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tubed preamp off and ss amp left on?

Why can't I leave my my ss amp turned on with the tubed preamp turned off? Loud hum occurs through speakers with this condition. When I had a ss preamp I could leave the amp powered all the time with the pre off. I would leave all powered up but concerned about the preamp tubes wearing prematurely. Is it a reasonable conclusion that I could leave everything powered on all the time and just change the tubes once per year?
twc
davt's avatar
davt
500 posts
 
It might be helpful to know what equipment you have, including cables. I have a Belles 21A tube/hybrid pre with a Belles Reference 150A SS power amp and I leave my power amp on and turn off my pre and never have had a hum.
czbbcl's avatar
czbbcl
1,752 posts
 
I would not leave a tubed pre on 24/7 and only leave the amp on when you are going to be around it and in general not over night. I do on occasion leave my ss amp on overnight but as a general rule I turn it off. Having said that you should not get a loud hum when leaving the amp on with the pre-amp off. For qualifiers I have a cj tubed pre amp and cj ss amp.
jea48
4,324 posts
 

If the preamp has a mute feature, switch the preamp to mute before you shut it down. See if that helps.

Otherwise you best turn off the power amp first then shut down the preamp.
warrenh's avatar
warrenh
2,299 posts
 
I can't figure out the possible reason for your hum, but be patient. There will be a 'goner that will set you free. Fortunately (shortens my waiting time for optimum sound) my SET rig has a standby/idle feature on both the amp and the pre. The amp is good to go after the 845s have 30 minutes on them and the pre just has to wait for the amp/845s to catch up. Idle would be a nice feature on all tube pre amps and amps.
arni
313 posts
 
Hm, some say that turning tubepre off and on is what kills the tubes prematurely.... preamps differ significantly in regards to how long their tubes last, where some reportedly should be turned off, others not. Knowing what your preamp is might help with answers. My tubes have been on for a year, and going strong (ECC 82).
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