I found this an interesting topic. It will be very nice when we have the DSP processors with more advanced bass control and that is the norm. Ultimately what we need is measurement and EQ that covers <200-300Hz and does it for every channel of the system. A measurement that you can see, allows for better placement choices also. As Kevin stated, having the best placement possible allows ultimately to get the best results. EQ is not a cure-all.

We also need a better standard for the crossover between a main/center/surround speaker that allows for steeper slopes on both sides of that crossover. As noted, there is overlap but I'd point out that 12dB/Oct is not what you get. You have to account for the acoustical rolloff and a 80Hz monitor is going to drop like a rock when it was designed for a typical HT small speaker application. The subwoofer on the other hand will have extension well north of 80Hz (and often an inductive hump) and depends almost completely on the electrical filter so you end up with an asymmetrical crossover between mains/sub in most application. It is fairly easy with DSPs to pick the slope you want and nail it. It has to be done and planned into the design though and there is not a comprehensive standard for how this should be accomplished by designers. The standards we have now, are over-simplified. It would be much nicer to see an total slope specification (acoustic + electrical) that designers could aim for. If we set a fixed standard for the HP slope generated by the DSP, loudspeaker designers should be required to design around that for a given total rolloff to hit a "standard" total rolloff. Having those be fixed items would allow consumers to mix-match with better results in terms of choosing subs and speakers.

Small sub vs. big sub. I sell big subs, with customers willing to build huge devices by the standards discussed in this Podcast. Most of them understand there is a tradeoff. Small subs can be equalized and you can get good results at low SPL. They can work well for music. High SPL in small boxes with deep bandwidth requires lots of driver and amp. The amount of power compression is directly related to how much heat you have to dissipate in the coil. Since subs are <1% efficient, every 99W of every 100W is dissipated as heat in the coil. Even large 4"-5" prosound coils will heat to extreme temps, with the DCR of the coil rising at alarming rates with steady-state high power levels required of content in a heavily equalized small box. Obviously, the tradeoff your making for size ultimately affects output no matter how much hand-waiving you do in the design. It is much easier to build a sub capable of high-output down deep with steady state signals using larger boxes and requiring much less power. The end-result, is that your better able to produced high output LF content for extended burst without the compression you see in smaller systems. Music has a lot less content that requires this capability. Movies has a fair amount of continuous high-output, LF content. Different tools are required are required for different situations. Part of designing a good system is knowing what you want, and making intelligent design choices based upon those priorities. For some, that steady-state output capability is important. For others it may not be a critical to their enjoyment and a small sub fits into a traditional room setting more successfully.

Owner/Engineer
Exodus Audio