[Keoma]

Dear all: I am new to the world of tubes, having recently purchased a Prima Luna DiaLogue One (and loving it), which I outfitted with Gold Lion's KT88's in place of the standard EL-34's to give my speakers (Sonus faber Toy Towers) that little extra tightness, control and dynamic punch (even though I do miss some of the EL-34's warmth and velvety glow).

Recently, I have been reading a lot about the new KT-120 tube, and supposedly they would work fine in my Prima Luna (the new Dialogue Premium amp will even come outfitted with them, as an option). Could you well-versed and more experienced folks give me a little bit of info and background about this particular type of tube? How would you compare it to a KT-88? Has anybody used them in their own system? Feedback and opinions would be greatly appreciated. Thank you!

[decal]

I tried the TungSol KT-120 in my Rogue Audio Tempest II Magnum for about a month. I found them too strident in my system. The Gold Lion trumped them in every way. Remember, this is what I heard in my system, you may find them perfectly acceptable in yours. Tubes are a very personal subject, you really need to try them in your system and decide for yourself. 

[rpf]

I tried the TungSol KT-120 in my Rogue Audio Tempest II Magnum for about a month. I found them too strident in my system. The Gold Lion trumped them in every way. Remember, this is what I heard in my system, you may find them perfectly acceptable in yours. Tubes are a very personal subject, you really need to try them in your system and decide for yourself.

Tubes are indeed very personal: they can produce highly varying sounds. And small signal tubes (pre-amp, drivers and phase splitters) can alter the sound substantially also.

That said, I find the KT120s to be the best match for my Rogue Cronus Magnum. IMS they have a good frequency balance, are resolving and holographic. I compared them in the Cronus with the Penta  KT88SC and the KT120s were uniformly better. I haven't heard the Gold Lion in the Cronus but did hear them in my system with a VAC 100/100 where they sounded excellent. That may have had as much, or more, to do with the amp as with the tubes however, as VAC amps are the only ones I've heard that sound linear with KT88s. Every other amp I've heard KT88s in (around a dozen) sounded bass heavy.

The KT120s, given their additional power capability will certainly be more dynamic.

[Mike D]

I have them in my Rogue M150 monos running the mid and treble sides of my Maggie IIIAs.

They basically have more of everything due to the increase in wattage.  I like them for my system (very inefficient) because they helped fill out the frequency extremes and the all important midrange.  The IIIAs need all the help they can get to fill up the low midrange coming out of the mid panels.  Most of the low midrange was coming from high end of the bass panels before I got the 120s and was able to adjust the crossover point at bit lower for the mid panels. 

[Keoma]

Thanks all for the feedback. But would there be any safety/long-term reliability issues if one drops them into a circuit that was not originally designed for them? I have heard conflicting opinions on the subject and, from what I understand, there are no amps in the market (yet) that offer this tube as a factory option...

[decal]

Thanks all for the feedback. But would there be any safety/long-term reliability issues if one drops them into a circuit that was not originally designed for them? I have heard conflicting opinions on the subject and, from what I understand, there are no amps in the market (yet) that offer this tube as a factory option...

You should really ask the manufacturer of your equipment if you want to get the correct answer to that question.

[h00hbt]

KT120 draws 100-300 mA more filament current than a standard 6550/KT88, check with your amp manufacturer to ensure you can use them.

/H

[h00hbt]

there are no amps in the market (yet) that offer this tube as a factory option...

http://www.kraudio.com/index.php?option=com_content&view=article&id=59%3Ava900&catid=3&Itemid=6&lang=en

[sunnydaze]

Check with Kevin Deal at Upscale Audio to see if the 120's will work in your PrimaLuna.  He is a major tube guru, and big time PrimaLuna dealer.

[sunnydaze]

........from what I understand, there are no amps in the market (yet) that offer this tube as a factory option...

I believe that Rogue now offers them as an option w the Magnum upgrade pkg.

[Keoma]

I got the chance to speak to the nice folks at Upscale Audio, and their answer was a definitive "no". They explained that the Prima Luna's amp section would be stressed and taxed when using KT120 tubes, so they advised against them. They would work, and some users actually reported good results with them, but prolonged use could become an issue, so I am not willing to go down that route. Can't wait to read more about how the new DiaLogue Premium model will sound with these tubes.

[JoshK]

Even though the pins fit doesn't mean you should sub them in.  Each tube has its own sweet spot in terms of where it operates.  If you don't know the circuit to determine the op points, how much the transformers (esp the heater ratings) can take.   Unless you know or have a tech you trust, its not a good idea to sub willy nilly.

[bunky]

Thanks all for the feedback. But would there be any safety/long-term reliability issues if one drops them into a circuit that was not originally designed for them? I have heard conflicting opinions on the subject and, from what I understand, there are no amps in the market (yet) that offer this tube as a factory option...

Audio Research offers four amplifiers designed around the KT120. the  VSi 60 = KT120 X 4 the VS115 = KT120 x 8 and Reference 150 = KT120 x 8 these all are Stereo Amplifier's and the Reference 250= KT120 x 6 as power tubes and KT120 x 2 as drivers the REF 250 is a Monoblock.

[Vapor Audio]

You can get the MingDa MD-75 from Pacific Valve with Tung Sol KT-120's.  I reviewed it for Stereomojo with the 6CA7's and it's a phenominal amp, even more so considering price. 

http://www.pacificvalve.us/MingDaMD75.html