Test results and observations on this new tube offering.
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The heater current mentioned? Not really an issue for any modern amp. A KT88 is around 1.6amps and this KT150 is noted at 2.0amps maximum and 1.75amps minimum. An EL34 is 1.5A as a sidenote.
https://d1sjrnpi226dnf.cloudfront.net/spree/attached_files/ts-kt150.pdf?1390421029 - the published design and performance specs.
For those that wish to compare so other power tube data sheets of some tubes these are intended to replace:
Here is the promotional stuff from my friends at Tube Depot:
These tubes look as if a burn in would improve initial stability.
When I came back from lunch and pistol shooting (shotgun shooting this morning as a side note) the duet of KT-150 tubes were still running. They have drifted and burn in is worthwhile... very worthwhile. If you use these in any amp recheck bias after the first hour, at five hours as well. I am still seeking stability. Running out again but will up the wattage demand and continue testing. There are now 10 hours of run time on the duet and three of those hours have been running at 50+ watts per duet, far below rated output but the first step in operational testing.
Date Time Average Peak
2014:02:07 09:11:07.71 49.44 51.27
2014:02:07 09:11:08.07 50.16 51.32
2014:02:07 09:11:08.11 49.02 51.32
2014:02:07 09:11:08.71 50.97 51.71
2014:02:07 09:11:09.31 50.09 52.96
2014:02:07 09:11:09.41 51.36 52.96
2014:02:07 09:11:09.51 49.31 52.96
2014:02:07 09:11:09.61 47.72 52.96
2014:02:07 09:11:09.71 60.03 60.04
2014:02:07 09:11:11.11 47.39 57.76
2014:02:07 09:11:14.89 46.76 57.76
2014:02:07 09:11:14.99 45.84 47.49
2014:02:07 09:11:15.09 45.36 48.68
Keep in mind this tube has a 70 watt max plate design spec. Then again, an EL34 has a 25 watt max plate spec yet four of them in some amps produce 140 to 170 watts without issue. The claim of 300 watts for a duet of these KT-150s is an interesting claim. We will see.
Side note - I have seen over 120 watts produced reliably by a duet of KT88SV tubes often.
2/7/14 - Duet #3 still running. No issues. Raising the power. 575/550 plate and screen voltage.
80+ watts is the maximum design rating (70 plate + 9 screen watts). I will run this duet for a long period or until one of the duet fail.
Factors to consider on first tubes tested which failed:
These are large tubes and large tubes are less durable physically. They don't like to travel and do not do as well in transport or shipment. Grid wires slip their posts and there are other things that can happen. The KT66 sees these issues quite often, another large tube. The tubes were pack as matched duets and the first duet may have been dropped while being packed for shipment perhaps. The second duet currently under test are performing properly at this point.
Side note from one of the best amp techs and designers in the business, Blackie Pagano:
hey myles, for grins i knocked together a kt-150 SE in a client supplied fender chassis a month or so ago. biased it all the way up to rated dissipation and it was stable and made 20 watts at clipping! nice, classic SE waveform, clipping softly into 2nd harmonic distortion. sounded great and very ballsy but...became quite microphonic shortly. too microphonic for combo use...boo. i sent it back.
If you want to contact Blackie you can find him at: