Anyone Compared the New 6550/KT88s out there in their Amps?

dminches

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Mendel, let’s be clear, in the few amps that I have heard the KT120’s, they were superior sounding to the amps that I heard that were using KT88’s or 6550’s.

Just to clarify, were these the same amps with different tube sets or entirely different amps?
 

DaveyF

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Just to clarify, were these the same amps with different tube sets or entirely different amps?

Both. The last pair I heard were different amps, like I posted above. However, I have heard a couple of ARC amps that were able to accommodate both tube types...KT88/6550's and KT120's. The difference was very significant once the tubes were rolled in.
 

Mendel

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Gentlemen, point taken. I will definitely be having a listen to the new ARC amps with KT150s.
But I love rolling! My Rogue can take KT120/KT90/KT88, 6550, KT66, EL34 and 6L6GC. Like have 6 different amps. I actually use KT66 most of the time, either GEC greyglass or the Gold Lion reissues which are excellent. KT66 is more linear than any KT88 or KT120 in my opinion and has the best highs. Many KT88 amps can use them if you can manually bias the tubes a little lower. You do give up a little power however. Ever try them?
 

Big Dog RJ

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Just to clarify the point with tubes:
I'm certainly not staying that the KT150 is better or by far superior... It's just a personal preference to me that it is by far a very radical design compared to most other KT series tubes.

With that in mind, my actual personal preference is the EL34's mid-range warmth and magical openness but it's not suited to drive a large stat full range, such as the CLX's.

Therefore, what had worked for me so far in terms of amplification:
1. Control & grip on the panels must be effortless.
2. Ease of presentation, smooth response with full body and depth.
3. Most importantly the musicality.

From the above three critical areas I'm after, so far the KT120 delivers exactly this! Then when I heard the KT150 driving stats, all of the above just went up a level in realism plus dynamics, including a profound level of resolution, unbelievable!

But again, I must emphasize that the KT150 may not be like by all. I know a few who still absolutely love the 6550C tubes on their CJ monoblocks, which are the premier 8's. There's another chap here who has similar amps to mine, CJ LP275's, and he's using 6550's as well. He tried the KT120's and did not like them, saying that it sort of forces the music out... Whereas the sound is more relaxing on the 6550's so he claims. I can see why but this is where you have to carefully match with the right preamp, for that finer touch in full control. I certainly have and very pleased with the results. I'm still wondering whether the move towards the KT150's is worthwhile...
It certainly was a game and mind Changer for me so far. Perhaps others may have similar experiences but as I said its a very personal preference.
The choice is yours!
Cheers, RJ
 

Mendel

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Sounds reasonable Big Dog.
Just to clarify, I too am using big full range panels (Acoustat Spectra 22).
Never felt that KT120 (or even KT88) were necessary to control the panels. I do find EL34 a little bloated and weak in the bass however. KT66 combines the control of the bigger KT88/KT120 tubes with a touch of EL34 sweetness and great top end extension (which the Acoustats can use).
As you say there is no right or wrong, just personal preference. I find the choice of input and driver tubes too make just as big a difference in tailoring the sound.
Enjoy the roll!!!
 

Big Dog RJ

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Yes that's a definite. Those smaller tubes also add significant differences in overall character of the amplifier. Just on another thread which I started on the Genalex Gold Lion 6922 /e88cc used on the CJ monoblocks as driver/phase inverter, they are superb! Far superior to the stock EH type that CJ utilizes. Which raises a big question for me, is why on earth do they incorporate the EH tube at all?
I guess it's to do with cost of parts and stock availability for production.

One thing I've learned over the decades, which has caused many fingers burnt, is if something definitely sounds good to your ears then by all means don't change it, unless you hear an improvement of at least over 25-30% of sonic performance.

I gather from what you've described, the KT66 seems to be your preferred choice and delivers all that you are looking for in the sound you want. This is a great thing! In fact us so called experts and audiophiles, there are quite a number of us who don't even know what we're after...
If you can identify exactly what it is in terms of musicality that you prefer, that is the sound you will eventually get to regardless of price.

At one point, just before I confirmed the order on the CLX's, I tried out the Avant Garde Duo XD speakers with my CJ integrated CAV45. It was marvelous, with just 45w of EL34 magic, I really enjoyed my time with them. However, after a while I began to realize that the AG horns force the sound out, as if something is always being propelled into the room. Transients are jumped out at you, and sort of hit you hard in the face. That type of forward sound results in the soundstage being forced forward rather than a well laid out soundstage behind the two channels. When the soundstage is laid out behind the two speakers, the imaging is SOTA and the speakers simply disappear. With the AG's that affect did not happen and it was annoying to me after a while. However, on the short term it was most fun and exciting to experience the liveliness of AG horns.

Please understand that this is only my experience with AG's and not a general trait of these horns. I sincerely think AG's are a superb design and having very high efficiency, can match with a host of different tubes, from EL34's to KT120's, AG's can also be tailor made to suit your sound.

As with full range stats, and my true inner passion was always with the CLX's, I just preferred the CJ monoblocks running KT120's in push pull config class AB topology. Whether the KT150 is superior, yes it is, because I've actually heard it, and it totally changed my thinking about pentode tube designs.

Acustats are classic full range stats, requires very stable power supplies to drive properly and effectively. Once you've found the perfect fit you will know it straight away, that's the beauty of full range stats!

Cheers to electrostats! Simply the best,
RJ
 
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DaveyF

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All this talk of rolling in KT120's and KT150's leads to me to want to bring up this fact--again. Please do NOT just roll these tubes into your tube amp without first checking with your manufacturer if they are compatible with your model. Most ( All?)of the tube amp from yesteryear are definitely NOT compatible with the KT150's...and probably the majority are not with the KT120's.
 

Big Dog RJ

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Yes, that's very true!
In fact "rolling" smaller signal tubes is rather safe compared to output tubes. Output tubes are active output devices and high voltage devices. At best they require very stable power supplies and anything lacking in the design of the mains and output transformers, will have disastrous consequences...

Always and a must do check, always consult your amplifier designer for tube compatibility, they will definitely let you know. Having said that, all the best with the quest for that ultimate output tube in push pull pentode design. Cheers, RJ
 

DaveyF

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Big Dog RJ, i agree with you...rolling in small signal tubes/driver tubes can indeed greatly change the overall character of the tube amp. It took me a considerable amount of experimentation with tube rolling to finally conclude that for my amps the NOS Telefunken ribbed plate 12AU7's were by far the most musical. I rolled in RCA Clear tops, Siemens NOS, Valvo's and a few others... all with differing results. ( and all superior to the original EH's that came stock....they come stock due to a) availability and b) price). All of the aforementioned tubes were a nice upgrade over stock, with the Tele's being the best to my ears.
 

Big Dog RJ

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G'day Maties, just wanted to share a few experiences. Had the fortunate chance to try out three different power tubes on similar amps that had no issues with the tube changes vs the transformers.

The amplifiers were not my monoblocks, rather the Classic 60se and 62se.
Both of these are designed based on the KT120 output tube, and the overall sound I preferred was with the KT120.

This I can confirm simply because the Classic 60se was the very same amp I used prior to the LP125m's!

The other tubes were as follows:
Sovtek 6550: very smooth all round sound, airy highs and lush mid-range with tuneful bass lines, easy to listen to and very enjoyable.

Tungsol KT120: the preferred tube, more grunt and power compared to the 6550's, more mid bass slam, full control in the bass and equally extended airy highs, with a very strong presence in the mid-range. Outstanding performance!

Tungsol KT150: this was more fuller, more forward sounding and definitely more heft in the bass but it was not a "balanced " sound. In fact something wasn't right, it was as if the highs, mids and bass operated at three different levels rather than be totally cohesive compared to the others. Not too good a choice but some may like this type of added fullness...

This is exactly the same phenomenon I got when I had the mv60se and replaced the original tubes with KT120's. Although the sound was fuller, it was not well balanced but I continued to use that amp with KT120's. The moment I sold it and got the Classic 60se, which is designed for KT120's, all was mighty fine! Everything fell into place very nicely, perfect match and perfect balance.

Similarly, when I first heard the ART150, that particular type of sound purely matches the kind of tube they use, which is the KT150, nothing else!

Therefore, I can clearly state that these tube types are definitely not for rolling, unless certain types of upgrades have been made on the amps itself, as is the case with my present monoblocks. The LP125's have been upgraded and although originally came fitted with 6550's, they sound superb with either tube. At present I am very pleased with the results of performance from the KT120's. Although these amps can very easily take the KT150's, I have a strong feeling of how that's going to sound...

In summary, unless I was planning on further upgrades and aiming for the ART150 or 300's, there's no point in tube rolling between KT120 & 150, they're nearly similar, with only a marginal difference but on a totally different amp, such as the ART150/300's, they're in a class of its own.

So with that said and done, for those who are trying to tube roll between the two, forget it unless you make the required upgrades. The KT120's are not too far off, and infact all three were marvelous in their own way.

Cheers and have a good one, RJ
 

DaveyF

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RJ, what amp were you hearing with the KT150's? IME, an amp that is not completely designed to run with the KT150's is going to sound like you described; although also IME one can get away with the KT120's in a design that primarily was worked up for 6550's (although still not ideal), so long as the transformers can accept the higher biasing and draw.
As you pointed out, these tubes really cannot be rolled in...and particularly so for the KT150! If you heard an amp that was not fully designed with the KT150 in mind, I would suggest you see if you can hear such an amp, it probably will change your opinion of the KT150 vs. all other power tubes!
 

Big Dog RJ

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G'day mate, how's it going...

Yes, the amp/s were actually of two brands; one was actually the CJ ART150, driving a pair of ML Ren15A's, superb! The preamp was the GATS2.

The other was actually the ARC Ref150se, only one of these units came in to the ARC dealers place and I went in for an audition, just to check out the comparisons...
Obviously I preferred the CJ but the ARC was very powerful indeed, and those KT150's did an excellent job driving the Sonus Faber Amati speakers effortlessly.

Hey Davey, I couldn't quite recall which power amp you're using now? I do remember that you had a Ref75, was that the standard or the SE version?

I also listened to the Ref75se with the KT150's and it sounded wonderful driving the SF Elipsa's, very nice open airy sound.

Currently this dealer is phasing out this particular range to take on new stock of the newly released M series monoblocks offered by ARC, along with a line up of the GS series preamps. Therefore, quite a few Ref75's, Ref150's and integrateds are up for special sale, offers on some great deals but no trade-ins.

He wants me to come in next week for a listen on the SF Aida speakers driven with a full line up of ARC ref monoblocks matched with a Ref pre and Ref CD player. Heard that I have the CLX's and thinks I should change over to ARC claiming that I should try something other than CJ... Yeah right!
I'll go for the demo in any case since I have bought my TT rig from him but I'm not ever changing my CJ amplification, hell no!

Cheers mate, I'll let you know how it goes.
RJ
 

Enoch Root

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After much research, tearing of hair and gnashing of teeth, I bought a used set of Psvane KT120 tubes for my Cary SLI-80. They were burned in for 150 hrs by Grant Fidelity and around 30 hrs by the original owner. I've put about 20 hrs on them and their biasing so far has been steady.

My previous tubes were the stock EH KT88's and I had no idea how shrill they are til now. The amp has the ability to change from 80 watt ultra linear operation to 40 watts triode (on the fly.) I had been listening almost exclusively in triode because ultra linear was too forward. Now, with the Psvane KT120, I prefer ultra linear.

They tick all the audiophile boxes; the amp's performance is better in every way.
Now if they'll just endure for a reasonable amount of time...
 

DaveyF

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RJ, I am currently enjoying the new Jadis JA30mk2 mono blocks. These amps use the KT150’s.
I am a little surprised that you thought the KT150’s in the ARC Ref 150 SE were in any way disjointed sounding? I have never heard these tubes sound that way in any gear that I have listened to that was designed with these tubes in mind.
Listening to the ARC ref amps on a SF Aida is a great way to stress the wallet to the max. Great combo! No wonder dealer wants you to come in and have a listen, lol.
 

joaovieira

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Feb 16, 2013
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My Audiopax M100 monoblocks need 6 KT88 each.
The best KT88 tubes I have ever tried was the EAT. Today I use that brand.

I compared them with:

KR KT88: those were the closest to EAT, but still not as good as it.
Gold Lion KT88: good, for the Audiopax is probably the best cost/benefit

The Audiopax are sold with the GL KT88.
 

Big Dog RJ

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RJ, I am currently enjoying the new Jadis JA30mk2 mono blocks. These amps use the KT150’s.
I am a little surprised that you thought the KT150’s in the ARC Ref 150 SE were in any way disjointed sounding? I have never heard these tubes sound that way in any gear that I have listened to that was designed with these tubes in mind.
Listening to the ARC ref amps on a SF Aida is a great way to stress the wallet to the max. Great combo! No wonder dealer wants you to come in and have a listen, lol.

Hey Davey,
OK, the Jadis is a very nice amp indeed! That must be one special sound.

No, seems like there's some confusion in my last post...
What I meant was-

1. For those trying to tube roll between 6550, KT120 & KT150, not very successful unless the required upgrades were done and the amps can handle the extra filament current required for the KT150's.

2. Replacing 6550's with KT120's may prove to be successful, provided again the amplifiers can handle the extra current required for the KT120 to operate optimally.

3. For best results, I recommend an amplifier designer around the KT150 tube, where the designer/team has based their circuits utilizing the KT150 optimally.

Which leads to my auditions of the following amplifiers:
ARC Ref75se
ARC Ref150se
ARC Ref250se (will be auditioning this Friday).
CJ ART150 / 300 monoblocks

All of the above incorporate the KT150, and all of them sound superb! Mainly because they're all designed towards the KT150 in mind and nothing else, although if a customer wanted to change over to a KT120, this is easily swapped.

In summary, I have been given the green light from CJ to try out the KT150's on my monoblocks but they warned me about the overall performance, that I won't be getting the full potential since the monoblocks I'm using were designed for 6550's or the KT120 successfully.

If I wanted to take full advantage of the KT150, then a few upgrades are required...
So with that in mind, I'm just sticking to the KT120's.

Cheers, RJ
 

bonzo75

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I have heard the CLX both with AR 250SE and CJ premier 140. I know you will do what you will eventually but I don't think they sound right with either. They need a clean SS amp, best will probably be Berning quadrature (which while being an OTL with valves is clean and fast like spectral and Soulution with valve decay but not the valve muddiness of AR) and Soulution. It is no wonder Roy Gregory uses Berning as a reference with his CLX and valin discovered the Soulution with CLX. Goldmund, spectral, boulder will all fall in this category. Gamut will be best value. The valves in the chain should go upstream with with Lampi and Allnic phono. Alternately instead of a clean sounding amp you can use a full bodied class A dense amp like Luxman m900u (best value) or pass, Vitus, etc.
 

DaveyF

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Hi RJ, yes the Jadis is a special amp, highly recommend you try and hear one of their new amps if you have an opportunity.

The Jadis JA200Mk2 got a luke warm review in Stereophile recently by a reviewer who wasn't concerned about the synergy between components, as such he basically screwed up the review with matching the amps to the Wilson Alexia's and a DAC as a preamp! Pity, as these amps deserved a much better review, and reviewer, imo.

Anyhow, thanks for clarifying your position.

BTW, Bonzo 75's suggestion of a lean and hard sounding ss amp for the CLX's isn't what i would consider. Stating that ARC are 'muddy' leads me to believe he hasn't heard ARC in some time...their amps from the last five years or so certainly aren't in any way 'muddy', IME. OTOH, if you like a lean and hard sounding presentation, then a Soulless ( er, sorry Soulution) will do the trick with those speakers.
 

Big Dog RJ

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Hi RJ, yes the Jadis is a special amp, highly recommend you try and hear one of their new amps if you have an opportunity.

The Jadis JA200Mk2 got a luke warm review in Stereophile recently by a reviewer who wasn't concerned about the synergy between components, as such he basically screwed up the review with matching the amps to the Wilson Alexia's and a DAC as a preamp! Pity, as these amps deserved a much better review, and reviewer, imo.

Anyhow, thanks for clarifying your position.

BTW, Bonzo 75's suggestion of a lean and hard sounding ss amp for the CLX's isn't what i would consider. Stating that ARC are 'muddy' leads me to believe he hasn't heard ARC in some time...their amps from the last five years or so certainly aren't in any way 'muddy', IME. OTOH, if you like a lean and hard sounding presentation, then a Soulless ( er, sorry Soulution) will do the trick with those speakers.

Nice one Mate, "Soulless"...
I've heard the Solutions and they're pretty good and dam expensive in the land of Aus. For that kind of spend, I would consider either Dan's Momemtums or Pass Labs, nothing else for my preferences.

I can certainly seems myself venture towards the CJ ART150 down the line but that is not really necessary at this stage. The LP125 monoblocks matched with the CT5 driving the CLX's is in a class of its own. I'm very passionate about stats and especially this pair and the way it portrays music, just marvelous!

I must check out your Jadis amps in the meantime, not sure if Jadis even exists in Aus...
Anyway, I'll check it out. Cheers Maties,
RJ
 

Big Dog RJ

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I have heard the CLX both with AR 250SE and CJ premier 140. I know you will do what you will eventually but I don't think they sound right with either. They need a clean SS amp, best will probably be Berning quadrature (which while being an OTL with valves is clean and fast like spectral and Soulution with valve decay but not the valve muddiness of AR) and Soulution. It is no wonder Roy Gregory uses Berning as a reference with his CLX and valin discovered the Soulution with CLX. Goldmund, spectral, boulder will all fall in this category. Gamut will be best value. The valves in the chain should go upstream with with Lampi and Allnic phono. Alternately instead of a clean sounding amp you can use a full bodied class A dense amp like Luxman m900u (best value) or pass, Vitus, etc.

Nah mate, the Luxman is just plain awful! I listened to their top of the line with nearly every ML hybrid stat before confirming on the CLX's, the Luxman was pretty much the same as Accuphase, I think they both come out of the same factory. Just didn't like the sound at all.

I can certainly understand your point on SS driving stats full range, and yes they do require the current stability. You're correct about the ARC sound, I too found it thick and sluggish, as if something heavy was moving across the room and with KT150's that sound was even heavier! Not to my liking at all.

However, mate you haven't listened to the monoblocks that I have with KT120's, or the LP275's or the top of the line ART150/300 Monos. They're in a class of their own! And they cost a fortune, over 50 grand for a pair of 300 monoblocks, hot dam!

The CJ amps you listened to are vintage, premier 140... No longer in production. These series were replaced by the series that I have referred to the LP series stands for Linear Pentode. They're extremely agile, lightening quick and far more open than the typical ARC sound. However, the new ARC sound is quite different to the former... Especially with KT150's in their new SE line up, very open, smooth and highly detailed. Not sure of how much they exactly cost now but if I'm correct, they're prices nearly the same as CJ and VTL.

Vitus Audio is another one I didn't mind but to me it was another Jeff Rowland type of SS sound. Which I didn't mind actually but still prefer the Pass Labs amps.

I'm a tube lunatic and highly passionate about tubes with stats, therefore to me this combination is the truth in sound. CJ have come a long way mate, the vintage CJ is gone... Check out either one of their Classic amps or the ART series and you'll be very surprised. All preconceived notions of tube performance will be shattered!
That is the finesse of the KT150.

Cheers and have a good one, RJ
 

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