Any dimmer light switch installed recently? Low-level DC voltage sitting on your AC power line can causes the power transformer to hum or buzz.
question for Luxman L-590AX owners
I own the subject amp, have had it for 3-4 years. I recently noticed a low hum or buzz coming from the amp itself (not the speakers), and would swear that it has been dead quiet up until now. You have to have your head right down beside it to hear it. I'd like to hear what other owners have to say. Are your amps completely quiet? Seems like I may have developed an issue. Thanks in advance, and Merry Christmas.
Showing 4 responses by imhififan
The Luxman power transformer core is constructed by stacking layers of thin laminated steel sheets. The transformer is magnetically excited by an alternating voltage and current so that it becomes extended and contracted twice during a full cycle of magnetization. Transformer noise is caused by magnetostriction: means that if a piece of magnetic sheet steel is magnetized it will extend itself, when the magnetization is taken away, it goes back to its original condition. Each laminated steel sheet with an induced magnetic field. That magnetic field acts between the adjacent plates stretching and squeezing the adhesive and insulation between them. Over time that adhesive starts to break apart and the laminated layers separate from each other slightly. That is the humming noise that you heard. It’s always present, but once the adhesive starts to break it gets louder. These micro-fractures in the adhesive may not be visible to the naked eye. Maybe this is the cure: https://www.youtube.com/watch?v=WW-QRar2RQ8 The more current draw through a transformer (class A amplifier) the larger the induced magnetic fields, and thus the louder the transformer hums. |
Yes, some toroidal transformer cores consist of a very long and thin metal strip that is wound up (like a spring) in a large circle rather than exist of lots of individual metal parts. A cross-section of the core: https://diyaudioheaven.files.wordpress.com/2013/08/o-cores.png |
@twoleftears
The power transformer in the Luxman is a EI type and not a toroidal transformer. https://6moons.com/audioreviews/luxman4/6.jpg |