Do the woofers flop with the sound turned down?
What program material? I have some classical recordings where the HVAC is blowing on an unscreened mic. The sub worked so hard it shut down.
If you can see your woofer’s flopping, it is likely below ≈10Hz which is very low for feedback.
It’s over 30 years since I had a turntable, the last ones had disc clamps which do wonders. The TT, HA & Pre were in a separate room... ZERO feedback at any playback level.
’Rumble’ filters on consoles and pre-amps are often quite high ≈40Hz.
The db systems HP is just a ≈140nF cap. Actual frequency will vary if phono impedance is not 45k. It will only ½ the excursion @ 12Hz. An adjustable multipole filter [4th order L-R HP] to the sub and bass driver amp is preferred.
The KAB RF1 is mono below 140Hz. Not all LPs are mono below that frequency.
What program material? I have some classical recordings where the HVAC is blowing on an unscreened mic. The sub worked so hard it shut down.
If you can see your woofer’s flopping, it is likely below ≈10Hz which is very low for feedback.
It’s over 30 years since I had a turntable, the last ones had disc clamps which do wonders. The TT, HA & Pre were in a separate room... ZERO feedback at any playback level.
’Rumble’ filters on consoles and pre-amps are often quite high ≈40Hz.
The db systems HP is just a ≈140nF cap. Actual frequency will vary if phono impedance is not 45k. It will only ½ the excursion @ 12Hz. An adjustable multipole filter [4th order L-R HP] to the sub and bass driver amp is preferred.
The KAB RF1 is mono below 140Hz. Not all LPs are mono below that frequency.