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Funny noise from Tube system

Hi everyone... I have a pair of Rogue Audio M-120 Magnum Monoblocks with the 99 magnum preamp. When I have the system on for about 1 and 1/2 hours I hear a pppppfffft...pppppfffft noise over and over. It comes out of both channels and stops when I engage the mute the sound stops. I think it's temprature related, only because when I turn on everything it is silent. I replaced the tubes in the 120's but have not replaced the 99's as of yet. I bought the equipment new in 2001. Any ideas???
Thanks,
Warren
warren11050
mcfarland
356 posts
 
I heard the same from my tubed system, but only out of one channel. I checked the tubes in the preamp, and, sure enough they were bad. I replaced them and that PFFFT sound went away. Roughly speaking my preamp tubes are good for about a year. Try changing them out if you con't have a tube tester.
reubent
3,587 posts
 
I think it's time for new tubes in the pre-amp....

TIC
elevick
2,439 posts
 
Pre-amp tubes should be good for 3000 to 10,000 hours, depending on which tubes and which amp???
reubent
3,587 posts
 
Depending on your listening habits, you could be well over 3000 hours on the pre-amp tubes since 2001. 10 hours per week for 6 years = 3120 hours of on time. 20 hours per week for 6 years is 6240 hours and 30 hours of on/listening time per week is 9360 hours over the course of 6 years.

Since the problem goes away when you place the pre-amp on mute, you know the issue is not in the amp. I think replacing the pre-amp tubes is the next logical step.

TIC
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