Why Rumble One Side of Album

@big_greg , You have to know what the slope is. What They mean by crossover point is that the filter is 3 dB down at 20 Hz. It starts rolling off a little higher depending on the slope. Analog filters can not get as steep as digital without causing problems. You probably start rolling off around 26 Hz. This is not something you would hear. It is something you would feel or rather would not feel.

@vonhelmholtz , that is extremely misleading. Speaker measurements are made at one meter. This means at a normal listening distance in a normal room your speakers are down 3 dB at something like 80 Hz! Never and I do mean never do you want to run subwoofers with just a high pass filter. You miss a huge opportunity to clean up your midrange and upper bass. Cross up higher and use a two way crossover. Subwoofer manufacturers do not want to scare you out of buying their product by telling you you have to spend another 3 or 4 thousand dollars in cross overs and wires to get their sub operating right. 

Subwoofer manufacturers do not want to scare you out of buying their product by telling you you have to spend another 3 or 4 thousand dollars in cross overs and wires to get their sub operating right.

True, it is partially about the money, but not my primary reason. Primarily, I really like the Sabrina X and didn’t want to ruin what I heard. If I can’t integrate the subwoofers, I would probably purchase Wilson’s crossover..but for now I need to work on power conditioning and room acoustics.

I should add that I believe that with a perfect crossover the Sabrina X would be relieved of that 1 meter 31 Hz requirement and the sound would improve,, but what crossover and which interconnects?

@mijostyn The jury is out on the Kab filter at this point.  As you mention, I don't feel the energy of the subwoofer quite as much, but so far everything sounds "better".  It will take some extended listening to sort it out and if I don't like the Kab unit, it was less than $200, one of the least expensive items in my analog chain.  I have 4 subwoofers with a combination of 4 15" drivers and 2 13.5" drivers, so I'm not lacking for bass, but there is a noticeable difference.

@big_greg , you are certainly not lacking in the subwoofer department. The two 13.5s I assume are JL Audios.  What subwoofer uses two 15" drivers?

Next time you are thinking about a new preamp you should check out the Trinnov Amethyst and the DEQX Pre 4 or 8. Digital subwoofer crossovers and time alignment are built in. You can get rid of the rumble and still feel the bass. 

@mijostyn  The dual 15" subs are Rythmik F25. The two 13.5" are SVS SB13 Ultra.  I'm really happy with my current preamp, the Herron VTSP-360.