You’re spinning vinyl. Everything feels right—organic, dimensional, alive. But during quiet moments, you notice it: your woofers are pulsing, visibly flapping in and out as if responding to something you can’t hear. Sometimes there’s a faint rumble. Other times, just motion. The sound might still be beautiful—but visually, it’s unnerving. You’ve likely done the work: leveled the platter, balanced the arm, even upgraded the rack. Still, the cones won’t rest.
The instinct is to reach for the subsonic filter. The wiser move might be to pause.
What to Do
Try mechanical first. If your table is light, add mass—like a slab of granite, butcher block, or constrained-layer damping base. If it’s already heavy, decouple it from suspended floors. Wall shelves or vibration-absorbing footers (like IsoAcoustics, Vibrapods, or Herbie’s Tenderfeet) can help. Re-check stylus pressure and anti-skate. If the stylus is riding low or bottoming on warped records, adjust. Consider a new mat with better energy absorption—cork-rubber blends or graphite compounds often outperform felt or basic rubber. And double-check your cartridge alignment—mistracking can sneak in rumble by way of misbehavior at the groove wall.
Only after exhausting the mechanical fixes, engage a subsonic filter. Look for one with a steep cutoff below 20Hz. If your phono stage doesn’t offer it, inline options like the KAB RF-1 can help without flattening the audible floor.
Here’s Why That Works
That woofer motion isn’t bass—it’s turbulence. Warped records, tonearm resonances, and structural vibrations can introduce inaudible low-frequency content that wastes amplifier power and muddies the music. A filter removes it—but at a cost. Some pressings have meaningful energy below 20Hz. A filter strips it all.
When you solve it upstream—through better support, cleaner tracking, tighter coupling—the cones quiet naturally. The sound doesn’t thin. It settles. And the music arrives with more intent.
Fixing the motion shouldn’t dull the magic. When done right, it deepens it.
