 winged Cs. ARC later approved the KT-120 for use in the VS-115. IMO, the KT-150 ... hands down ... was a big improvement over the SED 6550 winged C. Better dynamics. Better bass control. More headroom. Just plain sounded better.

Having said that, I couldn't stop "wining" when the Svetlana factory burned down and reliable SED 6550 winged Cs became scarce. As my fellow ARC preamp and source component owners may know, the SED 6550 winged C was used in the power supply of many ARC source components and preamps. ARC now uses the 6550WE, which I believe is made by Sovtek.

IMO, I think the difference between tube types is of much greater import in ARC's amp gain circuits as compared to the preamp or source component power supplies. IOW, I think the 6550WE, or the 6550 Tung Sol re-issue (also made in Russia) works just fine in the power supply applications.

Perhaps Al or Ralph could better explain why (if at all) that might matter.

Signing off for a glass of whine.
Thank you David, I am aware of that particular thread you have referenced.
However, the point that I am attempting to highlight is specific, and pertinant, to owners of these particular models who are still within the term of the manufacturers warranty.

I do not doubt that ARC Central has circulated some form of internal communication within their own distribution network, However, unless I am mistaken, at this point in time, there remains to be seen Any such affirmation, of this sanctioning, as made public by ARC! Indeed, we still labour under the farcical situation of ARC customer support continuing to
Refute any such official sanctioning of the use of the KT150 within the Reference line.

Therefore, as I commented earlier, IF, your Reference equipment is still under factory warranty then the Only and pertinent source of confirmation must surely come, Verbatum, from ones own dealer responsible for facilitating that factory warranty.
David, I am curious as to whether you may have contacted KJW1/ Absolute Sounds recently in this regard?

I have contacted my dealer, but not recently and they made no comment on the KT150s. I got tired of waiting and just changed to the 150s anyway, with a big improvement.

If you were really sneaky and the amp broke down, you could just put the old 120s in, that the amp came with and take it to the dealer. I never said that and of course, would not stoop so low. A large number of people have been using the 150s in the Ref series, for a long time, with no problems. I decided to switch when I was told that a significant number of rooms in the last RMAF were using 150 equipped ARC Reference amps. If it is good enough for dealers and manufacturers, it's good enough for me. I understand you want to be 110% certain of ARCs view on amps within their warranty.
The thing about dealers and manufacturers to consider; for audio shows they may have also installed different value resitors, redesigned a circuit, changed a power supply, etc, etc. I'm not saying don't try KT150's, just understand the risks without blaming ARC in the event of a failure. You do understand the risks and the sound you are enjoying is the result but the 150's are so new to the market....does anyone know in what manner they will fail? All tubes fail at some point, just sayin. Have fun.
My Jolida 502p about which I often wax enthusiastic (note to English majors...I really almost never say shit like that), albeit way less expensive that the hallowed ARC brand, sounds fabulous with 150s, and I am free of the spineless "blessed by ARC" paranoia that runs wild in the ARC camp where frightened owners huddle by their message boards hoping some ARC Corp. asshat loosens his grip on the their trembling sweaty balls to allow them to utterly overpay for tubes you can get elsewhere for half of what ARC grabs from those fearful (and likely empty) pockets. Did I need a comma back there someplace? (I worry about English majors WAY too much)
Well said Wolfy. I'm tired of wining (or is it whining) about those stupid KT-150 tubes. Oh ... and who ever said I would buy KT-150s from ARC for $200 each. Talk about meshuganah. Upscale charges $100 per tube and even that is too much.

@Jamnesta -- just for fun and giggles, I dropped a (Russian new issue) Tung Sol 6550 into my ARC Ref 5 SE. It sounded just fine. As I said, ARC uses the 6550 in the power supply (PS) of its preamps and source components. I surmise that the branding is less important in the PS application as compared to the gain circuits of the amps. Just a guess.
Ghasley, I contacted one of the manufacturers using the 150's in the Ref 75 at RMAF. He told me there were no modifications, just switched tubes and biased in the same range as the 120's, couldn't be easier
As we have become accustomed to of late ! It would appear that ARC Central have circulated an, as yet, confidential memorandum amongst their distribution network in respect to an SE upgrade program for the current Ref line. This leak emanating from a source 'close to' an ARC dealer.

Initial reports make mention of $1K for Ref75 and $2K for Ref150, which if close to accurate, surely cannot include any meaningful upgrade to the Iron, therefore we may well be looking at a handfull of PSU and bias circuit components in optimising the utilization of the KT150.

Bifwynne, thanks for the follow up. I'm in the market for a new preamp and the ARC REF 5SE is on my short list. I was concerned by some grumbling from owners who have received 6550we's as replacements and were not happy, so good news per your findings.
A recent clarification folks.

" My dealer answered my email this morning. It seems that Audio Research is being very tight lipped regarding the details however an upgrade will be available later this year and will run around $3,000 including KT150 tubes (for the Ref150). The upgrade price will include several parts upgrades but no specifics given. The new list price of the Ref150se will be $14,995 ($2,000 increase) which has been previously posted "