A friend loaned me an old Adcom GFA 545 that he bought years ago and never even plugged it in. I cleaned it up a little, checked the gain with a signal generator and oscilloscope (got 27.8db) then hooked it into my system.
I notice that there is more transformer buzz coming from the unit, not the speakers, than I am used to hearing. Is this normal with this model?
I notice that there is more transformer buzz coming from the unit, not the speakers, than I am used to hearing. Is this normal with this model?
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If that does not work, pot it in insulating - not furniture - varnish.
And if it needs potting, it will warm up too much and vibrate when hot, signs of gaps in the laminations and windings...which need filling.
And if it needs potting, it will warm up too much and vibrate when hot, signs of gaps in the laminations and windings...which need filling.
GFA-545 already has a potted transformer. I haven't noticed any unusual buzz from any GFA-545. Yeah try tightening the bolts. Otherwise you might have something else going on, like DC offset on your AC.
Sometimes transformer buzzes will magically disappear after a few days being powered up. There might be a residual ferromagnetic bias in the core, that eventually gets demagnetized by the alternating current, or eventually becomes biased in proportion with the DC bias on your house current.
Sometimes transformer buzzes will magically disappear after a few days being powered up. There might be a residual ferromagnetic bias in the core, that eventually gets demagnetized by the alternating current, or eventually becomes biased in proportion with the DC bias on your house current.