KT90's anyone using'em ? - Page 5

JoshK · 26th February 2010, 01:55 PM

I've seen it said numerous times that the OS EI KT-90s "killed" in triode. If those were based on the EL519 type tubes, would it follow that the EL519-types would also be glorious in triode?

I ask because the EL519-types are easier to come by and being a diy'er we are not tied to specific pinouts that the KT88 types require.

I am thinking that George's PP KT88 project idea that he has written about might be a good place for these types.

richwalters · 26th February 2010, 02:26 PM

EH KT90's are the solution. Can recommend them. I'm getting thd figures lower than all the variants of KT88's about and with an extra power bonus. I guess alot depends on the output stage match and especially the screens need to be driven fairly hard (9mA).

richy

pforeman · 27th November 2011, 03:08 PM

I have a unique stereo. Plate amps driving open baffle 15" woofers below 200Hz driven by my Moscode 600.
Tubelabs simple se in triode mode above that driving Audio Nirvana 10" open baffle.
I set up my dB meter and checked with a sterophile disc the freq response with both KT88 then my new EH KT90 (in the simple se) really no difference in output (not louder). A few frequencies were up (or down) a dB or so but mostly identicle output.
The only change was when I changed to the KT90 I upped the bias (according to my calculations about 43watts plate dissipation= no plate glow)
Tubes are still a little too young to say if I like them better or not, but this little amp shows clear differences in sound from other various tubes I've tried
Paul

rknize · 29th November 2011, 05:27 PM

I run mine at around 40+ Watts as well. They have a unique sound as triodes when biased hot.

Russ

27th November 2011, 03:08 PM	#43
pforeman diyAudio Member Join Date: Aug 2008	EHkt90 in simple se I have a unique stereo. Plate amps driving open baffle 15" woofers below 200Hz driven by my Moscode 600. Tubelabs simple se in triode mode above that driving Audio Nirvana 10" open baffle. I set up my dB meter and checked with a sterophile disc the freq response with both KT88 then my new EH KT90 (in the simple se) really no difference in output (not louder). A few frequencies were up (or down) a dB or so but mostly identicle output. The only change was when I changed to the KT90 I upped the bias (according to my calculations about 43watts plate dissipation= no plate glow) Tubes are still a little too young to say if I like them better or not, but this little amp shows clear differences in sound from other various tubes I've tried Paul

29th November 2011, 05:27 PM	#44
rknize All the best stuff comes from Chian diyAudio Member Join Date: Feb 2009 Location: Chicagoland	I run mine at around 40+ Watts as well. They have a unique sound as triodes when biased hot. Russ __________________ Russ http://www.knizefamily.net/russ/cate...ics/tubeaudio/

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26th February 2010, 01:55 PM	#41
JoshK diyAudio Member Join Date: May 2004 Location: Toronto, ON	I've seen it said numerous times that the OS EI KT-90s "killed" in triode. If those were based on the EL519 type tubes, would it follow that the EL519-types would also be glorious in triode? I ask because the EL519-types are easier to come by and being a diy'er we are not tied to specific pinouts that the KT88 types require. I am thinking that George's PP KT88 project idea that he has written about might be a good place for these types.

26th February 2010, 02:26 PM	#42
richwalters diyAudio Member Join Date: Sep 2003 Location: Alps:Tube amp designs over 150W, SMPS guru.	EH KT90's are the solution. Can recommend them. I'm getting thd figures lower than all the variants of KT88's about and with an extra power bonus. I guess alot depends on the output stage match and especially the screens need to be driven fairly hard (9mA). richy