[Bmotorcycle2003]

Can one use a KT90 tube in place of the KT88?  If so would the bias be the same?         Thanks..............Bob

[Roger A. Modjeski]

Can one use a KT90 tube in place of the KT88?  If so would the bias be the same?         Thanks..............Bob

You can use the KT-90 though I am not fond of that tube. The bias will be different but hopefully in the range of a KT-88 because that was the idea behind the 90.

[Bmotorcycle2003]

Thanks Roger, I was thinking I might get a little more power to run the Acoustat's........

[Roger A. Modjeski]

Thanks Roger, I was thinking I might get a little more power to run the Acoustat's........

Generally in properly designed power amps the power is determined by supply voltage and output transformer ratio. If the output tubes achieve saturation there is no more power to be had. In the RM-200 I have measured peak currents close to one ampere with the strongest KT-88s (the Shugangs and Genelex were the best and that's why the amp comes with them). I have not tried KT-90s in the RM-200 but there is little power gain to be had as the saturation is about 90 volts.

If there is interest I could try the new Tungsol KT-120. Readers, please let me know.

[Bmotorcycle2003]

KT120........really?  That would really be interesting.  Is that tube a plug and play?  Again Roger thanks for your input.........Bob

[Ericus Rex]

I have been wondering about that KT120.  It sure looks like a monster!

[hoppy08520]

I'd be curious to know if the KT-120 could work in my RM-9 which currently has RAM Tubes Siemens EL34 tubes, and where you'd recommend getting KT-120 tubes. I see that you're not selling them yet in Tube Audio Store.

[poseidonsvoice]

Roger,

If I were you, I would definitely recommend the KT-120's. My colleagues have been smitten with the tube, when used in an amplifier that is properly biased for it, even more than their NOS favorites. I've seen them used even as a driver to drive another KT-120 in the output stage!

Best,
Anand.

[jgb0194]

Yes, Roger, please  evaluate the KT-120 tubes in the RM200 MKII. My amp is the class A version and I'd like to know if these tubes can work in it.

John

[Roger A. Modjeski]

I had a pair here to evaluate but one of them lost its vacuum. Ill try to get another set as there is a lot of interest on this tube.

[hoppy08520]

I had a pair here to evaluate but one of them lost its vacuum. Ill try to get another set as there is a lot of interest on this tube.

Thanks Roger. I hope that you can also evaluate the KT-120 for the RM-9. I've been wanting to sample KT88s but if you are able to bless the KT-120 for this amp, then I'd be eager to try the KT-120.

[Roger A. Modjeski]

I see Bob Carver has some mono amps using the KT-120. The description reads a lot like what I have been doing in the RM-200. Has anyone any experience with these amps?

[Bmotorcycle2003]

Roger, ......... What is the worse that would/could happen if I plugged 4 KT120's, thanks..................Bob

[escultor]

I see Bob Carver has some mono amps using the KT-120. The description reads a lot like what I have been doing in the RM-200. Has anyone any experience with these amps?

   I own a pair of those, I have no complain they sound very good, you can play with bias and feedback and they
   go from very  soft tube sound to SS like sound depending on the settings.
   They run the tubes very cold ( you can touch them with your hands )
   They are very much silent on my 100db speakers.... very powerfull animals

[Roger A. Modjeski]

I'd be curious to know if the KT-120 could work in my RM-9 which currently has RAM Tubes Siemens EL34 tubes, and where you'd recommend getting KT-120 tubes. I see that you're not selling them yet in Tube Audio Store.

You can use 4 KT-120s in the RM-9. Just fill the front row and leave the back empty. Adjust the bias as usual. The amp will actually run a bit cooler and sound great. I have one RM-9 owner doing this now and loves it.

So far I have put KT-120s in several RM-200 amps with no problems. If you decide to raise the bias over the 40 mA just keep an eye (hand) over the power transformer to see that it doesn't get too hot.

The tubes have been on my tube store for half a year at least.  http://tubeaudiostore.com/tungsolkt120.html

I test them in large lots and can make very tight quads and pairs.