Axiom Home Page Forums General Discussion Advice from Axiom Owners SUB-terranean Blues..

Alan, I know you mentioned something on this not too long ago, but I can't find the thread.. ??
Axiom vs Downfiring subs.. Your thoughts ?
And if anyone else has a thought or two, please feel free to join in..
I'm looking hard at the SVS subs, as opposed to the Axiom line.. Two different approaches, no "1" perfect buy, eh ?
Music and Home theater use.. Good size room, M80's, VP150, QS8's..
Is there a huge diff in the sounds produced by the box type compaired to the tube type ? Would having one of each, SVS and EP350, serve any good purpose ? Does two EP175's make more, or less sense ?
Like I said, I'm sure this has all been gone over and over before, but being new to this high end stereo stuff does leave ya scratching yer head :>

Hello Mikey,

I can't recall what I said in the thread, but no matter--here's the lowdown (no pun intended!). There is no fundamental difference in the character of low bass sound because a sub fires downward or forward.

With subwoofers, the way the woofer pressurizes the air molecules doesn't really matter--except to the designer and the performance goals and costs he has set. It can fire downward, straight ahead, to the rear, or even inside the enclosure ( a bandpass design), venting the low frequencies through a port.

It's all a matter of trade-offs in design: the volume of the enclosure, the sensitivity you want to achieve, the degree of bass extension (is 20 Hz or below important, or will you trade off lower distortion, better sensitivity, and the ability to play cleanly at loud levels, for moderate extension to, say, 27 Hz?). For example, the Sunfire subwoofers really will produce 20 or 18 Hz from a tiny enclosure. But the trade-offs to do that are: a huge amp is necessary (1,000 watts or so) because the small box is very inefficient; an enormous and expensive magnet assembly; and the Sunfires won't fill a huge room at high levels with low frequencies. And the sub is very expensive. So you see? Trade-offs everywhere! Then again, it's so small, you can easily hide it out of sight. Big advantage, right? For some people, yes. For you, maybe not.

The SVS enclosures are round, fairly tall and fairly ugly (that's all a matter of degree; big black square boxes ain't so pretty either!). Everything I read about SVS says they do a lot of things well; so do Hsu subs. The Axiom EP175 supplies very tight musical bass--and it's clean, with no bloat or boom--to below 30 Hz, which is sufficient for all but one or two pipe-organ fundamentals and some very low-frequency effects. Then again, maybe you want those ultra-low frequency effects.

Never having heard SVS subs or compared them to the EP350 or EP175, I can't tell you how they differ. If you are getting two subs, I'd get two of the same brand and model. Using two subs, you can even out the effects of standing waves--areas within a room of selective cancellation and reinforcement of low bass frequencies--which occur in ALL rooms.

Regards,

Alan, thanks very much for the responce..
Say, would it be possible for Axiom to have a page in the website somewhere all about their subs ? Why they build them the way they do.. A few detail and/or close up shots of the speakers.. A few words on the stong points of their design, compaired to the other basic designs.. Ported, bandpass, folded, etc.. Direct radiating, over under sideways and down ? (wasn't that a song in the 60's? Yardbirds,right?)
We all seem to love the tech side of things, and I see that some others have been asking for similar facts and figures about the entire line.. Shoot, you guys are probably already working on something along these lines, right ?
Well, thanks again for the info.. Hope to see a few new pages on the Axiom web soon.. Keep up the good work..

I think rather than forward- or down-firing, you're more likely to hear a difference between sealed versus ported subs, with some people who will tell you that sealed subs are more "musical". Then again others will tell you that a well-made ported design can sound very clean also (which I would agree with). But the sealed subs tend to require more power to hit higher sound levels, and therefore tend to be more expensive. The SVS and Axiom subs are both ported.

I haven't heard the Axiom subs, but based on the Axiom speakers I do own I'm sure their subs perform well. In the end, I went with the SVS because it was the most affordable way to get clean bass all the way down to 20hz. The SVS subs are great for music, none of that mid-bass bloat that some cheaper subs use to give the false impression of powerful bass. Where the SVS really excels is in giving that last octave of performance, which really adds extra oomph for movies with lots of LFE.

The advantage that the SVS design has is enclosure volume. By using the cylindrical shape, the SVS has the capacity to hit low frequencies at high SPL's without lots of distortion and without requiring thousands of watts to get there. The cylinder also has the advantage of being very strong/rigid, so they don't have to use a bunch of bracing like you do to build a rigid cube subwoofer.

I'll admit the aesthetics are a mixed bag; some people like the look, and some people don't. The thing I like about it is although it's very tall, my 20-39PCi doens't take up a lot of floorspace. A cube with similar performance would take up considerably more floor-space (unless you're going to spend a fortune on one of those high-performance small subs such as the Sunfire that Alan mentioned).

Great.. That was a good part of my concern.. I love my M80's and all, and would have to believe that their line of subs was top notch as well.. But, when I hear about the infamous "20" hz and below issues, my ears perk..
I seems this is the magic mark, or Holy Grail if you will, of subwoofers.. And to reach this mark, and hit it solid, adds a whole new deminsion to Home Theater ? At the same time, to be great, it must be able to hold true to music reproduction, correct ?
I know from all I have read, that the Axioms will give me great music.. Clear, accurate, fast.. But, come up just shy of the deep tones.. You feel the SVS does a good job of both ?
I mentioned above that I might add two subs.. If you or Alan (or someone ?) could exbound on that a bit more ? Do I gain the missing lows by having two subs in the same room ? Something about the two coupling and creating the deeper tones ? Double the $$ to set up, but more effective all around ?

HI Mikey,

All good points from JohnK re sealed vs ported (I've never heard a meaningful difference about the quality of low bass from either design, although that controversy has gone on for years). You'll gain an extra 3 dB in output by using a second subwoofer--subjectively, 3 dB is "somewhat louder"--so at its low-frequency limit there should be more output using both subs. But it won't change the low-frequency extension, unless you got different subs and one was capable of deeper bass.

The main advantage of two subs is in averaging out the variations in low bass caused by the room resonances that I spoke of before, so you get smoother low bass with fewer hot spots and areas of cancellation. If you use one sub in a "difficult" room (like all of them!), and you sometimes just move a foot or two on the couch, or sit in a different chair, it will signifcantly alter the amount, smoothness, and quality of sub bass you'll hear. So if you set up two subs carefully, it's a favor to others watching the movie. Everyone will experience smoother and deeper bass from different locations in the room.

Go into the archives of SoundandVisionmag.com and check out Tom Nousaine's articles on subwoofers and their interaction with rooms. He's a friend of mine and one of the most knowledgable guys on subs.

Regards,

Mikey, I agree with the previous replies of Alan and Jeff Kohn. Using two subs won't actually extend the response of each sub lower, but since two are reproducing the same frequencies those frequencies will be louder. Also the use of two might smooth out variations in room response. Generally the best place to put subs is right in the corner.

I'll just add that using 2 subs can sometimes help even things out, but it can also sometimes make things worse, because you can actually end up with cancellations, in which case you would end up with less bass overall, not more. If you're going to use 2 subs, placement is pretty crucial, and if placement options are limited due to aesthetics, WAF, or space, you might have some trouble getting optimal results.

Personally I prefer to deal with room peaks and nulls by using a parametric EQ, I use a BFD with my sub to get a flat in-room response that sounds really great.

To answer your question, Yes I think the SVS does well with both music and HT, but I don't want to get too involved in an SVS discussion here since this is Axiom's forum.

For some opinions on the SVS subs, you might want to check out http://www.hometheaterforum.com in the speakers and subwoofers forum. You'll find lots of positive opinions on Axiomi speakers there too.