New KT150 tubes?

I might buy a quad of 150s when my 120s die just to see if my amp would blow up. Am I so wrong? Seems the amp (Jolida 502p) can take it...plus I'm getting curious about the 150s and starting to overcome the pickle-esque vibe.

People please do not ask ARC what the status of the KT-150 is. Thanks.

Why?

02-07-14: Wolf_garcia
I might buy a quad of 150s when my 120s die just to see if my amp would blow up. Am I so wrong? Seems the amp (Jolida 502p) can take it...plus I'm getting curious about the 150s and starting to overcome the pickle-esque vibe.

Wolf, proof me wrong that you don't have small ones. LOL!!!

I think the "don't ask ARC" thing was about protecting the sensitive ARC people from further stress, as Hifigeekl is nothing if not compassionate. I, however, am not. I read in a Brit hifi mag last night that 150s are a "drop in" replacement for 120s, and have a smoother sound...that's what the dude said. The tiny difference in heater requirements make it seem he might be right. I still have never seen anything regarding an amp tranny frying from 120s replacing kt88s anywhere ever at all even once. I'll keep looking.

Anyone have anything to report on pricing. I heard and/or read that pricing could be double that of KT-120s.

I may have mentioned someplace that I've seen 150s on Ebay for around 300 bucks for a quad...that seems almost reasonable.

Perhaps fellow interested parties might care to zoom in on the output tubes as sported within ARC's own demo Ref250 !!!~

http://www.monoandstereo.com/2014/03/audio-research-dream-demo-room.html

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.

If those are indeed KT-150's (difficult to tell) in the Ref250's that would make perfect sense as that is part of the life testing process. If I talk to the factory next week, I will inquire about the KT-150 status and availability. Hopefully our government does not start embargoing products shipped from Russia....

Bifwynne, Whilst not the sharpest of images when blown up I am pretty confident that they are indeed sporting the Mythical KT150! whether the circuit has been modified in any way is of course unknown.

I am aware of at least two intrepid ARC owners currently running KT150's in their 2x output valve per chanel VSi75's, bias set at 65mv , with no ill effect(as yet)noted.

Again one might theorize that ARC R&D may be a little more confident in respect of KT150 loading on the Mains transformer(s)as supplied on certain of their recent models, they may however be a little less comfortable ,as yet ,in respect of Mains headroom on other models , in particular were a Single Mains transformer is already supplying a Quad of 6550's or KT120's per channel .

Life testing of a new production valve and thorough evaluation of any potential implementation within existent models may take a reassuringly great deal of time .

Mere speculation on my part of course ,In which , as an Ref150 owner I would very much like to be proven wrong !

Is this an horizontal bi-amped configuration? What's sitting between the 250's?
I would bet that those are indeed 150's.
For room acoustics, they much favour diffusion than absorption in that room.

"Hopefully our government does not start embargoing products shipped from Russia...."

No they won't. Putin will take care of that including shutting down all the oil and gas pipelines heading towards Western Europe creating a global financial collapse.

One bit of hype that seems silly is the claim that the pickle shape eliminates microphonics...assuming this shape doesn't allow vibration from anywhere to get to the tube...nonesense.

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.

A great deal of time? How about listening to the amp to see how the tubes sound...that takes about 3 minutes.

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.

I'm not capable of mixing thoughts...one thought at a time for me. Does "life testing" involve carrying the tubes around with you? Restaurants, dentist visits, etc....or simply talking to the tubes about life..."You were sand and chemicals once...and NOW look at you!"

" 03-18-14: Bifwynne
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 So Bifwynne , altho I would consider that from an ARC perspective the most prescient factor would be due diligence
in respect of equipment safety margins and measurements , more so than valve denudation or even how each model responds audibly , even tho improved fidelity would be the the catalyst for such experimentation.

That said , I do feel that ARC's somewhat nebulous position on this matter and apparent disinclination to engage with their customer base , especially those who may have an material interest in the models,under/not under ? R&D,to be less than understanding!

Does "valve denudation" involve removing the glass tube? That certainly would have impact on longevity, and thankfully there is little "prescience" in audio, especially since these tubes have been clearly vetted by others. My bet is that ARC has piles of 120s to get rid of before sticking 150s in their amps.

Wolf.... please, let's keep it clean. Naked tubes ... really!

Wolfy Wolfy , really now , am I to be so misconstrued !
Surely a somewhat weak and Sophomoric humour cannot be the sum total of your input on this matter !

Florid language notwithstanding, never underestimate the potential of good natured criticism of pretentiously misused words, sloppy grammar, and self indulgent obfuscation, as it can reveal the insecurity of the offender and the air pressure sustained by the gasbag.

Wolfy ... you kill me. :)

Anyone try these out in Rogue Audio equipment?

The Wolfman scores ;-)

Oh, I seldom underestimate the 'potency' that is the playful use of the intentional parapraxis, or indeed the deployment of the mixed metaphor in bringing forth the 'small' man with their need to indulge in pompous grammatical correction , particularly when they have little of value to add in respect to the subject under discussion.

Wolfy ... I think what Tsushima1 is saying is that you are a lowbrow. LOL

Not to worry ... my wife says the same about me. ;-)

We have another ARC VSi75 owner, commenting elsewhere, in respect of his unsanctioned adoption of the KT150. He reports that no obvious anomalous behavior has manifest itself,as yet,from either amplifier or himself.

Commenting further, it would appear that he considers the substitution to have been quite efficacious.

"I'm so glad to tell you that this is the greatest improvement I 've ever heard for the money!

Maybe a 15 hours - break in is just a little bit to say that Vsi75 is born for KT150, but soundstage is wider and deeper than ever!

Bass is more bass and midrange is so natural and 3D through my Sophia 3!"

It would be useful if these guys were in a position to monitor bias readings and transformer/circuit temperature.

Perhaps I may make a few inquiries, and post any further information on this point.

I only ask that the poster understands the posted words, and at least attempts to use them correctly...example: "potency" makes little sense in the context of this exchange, and "intentional parapraxis" is an oxymoron. My criticism in this case avoids "mixed metaphor" as it is nothing if not direct, and sort of fun...man...I need to get out more...

Thanks for the update Tsushima. Hopefully Gary (Hifigeek) will catch this thread and post another ARC update on status.

I shall try and ask this week.

Good evening Gary.

I was wondering whether you had been in receipt of any further 'Official' news?

If so ,I sincerely hope that you have not been 'Clipped' for such temerity, And are not currently propping up a flyover, somewhere in Minnesota!

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.

I shall update If/When there is any response to the following,

Quote:
Originally Posted by cesare59
After 70 hours of use i can say that kt150 it's a must for vsi75 owners!
Soundstage IS wider and deeper! Midrage it's more realistic then with kt120!
Only bass in my system are lean than before..."

My question,

"Most interesting cesare59, Do you feel that the base notes on passages of music, familiar to you, have in fact altered sonically? Or, That due to a shift in emphasis perceived elsewhere in the spectrum you are mostly experiencing a different balance to those familiar passages."

BASE NOTES...man..."Base fishing anyone?" I may get a quad of 150s (300 bucks is the magic number here) and plop them in my Jolida and just stand back with a fire extinguisher and wait...either it blows up and destroys my entire neighborhood or the tubes actually work. Is a tiny increase in heater current really causing people to wait on these? I say MAN UP people...and report back.

Hey Wolf, where are sourcing the KT-150. A quad for $300 is not bad.

Ebay had that price from somebody a few times...seems actually fair.

04-20-14: Wolf_garcia
BASE NOTES...man..."Base fishing anyone?"

LMAO, Base fishing? No, not quite. I do however find 'Angling' for the Lesser Pedantic Grammar Pilchard considerably more edifying, Altho, a somewhat 'predictable' feeding habit does tend to leave them incapable of resisting the bait/bate as proffered.

;0}

I'm a bass player who doesn't fish.

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.

I'm confused...Only ARC has matched sets? Have other matched sets proved unreliable? I don't understand what that means since you say they haven't approved them for use, but then I'm easily confused. Many Ebay sellers know what they're doing and are rated by the customers so there's that, and my experience with non frozen or overpriced KT120s worked out fine.

I purchased a quad of kt150s from uncle kev at upscale.

I've had them in my primaluna prologue premium integrated for about three weeks now, replacing the stock el-34s. Wow! what an upgrade. Finally giving me that deep bass punch; it struck me like I bought a new amp when i dropped the needle on Talking Heads Stop Making Sense. At the same time all the sweet midrange is still there.

Absolutely no issues. The tube cage does need to be removed

@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.

There seems to be some confusion regarding 120s or 150s, and I like it.

Can I ask a stupid question, plainly, 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?

I agree with Bifwynne, I am not going to put KT150's in my ARC ref 75, until ARC says it is ok. It is the most expensive bit of kit I have ever bought and I can't afford for it to go up in smoke, or to void my warranty, by making the change.

In fact I have just bought a really nice 2nd hand Skoda car with low mileage. With a trade in, it cost about the same as the ARC. It makes you think how your sense of what is good value, can get a bit warped, in this hobby. Not that I am complaining about the ARC, it is a wonderful amp, I hope to be still using in 15 years. I suppose it's a question of which one of us blows a capacitor first, sobering thought

@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

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.

Wait...it's been another 2 days of waiting for Kal's testing results...I can't handle the suspense...I'm in audio LIMBO...

Ok. I have similar concern.
Have an aplifier designed to work with 6550/KT88 family of tubes.
Now I have KT120 installed - ok by manufacturer.

I was considering using KT150 im my amplifier, but manufacturer adviced not to do so. The point is not that both KT120 and KT150 have almost the same current draw. The point is different characteristics (curves) in KT150.
When used in amplifier with plate voltage lets say - 485 V and fixed bias point using KT150 will lead to use the tube in non optimal characteristic point (not the most linear part of characteristic). This is at least explanation I got from amplifier manufacturer.

Using KT150 in their optimum requires output transformer to be specially wound for them as well as setting proper working plate voltages.

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.

It's all a bit like waiting for the college of Cardinals to elect a new Pope. Perhaps there should be a chimney in Minesota, so we can all wait outside for the puff of white or black smoke.

David12, better that than a puff of white or black smoke from your amp. ;^)