Help with ringing bass from Dynaudio C1

Try moving the speakers back or forward 6 inches at a time
and then inward till it is least offensive
Best JohnnyR

Do you think there is a defect in either the speakers or amplifiers? The setup sounds absolutely perfect except for being out of control at the very bottom. Any bass above that sounds quite tight. However, the bottom is so out of control -- ringing for several seconds --, it is hard to believe that such highly reviewed products could have such a glaring flaw without someone else mentioning it.

what are the speakers standing on? if they have feet or footers, tighten them (or remove them if the footers are on a platform); are the screws lose which hold the driver?

They are on Core speaker stands. I tried picking up the speakers and holding them while they were ringing; it made no difference.

The driver screws are tight.

Having owned the C1 and now the C1 Signature I have never heard of that problem. Does it happen with both speakers? Does it happen only at high listening levels? I've driven mine with a Bryston B100 and now an Octave V70Se. I've heard C1's with Naim - Sim Audio and Burmester. Since the speakers are passive I would think it is something upstream. Try without the conditioner. Any possibility of borrowing a different amp? Another option may be to bring the speakers to a friend or dealer and listen to the same passages but on a different system.

That being said I have overdriven mine to where the woofers bottomed out. But that sounded more like someone hitting the cabinet with a padded baseball bat. But it didn't ring or last past the low note.