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KT-150 ???

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Posted on March 15, 2017 at 17:26:47
hifipaul
Audiophile

Posts: 671
Location: NY
Joined: December 22, 2008

Does anyone have experience with the TS KT-150. How does it sound?? does it work well in triode? Is it really better than old stock GEC KT-88s ?

 

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RE: KT-150 ???, posted on March 15, 2017 at 19:21:49
hahax@verizon.net
Audiophile

Posts: 3033
Location: New Jersey
Joined: March 22, 2006
I've spoken with a noted tube amp designer manufacturer about both the KT-150 and the KT-120 and he will not use either tube calling them inferior in linearity to the KT-88. He doesn't feel the extra output is worth the loss of linearity.

 

RE: KT-150 ???, posted on March 16, 2017 at 09:02:40
airtime
Audiophile

Posts: 8575
Location: Arizona
Joined: February 4, 2003
I know this is a limited and uninformed statement since I had only tried one KT-120 amp. But wow, I didn't care for the sound of that tube!

Again this is only my limited experience but I prefer the KT-88s over those tubes.

 

RE: KT-150 ???, posted on March 16, 2017 at 11:22:06
Nunki
Audiophile

Posts: 324
Joined: November 27, 2010
higher output? why? where should it come from when anode voltage remains the same?

N.



"How the fuck did our oil come under their sand?"

 

Plate dissipation., posted on March 16, 2017 at 15:55:24
Chip647
Audiophile

Posts: 1653
Location: The South
Joined: December 24, 2012
If the amp has fixed bias, an overrated power supply and output transformers that can handle the extra output wattage, then the tubes could produce higher output. (Not likely unless homebuilt)

 

RE: Plate dissipation., posted on March 17, 2017 at 01:12:47
Nunki
Audiophile

Posts: 324
Joined: November 27, 2010
hmm...very strange...fixed bias plus constant anode voltage means constant output power! right?
or does not?

N.



"How the fuck did our oil come under their sand?"

 

RE: Plate dissipation., posted on March 17, 2017 at 12:44:56
TubeAcolyte
Dealer

Posts: 314
Location: Ottawa, ON
Joined: December 13, 2009
Hmm, not quite. Bias voltage is one thing, actual current is another. Forget the KT120 or KT150 for the moment, and suppose you're installing a new fresh set of tubes, same model and make. A given bias voltage will not produce (or restrict, rather) the current in an equal fashion between the two sets of tubes. One set might have a higher current output (closer to an open circuit). For the same reasons, this is why one would adjust the bias as tubes age. As the use builds up, they lose life in the form of current output (and I think transconductance as a result), so you have raise your bias voltage (bring up the negative value closer to zero), to restore the output level. Of course, there's a point where this cannot be done anymore (limitation of bias circuit), and a new set of tubes is necessary. And, working from that point where you've adjusted the bias for older tubes, when installing a fresh set, you want to apply more negative bias to restrict the current to prevent an overload condition.
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
May your tubes be lively, warm, and long-lasting. Holy be thy heater.

 

RE: Plate dissipation., posted on March 17, 2017 at 23:30:54
JKT
Audiophile

Posts: 459
Location: Midwest
Joined: November 26, 2002
"Of course, there's a point where this cannot be done anymore (limitation of bias circuit), and a new set of tubes is necessary"

By this time the space charge around the cathode will be depleted to the point where the tube is in serious danger of arcing. One of the challenges of trying to suck the last once of life from a set of output tubes. I know from experience. ;~)


"It is better to remain silent and thought a fool, then speak and remove all doubt." A. Lincoln

 

RE: KT-150 ???, posted on March 17, 2017 at 23:51:37
Daverz
Audiophile

Posts: 1660
Location: So. California
Joined: September 24, 2002
I've been using KT-120s in my Rogue M-180s. Definitely better than the KT-90s that it came with. They last about 2 years before starting to sound dull. So I've been considering replacing them with KT-150s. At least one of the inmates seems to swear by them.

But now I'm curious about "downgrading" to KT-88s or other compatible power tubes. Has anyone tried this in the M-180s?

 

RE: KT-150 ???, posted on March 18, 2017 at 01:55:23
Nunki
Audiophile

Posts: 324
Joined: November 27, 2010
don
"How the fuck did our oil come under their sand?"

 

RE: KT-150 ???, posted on March 18, 2017 at 21:00:03
Daverz
Audiophile

Posts: 1660
Location: So. California
Joined: September 24, 2002
Thanks. The tube store seems to have these under the name "Preferred Series". I'll keep them in mind when I have the cash for the 8 power tubes.

 

RE: Plate dissipation., posted on March 20, 2017 at 04:18:06
PakProtector
Audiophile

Posts: 11272
Joined: May 14, 2002
To your question, look at the maximum possible voltage output across the load is. Ideally, for PP it is 2X that of B+. Not quite going to happen; can't get maximum load current at zero plate volts, yes? As the load goes from a-a/2 while both are conduction to a-a/4 when only one is, you are effectively looking at a bridged pair of SE amps...:)
cheers,
Douglas

Friend, I would not hurt thee for the world...but thou art standing where I am about to shoot.

 

I use kt120 in SEP mode w/fixed bias, posted on March 21, 2017 at 20:43:55
DAK
Audiophile

Posts: 1757
Location: PACIFIC
Joined: August 8, 2010
Contributor
  Since:
December 0, 0000
It sounds very good to me. I tried under the same plate voltages kt120, kt90 and kt88. I simply adjust the fixed bias to obtain 120ma or 100ma or 75ma with each respective power tube. The sound is excellent with each but the kt88 has a little more refinement, which what is what you would expect with the smaller plate structure. But you can really notice the power from the kt120. I could use kt150 by going to SSR which would bump out the B+ an extra 5% but I am not willing to risk my caps with the unfettered voltage surge.

 

RE: KT-150 ???, posted on March 22, 2017 at 07:20:00
Mendel
Audiophile

Posts: 958
Location: GTA
Joined: January 17, 2009
I don't have the M-180s but the Stereo 90. A very similar amp. I have tried many different power tubes in the amp including the Tung Sol KT120s. I do not care for the KT120 in my Rogue. I think the Preferred Series KT88 (I have the PentaLabs KT88SC which supposedly the same tube) is a much better sounding tube. So are the EI KT90 and the Gold Lion KT66. Probably the GL KT88 as well.
You would not be "downgrading" going to these tubes. Can't believe the Tung Sol KT120 is standard with all Rogue amps these days.

 

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