If the turntable is placed near the loudspeakers, acoustic feedback occurs in many cases. The turntable picks up sound from the loudspeakers via its cartridge and passes it on to the amplifier, which of course plays it back — amplified — through the speakers again. This creates a feedback loop, as known from microphone transmissions.
With a turntable, however, the sounds are lower in frequency; at first the bass reproduction becomes muddy, and at higher volumes a hum develops. Violent movements of the bass driver cones can also have their cause in acoustic feedback via the turntable.
This is very dangerous for the loudspeakers and can lead to the destruction of the bass drivers.
Possible causes of acoustic feedback:
Poor construction of the turntable:
As unbelievable as it may be, many turntable designers have ignored well-known physical facts and brought turntables to market that are extremely sensitive to feedback. Here, a little relief can only be achieved by placing the turntable in a favorable position.
Good turntables often have elaborate damping mechanisms to reduce resonance.
Wrong combination of turntable and cartridge:
The tonearm and the cartridge form a mechanical oscillating system that has a natural resonance, which should ideally lie between 8 and 15 hertz. It is influenced by the dynamic mass of the tonearm, the weight of the cartridge and the so-called stylus compliance. If these parameters are combined incorrectly, sound quality suffers and unwanted resonance effects occur.
Unfavorable placement of the turntable:
A turntable should stand on a solid but not too heavy surface. Many pieces of household furniture vibrate strongly and amplify feedback effects. You can clearly feel the resonances if you lightly place your hand on a piece of furniture.
Due to the laws of acoustics, bass buildup occurs in the corners of a room. This is not a suitable place for the turntable.
A wall unit in which loudspeakers and turntable are housed together is particularly unfavorable. If no other placement is possible, you can try to achieve an improvement with dampers under the loudspeakers or the turntable.
One should be aware that the tracking of a record involves movements in the micrometer range. It then quickly becomes clear that a turntable cannot simply be placed just anywhere; a little care in its placement is appropriate.
