Hum noise coming from chassis

[CALamb 3]

I hear an audible hum coming from the 1.0 chassis. The unit works but I suspect there is an issue that will cause a failure soon. What is the most likely cause of the humming?

[AndrewJohn 10,842]

Welcome @CALamb, glad you found us.

 

m1.0t amps are known to hum..., how loud is your hum?  Audible, yes, but across the room loud, or up-close loud...

 

I'm not a tech, so I can't comment on fixes, or potential other issues - someone else here may chime in.   

 

But do tell, how loud is the hum?  can you hear it when you are playing music through the amp to your speakers at regular listening levels?

 

Again, Welcome!  there's a lot of info here.  You might also try using the Search at the upper right on the home page for other threads on m1.0t and hum issues, experiences and fixes.

[Nahash5150 10,983]

1 hour ago, CALamb said:

I hear an audible hum coming from the 1.0 chassis. The unit works but I suspect there is an issue that will cause a failure soon. What is the most likely cause of the humming?

 

This is normal to hear from a mag coil amp like a M-1.0t, however, depending on how loud it is, could indicate several things...

 

1) magnetoconstriction - the phenomenon common to all transformers. The materials of the transformer symathetically vibrate with the changing magnetic fields which can be audible. Some mag coils get louder over time as the lacquer they are dipped in to dampen this noise dries out and cracks.

2) Idle bias current is too high. If the amp feels warm at idle after about 5 minutes, the idle bias is too high.

3) high current draw. There could be a fault that is drawing too much current. This would be unusual if the amp is functional.

4) Chassis is vibrating. Try dampening the chassis by tightening the screws, adding fiberglass insulation to the top of the mag coil under the cover.