Down Firing vs Front Firing sub?

[zoso0928]

I currently have a 7.1 home theater system and i am using a down firing sub.. My question is : I have a front firing sub in a box..which would sound better in my set up? TIA

[Fors*]

Originally Posted by zoso0928

I currently have a 7.1 home theater system and i am using a down firing sub.. My question is : I have a front firing sub in a box..which would sound better in my set up? TIA

Really neither should sound better as low frequency waves are non-directional. But room acoustics and location still play a pivotal role. So if you have one of each in a different location, more than likely it is the room influencing what you hear from them.

[kareface]

Doesn't make a large enough difference to matter. If you plan to isolate it I'd go with a front firing one.

[jomari]

front firing versus a down firing sub have no difference in regards to performance. what would be more essential is the proper placement to get the most out of either.

the only quirk a number of individuals have have mentioned is the gravitational effect on downfiring subs, and how they'd sag over time. im sure it will, but after a long period so to speak. nothing to worry about.

[Big Daddy]

The subject of front-firing versus down-firing subwoofers has been discussed several times before. Here is a link to my response in one of them.

https://forum.blu-ray.com/subwoofers...ml#post2676884

[Blu-Dog]

Originally Posted by zoso0928

I currently have a 7.1 home theater system and i am using a down firing sub.. My question is : I have a front firing sub in a box..which would sound better in my set up? TIA

Front firing if you can do it. Despite all the "it's all the same" talk, pounding energy into the floor from two or three inches away is definitely less efficient than directing it towards the listening area.

I have both types. Go front firing if it's an option for you. Having two subs, of both types, also can't hurt.

[Fors*]

Originally Posted by Blu-Dog

Front firing if you can do it. Despite all the "it's all the same" talk, pounding energy into the floor from two or three inches away is definitely less efficient than directing it towards the listening area.

I have both types. Go front firing if it's an option for you. Having two subs, of both types, also can't hurt.

Talk about energy pounding into the floor all you want, but there is scientific proof that bass waves are non-directional, so that statement becomes rather irrelevant. Did you try both subs in the same location when you made this decision? And may I ask for some kind of verification other than your own ears? Otherwise, this is just an opinion, which is fine, but nothing more.

Just a joke here, but Lancaster, PA > Lancaster, CA....

[Big Daddy]

Originally Posted by Blu-Dog

Front firing if you can do it. Despite all the "it's all the same" talk, pounding energy into the floor from two or three inches away is definitely less efficient than directing it towards the listening area.

I have both types. Go front firing if it's an option for you. Having two subs, of both types, also can't hurt.

Unfortunately, you are making the mistake of confusing subwoofers with regular speakers that generate higher frequency waves. For a down-firing subwoofer, it does not mean that most of the bass sound is toward the bottom and reflecting off the floor. If you place a front-firing subwoofer in the middle of a room and walk around it, you will not hear a lot of difference in front or behind the subwoofer.

The low frequency bass waves have very long wavelengths that are several times larger than the size of the driver and even larger than most HT rooms. The sound coming out of a down-firing subwoofer would radiate out like a sphere (omnidirectionally). Much of it would radiate horizontally from under the subwoofer. The floor and the gap in the bottom of a down-firing subwoofer act pretty much like a slot port.

[Blu-Dog]

Originally Posted by Big Daddy

Unfortunately, you are making the mistake of confusing subwoofers with regular speakers that generate higher frequency waves.

Actually, I'm not. The problem is, I'm not being specific enough.

Rare is the down-firing sub that doesn't have a port coming out of the side. Many people make the mistake of thinking the port doesn't make sound; it does, usually the majority of the sound output. Of course, you know this; I've seen you champion even more radical designs.

Many people say there's no difference in sound, because the port isn't facing the floor, and a huge amount of energy is coming from another direction.

Sound waves propagate in odd ways, based on more that just the frequency of the sound. Sound is energy moving air. Subsonic sound is not some freak of physics; energy is used, to move air, at a lower frequency.

This energy is diffused by whatever surfaces it strikes, either directly, or as secondary or tertiary reflections. If it's a floor, it rebounds, and immediately strikes against its source - the speaker driver. This sets up interference waves, a natural occurrence.

Being subsonic, this is a slower process than with higher frequency sound. Usually, however, it has greater energy, and if it "latches" - rebounds at the same frequency as the source, despite the delay - it can either amplify, or deplete, the sound source.

I have to note here that people are interested in risers for subs, and also discuss placing diffusing or absorbent materials below subwoofers, for this reason and others. Risers can also have an effect on front-firing speakers, but that too, is the result of characteristics of the room, including furniture and other objects that can reflect sound.

I personally find this feature easier to control with front-firing subwoofers, along with easier placement for finding the room's "sweet spot". I own and enjoy both types of subwoofers, and have dealt with this issue at length and under different types of circumstances.

Originally Posted by Big Daddy

For a down-firing subwoofer, it does not mean that most of the bass sound is toward the bottom and reflecting off the floor. If you place a front-firing subwoofer in the middle of a room and walk around it, you will not hear a lot of difference in front or behind the subwoofer.

There is a difference, however. More important, there is a difference in how a front firing subwoofer sounds from optimum listening positions. Since you've already dealt many times with issues of "room gain" in other discussions, I need not repeat them here. My own experience is that it's simpler to control subsonics with a front firing unit, and with more room for sound to propagate, I wind up with a less muddy result.

I would say it's less important for movies than with music, unless it's a large room - the larger the space, the more important it is to control the direction of the sound. I won't settle for boom boom boom; I want to sound to hit, then quit. Banging subsonics off the floor and waiting for the delayed tone to wander to my listening position via several reflected surfaces is a second-best solution, at least for me.

Originally Posted by Big Daddy

The low frequency bass waves have very long wavelengths that are several times larger than the size of the driver and even larger than most HT rooms. The sound coming out of a down-firing subwoofer would radiate out like a sphere (omnidirectionally). Much of it would radiate horizontally from under the subwoofer. The floor and the gap in the bottom of a down-firing subwoofer act pretty much like a slot port.

True, but the ideal empty, anechoic space where this might be optimized is not present in most home theater spaces. In the case of larger spaces, where delay from multiple reflections can cause serious time delay for the sound to reach the listener, it's a real issue. Subsonic waves, slow and powerful, can reverberate for a while. This is OK for the waterfall scene in "Apocalypto", but not so good for snapping rifle fire in a war film. The difference is detectable, and I've done A/B testing in two environments in my own home to determine this.

I used a dual Klipsch SUB-12 setup, down firing with a large port in each unit, and tried the same tracks and films against a JL Audio Fathom, which is a sealed front-firing unit. I dialed back the volume on the Fathom, since I wasn't testing for earthquake sound; I was looking for clarity.

The Klipsch units are excellent. They're fast and clean, if not over-driven. They will clip, and the huge port limits their range, but if dialed in right, they're terrific subs. But they induce delay - they can't "snap" sound, the way the Fathom can, an example being kick drums in music tracks.

I kept one, put it in a smaller HT setup, and gave the other one to my youngest son. My oldest advised me to get the Klipsch, he has one - and both of them have much smaller spaces for their main HT's that I do. I'd say that this topic depends on factors that are more than just the directionalty of the subwoofer.

It depends on the size of the room, the way sound propagates in it, the size of the subwoofer driver and resonance chamber, and whether or not it's ported. It also depends on the height of a downfiring subwoofer's driver from the closest reflecting surface, and the nature of that surface. I'll leave out more esoteric things like the crossover point, xmax of the driver, and power supplied to it.

I've been around the block with this more than once, my friend. And my preference for front firing subs is just that - a preference, based on experience, not a condemnation of any style of subwoofer.

[Blu-Dog]

Originally Posted by Fors*

Talk about energy pounding into the floor all you want, but there is scientific proof that bass waves are non-directional, so that statement becomes rather irrelevant. Did you try both subs in the same location when you made this decision? And may I ask for some kind of verification other than your own ears? Otherwise, this is just an opinion, which is fine, but nothing more.

Just a joke here, but Lancaster, PA > Lancaster, CA....

Dude, I was trying to check the weather on the Web, didn't put in the "CA", and found out it was snowing outside!

freaked me out when I looked out the window, not a cloud in the sky

Now I just put in the zip code, it's better for my nerves.

[Blu-Dog]

Originally Posted by Fors*

Talk about energy pounding into the floor all you want, but there is scientific proof that bass waves are non-directional, so that statement becomes rather irrelevant. Did you try both subs in the same location when you made this decision? And may I ask for some kind of verification other than your own ears? Otherwise, this is just an opinion, which is fine, but nothing more.

First, give me this "scientific proof that bass waves are non-directional"...

Low frequency sound carries a lot of energy, for long distances. They're directional, for obvious reasons, since they have a source. The thing about subwoofers is that these waves can rebound, and each wave front - rippling along, one behind the other - can actually magnify the sound, since it takes a long time to diffuse.

This is why people think that low frequency sound from subwoofers is non-directional. They can't tell where the source begins, or the difference between the primary wave, and one that's being reflected. But it has a source, and a delay from the time it leaves that source, and either goes straight to your ears, or reflects off of something and then reaches you.

Anyway, I've tested both types of speakers three ways:

Down firing alone;
Front firing alone;
Both units in tandem.

I tried two identical down firing units in tandem, on their own, and in tandem with my front-firing sub, and then just the dissimilar units paired.

In a large room, my living room/main theater, the front-firing unit won, hands down. In an even larger area - my "family room" area, where the kitchen, family area, and dining room share a huge open space - I got good performance from a single down firing sub, and I'm still using it. The saving grace for it is that it's in an open space - basically, the middle of the area - with the wall spaces in odd location, setting up sound reflections so odd that delays are so long the sound dissipates before it becomes a distraction. It acts like a smaller space than it is.

I've done this with other subs, and simply won't go the down-firing route again (I've owned three). But I'm not getting rid of the one I have, it's very nice.

[Fors*]

Originally Posted by Blu-Dog

First, give me this "scientific proof that bass waves are non-directional"...

Low frequency sound carries a lot of energy, for long distances. They're directional, for obvious reasons, since they have a source. The thing about subwoofers is that these waves can rebound, and each wave front - rippling along, one behind the other - can actually magnify the sound, since it takes a long time to diffuse.

This is why people think that low frequency sound from subwoofers is non-directional. They can't tell where the source begins, or the difference between the primary wave, and one that's being reflected. But it has a source, and a delay from the time it leaves that source, and either goes straight to your ears, or reflects off of something and then reaches you.

Anyway, I've tested both types of speakers three ways:

Down firing alone;
Front firing alone;
Both units in tandem.

I tried two identical down firing units in tandem, on their own, and in tandem with my front-firing sub, and then just the dissimilar units paired.

In a large room, my living room/main theater, the front-firing unit won, hands down. In an even larger area - my "family room" area, where the kitchen, family area, and dining room share a huge open space - I got good performance from a single down firing sub, and I'm still using it. The saving grace for it is that it's in an open space - basically, the middle of the area - with the wall spaces in odd location, setting up sound reflections so odd that delays are so long the sound dissipates before it becomes a distraction. It acts like a smaller space than it is.

I've done this with other subs, and simply won't go the down-firing route again (I've owned three). But I'm not getting rid of the one I have, it's very nice.

Nice about the snow in CA...you can have it! WE have had about 70" so far this year (a record) and we are getting another 6"-9" tonight!

I think you will agree that what you have found in your room is limited to your room. You know bass waves will interact with anything and everything in the room, and any reflection your hear from the subwoofer is a result of where the sub is located in that room and limited to that room. What bass waves you hear interacting in your room may not be the case in another room.

I'm not at all doubting what you hear and tested, but I don't think it is completely fair to totally encompass all bottom firing subs as sub-par in comparison to front firing ones.

One of the reasons I say this is because I have 2 cylinder subs from SVS, and the port is on top. I don't know if you have ever tested or heard one of these, but I feel fairly certain that there are no reflections of bass waves I have picked up when have used my SPL meter and REW. However, I would love to get the SMS-1 someday to get down to the nitty gritty of it all.

[kareface]

So many things that I want to say, but I'll keep it short and sweet for sleep sake.

I ran a test to see how much the drivers position matters, at least in my room. The receivers EQ and the PEQ are both off, I'm only running one of the subs, I moved my couch to get more space for the sub, the position of the sub was measured to match each time it was shifted based on the distance from the 2 closest walls, in all the tests the sub was raised the same height by the same pieces of foam and the microphone was not moved for any of the tests. The sub I'm using is also available with the same driver in a down firing cabinet. The sub was the only speaker being used, crossover was set to 120hz. The sub used is sealed. Carpet floors as you can see below.


Microphone at what is normally the primary listening position. The couch is moved to allow for greater space in front of the sub.


That's about as good as I could get spacing wise with out moving my theater back upstairs, lol.

Results with no octave smoothing.

Front firing (aiming forward):


Front firing (aiming backwards):


Down Firing:


Combined:

Zoomed in to highlight the areas of greatest deviation.

This is simply the results from a single listening position. It's quite clear that the direction of the driver has an impact on the response. It's interactions with nodes seem to be exaggerated depending on the drivers position. I don't have a the average room because of the supports for the house. However, if sound was truly radiating evenly from any side of the sub then the rooms unconventional shape shouldn't matter. I would argue that below 50hz, it's likely omnidirectional as the deviations are quite small (with the exception of the front test, which can be explained in large part by the fundamental resonance). If you can think of any more tests I'll be happy to oblige. I'd wager the further you got from the source the less the direction of the driver would matter. However I have to take the driver into account in my small room.

[Fors*]

It seems the front firing, aimed forward had the largest null, at around 60Hz, would you agree?

[kareface]

Originally Posted by Fors*

It seems the front firing, aimed forward had the largest null, at around 60Hz, would you agree?

In this instance, that isn't to say that every situation would end up this way. Moving the sub 1/2 a foot to the left might cure the problem only to created a null when it's faced to the rear. This graph isn't to prove that one direction is best, only that there are deviations between them and proper testing should be done to find the best results. In that vein, down firing might be more limiting, but only in the sense that not being able to move the sub around the room would be limiting for the same reason.

[Fors*]

Originally Posted by kareface

In this instance, that isn't to say that every situation would end up this way. Moving the sub 1/2 a foot to the left might cure the problem only to created a null when it's faced to the rear.

Underlying the importance as you stated of the room itself and the sub's location. But based on your results in your room, to me anyway, I would say the bottom firing sub performed just as admirably as the front firing ones.

Blu-Dog, I hope you don't think I am agruing with you. I am simply "defending" my opinion of bottom firing subs and their performance.

[kareface]

Yeah, I don't think the difference matters enough. If you are limited on where you can move your sub, it's going to be random chance if the sweet spots you can find are tailored more to down or front firing subs.

Edit: The most ironic thing is the point that should have resulted in the greatest deviation, the down firing, was closer in results to the rear then the front was. I might redo the tests with some solid surface below the sub, but not tonight.

[Fors*]

Originally Posted by kareface

Yeah, I don't think the difference matters enough. If you are limited on where you can move your sub, it's going to be random chance if the sweet spots you can find are tailored more to down or front firing subs.

Edit: The most ironic thing is the point that should have resulted in the greatest deviation, the down firing, was closer in results to the rear then the front was. I might redo the tests with some solid surface below the sub, but not tonight.

I was thinking the same thing about the down-firing results being soo comparable to the rear in their results. I'll be looking forward to the results in other locations......

I have a strong affinity to my SVS cylinder subs, so I may come off more strongly than I usually do otherwise. If any of my comments seem as such, please know that this is the reason. But what can I say, I think they are great subs!! I think a few other members with them would agree with me as well.

[Blu-Dog]

Originally Posted by Fors*

Nice about the snow in CA...you can have it! WE have had about 70" so far this year (a record) and we are getting another 6"-9" tonight!

sheesh...my definition of a nightmare...

Originally Posted by Fors*

I think you will agree that what you have found in your room is limited to your room.

I tested this at my old home; and two large rooms in my new one. Very different configurations, and in the old home, different subs. It's not a one-shot deal for me.

Originally Posted by Fors*

You know bass waves will interact with anything and everything in the room, and any reflection your hear from the subwoofer is a result of where the sub is located in that room and limited to that room. What bass waves you hear interacting in your room may not be the case in another room.

That's why I tested multiple configurations, in multiple rooms. Subs were moved to different positions.

Originally Posted by Fors*

I'm not at all doubting what you hear and tested, but I don't think it is completely fair to totally encompass all bottom firing subs as sub-par in comparison to front firing ones.

"Sub-par" is a bit wicked as a condemnation, as I thoroughly enjoy my Klipsch sub. The point is, most higher end subwoofers are not ported, and not down-firing (see offerings from Klipsch, Martin Logan, Definitive, JL Audio, Velodyne, etc. etc.). This allows flexibility of placement, especially in larger areas. Small areas do fine with any sub source, at much lower cost for down-firing models.

Originally Posted by Fors*

One of the reasons I say this is because I have 2 cylinder subs from SVS, and the port is on top. I don't know if you have ever tested or heard one of these, but I feel fairly certain that there are no reflections of bass waves I have picked up when have used my SPL meter and REW. However, I would love to get the SMS-1 someday to get down to the nitty gritty of it all.

SVS is in a different realm. I've been discussing this generically - not by model. You won't find SVS at Best Buy...and I wouldn't mind finding one in my house!

[Fors*]

Originally Posted by Blu-Dog

sheesh...my definition of a nightmare...



I tested this at my old home; and two large rooms in my new one. Very different configurations, and in the old home, different subs. It's not a one-shot deal for me.




That's why I tested multiple configurations, in multiple rooms. Subs were moved to different positions.



"Sub-par" is a bit wicked as a condemnation, as I thoroughly enjoy my Klipsch sub. The point is, most higher end subwoofers are not ported, and not down-firing (see offerings from Klipsch, Martin Logan, Definitive, JL Audio, Velodyne, etc. etc.). This allows flexibility of placement, especially in larger areas. Small areas do fine with any sub source, at much lower cost for down-firing models.



SVS is in a different realm. I've been discussing this generically - not by model. You won't find SVS at Best Buy...and I wouldn't mind finding one in my house!

All valid points, and I find the results you got to be interesting to say the least. With your statement about "generic" subs, and those being the subwoofers you have been talking about, I have a better understanding of what you mean.