Home » Audio » Thermionic Emissions » KT120 and KT150 tubes not up to spec
KT120 and KT150 tubes not up to spec [message #84517] Wed, 08 February 2017 15:27 Go to next message
gofar99  is currently offline gofar99
Messages: 1068
Registered: May 2010
Location: Southern Arizona
Illuminati (2nd Degree)
Hi everyone one of my worst fears (others no doubt share it) seems to be happening. Tungsol KT120s are red plating well below their rated dissipation. Seems like at 60-70%. Not good for class A amps. KT150s are being received that are just plain defective. A UK licensee of some of my designs has reported the problems starting about 4 months ago and now it is a thread on diyaudio.com (see the link).

http://www.diyaudio.com/forums/tubes-valves/303273-anyone-out-there-kt150.html#post4975833

My suggestion is that if you get any tubes that red plate or just don't seem right...send them back until you get good ones. Maybe the suppliers will get the word and not accept seconds from the factory and QC will improve. There is always hope.


Good Listening
Bruce
Re: KT120 and KT150 tubes not up to spec [message #84530 is a reply to message #84517 ] Thu, 09 February 2017 09:38 Go to previous messageGo to next message
Wayne Parham  is currently offline Wayne Parham
Messages: 16836
Registered: May 2009
Illuminati (33rd Degree)

I hate this, Bruce. But I feared it might happen too.

I think it's a two-fold problem. One problem is the materials needed. Some aren't as readily available, and are expensive. So I would expect the temptation to substitute for cheaper materials might come into play. And a second problem is modern tube manufacturers aren't as likely to even try to be as concerned with quality as they were decades earlier. Their market is smaller, and I think the companies themselves are smaller. I have a hunch they feel less "visible" and more likely to cut corners.

Tube loving audiophiles will naturally suggest NOS tubes. That's awesome where you can find them. But new equipment manufacturers need to be able to find consistent quality new production tubes. So I'm with you on this: I hope the current tube manufacturers understand that they are visible, and that their products are used by sophisticated customers. They can't slack on quality without losing their place in the market.

Re: KT120 and KT150 tubes not up to spec [message #84561 is a reply to message #84530 ] Sat, 11 February 2017 16:47 Go to previous message
gofar99  is currently offline gofar99
Messages: 1068
Registered: May 2010
Location: Southern Arizona
Illuminati (2nd Degree)
Hi, I got confirmation from a Rogue Audio dealer that they have run into the problem as well.


Good Listening
Bruce
Previous Topic:Amp for bass guitars
Goto Forum:
  


Current Time: Fri Feb 24 04:26:51 CST 2017

Sponsoring Organizations

AudioKinesis
AudioKinesis
BOI Audioworks
BOI Audioworks
BuildAnAmp.com
BuildAnAmp.com
Crescendo Systems
Crescendo Systems
DIY Audio Projects
DIY Audio Projects
OddWatt Audio
OddWatt Audio
Pi Speakers
Pi Speakers
Prosound Shootout
Prosound Shootout
Smith & Larson Audio
Smith & Larson Audio
Lone Star Audiofest