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Acceptable level of hum at max volume?

so i am noticing a faint hum when i set my amp to full volume. not sure if it's been there all along but i was tinkering around and noticed it. here is my setup: rega p3-24 w/ttpsu and herbie mat into jolida jd 9 into decware mini torii. if i switch the mini torii to the second input via the switch i get no hum, but when i switch back to the phono i can hear it. mind you this is at FULL VOLUME. my question is, is there an acceptable level of hum at these outrageous volumes. it's not present in the music at normal or even loud listening levels it's just something i noticed while dickering around. i've tried all the usual solutions to eliminating hum like cheater plugs and moving components and swapping cables. i even have a line conditioner. what say you enthusiasts?
roggae
Post removed 
tketcham
291 posts
 
Roggae, you might check to see if you can lower the gain on the JD9 and still have enough signal strength feeding your integrated amp. I don't know which cartridge you're using or which outputs on the JD9 you have connected but if you use the high ("HI") output and the lowest gain setting ("MM") it should have the least amount of signal noise, which might reduce the hum you're hearing.

Regards,
Tom
bpoletti
1,546 posts
 
Why are you listening at max volume? Is that the setting you usually use for for listening? If not, how about just checking hum at normal listening levels?
lewm
12,839 posts
 
True hum, by the classical definition, is 60Hz OR 120Hz noise generated by unrectified AC voltage getting in to the signal path or by improper or inadequate grounding. The frequency would depend on the configuration of the rectifiers in your power supply. Since tubes and transistors are capable of amplifying those frequencies with equal efficiency, I see no reason why "hum" would be associated with tube equipment vs solid state. If this is what you are hearing, and if it bothers you, you could ask a technician to improve the rectification in your power supply or check the ground scheme, to reduce the hum. Any experienced tech or DIY guy would have some ideas of what to do. But as to what you are complaining about, I would do nothing.
ths364
181 posts
 
Lewm> Hum coud be present in a tube circuit if tubes are not shielded. Leaving tubes unshielded helps get heat out and is a point of visual appeal for many people, whereas transistors are usually contained in a shielded box, because they aren't usually all that hot (they don't have a heater element like a tube for one thing), and I don't think they have a special visual appeal to a significant portion of the market. I'm not trying to be a wise guy here- I totally agree that if the hum isn't present at normal listening levels why feel the need to do something about it?
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