I'm curious about something. In perusing the various a/v forums, I frequently see debates about large vs. small settings on a/v receivers/processors, variable crossover frequencies on those processors, difficulty in integrating subwoofers in a/v systems etc. I find myself wondering why people spend so much time fighting with their a/v processors, trying so hard to get things integrated properly. Why don't more people buy speakers that work with the 80Hz 12dB/oct high pass, 24dB/oct low pass crossovers built into most a/v gear. A sealed speaker with an F3 of 80Hz would seem to work perfectly with most receivers. Do people not buy them because there aren't many available? Or is there just a general preference for vented speakers that play lower? I'm genuinely curious about this and would be very interested in hearing your comments on the matter.

Good questions.

First, for the sake of discussion, let me define two categories of speaker: large (capable of full-range bass response) and small (less capable.) I know it's an oversimplification.

Personally I'd aim to put together a system comprised only of large speakers, where all of them had "flat" bass response down to below 30 Hz, run everything full range, and let true subs (4 in total) handle what is essentially only the LFE's. Unfortunately space constraints and budget prevent me, and probably most others, from accomplishing this.

However I am part way towards this goal, and in my main home theatre room am running large full-range arrays for all 3 front channels - and three subs. And while I hate to overuse the adjective, I can say that nothing beats the impact that you can achieve with full range speakers.

Having stated this own personal ideal you can guess that going to smaller and smaller speakers would be, for me, less than ideal. Where budget and space considerations come into play (as they always do) I would still aim for as extended bass as possible - coupled with electronics that would allow me to match up with each speaker's low-level ability.

I'm not saying that smaller 80 Hz speakers are in any way inferior. Or that you can't build an excellent system around them. It's just that having experienced both large and small set-ups, this is one of those rare occasions where size really does matter, in my opinion.

Besides, (and I know I'm generalizing) you can always get a large speaker to behave like a smaller one by slecting a higher crossover point. But the reverse is not true.

Regards.

Jeff Mackwood

Jeff,

Thanks for your comments. They raise another question for me. Is a large speaker with flat frequency response to 30Hz necessarily going to provide more impact in the, say, 200Hz-1kHz range, than would a smaller speaker with flat response to 80Hz?

E

Ellen,

If I remember correctly from HT article, human ear cannot locate the source of sound raging from 40 HZ to 90 HZ (someone correct me if I’m wrong) thus using one equipment (subwoofer) to take over that duty for 5 or 7 speakers makes it economical in general. There are some disadvantages to it if you get really picky like this thread here: http://ubb.outlawaudio.com/ubb/Forum4/HTML/000250.html

For speaker design fundamentals, try these two sites. They should give you a good explanation of why different crossover matters so much.
http://www.speakerbuilder.net
http://www.loudspeakers101.com/Sound.htm

Spiker, thanks for the info. I am familiar with the rudiments of loudspeaker design, having toyed at one point with the idea of building some speakers.

I am also aware that the folks at THX and Dolby have found thru their testing that bass frequencies under 80Hz are not localizable, hence the 80Hz crossover in most a/v and all THX certified processors. But all of that is more reason to use sealed speakers with F3 of 80Hz. Yet I get the impression that most people do not. I'm very curious to know why.

Ellen and Spiker,

Let me again start by saying that what I am about to say is a generality - which is always open to exceptions.

All else being equal, a large speaker with extended bass response should sound no different in the other (upper bass, mid, high) frequencies than a small speaker. One way to prove it might be to take two or three models from the same line of speaker company (Paradigm, Energy, psb, etc.) and compare them side-by-side with the same relatively high crossover point (80 Hz or what have you.) I suspect that they will all have just about the same sound and impact - especially if they share the same mid and high drivers, crossover design philosophy, etc.

What I meant by my earlier comment regarding "impact" is at the lower frequencies where they are present in large, and by my definition, not present in small speakers.

I agree that nothing much below 80 Hz is localizable (if that's a word) - and do know that this has been the subject of debate in other threads regarding "stereo subs" - however having multiple full-range speakers PLUS subs (handling mostly the LFE's) impacting on you, is simply a completely different experience than with small speakers and the same subs. I can prove it by simply by dialing up the crossover point on my full-range front and centre front speaker arrays and redirecting that bass to my three subs. It's just not the same.

(One sidebar comment: a single subwoofer will be more noticeable than multiple subs. Not necessarily localized. However it's more likely to set up all sorts of room response variations which you will notice. Multiple (mono) subs, properly positionned, will tame the peaks and troughs - and does, in my opinion, contribute, incorrectly, to the argument that stereo subs are the way to go. My own listening experience is that multiple mono subs are more effective, Again it's open to debate - but I would refer you to the excellent white paper on the subject on the Harmon International web site.)

But as I said before space and budget (economics) will almost always cause us to compromise. I personally believe that the THX standard is a compromise - even though it's a darn good one.

Regards.

Jeff Mackwood

Jeff,


Believe it not, Webster says it is


In what way is it not the same? Do you mean that the bass is louder? Does it have less audible distortion? I would expect problems in using the SMALL setting on the receiver with large full range speakers that do not roll off at crossover point. I would think that there would be a hump in the response because the speaker is not rolling off. There would be no 12dB/oct roll off at the crossover point to combine with the 12dB/oct highpass in the processor. So instead of combining with the 24dB/oct low pass to get flat response in the crossover region, you'd get something else that wasn't flat.


I am surprised to read this. I had always thought that multiple subs placed at varying positions throughout the room can cause cancellation. But perhaps that's only if both/all subs are receiving the exact same signal.


No doubt.

E

edit to fix myriad typos




[This message has been edited by Ellen (edited November 10, 2003).]

Jeff,
I’ve thought about getting a set up like yours at one point after reading about “Stereo Subs”. Of course it will cost more but for people just wanting to enjoy decent audio quality (not necessarily top notch) in music and movies at home, will it be really worth the investment? Is it night and day difference or less? I’m debating…

I would say that if you have two subs already, setting them up in stereo is worth a try. If you have to buy another sub, I would say it would probably not be worth it unless you already wanted to buy the extra sub. With two subs, you can always set them up conventionally if you find that running them in stereo doesn't work for you. The nice thing about the stereo sub setup is that if you already have the two subs, there is really no cost to do it other than some extra interconnects.

soundhound,


This requires that your subs have a built in electronic crossover, right? Those with passive subs powered by a couple of spare amp channels would have to purchase an external crossover, no?