Subwoofer's Front Firing vs. Down Firing


What are the benefits of a front-firing sub-woofer (if any) vs. a down-firing? Some have suggested that a front-firing sub may be easier and more flexible in it's room placement. Has this been your experience?
stickman451
It is literally impossible to hear a subwoofer in a room without hearing the room. By the time your ears have heard enough full cycles to detect the pitch, those long wavelengths have been around the room several times. Point being, it's always subwoofer + room that we hear, never just the subwoofer.

So what we want is a sub that synergizes well with whatever the room is going to do to it. Assuming we're talking about a single sub (there are major advantages to using multiple smaller subs, but I don't think that's on the menu here), probably the best we can hope for is a sub whose native response is the approximate inverse of room gain. That way, sub + room = neither broadly rising low end, nor broadly falling low end. We'll still have major room-induced peaks and dips, but that's another problem for another day.

Neither front-firing nor down-firing have any significant advantage as far as room interaction. Box and woofer being equal, the air mass underneath the cone will change the effective woofer parameters a bit, resulting in a slightly "fatter" low-end from the downfiring iteration, but that just means the designer would start out with a different woofer and/or different enclosure in order to meet a given target.

Back to subwoofer performance targets for a minute. It's been mentioned that sealed subs are better for high quality sound, and the presumption is that that's due to their superior transient response. But the ear's time-domain resolution at low frequencies is extremely poor (which is why we can't localize the source at long wavelengths - our two ears don't detect the arrival time differences down there). It's not really the transient response itself we are hearing; rather, it's the in-room frequency response (something our ears are very good at hearing). Vented sub + room often results in a rise in the deep bass, which sounds "slow", whereas a sealed sub + room tends to have a gentle falloff in the low bass, which sounds "fast".

You see, typical broadband room gain due to boundary reinforcement is approximately 3 dB per octave. So, based on the room + sub paradigm, we'd arguably want the sub's inherent output to fall gently at 3 dB per octave as we go down the bass region. This way sub + room = roughly "flat" (aside from room-induced peak and dips). Vented cabinets are often tuned for deepest loudest bass, so the room's +3 dB per octave tends to make them sound boomy. Sealed boxes typically start rolling off higher, but it's a gentle rolloff, often between 6 dB and 12 dB per octave, so it synergizes better with the room.

As proof that it's the sub + room, and not the sub itself, haul both subs outdoors. Now the sealed sub sounds weak and anemic, but the vented sub sounds faster than it did indoors - now the vented sub is clearly the qualitative winner. These are generalities, of course - there are exceptions.

Imo vented sub technology has the greater potential for good in-room bass because a vented sub can be designed to gently roll off by approximately 3 dB per octave from 80 Hz down to 20 Hz (before room gain), whereas such performance is not really possible from an unequalized sealed box.

Sorry for the long digression, and I know that's not the question that was asked. The imo theoretically ideal 3 dB per octave native rolloff can be realized with either a front-firing or a down-firing sub. So it's not driver location itself that matters, it's the overall system design and how it synergizes with the inevitable effects of the room.

Imo, ime, ymmv, etc.

Duke
dealer/manufacturer
Dear Duke,

I understand your story, but.....with the use of Audyssey Pro ( my way which it a lot different compared to the Audyssey way) I can play so much louder than without. Even with the most dynamic music I do not have the problems I had in the past without it. It feels like freedom because the limitations are almost gone.

Time changes and technique as well. I have proven that I have created a much higher level of integration. A few surround specialists has been here to listen to it. They were amazed that for the first time that what I call Stealth integration is possible. One surround specialist said; You have gold in your hands.

I use my subwoofer from 16 hz till 140 hz. The energy is so much better placed than most people can imagine. It is exactly comming from were it is, and it is more one with the speakers.

When I do test at clients there home without Audyssey Pro they all fail. They also have acoustic limitations. The integration is of a much lower level.

Using Audyssey Pro, Purist Audio powercables, New Wild Dog subwoofercable from Audioquest sets a subwoofer to a new level of integration!

The level of integration is the key to succes in integration!
What about dispersion 'efficiency' of a front vs down.

It would seem that a down firing is sending output in all directions - to the sides and the rear - and resultant interactions and add'l reflections with the front wall, equipment to the sides. Whereas a front firing would be more efficient at beaming energy/content into the listening area.

Just guessing....never tried any tests - but it is something I've wondered about front vs down firing.
Hi guys, I've been building speakers for 35 or so years, Dukes Explanation is accurate. I personally prefer a sealed sub when done correctly and well placed in a room, but vented/ported boxes have a better chance of easy setup. As far as Dispersion? Duke handles that when he talks of wave length, travel time etc. Bass has been around a room a couple of times by the time you hear it, that's why it has time to interact with the room and muck everything up. Bo is speaking on another level by adding an EQ/DSP room correction software. With this, you can analyze peaks and dips in your room and correct them electronically. Bo is doing something that I've never heard sound great in a 2 channel high end system... Crossing at 140hz... I normally target anywhere from 40 to 100 depending on room interaction, main speakers natural roll off or electronic crossover and the powered woofers own crossover slope on the top end... I hope this helps, Tim
I have a sealed downfiring REL, but I turn it upside down and use it upfiring. I find this to produce a more accurate, and quicker sound in my room. It's not in a corner either, but between the speakers. I do place a board on the upturned feet with something heavy on top of that.

Experiment, it pays off in spades.