Dual magic

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Dual magic – one of the suggestions sometimes made on forums when discussing subwoofers is ‘going dual’.

Subwoofer specialists SVS are big fans of running dual subwoofers whenever possible, and they recon they can be a great upgrade to any home theater or music system. We were allowed to borrow this excellent SVS newsletter on dual subwoofers to share with you. It sums up in a very clear way some of the benefits of running dual subwoofers in your system:

Two small subwoofers can fit where one large subwoofer can’t. Dual magic

Many enthusiasts have their music and home theater systems located in mixed use living areas, where subwoofer performance must be balanced with décor and aesthetics. In situations like this, a single larger subwoofer might have too much visual impact in the room or might not even fit in the allocated areas, whereas two smaller subwoofers can offer similar performance, less visual impact, and can also fit into more locations in the room.

Optimal sound quality at more listening positions

Even with careful placement, a single subwoofer will not have an optimal frequency response at all listening positions in the room.

In any given room location, a subwoofer has a unique ‘modal pattern’ (standing waves with peaks/nulls) and associated frequency response at the listening position.

Listeners will often notice that moving even a few feet away from the ‘sweet spot’ will often result in notably worse bass sound quality. With properly located dual subwoofers, the respective modal patterns will overlap, which greatly increases the modal density in the room.

The result is a smoother frequency response at more listening positions in the room, with less potential for obvious peaks/nulls in the frequency response. This also makes it easier for auto-set-up programs like Audyssey MultEQ to equalize the subwoofer channel.

Effortless bass with greater headroom

A popular phrase with the SVS Sales staff is “headroom has a quality all its own”.

Dual subwoofers will greatly increase the available system headroom, providing greater dynamic range, reduced output compression, lower distortion, and less potential for overdrive artifacts. If you like to listen at loud levels and crave a lot of slam, impact and pressure from action and sci-fi movies, then dual subwoofers are an excellent option, and will provide effortless bass on demanding passages.

Stereo bass for dedicated 2-channel systems

2-channel purists know that directional bass cues are important to imaging and preserving the solidity of the soundstage. Using dual subwoofers in a dedicated 2-channel system will preserve stereo bass cues, and prevent the soundstage from collapsing, particularly when small bookshelf monitors with limited bass extension are being used.

Harder to localize

Even with a fairly deep speaker/subwoofer crossover frequency and the associated masking effects of the surround speakers, it’s often possible to localize a single subwoofer in the room, particularly if it is not located on the front stage. In comparison, dual subwoofers are nearly impossible to localize. Once listeners experience this immersive bass which seems to emanate from everywhere in the room, they never want to go back to a single subwoofer set-up.

Recommended placement locations for Dual magic subwoofers

Based on SVS extensive testing, and research done by the professional audio community, SVS recommend the following placement options for dual subwoofer:

on the front stage in the corners
on the front stage at the 1/3 wall points (basically flanking the center channel near each main speaker)
at the mid-point of the front and back wall.

Option 3 is usually a non-starter due to the presence of the equipment rack and center channel, so the first two options are the most common. All rooms are different, so we recommend staying flexible and trying a few different locations, but the first two options have generally provided outstanding results for our customers and in our high-end installs.

Thanks to Ed Mullen from SVS for this week’s blog. As always, please feel free to contact Bart or Nick from Rapallo if you need help deciding or if you have further questions. We are always happy to help.

The Rapallo Team