New KT150 tubes?

Has anyone any experience with these pretty new tubes. There are already one or 2 amps I know of, that use them. The review of one of these amps in a UK magazine suggested they were a little warmer and more natural sounding than the nearly new KT120's

The article also suggested they were a straight swap for KT120 based amps, with no adjustment necessary. They are more than twice the cost of KT120's, but still not too costly compared with NOS tubes. I know changing from KT88's or 90's to 120's. did require some amp modification. I have an ARC reference 75 and might want to try the new tubes at some point, ARC don't seem to have a customer E-mail service, to ask the question
Curious. My Jolida 502 handles KT120s fine (although not necessarily designed for that tube), but I have to wonder if I'd be pushing my luck with 150s...I have no need to go beyond 120s but since my quad are getting older I'll have to change 'em eventually. I don't particularly like the 150's "pickle innuendo" look, but maybe it would grow on me. I bet, unless some unforseen issue exists, these will be a hit.
Could be very interesting for me. I have an Octave V110 designed for the KT120 and I don't care for the KT120 sound (but like a little more 'control' because of a little more power). I also have the option (though a switch on the back) to go to the EL34/6550/KT88 tubes (my Ei KT90's sound great at the higher plate voltage - KT120 setting). The KT150 may be more to my liking if they are warmer and more natural sounding. To me the KT120 is forward and bright.

That's my opinion
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.
I have to say, I love the sound of my amp, but it would be good to have the option of a different sounding tube.
I explored if the new KT150 tubes can be used in any of the Jadis amplifiers (besides of i50 designed for KT150).

I got reply that KT150 are not interchangable with KT120, at least in Jadis amplifiers.
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.
the kt 150 tube is in. $100 each. so all you folks out there that have 120's if you want to spent $400 for four for another 10 wpc,go for it!!
KT150s are on Ebay for less than that, so maybe those are cryoed or something.
I agree that the 150's are not cheap, though compared with some other NOS tubes, $100 is petty cash. If I did look at them, it would'nt be for the extra power, a recent review in a UK magazine, HIFI World, of a KT150 integrated, suugests that they produce a different, more refined sound to the 120's. If they were interchangeable with the 120's without modification, it would give you a way of periodically changing the sound of your rig, which was relatively painless
The current best price for a quad is 300 bucks...that's where they should be I think. My 4 120s have been in heavy daily use for a year and a half with no signs of weakening...serious hours...they refuse to die...what the hell is wrong with them?
your right wolf,$300 is about the lowest ive seen them plus shipping. most have them for $380 for four plus shipping.
the big question here is to all of us who went out and spent $160 for four kt120's last year are going to want to spend more money now 10 more wpc. thats like twice the price. i think its a rip off. they know everybody will want them because they are new and cool looking. the kt 120's should be around $30-$40 ea and the kt150's around $50-$60,not the $90-$100 premium they are asking for. but we all know in this business tube guys seem to have deep pockets and will pay whatever they cost. i have two jolida amps running in mono. that would be 8 tubes for $750. the 120's are $300. are they really worth double the cost
They should be good for at least 2000 hours is'nt it? That in practice, is a long term and if not stressed to near maximum output, as they are'nt in the ARC, I suspect it's a lot longer than that. Standing in front of your amp, saying "die dam you", probably is'nt going to work.
My amp manufacturer suggests 7000hrs for the KT120.....maybe the last power tubes you ever buy!!!!
7000 hours is two years or so at 10 hours a day...or 30 years at one hour a day...300 years at a minute a day?
will keep my fingers crossed that these will be better quality and can be used in place of KT-120's. Love the sound of the KT-120 but quality of manufacturing precision is erratic compared to the GL KT-88's they retired for my amp. Given what we saw with the KT-120's no doubt will have to wait a year before the various manufacturers render opinion on whether they are safe to use with the different models in their product lines. I suspect we could all get better results out of an improved QC version of KT-120 (or KT-150 if similar to 120 for tonal balance)
This is the first I've heard of KT120 quality issues, and I think it's interesting Davide has experienced "erratic" manufacturing when they're made in the same factory as GL tubes (maybe the Gold Lion quality control team should visit other parts of the factory...lazy bastards!). I'd say that's some bad tube luck as New Sensor must have made a batch after lunch on a Wednesday. I don't doubt other people must have had issues at some point with 120s as they're everywhere, but I've made it a quest to find criticism of 120s as they're such a hit. The official score is 752 to 3 against 120s! Also it's interesting to see such interest in 150s when (like me) 120s work so well (except Davide's). Premium 120s with gold pins, etc., have surprisingly never appeared...Psvane should make some of those as I'd try 'em!
The KT-120s sound fine but the internals of 1 were clearly not given a good visual QC... the posts (anode?) for the vertical glowing conductors are shorter above the top mica plate than the other 3 and guaranteed that when circuit protection cuts in, that's the culprit tube.
I do have one dissimilar 120, and since it works fine I ignore that although it did bug me...but I get it. I suppose the good news is the fact that anybody makes tubes at all since it really seems to be a fiddly hands on thing. I watched an entire old film about the Blackburn Mullard factory (somebody here posted the link)...amazing.
Has anyone contacted ARC about using KT150s in their amps?

Also, Naggots, which manufacturer suggests 7000 hours for the KT120?
Xri16 just heard the KT-150 the other day on a Octave RE-290, compared to the KT-120 is like comparing a Rolls Royce to a Toyota. Surpasses the KT-120 in every way. A more extended bandwidth with a blacker background, bigger and deeper soundstage, a much fuller sound with a lot less grain. Once you hear this tube, all the other tubes just simply became obsolete, a perfect match with the current Genelex Gold Lion input tubes, in this case the 12AU-7's. Can't wait for them to issue a Gold Lion version of this tube.
Yes, The KT 150's have arrived and they are spectacular. I am originally an EL-34 guy who was addicted to the midrange but also played with SED winged C 6550's for their better extension and somewhat more openness, speed and clarity across the board. I've also run EH KT-88's, so this is the extent of the brand and models my Cary Sa 280 V12R's and my CJ Premier 12's were fed. I have used both amps individually and both amps together bi-amping my Apogee Duetta Sigs (Rebuilt by True Sound Works). A lot of fun. I used an active dedicated electronic crossover in the final combination before I switched out both amps but at the time it was CJ's handling the woofers and the Cary handling the mid/tweeter...Punch/dynamics, extension, serious imaging and space and glorious vocals.
Fast forward to my new TRL mono blocs and the arrival of the KT 120's. Very punchy, good extension, nice air and a mid that wasn't quite the same as an EL-34 but surprisingly on the warm-er side of things....I had heard it would have the extension of a high powered KT-88 along with mids approaching a 34...Overall it wasn't too far off but I felt the mids were perhaps just a little too "warm and fuzzy" for my application... You had to really be discerning because the overall sound of the tube was very nice, but for my system it came pretty close but didn't quite replace the 34/6550 combo I had hoped.
Don't get me wrong...I was pretty much "Done" as far as tubes...they were reliable, seemingly robust, and did a very satisfying job, albeit with the described points...
When someone first mentioned KT 150's my first instinct was to say 'Why do we need that??" Will it be an improvement? Really? And is there really a market for even more power? (the 120's were "plenty" although the expression about having more power is usually nice...).
Fast forward again and I managed to get myself 2 matched quads of brand new 150's (My amp manufacturer (TRL) not only said my amps could handle them but actually encouraged me to try them as he was having great results and really liked the tube). So I replaced the 120's with the 150's and was very pleasantly surprised by how much more they added to the mix...Essentially all the benefits of the 120's plus a midrange that rivals my beloved EL-34's AND gets me the top to bottom extension of an 88 or the 120's in spades. Even more dynamic than you thought you'd ever want, as I said: "great mids"...and sweet highs [though I haven't completely explored to full top and bottom yet as my amps had been recently rebuilt and are still breaking in]. Very very promising though..I think they're a real winner.
Try them.
for $7oo they better sound good!!!!!!!
Is the KT-150 similar to the KT-120 in that it is not a direct replacement for a KT-88?
Lissnr, what TRL tube amp do you have? Paul makes excellent stuff that are competitive with anything on the market.
Hi Knghifi, A friend of mine had a new pair of GT 200's recently built for him by Paul so I fortunately arranged for him to sell me his "old pair". I had him ship them directly to Paul where he pretty much gutted anything not worth saving and replaced 'lots of stuff' including all new transformers as well as new Duelund cast caps. I also had him send the faceplates back to the anodizer where we had them done to match the one on my Dude pre-amp(Gun-metal gray). They are simply the most musical amps I have ever heard and when combined with the Dude (also Duelund cast equipped) and my Lampizator Big 6... it's truly sublime. Yes, I feel Paul's equipment really does compete across the board with almost anything out there?!? Thanks for your interest and kind words.
Btselect - Thanks for the info. I just wrote to Mick at Dynaudio to ask Andreas if the KT150's will be OK in the V110. Mick's response is Andreas is currently working with them in the V110. Makes me want to try them for sure.
Lissnr, Congrats on a terrific system and I would love to hear it. It's unfortunate not enough audiophiles get to experience Paul's creations.
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.
Btselect - Forgot to ask. When you compared the KT150's were they fully broken in? I ask because when my KT120's were new I really liked them. After 100 hrs I had to take them out. Too forward and a bit grainy. I loaned them to a friend who said he loved them. He put about 150 hrs on them when I got them back. I tried them again although better (very linear) I also replaced my driver tubes (Telefunken 12at7's) with some warm sounding Mullards which helped even more but still not as good as EiKT90's.
If ARC starts using them in their Ref series amps i would likely want to have a listen to a REF75 with those inside before making a decision on a REF150 with KT120's.
I would like to replace my aging Classic 120's although they were upgraded by GNSC in 2005. I am using 8 SED 6550C in each of them and they still sound fabulous. Just looking at getting something else in the ARC line with close to same power output but with fewer tubes.

Let us know what Kal says.
Thanks Knghifi, Paul's work is truly SOTA it just takes a lot of time to build them one at a time and there's no substitute for that...
As for ARC products I'm hearing such great things about the Ref 75 and I'm sure we would all like to know about the 150's in there too. Keep us guess/hope is that they will work??? and we all will be in for an even further treat. Good luck
I have the new GT200 Monos by TRL and have put the KT150 in place of the KT120 tubes. They blow them away. Being that the tubes have such large plates it takes a lot of hours to get them to open up. They are becoming the best tubes I have ever heard. The GT200 monos take complete advantage of the tubes. With the large power supplies and massive caps the tubes really shine. I had a few friends over and the two women actually cried on a piece I played for them. One comment that they made was " I want to stand up and applause". One mistake that some people make is they don't give them time to break in and they don't bias them high enough in order to run a signal through fully.Human voices are a dead give away. Give them time

The tubes were right out of the box, it could be the input tubes you were using may not be a good match for the KT-120. I just heard the V110 today with the KT-150 tube, again the results were spectacular. We used the Gold Lion 12AT-7, but preferred the Gold Lion 12AU-7 with the Gold Lion 12AX-7. I never cared for the Tele or Mullards or any of the NOS tubes in the Octave components, I prefer the wider bandwidth of the current Gold Lions.

Booboobaer - How many hrs are you talking about? I found with the KT120's they took at least 200 hrs to settle down.
I had a word with the UK importer at a small show over the weekend. He has tried the 150's in his amp and was'nt impressed. Good for a guitar amp, was his response, too rich, too much midrange bloom.

He said the 150's would be ok in the Ref 75, which I have. He thought the Ref 150 would'nt be ok. There would'nt be a high enough plate voltage to drive more tubes than the 4 in the ref 75. Just what he said, I have'nt heard the KT150's myself. I too would welcome feedback from ARC, I could'nt find an E-mail address to contact them, on the website.
KT 150s are likely to never appear in a guitar amp, unless somebody thinks they need a very clean unusually high powered guitar amp, which most guitar players don't. I don't think anybody makes a KT120 powered guitar amp, although a tube bass amp might be a good idea for those.

I found that the new-ish version Psvane 12AX7-T II is a great match with my Jolida 502 anyway.
Btselect - My V110 came with a Sovtek 12ax7lps and the drivers are current production Tung Sol. I don't care fgor either of those tubes. Like I said before I did like the KT120's for the first 25 hrs. If you like bandwidth check out the Gec CV6091/A2900 (12at7's).
Actually Xtil6 I have about 200 hours and they are still opening up.I have been told by Paul Weitzel that I should give them at least 500 hours to start seing what they can do. This is not unreasonable since I saw the same results with the KT 120.
David12, the KT150 tubes had rediculous bloom in mid and bass. But given time that all goes away.
the KT150 tubes had rediculous bloom in mid and bass. But given time that all goes away.

Funny that would be how I would explain the first 25 hrs with the KT120's. Kind of reminds me of the original Tung Sol 6550 solid black plates with deeper lows. Although the mids of the TS 6550 bp has mids that rival the EL34 sound which I thought was close to the KT120's when new.

Booboobaer - Please post back when they are fully broken in.
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.
I will. I have a lot going on in my system. Fairly new amps, new Dueland caps, different DAC, DC filter. It never stops!
Bifwynne If you or anyone else could report back with a definitive answer from ARC, that would be great. To just remind you, the UK importer said the Ref 75 should be OK, not the 150 and above, but I would rather hear what the company has to say.
It may prove to be the case that the Mains / KT ratio of the Ref 75 might receive sanction , however we may speculate that the Ref 150's 8 x KT / Mains ratio may prove too near the Red Line without major surgery , if at all.

However it would seem prudent to await the 'The Word' from ARC central on this matter regardless of model , especially for units still under warranty .
Hopefully we may hear some definitive direction from ARC in the not toooooooooo distant future as to which models , if any , may be certified to utilize the KT150 .
ARC are currently not using this tube nor have they sonically tested or life tested it as far as I know. They continue to use the KT-120 for those amps designed to use it.
Thank you for your input Hifigeek1 .

May I inquire whether you have in fact spoken with , or had direct and very recent contact with ARC R&D on this matter ?

I ask as your comment ~

" nor have they sonically tested or life tested it as far as I know"

would tend to contradict what scant information we have at this time some of which purports to be from ARC themselves !

ARC is in the process of testing this tube. They are in the process of life testing the tube as well as sonic evaluations. They have not come to any decisions as of today. When I hear something more I will post it to this thread..
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.
Good morning Hifigeek1 .

Thank you for the qualification and for the most current situation report we have had to date.
I am certain many ARC owners will be eagerly awaiting your future posts in this regard .