Subwoofer X/O frequency experiments


I have really been going crazy trying to find the best X/O frequency for my elaborate 6-driver subwoofer set and my three Maggie MG1.6. I finally had the thought that the optimum frequency depends on the kind of music being played. So I bought an electronic crossover that I can locate in the listening room and make various adjustments (including X/O frequency) while music is playing. (My old X/O was located in the cellar with my power amps, and the frequency can only be changed by plugging in a different module…not very convenient for experimentation). Initial tests confirm what I thought.

First I played a CD of Wurlitzer theatre organ music. Heavy duty bass! No doubt that the best results were with the X/O set to 300-400Hz. Not all subwoofers can do 400 Hz, but mine can. Interestingly when I cranked it up to about 800Hz harmonic distortion became evident, but not unpleasant…it sounded exactly as if the organist had pulled out another stop. Organ pipes produce very pure tones, and little pipes are played simultaneously (via stops) so as to produce harmonics and make it sound nice. I did the same thing electronically. Sort of “tube amp sound”.

Next I played a Mozart Symphony DVDA (MDG 940 0967-5). Again this is a massive complex sound source, mostly loud, and 130 Hz or thereabouts seemed best.

Last I played a DVDA Emmylou Harris, Producer’s cut (Warner R9 78174). On this one anything over 50 Hz was bad. It has the usual pop music bass line, probably exaggerated to sound better on inferior systems.

I know that the audiophile party line is that the subwoofer should be crossed over where the main speakers roll off, generally below 50 Hz. This is a “safe” bet if you have to pick one frequency and stick to it. Been there, done that. However, I suggest that there is (or ought to be) a significant overlap of frequencies that both the main and the subwoofer can reproduce well, and that the optimum X/O varies depending on the music.
eldartford
My experiments indicate the same.
In fact I have found that music from the same disc/recording also has differing optimum X/O frequencies!
This problem has driven me crazy as well.
It would be great if a box of electronics could recognize this and automatically adjust the X/O optimumly track by track.
It is so frustrating achieving the correct X/O for every track/recording that my subs often get turned off.
I think the main reasons for this problem is that all audio engineering environments (monitoring hardware etc) are not identical.Also engineers differ in their approach to the varying material they are working on.
I love my subs with music but find it hard to conrol them because of the constant adjustments required for optimum performance.
I think all subwoofer owners,regardless of the make they own,have encountered this problem when listening to music.
Anyone out there with advice/solutions to achieving perfect balance of low frequency that does not requre constant adjustment?
...advice/solutions to achieving PERFECT balance of low frequency that does not requre constant adjustment? (my emphasis)
Haven't found any:( As Eldartford, above, I found that 120-130Hz on classical (+0/-1 octave, LR 24 or Bessel) is the easiest compro to live with -- but I still end up adjusting the VOLUME on the sub amps...

I use a two 15" driver, open baffle, subwoof per side. I experimented in the same way as both of you using a friend's Behringer 2496... not only did the "better sounding" frequency oscillate from recording (or even track) to recording, but the "optimum" SLOPE did, too.

There are too many variables that complicate our lives here... maybe setting up a mike in the room & feeding input to a preset equaliser (s/thing like that B&O spkr thingy)? Rather ugly, complicated, and with too many opamps in the signal path...
>>"Anyone out there with advice/solutions to achieving perfect balance of low frequency that does not requre constant adjustment?"<<

Try setting your sub's crossover 1 octive above your speakers -3db point, and use the subs volume control for blending.

If your speakers are full range, and lets say their -3db point is 25hz, set the sub crossover at 50hz, if you are using a mini monitors whose -3db point is lets say 40hz, then set the crossover on the sub at 80hz.

Now all you have to deal with is the standing waves, and bloat from the rooms Primary Resonate Frequency points.
Here is an interesting link related to your question. http://www.hometheaterhifi.com/volume_9_3/feature-article-multiple-crossovers-9-2002.html