View Full Version : feedback from phono input on receiver
02-22-2008, 10:41 AM
When using Phono if I turn the volume up past the half way point one of my
speakers starts picking up a wild amount of bass and I can see it
thumping in and out. This doesnt happen with the other inputs on my receiver, which btw is a vintage harmon kardon 630. Any help appreciated.
02-22-2008, 11:54 AM
You need to move your turntable to another spot which has less bass. This is called rumble.
02-22-2008, 12:03 PM
Yep, madmax is right on the money. I found that the rumble evident in my system was reduced a great deal when I changed the placement of my 'table. I went from a bookshelf used as a stand to a dedicated audio stand. The stand has spikes to isolate the table from external vibration, as well as provisions for making the platter of the 'table level in all respects. I was able to turn off the subsonic filter on my pre amp without any problems.
02-22-2008, 12:27 PM
It is acoustic feedback, not rumble per se. Rumble is low frequency noise generated by the drivetrain of the turntable. What you hear is generated via interaction between your tt (could be ultimately caused by its rumble, but also could reflect the system resonance of the arm/cartridge/stylus suspension) and speakers. The solution has already been correctly identified: move and/or isolate the tt.
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