Skeptoid: Digital vs Vinyl, Podcast casts its skeptical eye on digital audio Options

[rick.hughes]

Skeptoid: Digital vs Vinyl

[Pio2001]

Yes, that is something that I noticed too. Never listen to something else while you record a vinyl ! But it seems that either this kind of feedback is harmless if the signal is the record itself, or some turntables are more sensitive than others. The one used for the feedback test was a Technics SL-3100.

[mzil]

On some receivers/preamps the record out selector (or just input selector) doesn't have perfect isolation between inputs, there is electrical bleed through -[just like the L and R ch also sometimes bleed through to each other], even if those other inputs aren't being listened to. On receivers this can particularly be a problem since you can't really turn off the tuner section on many, it is always "on" even if no frequency is displayed. The best you can do is tune to dead air and/or disconnect the antenna, if it is a problem.
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On turntables acoustic feedback is often via vibration from the resting surface and not via sound waves through the air. If one were to want to induce it, try placing the turntable on the (full range) speaker and defeat (if possible) the phono preamp's subsonic filter.

In its extreme form it will make a loud howling noise, just like stage mics are known to, however it also can subtly color the music at lower levels. The effect is subtle and easily masked in many situations. Turntables with good vibration isolation, such as ones with a floppy, floating sub-chassis (keeping the arm and platter suspended in their own separate world, without a direct connection to the plinth), are typically immune to this problem, in fact that is why they are made this way.

This post has been edited by mzil: Sep 16 2012, 01:23