Thinking about trying KT120 tubes

[JD0x0]

Will a 400mA 100 watt power transformer be able to handle the new KT120 tubes? I can't seem to find the official specs.

This will be in a Dstyle amp with 3 12AX7's. Im pretty sure the heater amperage on the trasformer is 8A

[David Root]

You will need to put +500V on the plates of a pair to get 100W. If your PT is rated 400mA @ 500VDC or better you should be OK. The 8A heater winding w/3-12AX7 is fine. Figure 2A each KT120 to be safe.

I'm curious about these too, and there is another thread on the KT120. The specs are on it.

If you want a solid 100W from a pair of tubes without 600 Vp or a real high gain PI try the 8417, but only Sylvania, not GE. 8417s are very high Gm for a power tube, but they have a tendency to go into thermal runaway, especially GEs.

I have a pair of JAN Sylvanias that produce a real 100W super clean/warm at ~520 Vp.

[ToneMerc]

http://www.newsensor.com/releases/KT120TungSol.pdf

[JD0x0]

thanks my PT is 700V/400mA that should be okay right?

[David Root]

I think so! A pair of KT 120 should not stress that at all at 100W.
Assuming they can actually handle 700 Vp, I think you would get 120W no problem, unless the KT120 specs are BS.

[ToneMerc]

thanks my PT is 700V/400mA that should be okay right?

Personally, sometimes I cherish being the odd man out and have thought about these. However, if I was going to run them, I would put at least 525-550 volts on the plates and that of course would certainly turn the amp into a one trick pony, not to mention only one source to feed it. Besides, I've never really heard anyone say enough good things about it in a guitar amp application to make me jump. When I think about, much of that may be because I bet most aren't running the tube in a circuit designed to take the best advantage of it either.

Yes you can use it, but "okay" is relative.

TM

[breakfastbuddy]

with these tubes you have to make something like this
engl savage 2xkt 88 (6550)
youtube

http://www.youtube.com/watch?v=UsjvveWOJ3Y

[Andy Le Blanc]

I've used KT90, I don't like the tone of the higher plate voltage, maybe for audio
but not for guitar. they sound good at regular fender voltages and with the
high plate dissipation allowing you to ramp up the static idle.
I suspect the KT120 will be not much different. One loud rugged tube.

The last one with KT90 was marshal opt purposely mismatched up, the get a
lower DCR and match the plate load on the sheet, floating paraphase inverter.
I used a twin PT, the thing sounded very good with the plate dissipation
allowed by the tube, plenty of nutz for two tubes.
Pushing current is a different tone than pushing voltage, more the right kind of color.
Not the the harsh volume you get with high plate voltage, the natural distortion seemed much sweeter.

[JD0x0]

savage enough for you guys?

[IMG768]http://i89.photobucket.com/albums/k201/ ... 01-1-1.jpg[/img]
I actually swapped the choke to a larger better quality one.

I want the power amp to pretty much have as much clean room as possible since this will be an ODS type amp and i use the preamp OD
This was originally going to be a KT88/90 build but tose KT120's interest me too much to pass by

[Sonny ReVerb]

savage enough for you guys?

Better put wheels on that thing. Ouch, my back hurts just looking at it.

[breakfastbuddy]

so what are your B+ voltage and schem on this one ?
i have a 5k ot and 2x kt 90 tubes , i think the B+ will have to be 707vdc to get 100w . or i can missmatch the ot and use 500 vdc to get the same result . but i will also use the preamp distortion so will be good anyway .