Separate vs. Integrated Subwoofers

I have a couple of questions:

1. Should a home-theater speaker system have separate subwoofers instead of subwoofers in the main front towers?

2. Should an amplifier's power-output rating match the power-handing rating of a speaker system?

Bob Spencer

I prefer to have separate subwoofers that are not incorporated in the main front towers. Why? Because the best placement for subwoofers in a room is not necessarily the same as the best placement for the front left and right main speakers. Subwoofers reproduce the lowest frequencies, which can cause the most problems in a room, especially the frequencies that cancel and reinforce themselves at particular locations because of the room's dimensions. These problems can be minimized with judicious placement of the subwoofers, often at the halfway or quarter points along the walls, which is certainly not where you'd want to put the front left and right speakers.

As for your second question, in general, an amplifier's power output should more or less match the maximum power-handling capability of the speaker it's connected to. If the amp has way too little power, it must work very hard to drive the speaker, leading to higher distortion; if it has way too much power, you might overdrive the speaker if you crank the volume, damaging it as a result. If you only listen at moderate levels, having an amp with more power than the speakers are rated for is not a problem—in fact, the amp operates with lower distortion in this case, leading to better overall sound.

Another critical factor in matching an amplifier to a speaker is impedance, which is a speaker's resistance to alternating current—that is, an audio signal. As a speaker's impedance drops, it offers less resistance and thus draws more power from the amp. If the impedance is too low for the amp, it might overheat and/or the signal might become highly distorted, which can also damage the speaker, especially the high-frequency tweeter.

If you have an A/V question, please send it to askhometheater@gmail.com.

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COMMENTS
K.Reid's picture

Bob,

I agree with Scott's response insofar as multiple subwoofers will even out room response and aid in preventing nulls and areas of over attenuation.

That said, for some individuals, purchasing multiple subwoofers may not be a viable option and your room may not accommodate 2-4 subwoofers unless your room is large or you plan to go the in-wall route. One alternative may be tower speakers such Definitive Technology or Golden Ear Technology which incorporate well designed powered subwoofers. Consider purchasing an av receiver that incorporates Audyssey MultiEQ XT or XT 32 room correction as it may help even out bass response and minimize frequency anomalies. It's not a "cure all" but could help if you cannot afford to buy 2 or 4 stand alone subwoofers.

If you only want to purchase one subwoofer, consider one that has EQ built in to help minimize room modes. Consider Velodyne's DD+ series, JL Fathom, B&W DB1, or Paradigm subwoofers that include its PBK (Perfect Bass Kit).

Hope this helps

dlaloum's picture

I disagree with the final comments with regards to amp/speaker power.

Having an amp which is higher in power than the speakers are rated at, ensures that the amp puts out pure music - clipping is the one thing that is really likely to destroy a speaker - that type of distortion is physically nasty - especially to tweeters.

You can blow a 100w pair of speakers with a clipping 20W amp fairly easily....

It is harder to do the same with the reverse...

In fact it is safest to have an amplifier with somewhat more power than the speakers rated handling capacity.

In reality most amps spend most of their time idling at around 1W to 5W outputs.... the rest is mostly headroom... and as long as the peaks are real music and not sustained clipping - speakers can handle a lot more than the rated values... (which are a continuous value in any case...)

So my advice would be run 100W amps with 20W speakers in preference to 20W amps with 100W speakers.

With regards to subs - if one has to choose between a sub-sat system (single sub) or a full range (twin subs) - I would opt for the latter!

But sometimes additional subs elsewhere in the room can help further - especially when combined with current room DSP EQ systems...

bye for now

David

DaleC's picture

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