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how does a sub help a tower speaker


quadklipsh

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guys.

if a subwoofer is added to play with a pair of floorstanders that are rated to go as low as 37 db at 100db. would this sub add 3-6 dbs more to the already low going woofers of the towers.how does a sub improve the bass if most of the frequencies that are in a music are reproducable by the floorstanders themselves too ????

usually 50 to 90 hz....

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Quad,

A good sub gets down to the low 20s.

Most full range speakers can get to mid 30s to mid 40s.

Most modern music (and even more present in HT soundtracks/ Movies) gets down into the 20s; some HT into the teens.

My Heresies roll off around 50hz. I have them crossed at 60 and let the sub do the work below this.

It frees up more power to the speakers instead of "trying" to drive the speakers lower; when they really can't perform that low anyway.

Some run their speakers "small" and let the subs take over at 40; 50or even 60 hz.

Some run their speakers "large" or "full" and let the sub augment their speakers bass instead of replacing it.

In my case; "small" just sounds better to me.

It depends on personal preference. There is no correct answer; only what sounds correct to you......

Also; sub placement and phase both play important roles in how the overall system feels.

The consensus is to get your sub to disappear; so you can not hear where it is coming from; it just blends......

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Guest Anonymous

Some run their speakers "small" and let the subs take over at 40; 50or even 60 hz.

Some run their speakers "large" or "full" and let the sub augment their speakers bass instead of replacing it.

I've never really heard it explained this way. I run mine in full. Everything i have rolls off at 50Hz, and nothing below 45Hz. Heresy, La Scala, and Belles.

I have had my THX KT-SWII sub since 98. Even for music, i'd never go back to not having a sub.

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It is more likely that a sub is less helpful depending on how multi-way your speakers are.

On two way speakers you will typically get more bang for the buck because if you can raise the cut off of the two -ways, you can usually clean up the midrange since the midrange is done by the woofers.

The key is to keep each driver in it's happy zone and avoid driver distortions. Having the towers continue to do the ultra low frequencies usually doesn't clean up anything and just makes over-powering bass, unless they are already bass shy.

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Yeah, the Heresies do not "hit" hard, so running them full (large) paired with the sub makes the bass seem undefined at times.

They do produce a surpirising amount of bass since I sealed the cabs; did the caps; etc... The lack of definition occurs (I believe) because the sub cancels out with the Heresies on some notes/frequencies.....

By running them small (60hz Xover) I am still getting most of the frequency range to the Heresies, but allowing the sub to completely handle the lower stuff.

And yeah..... It "hits" hard.

If I ever decide to do the Crites woofers; I may revisit this setup; as I bet they would make a nice difference......

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if a subwoofer is added to play with a pair of floorstanders that are rated to go as low as 37 db at 100db. would this sub add 3-6 dbs more to the already low going woofers of the towers

Only if the the tower speakers and subwoofer signal arrive at your ears, in phase, across all frequencies with which they share...So in reality, not a chance.

how does a sub improve the bass if most of the frequencies that are in a music are reproducable by the floorstanders themselves too ????

By neutering the signal going to the floorstanders and letting the sub become part of the big picture.

usually 50 to 90 hz....

The bandwidth of a typical sub, properly implemented, is much wider than that. More like 25-250 Hz. (even higher if you include induced harmonic content from certain woofer alignments)

So, how does a sub really help a tower speaker?

Mind you, this is a question that requires a book to fully describe, but I'll try to give it a go in a nutshell.

1. When crossed over properly, a sub prevents the two towers from fighting with one another acoustically over a pre-determined bandwidth.

2. When placed properly, boundary-loading significantly reduces the amount of power required to achieve desired low frequency SPL's at the listening position. Lower power equates to less induced harmonic content = better sound.

3. Low frequency content (less than 250 Hz) requires a unique combination of space, cabinetry, power, and / or signal processing that is not taken into account in your average sub-$10,000 tower speaker. There are of course exceptions, but I've never seen these special cases as affordable as even the most high-zoot subwoofer, if you know what I mean.

It's the nature of the beast. By virtue of design, a pair of standard tower speakers, played full-range, are acoustically poised to have low frequency issues (destructive interference between the cabs in the mid-bass region most audibly). As PWK said, put'em in a corner. That solves a lot of the issue if the room is big enough. Using a separate sub, or Bi-amping the towers in some instances can take care of the rest, typically sounding better due to the increased low frequency extension, in most cases.
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