Originally Posted by jedi.night
Do you recommend crossing True sub at the same point as the MBM?
What I mean is that in my current setup I have my PC-Ultra cut at 50hz and then the MBM picks up at 50-80hz with my receiver crossing the mains at 80hz.
So Ultra is handling everything below 50hz , mbm 50-80 and mains 80 hz and up.
I use a crossover of 120Hz.
I have Atlantic Technology System 170 speakers. My speakers are rated to 90Hz, but both reviews and testing with Room Equalization Wizard (REW) show output dropping at about 100Hz. Since I wanted a higher crossover than 100Hz so that I wouldn't drive the speakers all the way to their maximum extension, I decided to purchase the MBM-12 (this isn't the only reason I purchased it ). Since the MBM-12 also relieves the subwoofer of playing higher frequencies, I purchased the VTF 2.3 instead of a more powerful model.
I tested various cutoffs from 150Hz to 90Hz and found that I liked 120Hz and could not localize the MBM-12 at that frequency. I use a Behringer DCX2496 to provide crossovers and delay for the MBM-12 and VTF-2.3.
As an experiment, I turned off the sub and listened to the speakers with different crossover settings. The higher the crossover, the better the speakers sounded. In the article, Miscellaneous Ramblings on Subwoofer Crossover Frequencies
I found the reason why my speakers sounded better: less output was required for the same SPL. Here is a brief summary of the article:Benefits of higher crossover points
Less output is demanded for the same SPL by both amplifiers and speakers resulting in less distortion, less compression, and greater dynamics.
The LFE channel can contain information up to 120Hz that can get lost with a lower crossover point.
More consistent frequency response between channels.
Since the sub (or MBM-12) is producing a greater frequency range, it is easier to control room interaction through equalization.The Detection of Subwoofer Depending on Crossover Frequency
I also found a convention paper for the Audio Engineering Society about the detection of subwoofer depending on crossover frequency
. The study found that a crossover of ~120Hz seemed to be the highest you could go before localization with most of their test sounds. They tested 30 crossover frequencies between 55 and 227Hz. It is interesting to note that "the selected crossover frequency range was not wide enough for half of the listeners, as at some cases they did not detect the difference between reference and split signal even at the highest crossover frequency value."Localization Below 120Hz
If you are experiencing localization below 120Hz, there are a few things you could check.
Have you level matched your sub/MBM-12 with the speakers? If your sub/MBM-12 level is too high, they will be easier to localize.
If you are using the MBM-12, do you have a method of setting its delay if it is closer than your mains? If your delay is off, the MBM-12 is easier to localize.
You might just have very good ears. Try putting cotton in them.
(Note: I also posted the above at HSU's forum back in August.)