KT-150 ???

RE: KT-150 ???, posted on April 6, 2017 at 09:38:29
hifipaul Audiophile Posts: 735 Location: NY Joined: December 22, 2008	Has anyone actually listened to the KT 150???

RE: KT-150 ???, posted on June 29, 2017 at 09:13:34
jhrlrd Audiophile Posts: 135 Joined: October 21, 2014	I love the KT-150s in my Jolida integrated. It was previously very flabby in the bass/lower mid with EL34s. There is a switch allowing various tubes. The 150s turned it into a much tighter presentation when you crank it up, but also didn't lose any of the midrange sweetness of the EL34s. Haven't tried KT-120s though.

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

DAK
Audiophile

Posts: 2712
Location: PACIFIC
Joined: August 8, 2010

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 17, 2017 at 23:51:37
Daverz Audiophile Posts: 2104 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 22, 2017 at 07:20:00

Mendel
Audiophile

Posts: 1207
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.

RE: KT-150 ???, posted on March 27, 2017 at 09:38:36
Daverz Audiophile Posts: 2104 Location: So. California Joined: September 24, 2002	Thanks for you comments. The 90 uses 6SN7s, right? Not sure how this would effect comparisons with the M 180s.

RE: KT-150 ???, posted on March 27, 2017 at 10:38:47

Mendel
Audiophile

Posts: 1207
Location: GTA
Joined: January 17, 2009

Yes 6SN7 for drivers. I much prefer these to 12au7, more linear, more current, more variety in types.
My Stereo 90 began life as a Stereo 88 which had 12au7 for drivers. I rolled many different types but they all sounded mostly the same to me. Sent the amp back to Rogue for upgrade to Stereo 90 Magnum and was surprised by how much the choice of 6SN7 could alter the sound. I think Rogue took a step backwards when they went back to 12au7 for drivers.
The M-180s are gorgeous amps (I could really use the extra power!). Given the power they produce, unless you are running very difficult to drive speakers you could probably give up a little power to try another output tube.

RE: KT-150 ???, posted on March 25, 2017 at 11:04:37
tullman Audiophile Posts: 208 Joined: August 15, 2002	I use KT120's in my Convergent Audio Technology JL1 mono's. The amps were upgraded to receive KT 120's by Ken Stevens. Ken feels KT120's sound best in his amps and I can't argue. I have have used KT88, 6550's and the KT 120's are by far the best.

RE: KT-150 ???, posted on March 18, 2017 at 01:55:23
Nunki Audiophile Posts: 644 Joined: November 27, 2010	don

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

Daverz
Audiophile

Posts: 2104
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.

http://www.thetubestore.com/Tubes/KT88-Tube-Types/Preferred-

RE: KT-150 ???, posted on March 15, 2017 at 19:21:49
hahax@verizon.net Audiophile Posts: 4310 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: 11287
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: 644 Joined: November 27, 2010	higher output? why? where should it come from when anode voltage remains the same? N.

Plate dissipation., posted on March 16, 2017 at 15:55:24
Chip647 Audiophile Posts: 2652 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: 644 Joined: November 27, 2010	hmm...very strange...fixed bias plus constant anode voltage means constant output power! right? or does not? N.

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

PakProtector
Audiophile

Posts: 12366
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.

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

TubeAcolyte
Dealer

Posts: 366
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: 613
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

Tubes Asylum

KT-150 ???

67.243.15.148