Subwoofers - Front Firing or Down Firing - Which Sounds Best?

@geoffkait 

Thank you for sharing your experience of 4' concrete cylinders.

Aside from a Geoff K DIY cement open baffle one needs a with a proper amp and XO = $$$$- $$$$$

My 2 SVS 12' subs (Ultra and Plus) suck primarily because the volume control comes on at full blast when barely opened from zero. Impossible to blend, making the built in XO adjustments moot. I thought to remove the cabinet and do open baffle DIY, but...

In the meantime, Emerald Physics has several open baffle speakers with double 15" carbon fiber woofers. I am awaiting arrival of 2.8s before doing anything with the SVSs

I think you will probably find every sub added brings improvement. My initial plan when building my DBA was to sell my Talon Roc to offset the cost of the four DBA. So when the subs went in the Talon went out of the room. The four were amazing! But then just being curious I decided to try with 5. The Roc went back in. Wasn't expecting too much. The literature after all says going from 4 to 5 should only be a very small improvement. What I heard though, or more accurately what I felt, was not small at all! Most amazing of all was the definite feeling that the bass I was getting with 5 was so much lower than anything I ever felt was coming out of the Talon at any point ever.

I think what happens is any one sub on its own, it does go very low but because of room resonances does so at a much reduced level. Then we get a double-whammy because of the way human hearing works, Fletcher-Munson equal loudness counters rise a lot at low frequencies. In other words really low bass has to be quite loud in order to be heard at all. We simply aren't that sensitive to it. But then the instant it crosses that threshold where we do hear it, wow! Impressive!

So more subs increases the lowest frequencies to where we can really hear them. 

Well I tried my "mini swarm" today. I brought my 12" Polk sub (HT sub) into my music room, hooked it up and (sound of air coming out of balloon) my B&W sub wouldn't turn on. I was doing some electrical work this week (throwing breakers) and thought I blew a fuse. I opened up the B&W and found a wire looking like it was not connected (to the driver) but inspected the fuse anyway (a LOT easier said than done). Anyway, got everything working and Tool's "46 & 2" never sounded so good. Gobs of bass! Will need to optimize things (ordering another Polk) but looks very promising. Don't have room for the "holy grail" of four subs but think the matching Polk's should keep me happy for awhile. Party on Garth! 

I have a down firing woofer that I can just lay on its side, and experiment with positioning.  I've found that facing it forward helps it blend just a bit better with the mains, but I keep it pointed down for aesthetics.  While I doubt the phase means much at 30Hz, how the driver is facing relative to your mains at 100-200 Hz will change the integration.  Sure, your sub crossover may be set for 80Hz, but that's only its -3dB point.  It still will have some audible output at 150-200Hz.

And don't believe that "Sub is omnidirectional, so you cannot localize where it's coming from".  THAT IS FALSE!   The first part does not begat the second part of that statement.  YES, bass is omni.  It will eminate from the subwoofer in all directions equally.  But that does not mean that you cannot localize it from your listening position.  That's an entirely different thing!  The BEST is to have STEREO subs alongside your main speakers (or 1 sub in the middle).  This will expand your soundstage tremendously.  For me, having a sub off to one side makes me feel uneasy.  I can feel the pressure differential in my ears. 

I like the design of the REL subwoofers. Rythmik would also be another option.

I bought a Rythmik F12G from an A'gon member a few years ago.  He told me something about setting it up that was spot on and relates to the earlier reference to time and sound waves. He told me to add a few feet when it came to any room EQ setup where the distance between the speakers/sub and listening position was  adjustable.  My room EQ automatically adds about 1.75' extra feet to the distance.  I played around with it and eventually landed on adding 8-9' to the distance between the sub and the setup mic.  Actually it's something like 8.3 - 8.7 feet depending on how I have the room arranged furniture-wise.
I have been been able to integrate - for lack of a better word - my single Rythmik sub between my MMGs through this added distance and it truly incorporates itself quite well.  The integration is MUCH tighter after the additional distance, the lower frequencies do a much better job of disappearing and melding into the music, and it makes for a fine two-channel listening experience (to me).  The sub is spec'd to extend to 14 Hz and is highly adjustable.  I set it at a 20 Hz extension (with high damping) for the Bach pipe organ music I occasionally treat my cross-water neighbors to, and it does a fine job of rattling the wall hangings (it that happens to be your bag).
I don't happen to have the room for a swarm in my listening room (that happens to double as my living room) nor do I particularly want one.  I'm quite content with what I ended up with after much research, adjusting and listening.  But you CAN achieve perfectly enjoyable results that sound very, very good with a single sub when faced with certain limitations.

I have one set that is downward firing (a pair of woofers mounted face to face (isobaric on a vertical axis, vented laterally) and one set that is forward firing and find no significant difference between them.  It is more important that you have two of them than which way they point, IMHO.

@shakira - Nice response! Simple, clear and to-the-point! I like that...

It depends on the driver. Drivers with stiff suspensions can fire downwards fine. Those with looser suspensions are better off front firing as they may sag mounted downwards and the driver becomes non linear. Given a driver that can go either way there is little if any difference. More important is that the driver have one edge right up against a wall or corner. Then multiple drivers and finally room control. The radiation pattern of the sub should match that of the satellites. Point source speakers should have a point source sub system. Line source speakers require a line source subwoofer system. A Line source sub will dominate a point source satellite and a point source sub will get lost under a line source speaker. 

I find down firing subs are good for 
Home Theater and Front firing subs 
are good for two channel music.

     Since I use physically time-aligned B&W 803's, I have my subs positioned to be in phase with the main speakers.  To do this, I measured the center of the B&W magnets, which are all the same, and the subs, then measured where to place the subs.  Of course, I then had to determine whether to place the subs inside or outside the speakers, and finally decided on under them. It worked the best, largely because my speaker room floor is several inches lower than the living room into which it is open through a 12' x 14' hole in the wall (Actually, a lack of a wall).     Otherwise, I would have to use a high chair, but I might just have done that, but probably would have kept them between the speakers.

Love my down firing REL T/5i. Everything it’s cracked up to be. Hi-level Speakon input, 120 W A/B power with precise rotary click control of volume and roll-off, corner mounted, with a unobstructed plane of 100 year old maple extending 20 ft in front of it. Super fast long-throw lightweight 8" speaker.

The REL compliments my towers, creates a base source that is centered in the sound stage between the towers despite a distant position on the sub. I am amazed at how close this experience is to John Hunter’s claimed performance. Great company, great products, IMO.

The fact that the listener can’t locate the sub once everything is adjusted in the room is magic to me.

noromance: I know you have a lot of concrete in your rack. But if it's sitting on bouncy floors, what then?

Well what then is mass equals inertia. That much mass simply cannot be moved very fast without a great deal of energy. Way more energy than a bouncy floor. That much mass can only be moved slowly. The effect of massive concrete and damping sand combines to drive all energy into a very low fundamental resonance frequency range. You can see this in action. Stamping or jumping on the floor does move the rack. But it moves very slowly, and very subsonic, around a few Hz.

The response of this massive rack on a suspended wood floor is actually better than a lightweight rack on a solid concrete floor. Because the lightweight rack is subject to vibrate from acoustic energy. Also I lived for years on concrete enough to know even concrete slab can still move and if it does the lightweight rack will transmit that energy right up to the table. A massive rack will absorb and dissipate that energy into its mass.

So that's what then.
btw, I never have recommended "using any old subs". What I have said is they don't need to match, and more is better than few. Which is true.

I know the experts say it ain’t so but my old mirage with 2 opposite side firing woofers does a really good job without needing any room correction software.

I’m no expert, but I’ve also never felt this was a must. Rooms vary, and subs vary in how deep they go, as does placement, and choices of material to play. I’ve lived in one apartment where EQ was 100% necessary due to a 20 dB peak in the 25-30 Hz range. 20 dB!! In this apartment with an open layout, and bass traps I only need to do modest adjustments.

Room acoustics, equalization, and placement are good tools to have handy when this doesn’t work out. Far better than attempting to fix problems with power cables or cycling through subwoofers.  Also, the one thing almost all automated tools do very well is set up the crossover points and delay/phase matching. That's a real tough one for many.

Best,
E

I know the experts say it ain't so but my old mirage with 2 opposite side firing woofers does a really good job without needing any room correction software. That said I needed a sub to double as an end table in the family room and bought an entry level paradigm 15" with arc that doesn't draw to much attention to itself.

I like the design of the REL subwoofers.  Rythmik would also be another option.  However, no dealers carry them to listen to them.

Here you go:

http://usr.audioasylum.com/images/0/4120/Me___HQD.jpg

Get yourself a couple of Hartley 24" subs and you will have all the bass you need, I would guess...

Cheers!

(Full disclosure:  We made some cabs for these back in the day..not the ones in the pics.  Ours were about 5.5' high and weighed in about about 200 lbs each...they were tanks!)

i found that the direction the driver aims has an impact on the quality of the bass.  front facing subs, in my room, projected and distributed the impactful, tight bass out into the listening area the best.  
some people even adjust the angle of the axis to get the best results. 

Syzygy subs, fires front or down, your choice, control from your seat, and EQ. Sealed and fast. 

I have had two rear firing subs placed between my speakers for years.  As I started more critical listening, I noticed dips.  I purchased corner bass traps.  This really evened out the response.  Then I talked to GIK and have purchased bass traps which go on the front wall at floor level.  The subs will fire bass into these traps first.  Panels are about 16 inches away from the ports of the subs  I was assured that this will only improve the bass not reduce it.  Actually the first reflection panels and rear diffusion panels are also listed as bass traps as well as higher frequencies.  I will be interested to see my outcome.  They arrive in mid June.  COVID has helped GIK with orders!

Get 2 subs. If your speakers could go as low as you wanted, there would be a driver in each speaker to accomplish that. For a few years I tried to integrate a single sub in my system, different ways of connecting it, even different subs, always fiddling with settings, taking it in and out of the equation. Then I got 2 down-firing subs, placed them on the outside edge (not touching) close to each speaker, on tile squares (as speakers). Tried to place them as close as I could if they were actually part of the speakers. Problem solved. They sound great and very well integrated. I am not a big bass fan at all. My speakers are rated down to 38hz. Just needed that little extra low if it is part of the recording. I am sure all the other suggestions are great, this was just my experience with 2 vs. 1. Have fun!

If you live on a ground floor ...Step 1 Buy a chainsaw /Step 2 Cut a hole large enough to house your hi-fi on through the floor /Step 3 Pour concrete in the hole to create a stand for hi-fi /Step 4 enjoy/ or repurpose your fireplace.

@eric_squires.  😂🤣

It's just me and the sweet spot fuzzy. Going to give the "swarm" a try first.

One 15" can give you what you want?
If you want good bass in one position only and a wife bitchin' about the whole house booming/pressurized, have at it.

Great start!
Worth losing the plant stand.
Don't worry about symmetry. Unless you mean visually.

How does this sound: My B&W "12 inch" ASW-650 plus a spiffy Polk 12 incher recently purchased for HT and the four six-inch woofers in my B&W 804d3s? Is this "swarm" enough? If it works, I could swap the B&W for HT duty and get another Polk (for symmetry) for the main two channel system. I'd be losing the plant stand, however.

It seems the room size is also a concern for the OP.

My room is (10 x 14) minus closets. Tried several subwoofers of different sizes, configurations, etc.

I couldn’t get any of them to just add bass without things sounding muddy. I pulled everything out of the room to lay down carpet. Perfect opportunity to test the subwoofer anywhere in the room.
The carpet helped a bit but it still sounded pretty bad.

My DBA order came in stages. Two subs arrived first. I hooked up just one of them, listened, played around with the crossover, gain, etc.
Didn’t sound good. Got near acceptable results in my listening chair after moving the sub around.

Hooked up the second sub, listened, played with knobs, ...
I never had more than one sub so was very curious to listen for any differences.

The 2nd sub made a big difference. Less muddy. A bit faster.
It actually sounded pretty good. This, I could live with. Easily.

A few days later, the 3rd and 4th subs arrived.

2 subs are up on heavy duty steel wire shelf units facing the ceiling.
1 sub is on a long shelf on the wall behind me also facing the ceiling.

The last sub is on the floor next to my desk facing forward and supporting a nice lamp.

I look forward to hours (days?) tweaking the sub positions (especially different heights for the ceiling subs).

It was suggested by Duke at AudioKinesis to try varying the heights of any ceiling facing subs as this affects dispersion in the vertical plane.

But even after muscling up 3 subs to their respective perches and putting the 4th sub down by the desk, no placement tweaking as my back was protesting, the bass sounded great.

Didn’t play around with ports, polarity, phase,...

This is very noticeable. I now can hear cellos, tubas, trombones, bass guitars, etc. with much greater detail.

It’s like hearing more "things" on your favorite record on a "better" sound system at a store or show.

But now the more "things" you hear are coming from the bass frequencies.

Further, multiple subs, properly placed, will open up the soundstage.

My little Maggies (LRS) make the room sound larger.
The subs make it sound even larger but also more full.

The effect is really amazing! Actually regained more space in here with the shelf units!

OK. Do you really need to go for a DBA?

Or will adding just a second sub do it for you?

For now, I would just add another sub. Spreads the load. Evens out the bass.

As millercarbon indicated, don’t worry about "matching" the subs.
See if you like it (2 subs vs 1 big sub).

Do your research. I did and found the science behind it supports why rooms (especially smaller rooms) benefit the most using multiple subs.

Then, later on, borrow another sub or two to experiment with.
If you like it, you’re just a few subs away from a DBA.

And yes, 4 subs will rattle your windows!

@millercarbon 5" is what I have so I only speak from experience.
I know you have a lot of concrete in your rack. But if it's sitting on bouncy floors, what then?

Bass is Omni directional in low Bass your room and how solid the floor is has more to do with it then front or down ,on my ML speakers it had front and rear subs with room correction for bass.

Nix the down firing. That produces the most floor interaction which muddies the bass and obscures the midrange most especially with the suspended plywood floors found in most modern construction homes.

Interesting. Except mine fire right into the walls, as do Tim’s, as do all of Duke’s, and there is another very similar DBA design that fires down into the floor. The one thing they all have in common is exceptionally clean, clear, articulate and fast bass. The opposite of muddy. Oh well. Think and is don’t always agree.

You can’t have a good turntable rig on suspended floors. You can bolster it and reinforce it but there’s no beating 5" of concrete.

Okay. If you say so. But who says it has to be in the floor? And why only 5"?
https://systems.audiogon.com/systems/8367

I'm trying out a single Syzygy 10" subwoofer, with a stereo system on a concrete slab and engineered red oak flooring. The room is not exactly rectangular, but it's basically 18' W X 28' L X 9' H.
1)The single sub sounds best when it is adjacent to or between my stereo speakers, but the exact location does not make a lasting difference. (I can move the sub and think the new position is better, but the next day I can move it back with the same effect--I can't find a single best location.
2) There is a difference in the sound between forward firing and down firing, but it is more about the music than a single best presentation. For rock, forward-firing in-your-face bass delivers, but that doesn't mean it's better overall.
3) It is a fairly advanced sub which reads and graphs the room and is controlled by a smart-phone (which means one can listen anywhere in the room). The sub itself may be optimizable for the room, but it does not blend well with the stereo speakers. I can get drama--not a problem for Star Wars--but it's annoying for serious listening.
4) The experience has helped me understand why multiple subs would do better than one, and how the placement of multiple subs would be easier than one.
5) At the same time the experience has helped me understand how better quality--"faster, taut, deeper, and more musical" could help, and probably more than equalization.

+1 You can't have a good turntable rig on suspended floors. You can bolster it and reinforce it but there's no beating 5" of concrete. I tried once. Now I'm in the basement.
Not sure I agree with using any old subs, @millercarbon. I replaced an older REL sub with the new S3 and it is in a different league. Faster, taut, deeper, and more musical. 

I built downward firing 4’ high cement cylinders with 8” drivers mounted in the bottom, raised four inches of the cement floor. Awesome sound, like cannons going off. Tighter than a bull’s you know what. 🐂 The back wave reinforces the motion of the sub.

Tip for the day: never move into a place with suspended wooden floor where your hi fi is going to be. Think ahead. 

Nix the down firing. That produces the most floor interaction which muddies the bass and obscures the midrange most especially with the suspended plywood floors found in most modern construction homes.

Sound travels at 1125 feet/second per Wikipedia. That means wavelength is 56 feet at 20 hz and 14 feet at 80 hz. Resonances are caused by reflected waves reinforcing the direct wave. If your room has, say, a 37.5 foot dimension, expect to have a peak at 30 hz, 60hz, and possibly higher multiples of the resonant frequency.

When I was in my twenties I bought a real time analyzer and measurement mic so I could test the calculations. In that period I upgraded from B&W N804s to B&W N802s. That was a change from a front port to a down port. Since the port output is at subwoofer frequencies I consider this a reasonable comparison. The 804s had atrocious in-room measurements. They were actually flat at 20hz. All over the place from 20-100hz. 30db swings in my room. The 802s measured far, far better in the deep bass. They were actually very close to the published spec. They hit the -3db point at almost exactly the published point and the overall deep bass measurements were far smoother. The only plausible explanation is that the down-firing port doesn’t excite resonances to nearly the same degree as a front-firing one. Which means direction matters, even at very low frequencies.

freq/length in feet
20 56.25
30 37.5
40 28.125
50 22.5
60 18.75
70 16.07142857
80 14.0625

I'm pretty sure a single 15-inch SW will give me what I want. But being retired, cost is a consideration. In my smallish (12 X 13) room, I could use the tube SVS as a plant stand and it doesn't take up much room (as well as being affordable). Thanks to all for the replies! 

Yes, I actually bother to read such drivel. Otherwise, how you gonna know its drivel? We read him so you don't have to!

Knowing I have the power to make @millercarbon 's knee jerk whenever I want to, as often as I want to is what keeps me going.  I feel like I can bypass his frontal lobes and directly stimulate his knee-jerk response long before he has the opportunity to process anything consciously is a little overwhelming.  I love it.

OP,

You didn’t say anything about your room dimensions. The 200 watts, single sub probably inadequate (don’t think you want to rattle your windows...lol). I would recommend adding a second sub to improve bass response.

I am using a pair of REL’s (500w) in a room 30”w x 15”d, they produce very musical bass and complement my main speakers fabulously.

@dweller .
I would suggest the new Vandy 3 subs. Though not inexpensive, it should give you the ability to get those 20-ish frequencies, as well as integrating seamlessly with your speakers with the integrated equalizer. Though, you do need to buy the high pass filter.
And, Vandy subs are built like tanks, so they should last 20 years, at well.

Bob 

That's where I was. Had one Talon Roc sub that seemed to do everything right, except it just wouldn't go low. Exactly like yours, it was just way down at those low frequencies. It is, or was at the time, a really highly regarded and powerful sub. Oh well. 

The solution was to add more small subs. With those the bass extends so low and flat and articulate its hard to believe. Its not just that there is more volume and deeper, there is definition and character way beyond anything I ever even imagined was there before. Its not me, and its not my subs. All the guys who have done this have the same experience. Its the DBA. Just get more subs. You will see.

I'm totally happy with what my single B&W sub is doing. I only wish it would go lower. Technically, it is producing sound in the lower, 20-ish, frequencies but probably down 5db or more. Its amp+cone just can't pump out the gusto. The 200 watt ASW-650 is nominally a twelve inch cone. Actual measurement is more like 10 1/2 - 11 inches. That's kind of meager by today's standards. I'd like something (or two) that will occasionally rattle my windows. That's all.  

Its not the manner. Its the frequency. At low bass frequency the wavelengths are as long or longer than the room. So long that no matter where you put the sub or what direction the sound travels out and reflects and can even return all the way back to the sub even before one full wave cycle.

Then add onto that the fact these low frequencies do not even register on human hearing at less than a full wavelength.

Put it all together, this is why it doesn’t matter where the subs go relative to the stereo speakers. Because timing is not a factor. Cannot even be a factor!

What is a factor are the room modes. Room modes happen because the room is smaller than the wavelength. So they bounce around and reinforce and cancel. This is why people find it so hard to figure out where to put a sub. They have to keep moving it around trying to find the one spot where it gives the smoothest bass. Then they get confused and say its coherent, or matched, or synchronized, or integrated, or whatever. They got a million terms. None of which is right. Because they are all based on the same false understanding, the one that applies to short wavelength midrange and treble not low bass.

This is why "you know the answer" dweller is multiple subs. Multiple subs allows you to place them in different locations around the room. Each sub in each location has its own lumpy bass response because of the modes. But each one is a lot smaller because each one puts out less bass because there’s more of them. So they all average together into one extremely smooth bass response.

This cannot work with EQ. All EQ can do is make bass smoother at the one place its measured- but at the cost of making even more bass somewhere else. This excess bass hangs around until it fades out, in the meantime muddying up the bass. So you pay big money for GIK trying to soak up the excess bass you paid big money to create with the EQ. This is the old school solution still being promoted by people who can’t be bothered to learn something new.

Buy whatever sub puts out the most bass for the money. Buy as many of them as you can afford. Put them in different locations around the room. Point them whatever direction you like. Just so there’s at least four of em.

Some where I read that the manner in which low bass propagates from a woofer reduces any meaningful differences between bottom firing or front (or rear) firing. I can't recall my source -  

If you have carpeted floor a down-firing subwoofer would be a bad idea.

The gift that keeps on giving-

But I Still Want a Subwoofer! That's fine, get one.

Yes, I actually bother to read such drivel. Otherwise, how you gonna know its drivel? We read him so you don't have to!

In my experience down-firing is less likely to excite room nodes.  I assume because they essentially fire in four different directions rather than one.  I would speculate that in a perfect room, front-firing would be best because you could line it up perfectly with the mains and have a perfectly in-phase wave launch.  In practice I imagine down-firing is better in a lot of rooms.  

The sub that is best integrated into the room. Room acoustics, configuration, EQ and placement all matter more than the type of box (sealed vs. ported).

Here are my thoughts:

https://speakermakersjourney.blogspot.com/2020/04/how-to-not-buy-subwoofer.html

Interesting. Any more opinions?