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Oh the Joy

NOSValves

NOSValves

Super Member
One of the Joy's of being in the biz...manufacturers allow you to squeeze them for free tubes and other components for evaluation :thmbsp: Too early to form an opinion just got a chance to get them hot... my NBS prototype preamp is on the bench for some tweaking so it maybe a few days before I comment about Sonics. Without it in my system my sonic evaluation would be flawed at this time. Electrically they seem to work fine. I really question the raised heater voltage specification since it does not cause a bit of voltage drop on my heater circuit. The KT-120 didn't either... The plate structure of this KT-150 tube is visually dead nuts identical to the KT-120 just taller and KT-120 plate structure is identical to the Tung-sol reissue 6550 just taller. I suppose the KT-200 will most likely be a bit taller than the KT-150.....and so on ;)

Cheers Craig
 

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I built a SET amp years ago with a 811-30. I asked Svetlana if the 572-30 would sound different. They said a few samples would be sent for my evaluation. They sent a case of 24 tubes!
 
Looking forward to the evaluation,
Got some KT120's cryo-d a couple of weeks ago, made the difference
 
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Beautiful amps... I love attractive gear. That's part of the fun IMO.

Those preamp tubes in the front are tiny... They look like they'd get dwarfed by a pair of 12ax7's.
 
sony6060 said:
I built a SET amp years ago with a 811-30. I asked Svetlana if the 572-30 would sound different. They said a few samples would be sent for my evaluation. They sent a case of 24 tubes!
Click to expand...

Awesome, How long ago was this? Where are all those tubes now?
 
So far I have been burning them about as hard as I can without putting undo stress on my NOS Mullard 5AR4's... I've had them at about 42 watts of plate dissipation and they have held rock stable overnight. Not a huge thing...I've done the same thing with Valve Art KT-100, Penta KT-88SC. Tung-sol KT-120 and the few more that escape me at this time for prolonged periods without issue.

Later I will pop some SS rectifiers in my amps and really push these babies. I suspect they will be very much a basic beefed up KT-88/6550. Nice but nothing revolutionary.
 
Well popped in some SS plug in rectifiers to save my Mullard 5AR4's and pumped them up to 100ma @ 515V on the plates and screens for 51.5 watts of plate dissipation. I'm sorry to report that two of the plates were starting to glow from the red plate syndrome. No way can these samples live up to the published spec of 70 watts of plate dissipation. Maybe after some production time that will improve but I think I'd have a hard time running them at much more then about 45 watt dissipation.
 
Including heater dissipation you're at a hair over 64 watts. Not 70, but not terrible.
 
Anyone run some plate curves and/or distortion spectra measurements on these, compared to KT120s and KT88s?

I'd love to see a back-to-back comparison of KT88s, KT90s, KT120s and KT150s in terms of distortion and linearity. That, more than dissipation, would tell the tale of which is the better tube, IMHO...

Regards,
Gordon.
 
jjones3 said:
Including heater dissipation you're at a hair over 64 watts. Not 70, but not terrible.
Click to expand...

Is your heater comment a typo? You do not combine any other disipation rating with the plate disipation to reach the maximum. The Screen is most likely what you are referring too?, the screen has an entirely dedicated disipation rating on these tubes and in this case its 9 watts. So the tube should reach 79 watts combined total. I'm about 99% sure this tube is using the identical plate to the KT-120 and 6550 reissue and I guess New Sensor does not realize to get where they are sayingn they accomplished it would take not just a taller plate but the thicker plate.
The real kicker is the original NOS Tung-sol 6550 can take just as much of a beating before red plating as this KT-150 in the very same amplifier!

Craig
 
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GordonW said:
Anyone run some plate curves and/or distortion spectra measurements on these, compared to KT120s and KT88s?

I'd love to see a back-to-back comparison of KT88s, KT90s, KT120s and KT150s in terms of distortion and linearity. That, more than dissipation, would tell the tale of which is the better tube, IMHO...

Regards,
Gordon.
Click to expand...

Gordon,

If you have any faith in New Sensor they have plate curves and distortion numbers on the published tube data they released. I'll be doing a distortion comparison when I have time over the winter. I will say they sound really friggen good in my amplifiers. So did the KT-120's and even the reissue 6550. Problem with the 6550 is you better stay under 450V on the plates and even then it is NOT a long lived tube like the original. Making the plates taller helps but it is just not going to get them to the pinnacle New Sensor is stating they have reached.

Craig
 
jaymanaa said:
Gosh that's a goofy looking tube, and chance they were made by "Wang"? Yikes!
Click to expand...

I think the tube is flat out cool looking! It is also in the grand scheme of things used in a KT-88 electrical enviorment is one tough MFer...After running the KT-120's for a few weeks about a year ago I would not dare do what I did to this tube.....I ran the KT-120 at 70mA 500 on the plates and after a year they show signs of instabilty and reduced test scores which is not a good sign for longevity even in 60 WPC a KT-88 amplifier. Basically the KT-120 can be equalled by many modern KT-88's on market today in respect to longevity. The thing is the KT-120 sounds great and has a reasonable cost versus performance which to me equals value. And it is not made in China which to me is important!!!

Craig
 
NOSValves said:
Is your heater comment a typo? You do not combine any other disipation rating with the plate disipation to reach the maximum.
Click to expand...

I do. The heater at max characteristics in the KT150 will dissipate 12.6 watts. That heat has to go somewhere, and a large amount of it will radiate to the plate and add to the plate's thermal load, which it then needs to dissipate.

Ultimately we should calculate it the same way the mfg does, but I've never seen a mfg disclose their method.

In the absence of that information, I take the plate max dissipation to mean just that, from any sources that contribute. When add all the dissipations that contribute to the plate's thermal load, things start lining up with the datasheet specs rather nicely.
 
jjones3 said:
I do. The heater at max characteristics in the KT150 will dissipate 12.6 watts. That heat has to go somewhere, and a large amount of it will radiate to the plate and add to the plate's thermal load, which it then needs to dissipate.

Ultimately we should calculate it the same way the mfg does, but I've never seen a mfg disclose their method.

In the absence of that information, I take the plate max dissipation to mean just that, from any sources that contribute. When add all the dissipations that contribute to the plate's thermal load, things start lining up with the datasheet specs rather nicely.
Click to expand...

I'd suggest you read tube spec's a bit better... they give the maximum for each element (plate, screen and so on) for a reason. you do not combine them although you also should not run them all at maximum either. But I'm well short of maximum. Look for instance at the complete specification sheet and recommended operating criteria for the MOV KT-88 or the Tung-sol 6550 or the GE 6550/6550A...

This isn't rocket science stuff. I should be able to bias these KT-150 way more then a 100mA at 510V on the plates... heck I can do it to an original Tung-sol 6550 without issue..been there done it. Heck I own 30 of them and could pull them out and do it right now...Will they last 20 years like that...nope but they sure were not red plating. Heck the lowly Chinese made Valve Art KT-100 could do it without issue, too bad they quit making that tube.
 
NOSValves said:
Is your heater comment a typo? You do not combine any other disipation rating with the plate disipation to reach the maximum. The Screen is most likely what you are referring too?, the screen has an entirely dedicated disipation rating on these tubes and in this case its 9 watts. So the tube should reach 79 watts combined total. I'm about 99% sure this tube is using the identical plate to the KT-120 and 6550 reissue and I guess New Sensor does not realize to get where they are sayingn they accomplished it would take not just a taller plate but the thicker plate.
The real kicker is the original NOS Tung-sol 6550 can take just as much of a beating before red plating as this KT-150 in the very same amplifier!

Craig
Click to expand...

Very interesting, but I'm not too surprised.
 
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