Traded some e mails with Kal at ARC. He reported that ARC is still doing life testing on the KT-150. Kal declined to provide any further information or advice. That's all there is to report. |
Just sent a note to Uncle Kevin Deal at Upscale Audio and asked about the KT-150. I'll post any response I get that's fit to post. :-)
Xti16, I've been running with KT-120s in my last 2 ARC amps. The older amp was originally fitted out with SED Winged "C" 6550 tubes. The KT-120s made a huge positive difference across the board, in my opinion. I'm kinda' glad that all of ARC's current amp offerings use the KT-120 as a power tube. |
Just heard back from Uncle Kevin Deal. No news yet. He said he hasn't gotten a hold of the new tube yet, so has nothing to report. He suggested that folks who own amps using the KT-120 contact their manufacturers for additional information if interested. |
Just sent off another e mail to Kal at ARC about the KT-150. I'll post his response when he comes back to me. |
To ARC tube amp owners, this is Kalvin Dahl's response:
"Until engineering tests the KT150s I would not use them in the Ref 150."
I think it's a fair inference that Kal's advice covers all ARC tube amps.
Patience, patience. |
Gary (Hifigeek) -- does ARC still hold that the KT-120s have a 2000 useful life. I thought I read a 2012 review of the Ref 150 that quoted an ARC rep as saying the KT-120 tube life was considerably longer. In the same view, is the 6550 WE tube life also 2000 hours. I have 6550 WE tubes in my ARC front end gear. |
More importantly ... do the KT-150s sound better than the KT-120s and if so how much better. Even more important, how much do they cost and is the cost increase worth it. |
Joe ... that's an interesting bit of data. I understand that ARC is looking at the KT-150 now.
Here's my little dilemma. My KT-120s have about 1900 hours on them. According to Gary (Hifigeek1) and ARC, I'm just about at the end of their useful life and should get ready to replace them. I wonder how much longer it will be before ARC announces yeah or nay?? |
Wolf ... point taken. All I can say is that ARC and Gary (Hifegeek1) are touting the company line here. I contacted Kal at ARC by e-mail. He continues to hold that 2000 hours is when both the KT-120s and the 6550 WE regulator tubes should be replaced. |
I understand that Upscale Audio has a batch of KT-150s in stock that are being tested. Not for sale yet, but possibly early next year. Retail pricing not set yet either, but early thought is more than the KT-120s, which as an aside, may take a price increase (TBD).
Put it to you this way. If the KT-150 is twice as expensive as the KT-120, I doubt it would be cost effective for me unless the useful life of the tube increased proportionally with price. Otherwise, I'd be sweating bullets every minute the rig was running.
I heard a buzz that ARC may complete life testing the KT-150 in February/March next year. My current set of KT-120s is ready to be replaced now. I'm inclined to retube my amp with the KT-120s and catch others' comments and reactions.
Happy Holidays,
Bruce |
Wolf ... when speaking with Upscale Audio, one of the guys slipped that the KT-150s may rtail for about $100 per tube, or thereabouts. However, that price is not fixed yet as I mentioned above.
Even still ... if that is indeed the final price, it's almost twice that of the KT-120s. And ... unless the KT-150s have longer life, I'll probably take a pass, unless I inherit some money and get an itch to road test um' on a whim. I use my rig pretty much every day. The cost of tubes will get prohobitively expensive.
Let's see what somes back in user comments.
Happy Holidays,
Bruce |
Gary (Hifigeek) - looking forward to reading your reactions after CES.
Hopefully, even if ARC should decide NOT to sell/or use the KT-150s, it will at least advise whether the KT-150s may still be used in ARC amps at the customer's option. IOW, that the KT-150 will not damage those amps that are already cleared to use the KT-120s.
It's bitter cold here in Philly. Hope the weather is better on the West Coast.
BIF |
Tsushima1, please explain what you meant when you posted that ARC was "phasing out of the 2Uf Teflon coupling capacitors on the Ref 150." I own the Ref 150 so I have a real interest. |
Thanks Tsushima1. I read the various posts in the attached link. I suspect that ARC had either supplier issues and/or there were performance improvement gains by going with the new caps. My Ref 5 SE and Ref 150 both have the "old" white Teflon monsters.
I'm a big ARC fan and I believe that if ARC is using different coupling caps, it made the switch-out for good reason. I recall that I had to wait about a year before ARC called me to upgrade my Ref 5 to the SE version. One of the reasons for the delay: supplier problems. But as I said, it may be there are reliability or performance issues with the Teflon caps. Dunno.
Maybe if Hifigeek catches this thread, he will chime in. |
Anyone have anything to report on pricing. I heard and/or read that pricing could be double that of KT-120s. |
Tsushima, my eyes ain't what they used to be. I assume you are implying that ARC is hogging the KT-150s for itself? Rats!!! I hate hogs. Well ... I don't feel like getting my head snapped off by calling ARC. Perhaps Gary (Hifigeek) will weigh in again with a status report. |
Wolf, are you mixing and matching thoughts. I think Tsushima's comment refers to life testing the KT-150, not so much the sound.
Just my own lay reaction is that from what I've read, the KT-150 doesn't draw a heck of a lot more current than the KT-120s. My knee jerk thought is that the KT-150s would NOT damage the power trannies.
Further, the KT-150's power output is not that much greater than the KT-120s. Again, my knee jerk reaction is that the KT-150s wouldn't harm the downstream components in the gain stage.
But ... hey, I'm not a EE. So, like the rest of us, I'll patiently wait. I love my Ref 150. Dam* if I'll stick a tube into it that ARC doesn't bless. |
Wolf.... please, let's keep it clean. Naked tubes ... really! |
Wolfy ... you kill me. :) |
Wolfy ... I think what Tsushima1 is saying is that you are a lowbrow. LOL
Not to worry ... my wife says the same about me. ;-) |
Thanks for the update Tsushima. Hopefully Gary (Hifigeek) will catch this thread and post another ARC update on status. |
Was just trolling on the Upscale Audio website and noticed they are listing the KT-150 for $92 per tube. I also checked NewSensor's posted stats for the KT-120 and KT-150. The KT-120 filament draw ranges from 1.75 to 1.95 amps. In contrast, the KT-150 is reported to pull 2 amps. To my non-techie head, the extra draw is not significant. Nevertheless, I will not drop the KT-150s into my Ref 150 amp until ARC officially clears the tube. Hopefully Gary will have something to report shortly. |
Hey Wolf, where are sourcing the KT-150. A quad for $300 is not bad. |
Wolf ... I checked eBay. Right you are. Number of vendors offering to sell KT-150s for prices you mentioned above. Even still, I have three concerns.
First is that ARC hasn't approved the tube for use in its amps yet. I suspect that the additional current draw is not signficant, but I don't want to experiment with my amp.
Second, my amp requires matched tube sets. I've had some difficulty in sourcing pairs that match well. So far, only ARC has been able to provide reliable matched sets.
Third, I do not know anything about the reliability of the eBay vendors. At least with vendors ARC and Upscale Audio, I am comfortable that the tubes are properly run in and tested before being sold.
In short, it might cost me $700+ to buy 2 quads just to satisfy my curiosity .. although I am curious about the tubes. |
@Wolf .... of course not Wolf. Many reputable vendors match tubes. It just happens to be IME that ARC matched power tubes bias much easier in my amp. Btw, for the sake of clarity, I am referring to KT-120s.
As an fyi, my amp has a bias "set" tube and a "slave" companion for each pair of tubes, which are configured in push-pull topology. The way the tubes are biased is that I can adjust bias (65 mV)for the set tube, but not the slave.
If the tubes are well matched, the slave will show a bias voltage ranging between 57 mV and 73 mV. If the slave tube bias is out that range, the amp will not operate within spec.
As I said, even though I have bought "matched" tubes from private venders, sometimes the slave doesn't fall within the spec range. IME, this hasn't occurred with ARC spec'd tubes.
Now, as to the KT-150s, that's right, ARC has not blessed using that tube ... yet. Will it work?? Dunno. Some have tried it in their ARC amps and report great results. Will it hurt the amp? Dunno. Will just have to wait for ARC to approve the tube.
Wolf ... like most A'goners, my gear represents a significant monetary investment. In particular, my amp is a pricey piece of kit. Maybe I'm just being over-cautious, ... but until ARC says the KT-120 will not damage my amp, I'm not experimenting. I will defer gratification.
Cheers. |
@David12, you asked "if you are using an auto bias amp, you need a matched pair or quad of tubes. If you are using an amp, like the ARC power amps, where you have to set the bias yourself, does it matter if they are matched or not?"
Yes, ... I think it does matter for the reason I explained above. In both the ARC Ref 75 and Ref 150, each tube pair has a "set" tube and a "slave" tube. As you know, only one tube, the "set" tube takes the bias adjustment. The "slave" tube bias has to read between 58 mV and 73 mV in order to be in spec. So matching is important.
In addition, and this comment (or better, "guess") is best expanded on by techs like Gary (Hifigeek1). Gary is an authorized ARC service tech. That is there may be other electrical parameters that should be matched, like power output. Obviously, if that is a key spec, I intuit that in a push-pull configuration, if tube output power doesn't match within spec, the waveform could be distorted. I'll stop there because I am now way north of my pay-grade.
Bruce |
Milimetr ... that's a great explanation. I'm sure the factors you describe are (or were) also under consideration by ARC.
Quite honestly, I'm not sure what "life testing" entails. Perhaps it involves running the tube in actual operation in the amp to check if it has a deleterious effect on other components. It might involve long term subjective sonic testing. Not really sure.
That's why although I am personally interested in following the outcome of ARC's testing process, I'm not so curious to plop those tubes into my ARC until ARC gives the green light. |
Gary (Hifigeek), I caught that pic too. Just a peek though. What's with all the suspense?? |
Gary (Hifigeek), does the G series employ some new technology? Or is it some type of super reference amp designed to mate with the Ref 10 and Ref Phono 10?? |
I just started a new thread where I report on ARC's new G series. I have a URL x-ref to where you can see pics and prices.
It's a new "higher-end" series which is priced higher than the "normal" Reference product equivalent analogues; namely: the Ref 5 SE and Ref 150. There's also an integrated version of the Ref 75. The G series is really gorgeous and uses the new KT-150 power tube.
Looking forward to reading and learning more about the G series. |
Here's some pics:
www DOT theaudiobeat.com/highend2014/highend2014_arc.htm
Gary, TAB says the new models "are 'reimagined' versions of current models." Do you know yet if the G series incorporates new or improved technology, other than the KT-150 tubes.
Just speculating of course, but if the G series is essentially repackaged existing products, the use of KT-150 tubes may permit one or both inferences (or surmises) that (1) the existing product line can handle the tubes and (2) that ARC completed "life testing." |
Gary, my non-tech instinct (surmise) is that the KT-150 should be a drop in option for ARC's current Ref series amps (75, 150, 250 and 750). I base this conjecture on the following facts: (1) the KT-150 plate draw is just a few milli-amps more than the KT-120; and (2) the KT-150 plate impedance is very close to the KT-120.
In the former case, I would be surprised to learn that the current Ref amps already beefed up power tranny couldn't handle the slight power draw increase. In the second case, if the KT-120 and 150 tube impedances are in the same neighborhood, I would think that the output tranny should do a good job with impedance matching.
If my recollection of the facts is correct, I am puzzled why the KT-150 isn't a non-brainer tube rolling option. I'll double check the KT-120 and 150 specs and report back if my recollection is faulty.
I wonder if ARC's reluctance to "sprinkle holy water" on the KT-150 has anything to do with the pending 2014 introduction of the new G series gear, which apparently will use the KT-150. Well .... as I have written before, I trust ARC and will not drop in the KT-150s until ARC blesses the new tube. I have too much invested in my gear to impulsively drop a component into my Ref 150 until ARC says its ok. |
Gary ... I don't like to guess or talk about stuff above my pay grade. So, I checked the New Sensor web site and copied the following specs:
KT-120
Plate resistance - 3000 ohms
Heater characteristics - 1.70 to 1.95 A
Plate current – 135 to 165 mA
Plate dissipation – 60 watts
KT-150
Plate resistance - 3000 ohms
Heater characteristics - 1.70 to 2.00 A
Plate current – 150 to 180 mA
Plate dissipation – 70 watts
I really don't know if the increase in plate dissipation current or plate current draw is electrically significant. Perhaps you can weigh in. However, to the extent that plate resistance is an important spec, the two tubes share the same stat.
Regards,
BIF |
Ariess ... a related issue to the one you just mentioned pertains to resale. My ARC Ref 150 amp is used. I'm not sure how I'd react if I learned that the prior owner used KT-150 tubes if ARC had not blessed their use as of the date I extended an offer. Of course, if ARC sprinkled pixie dust on the KT-150s by the time I was ready to make an offer -- then no harm, no foul.
As an fyi -- ARC recently told me KT-150 life testing continues. Hopefully, I will survive ARC's life testing process. Seems like it will take a life time. :) |
Wolf .... I am VERY, VERY upset. Nola Speakers used KT -150 tubes in a Ref 75 .... So far, because KT - 150 life testing is ongoing, Nola may (??) have used the tubes without an ARC pixie dust sprinkle. I may turn this over to ARC for disciplnary follow up -- abuse of equipment. Could result in equipment confiscation. :) LOL
www DOT theaudiobeat.com/newport2014/newport2014_favorites.htm
P.S. -- I wonder if Nola got dispensation. |
Wolfy ... you'd be quite fortunate if it was JUST the tubes. Unauthorized tube use could cost you the amp.
Who in their right mind would willfully and knowingly abuse their ARC amp by using tubes that weren't sourced from ARC. Shocking!!!
Sorry if I'm pushing into your personal business, but please confess ... how often do you check the bias of the tubes? Do you religiously set the bias at 65 mV??
Just tryin' to be a friend. :)
P.S. Upscale Audio sells the KT-150 for $92 a pop. :) |
Tsushima1 .... very interesting bit of news ... but I'm still not dropping those pickles into my amp until ARC says it's ok. Why the wait? Dunno. But until ARC sprinkles pixie dust on the KT-150s ... not in my amp. |
Tsushima1 ... I believe to a near certainty that the KT-150 will do NO harm to my amp. Nevertheless, I will not drop that tube or any other tube type into my amp until and unless ARC formally announces its approval. Period.
I don't know why ARC is taking this long to announce its approval. Maybe "life testing" takes this long. Or, maybe the delay is wrapped up in some way with ARC's pending release of the new G Series. Dunno.
As an aside, I still have about 1000 hours of life on my KT-120s. So, in a way, other than mere curiosity, I'm in no rush. Also, the KT-150s will cost twice as much as the KT-120s. Why the extra cost??? Haven't a clue. Supply and demand??? Dunno. |
Djcxxx .... one other issue comes to mind. I'm thinking about resale issues. If I was interested in buying a preowned ARC amp, I would ask the owner if he rolled the KT-150s. All things being equal, if I could buy the same model, sans KT-150, I likely would. Having said that, this concern would be moot the moment ARC officially approves the use of the KT-150. |
Xumbug .... as a general matter, I would be remiss to advise fellow ARC owners to drop KT-150s into their amps unless ARC said it was ok. Much of the discussion in this thread pertains to dropping KT-150s into current vintage ARC Ref amps, namely the Ref 75, 150 and 250. These amps were specifically designed to handle the KT-120s. The design changes included a beefed up power transformer and power supply.
Admittedly the predecessor Ref amps (namely the Ref 110 and 210) are able to handle the KT-120s. However, as reluctant as I would be to drop the KT-150s into the current Ref amps (such as my Ref 150) until ARC sprinkles pixie dust on the tube, I would be even more circumspect about the earlier version Ref amps.
My thought process is that these earlier amps may not have sufficient power supply head room to handle the additional demands of the KT-150s. And that doesn't even speak to whether the KT-150s are compatible with the older circuit designs.
Just my humble opinion.
I get that you are ready for new tubes since you have 2300 hours on your KT-120s. And those pups are ripe to the point of rotten. I sure wish ARC would fish or cut bait already.
And since poor Kal and Chris at ARC have been pummeled with a million calls about the KT-150s, I'm afraid they will confiscate my amp if they suspect I directed anyone else call them. LOL :) |
Xumbug and Joe ... I don't think I'm contradicting the comments and caveats posted above by saying that even if the Ref 210 "seems" to work ok, how can one know for sure whether using the KT-150s will, or will not, prematurely age the amp over the long term. To me 100+ hours is not "the long term."
Maybe it won't hurt the amp, but I surmise that Xumbug dropped some major bucks to buy his Ref 210. Unless he has DEEP pockets and doesn't care, my advice is wait until ARC approves the KT-150s for his Ref 210.
I sure as sh*t, I am not dropping those pups into my Ref 150 until ARC gives the green light. So, I'm taking my own advice. |
Wolf, .... Undertow makes an interesting point, but ... the KT-150 will list for twice the price of the KT-120. I am dubious that ARC will get stuck with thousands of KT-120 tubes even if the KT-150s are approved for use in the current product offerings.
I've used approximately 75% of the tube life of my KT-120s. I may spring for 2 quads of KT-150s, but not from ARC. Too damn expensive. The good news is I understand that the KT-150s have a life span of 4000 hours. |
David256, ARC has unofficially said that their tested and calibrated KT-150s will sell for almost $200 per tube. By contrast, ARC sells KT-120s for about $100 a tube. Way over my what I will spend for a tube. By contrast, Upscale Audio is charging about half those amounts.
When ARC blesses the KT-150, I'll probably go to Upscale. No f***ing way I'll spring for $200 a tube from ARC. My current set of KT-120s is getting long in the tooth. I might spring for the KT-150s with or without ARCs blessing ... maybe
Btw, I read somewhere that the KT-150 has a life span of 4000 hours, which is twice the suggested limit for KT-120s. Let's see what is officially reported, all of which I suspect will be shortly after the ARC G Series is released.
BIF |
Sent another message to Kal. Waiting for a response. I asked him how the GS 150 differs from the Ref 150. The specs are identical, except the GS 150 uses KT150 tubes. I think there's a marketing wrinkle here. |
Veerapaaneni ... I e mailed ARC about using the KT-150s in the current Ref line and whether the GS-150 (soon to be released) and the Ref 150 have different innards. So far, no answer.
Here's my cynical speculation. I think the GS-150 WILL sound better than the Ref 150 only because it uses the KT-150 tubes. Otherwise, until someone tells me that the GS-150 has different innards than the Ref 150, I think it's just a dressed up Ref 150 with KT-150 tubes.
I hope an ARC dealer or ARC service tech catches this thread and disabuses me of my cynical comments. I WANT to be wrong, so please someone disabuse me. But so far I see no rational reason for ARC continuing to be officially mum about dropping the KT-150s into their current Ref line. In the meantime, I wait.
BIF |
David12 and Tsushima ... I took a close look at the specs for the KT-120 and KT-150. Take what I say with a grain of salt because I am not a techie, but the current draw, plate dissipation and impedance specs of the two tube types are very similar. I surmise that any additional power demands that the KT-150 would place on the power transformer and other relevant passives would not be significant.
And I continue to wait.
P.S. to David -- how close was the "slave" tube's bias spec to the "set" tube's 65 mV bias number? I ask because for some reason that I cannot explain, IME, the delta between Upscale sourced KT-120 "set" tubes and "slave" tubes specs can be as much as 5+ to 8 mVs??? Not so with ARC matched tubes. |
Gary (Hifigeek1) ... still no official word from ARC yet about dropping the KT-150s into its "standard" current Ref amps???? Has the new G series gear hit the stores yet???
In a private message from Kal a while back, he mentioned that the GS-150 is the best sounding amp ARC that has made to date. He did not answer my question about how the innards of the GS-150 changed from the Ref-150. On paper, they spec identically. |
Veerapaneni ...my Ref 150 is almost ready for a retube. The KT-120s have almost 2000 hours of use on them.
I am frustrated that ARC will not bless the KT-150 for use in their current Ref series. At this point I have only ONE question: will the KT-150s damage my Ref 150? Period.
I'll take my chances on life testing and sound quality. I just want to know the answer to that simple question. Will I damage my Ref 150
Though a non-techie, the KT-150 additional current draw looks immaterial as compared to the KT-120. The GS-150 and Ref 150 specs look identical. I infer that the GS-150 is a goosed up Ref 150, with just a prettier fascia. It is not even clear to me that the GS-150 has better innards.
Take a look at the ARC web site and check the GS-150 and Ref 150 tech specs ... IDENTICAL in every reported aspect!!!
As many of you who follow my posts know, I am an ARC fan. But I am getting a tad irritated by ARC's refusal to answer my question: will the KT-150 damage my amp???
Bruce |
Agreed David. Take a look at the ARC web site and stare at the GS-150 and Ref 150 specs. The GS-150 specs identically to the Ref 150, but for a few extra watts of rated power ..., no doubt because the GS-150 uses KT-150 tubes.
If the GS-150 has different innards, ARC should say so. Bad marketing in my opinion. At this point, as a consumer, all I see is a retro'ish looking fascia and KT-150 tubes. If that's all there is, one would be crazy to part with the extra cash for this new entry to the ARC line-up.
In the 60s, we used to describe good looking so called muscle cars as "no-go showboats." Until I hear otherwise, that's what I think of the GS-150.
Really annoyed with ARC. My amp is close to a retube and I would like to drop in the KT-150s. All I want to hear from ARC is that the KT-150s will NOT damage my amp. I'll take my chances on sonics and tube life. |
Thanks Johnny R ... finally a straight no BS answer.
Johnny, one other question. The GS-150 and Ref 150 spec identically on the ARC site. Everything .... distortion, power supply, bandwidth, whatever. So what changed??
Also, will ARC sell KT-150 tubes for regular stock Ref amps and at what price?
Johnny ... you are the best. |
