Subwoofer Placement Tips for Cabinetry Installations
I have been asked repeatedly by members of this forum about recommendations for putting subwoofers into custom or pre-made cabinetry so here are my opinions and recommendations.
Tip #1: Only as a Last Resort
Placing subwoofers and to a lesser degree speakers in cabinetry can be a tricky proposition unless the subwoofer or speaker is included as part of the design of the cabinetry and the design of the room. It is my opinion that this should be done only as a last resort.
Here is the reasoning why
When you place subwoofers in cabinetry, the subwoofer then becomes stationary. If the placement of the subwoofer in relation to the listening position results in a dip or a hump in a critical frequency you will then need to use equalization or move the listening position to compensate for this. I have heard many complaints by the DIY Home Theater enthusiast that their subwoofers sound flat with no punch or distorted only to find that their subwoofer was placed in an inappropriate position. They then try to compensate for this by cranking the gain control up on the subwoofer causing it to bottom out or distort. Subwoofer placement is critical. You give up placement flexibility when you install them in cabinetry unless you have done the calculations and tuned the custom built subwoofer to the room and your listening position.
Tip #2: Bracing & Acoustics
If you must place a marketed subwoofer in cabinetry make sure the cavity where you are placing it is heavily braced and make sure that the cavity when lined with heavy acoustical foam is just big enough for your subwoofer to fit in. This will eliminate potential unwanted resonance from the cabinetry and the subwoofer. A little finish carpentry will be necessary here; sealed front firing subwoofers work best in this application but front ported front firing subs can work as well. Rear ported subwoofers are not recommended because of port huffing and obviously floor firing subwoofers are not recommended. I like to use subwoofers from manufacturers that use an external rack designed subwoofer amp That way I can get a super tight fitting subwoofer and have all the adjustments for the amp in the rack this also prevents the subwoofer amp from overheating.
Tip #3: Use an Adequately Powered Sub
Placing a subwoofer in cabinetry will drop the in room Sound Pressure Level (SPL) of a subwoofer. Try to find a subwoofer that provides a high amount of SPL in the lower frequencies. These are typically high power high excursion subwoofers. "Audiophile" type subwoofers need not apply for this application if you are setting this up for Home Theater. At this time, I don't want to make recommendations for brands as this would appear like marketing.
There are many good brands on the market and a little research on your part will make your choices easier. If you have specific questions on subwoofer brands feel free to PM me and I will try and answer your questions.