Anyone tried the new KT120 tubes?

Has anyone tried the new KT120's, that are supposed to be a direct replacement for the 6550/KT88? These look interesting. Got a set on order.

http://www.upscaleaudio.com/products/tubes/kt88/tung-kt120.html

 

Good to know, thanks! Guess I won't be dropping em in my MC275!

 

Interesting tube. Someone with a PrimaLuna, or similar amp with adjustable bias, needs to get us a review. I guess a manufacturer may make an amp around this tube, also, given it's current requirements.

 

I'll be trying them in the Prima Luna amp I've got here as well as the Octave 130's.. Kevin Deal told me that the KT120's work great in the Prima Luna amps, so I'm anxious to hear the diff. I'll keep you posted.

 

OK, so maybe I won't give 'em a try then.

Related question, can I drop the KT88 straight into the CJ (replacing the 6550) or do you need to get any adjustments first?

 

So this means my Prologue 7 monoblocks will go from 70 WPC with the 6550s to 120 WPC with the 120s??

Might have to drop plans for a new phono stage and cart and jump on a couple quads of these.

Eric

 

Man, imagine the power they would produce from 300b tubes!

 

Unless the amplifier is built for them from the ground up, you probably won't see a huge jump in power.

 

You can use the KT88, no problem. They can be rather fragile though. If you get a good set, they sound very nice and are a better match for a C-J sonically.

You'll get the best life and performance from a set of KT90 if the output transformers can handle it. I doubt that it's a problem but I'd ask C-J about it first.

 

And when was the last time you put KT90's or KT120's in a pair of LP series CJ amps?

 

Just got off the phone with Lew Johnson. KT90 "is not recommended", and they have had bad results with the KT120. Also "not recommended" for the LP series.

That's the official word.

 

Thanks Jeff for taking the time to investigate with CJ on these -- IMO, If I had a nice pair of amps, I'd be reluctant to try them without first getting firm confirmation from either the designer of the amp or written correspondance from the company. Too much risk for such a slight gain in all probability.

Not to beat this to death -- but someone mentioned ARC is installing these (KT120's). Have you heard anything regarding that?

Bob

 

Andreas Hoffman just sent me a note and said that the KT120 will work fine in all the Octave amplifiers, but also made the comment that in order for the amplifier to put out a significant increase in power, it would have to be designed from the ground up to take full advantage of the tube.

 

Thanks for the follow up Jeff, might play with the KT88 early next year.

 

I've used these in the LP70 with excellent results:

http://grantfidelity.com/site/Shuguang_Treasure_KT88-Z

Because these have only been out for about a year or two, no one knows the ultimate lifespan yet. Not as expensive as NOS 6550's but great sound. A little more dynamic, slightly quieter and less grainy than the standard issue.

Here's the killer tube for the LP amps, but at $1600 a quad, pretty spendy....

http://www.musichallaudio.com/detail.php?p=29

The EAT KT88 Diamond will take your amps to another level, and they are claiming 10,000 hour life. When we are at CES, let's go chat with Leland at Music Hall. He might give you a quantity/show price on 16 of them if you are interested!

 

Wow, they better last 10k hours - beautiful tube. I might want to start with the Shuguang.

 

I'd follow-up myself to get the word from the horse's "mouth". The KT90 works fine in the Rogue Audio amplifiers. Of course they have large enough power transformers to handle them. C-J generally uses some pretty heavy iron, but they might have a lower power rating in your specific amp, hence my advice to ask them directly. Assuming the voltages and biasing was the same, I doubt it's an issue. C-J does tend to favor the 6550 for other reasons than power and reliability, so you need to get the real info on if the amp can handle the KT90 or not. Since the question wasn't about what flavor is preferred by any one individual or the fate of a particular lot of tubes as far as QC or shipping damage goes, rather the suitability of a particular tube for a particular amp due to the electrical characteristics, you owe it to yourself to find out. C-J amps can be hard on tubes and using a more robust tube design can help offset costs as well as provide tighter frequency response. The response is a matter of taste as it simply makes the amp more accurate. If it has the potential to saturate the transformers then that would put a damper on things. The real issue may be if your amps cover will fit over them as they are a bit taller than the KT88s that I have seen.
-Bill

 

I'm thinking these might work a bit a better in one of my vintage Sunn guitar amps...

 

Yes indeed.


-Bill

 

None of the CJ amplifiers or preamplifiers I've ever owned (and I've owned about 20 of them over the last 33 years) have ever been hard on tubes.

 

Just out of curosity more than anything else, spoke to ARC tech support and they are now installing the KT120's in their newer amps as of the 3d (or 3d week) of November. They believe the KT120 tube has better foundation, more weight, bass and more authority than the 6550's.

However, regarding their legacy amps, they have not yet tested them in those and to be on the safe side, recommend no one try as yet.

They will eventually evaluate the KT120's in the legacy products and will post their findings on their web site. As a side note, of course, the KT120 will not fit some of those legacy amps.

Bob

 

I need to call them and be sure...

But the question still remains, who has actually tried these tubes and what did you think?

 

Yep. I'm thinking of these in a Sound City 120 head. Maybe a modern tube that it won't for breakfast.