Down firing vs side firing?

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I don't see how a downfiring sub is more stable, can you please explain what you mean?

I have read that manufactured downfiring subs have the suspension biased to account for the potential sag, but I really don't think thats much of an issue. I would say, if the sub is working from 60-80hz and lower, having it downfire shouldn't affect sound any, as long as it had a clear path underneath it. You don't want to burry your driver in deep pile carpet. The advantages of such a setup are that its protected from hands, it transmits vibrations more effectivly to the floor, and if the floor is carpeted, it will absorb higher frequency sounds from the driver, making it harder to detect its location.

The downsides are that a lot of people feel it sounds worse. Again, I can only see this being so in the higher bass frequencies, but its possible that higher harmonics still produced by the sub play a roll in our perception of bass instruments, and that the downfiring position absorbs those. It's also possible that it effects the FR, but again, I've never seen anything to really suggest that.

I don't happen to like downfiring subs myself, but its a subjective reason. I couldn't give you a good technical reason why. My last subwoofer design was downfiring, my current one faces forward. So many variables changed between those two designs, that I don't know what caused what, but I like the new one better. It has much better upper sub-bass sound. I did try firing it toward the floor by supprting its front on wood blocks, and I didn't like the sound as much, so thats the best A/B test I ever did, keeping everything equal, but again, I have no techincal explenation for the differences I heard.
 
Tee-Bruce said:
What are the advantages/disadvantages of a down firing sub vs a side firing sub? Would it matter if the port fired down into the floor? Just trying to find some middle ground for HT and music use. I have a JBL PB12...trashed the amp...just wondering!


Down firing is "acoustically loaded" more efficiently than a side firing woofer. By that I mean a down firing woofer will have a better transfer of energy from the mechanical device to the acoustic pressure wave.

The DF woofer will displace x amount of air under the enclosure which in turn will push more air on the sides of the enclosure. Similar to a horn loaded design.

A "free firing" woofer is trying to pressurize the entire room immediately verses the confined space beneath the enclosure.

Same woofer in optimal SF and DF boxes, the DF will give more pressure. Might not sound as good, but should generate more pressure.

I use front or side firing but that is preference. I'm about to make a dual 8 DF for under a couch..

BTW, I'm in Lafayette.
 
One advantage that I can see for the DF is it can be anywhere on the floor it needs to be, to fill up the room with bass, even in the middle of the room. Now whether that outweighs all the other downsides is something that may have many different opinions.

Regards//Keith
 
I've had both DF and SF subs, and I prefer SF. The reason is that I just cannot get my head around the fact that I feel that downward firing subwoofers must surely have to contend with some kind of back-pressure, call it 'pressure echo' (my new phrase of the week), :) coming back at the cone from the floor.

My feeling is that that this 'echo' would mess with the cone's intended travel as it attempts to reproduce further notes to some [small] extent, thus inducing distortion.

Has anyone here ever read of any tests / evaluations of said ‘back-pressure theory’?

Andrew D.
www.cdnav.com
 
digitalfrontier said:
....

My feeling is that that this 'echo' would mess with the cone's intended travel as it attempts to reproduce further notes to some [small] extent, thus inducing distortion....

Andrew D.
www.cdnav.com


Horn loading, slot loading and boundary loading have been around for quite some time.. All work well when designed appropriately. They (including down fire) are not standard / typical text book designs. They require much more engineering to be "right".

Side or front mounting is MUCH easier and ALMOST idiot proof.. But as I have demonstrated time and again, idiots get more and more creative.


I PERSONALLY like front mount woofers so I can hear the pitch and tone of the bass. I do not like soundless pressure fluctuations. But then I use servos on my amps and woofers.
 
A downfiring sub is more stable because the cone motion is working against the weight of the cabinet and gravity, side firing has the potential for the cabinet to move across the floor in extreme conditions.

This back pressure thing some of you are concerned about is an issue, you need the exit area of the drive unit to be at least double the displacement area of the drive unit. What this means in practice is that you need to stand the sub off the floor by a certain amount and have sufficient cutout round the legs etc so as not to impede the airflow.

If you have sufficient exit area there is no problem putting the vent downfiring either.
 
I've tended to prefer sidefiring woofers with downfiring ports. All the sub drivers I've used have never been suited to downfiring due to sag problems and the port on the bottom tended to couple with the room better soundwise.

The sub in the pic has the plate amp on the back, controls on the front, woofer on the side firing into a wall (pseudo downfiring?), port at the bottom firing of course to the floor. It was the best sounding combination with these components.

Change to other components and I'm sure would be different so you have to just try as see... er.... listen.
 

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rabbitz said:
I've tended to prefer sidefiring woofers with downfiring ports. All the sub drivers I've used have never been suited to downfiring due to sag problems and the port on the bottom tended to couple with the room better soundwise.

The sub in the pic has the plate amp on the back, controls on the front, woofer on the side firing into a wall (pseudo downfiring?), port at the bottom firing of course to the floor. It was the best sounding combination with these components.

Change to other components and I'm sure would be different so you have to just try as see... er.... listen.

Nice port, where did you get it?
 
Marsh said:


Nice port, where did you get it?

The port was stolen out of a B&W ASW500 after the driver failed. It's one of their Flowports that in theory should chuff like crazy.... only 65mm dia.

troystg
The driver is a 10" Peerless XLS, 830452. Does a nice job and has only ever bottomed out on "The Incredibles" movie.... was very severe and not sure if it's a DVD authoring problem or my sub.
 
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