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New tubes in Rogue M-180 Monoblocks

I understand the M-180s now ship with the KT-120 power tubes, instead of the KT-80. You can also simply replace the KT-80 with the KT-120 if you already own these amps. I'm curious whether anyone has done it and what their impressions are as far as the difference in sound. Is the over $300 upgrade worth it?
actusreus
shakeydeal
979 posts
 
I think you took a wrong turn somewhere.......
nr9
35 posts
 
I have a pair original 1 year old Rouge M-180 which I will try KT120. This amp was delivered from Rouge with KT90.

The issue is that there is a red capacitor seen in the tube hole. Shall I force the KT120 tubes down? I think I can do this, but the cap will be in touch with the tube socket. Are the amps delivered from Rouge with KT120 the same way?

Best NR9
roscoeiii's avatar
roscoeiii
1,155 posts
 
On the issue of the recommended bias for KT120s, in the Stereo 90, the bias meters are off by 5mA (as stated in the manual), so to bias to Rogue's recommended 40mA, the meter should read 35mA.
actusreus OP
733 posts
 
Roscoe,
I'm not sure what's going on with your amp, but Mark was perfectly clear that you should bias the KT-120s at 40 mA in the M-180 monoblocks, and that's what the meter should read. The M-180 manual says nothing about the meter being off, which frankly does not make sense.
roscoeiii's avatar
roscoeiii
1,155 posts
 
As I mentioned, the bias meter on the Stereo 90 reads 5mA low. As is stated in the Stereo 90 manual. I don't know about the other Rogue models. But for the Stereo 90, when the meter reads 35mA, the actual value is 40mA. And an actual value of 40mA is also what I was recommended by Rogue.

Other people with KT120 tubes have recommended a higher bias than this.
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