Dear @mijostyn : "" much steeper slope without phase issues. ""
I use first order high-pass and the blend between main speakers and the Velodynes are in " heaven ".
"" It was digital bass management that finally solved this problem ""
not really must be digital IMD goes really low if you cross over 80hz to 100hz and does not needs to be digital.
"" I am working on new enclosures and will use 8 instead of 4 drivers which will halve their excursions. ""
Look, contrary of what you think my take is not more drivers or more subs. What we and you need is proved bass quality performance developed by each driver and that means low bass driver it self.
Velodyne subs are the lower distortions levels in the world. Eacg bass driver in the Velodyne is monitored over 16K times at each second and when the driver distortion goes near the Velodyne limit of distortions impedes that the distortion levels goes up and no matters if the subs are developing 120db SPL.
Quality is the name of the game in overall bass management too.
I understand that you designed and builded your four subs, well maybe needs not more drivers but a different design but I can’t know for sure.
In the mean time enjoy the MUSIC with out dust cover because life is to short and you have not bougth it.
R.
"" On my system page you can also see graphs of the frequency response at the turntable dustcover up and down. There is a definite rise in the bass but no really big peak or trough. Over 1 kHz the response drops 10 dB with the cover down ""
Maybe you are not measuring what you need to measure that can tell you what is going own down the dust cover. You like science then use it in the rigth way.