AVS Forum banner
1 - 20 of 40 Posts

·
Registered
Joined
·
27 Posts
Discussion Starter · #1 ·
I have a question regarding the placement of a forward firing subwoofer. Should the driver be facing the seating area? In other words, should it be placed along side of the front speakers in the typical HT setup? I have a Def Tech Prosub 1000 and was playing with the idea of placing it between the side of my couch and a long wall. (The driver will be facing away from me). It currently sits by my RF speaker near a room opening, and I believe this is hurting the bass response.


Thanks!
 

·
Banned
Joined
·
15,491 Posts
You'll usually get best results with the driver aimed at a wall from 6 to 12 inches away. Forward firing gives the worst results compared to down, rear or side firing, but the average consumer thinks that if they don't see the cone they won't hear the sound.
 
  • Like
Reactions: saginawjuggalo

·
Registered
Joined
·
27 Posts
Discussion Starter · #4 ·
Thank you for the responses, I appreciate the advice. I'll have to do a little experimentation with my setup...and take the leap of faith by pointing the driver away from my listening area ; )
 

·
Registered
Joined
·
1,366 Posts
The only issue I have with Bill's advice is that it defeats the whole purpose of even buying a front firing sub. If I didn't want to be able to see the driver then I might as well have bought a bottom firing sub. Why buy a red car if I really want a blue one. As stated before, there's no real benefit of buying a front firing sub besides aesthetics.
 

·
Premium Member
Joined
·
14,100 Posts

Quote:
Originally Posted by Bill Fitzmaurice  /t/1469035/placement-of-a-forward-firing-subwoofer#post_23224927


You'll usually get best results with the driver aimed at a wall from 6 to 12 inches away.
Please explain the physics involved here. By "best results" do you mean highest output, flattest frequency response or both? Are there any additional considerations if the wall is also a corner? How far from the corner does one need to be to be considered "out of the corner"? Does the reflectivity/porosity of the wall construction method make a difference? IOW, is a concrete block wall better for this than a "drywall over studs" wall?
Quote:
Originally Posted by Bill Fitzmaurice  /t/1469035/placement-of-a-forward-firing-subwoofer#post_23224927


Forward firing gives the worst results compared to down, rear or side firing, but the average consumer thinks that if they don't see the cone they won't hear the sound.
Why would forward firing give worse results that down, rear or side firing. Please explain the physics involved here.


Craig
 

·
Banned
Joined
·
8,744 Posts

Quote:
Originally Posted by craig john  /t/1469035/placement-of-a-forward-firing-subwoofer#post_23227287


Why would forward firing give worse results that down, rear or side firing. Please explain the physics involved here.

I would guess that since the woofer isn't facing you, you aren't as exposed to the sounds that the subwoofer isn't supposed to be making, like mechanical driver noises and harmonic distortion, as opposed to the
 

·
Registered
Joined
·
3,767 Posts
Forward firing dose not use a wall or boundary so the spl is less. That is why Bill suggested placing the sub to fire toward a wall. Port noise only occurs if the sub is being over driven, badly design, or to close to the wall. Secondary harmonics problems are less with down firing subs, and less localization. Corner placement excites more room modes and has a higher spl compared to not placing the sub in a corner. I am not one to care about looking at the drivers and leave the grills on all the speakers. They are less likely to be damaged.
 

·
Banned
Joined
·
15,491 Posts

Quote:
Originally Posted by derrickdj1  /t/1469035/placement-of-a-forward-firing-subwoofer#post_23227570


Forward firing dose not use a wall or boundary...
It does if the baffle is within 1/4 wavelength of the wall. At 80Hz that's 3.5 feet, so boundary loading isn't much of a concern. Having the sub aimed at the wall acoustically loads the driver, for better lows, and filters harmonics, for less distortion and reduced localization. Corner placement doesn't excite more room modes, but it does increase low frequency output by adding another boundary. Depending on the sub that might give better results, or it might make it too strong on the low end.
 

·
Registered
Joined
·
344 Posts

Quote:
Originally Posted by Prime316  /t/1469035/placement-of-a-forward-firing-subwoofer#post_23226991


The only issue I have with Bill's advice is that it defeats the whole purpose of even buying a front firing sub. If I didn't want to be able to see the driver then I might as well have bought a bottom firing sub. Why buy a red car if I really want a blue one. As stated before, there's no real benefit of buying a front firing sub besides aesthetics.

I have my Hsu VTF-15 facing downward...i was having trouble with ear pressure. I spun the sub on it's side and on it's feet 360 degrees to see which was best position to get less pressure.With the driver facing side ways like the VTF-MK4, it then became my second best solution in my room..much less ear pressure. I then decided to just place the sub with the driver facing downwards and WALLA that eliminated all my ear pressure in my room during powerfull scenes and added even MORE tactile feel to the VTF-15. I just used and custom molded the foam pads that came with the VTF-15 in a triangular pattern to get away with it. Now the room is pressurized BUT i can feel it in my body not my ears. It has been in that position for about 3 months now. My room is solid wood throughout, no windows and solid 2x6 boarded ceiling "very efficient". I think that the VTF-15 even when calibrated is too much for my 15x25 solid box. but i tamed it!
All of that extra energy just needed to be directed the right way!
 

·
Registered
Joined
·
6,980 Posts

Quote:
Originally Posted by Bill Fitzmaurice  /t/1469035/placement-of-a-forward-firing-subwoofer#post_23228067

Quote:
Originally Posted by derrickdj1  /t/1469035/placement-of-a-forward-firing-subwoofer#post_23227570


Forward firing dose not use a wall or boundary...
It does if the baffle is within 1/4 wavelength of the wall. At 80Hz that's 3.5 feet, so boundary loading isn't much of a concern. Having the sub aimed at the wall acoustically loads the driver, for better lows, and filters harmonics, for less distortion and reduced localization. Corner placement doesn't excite more room modes, but it does increase low frequency output by adding another boundary. Depending on the sub that might give better results, or it might make it too strong on the low end.

Per your own description, moving away from the corner only changes the frequency at which it couples to the boundary, not if the boundary has effect. I would also suggest that 1/8 wavelength is a better reference point for fully coupling to a boundary, as at 90 deg to the boundary, 1/4 wavelength results in a cancellation in that axis.


So far as loading of the driver by facing it to a wall, you usually need to place it close enough that the open area to the room is similar to the area of the cone before any real loading is observed. Most of the changes observed by flipping a sub around are at the upper end of the subwoofer range and are the result of changing the effective source location by roughly the depth of the subwoofer.
 

·
Registered
Joined
·
1,366 Posts

Quote:
Originally Posted by matrixj3  /t/1469035/placement-of-a-forward-firing-subwoofer#post_23228343


I have my Hsu VTF-15 facing downward...i was having trouble with ear pressure. I spun the sub on it's side and on it's feet 360 degrees to see which was best position to get less pressure.With the driver facing side ways like the VTF-MK4, it then became my second best solution in my room..much less ear pressure. I then decided to just place the sub with the driver facing downwards and WALLA that eliminated all my ear pressure in my room during powerfull scenes and added even MORE tactile feel to the VTF-15. I just used and custom molded the foam pads that came with the VTF-15 in a triangular pattern to get away with it. Now the room is pressurized BUT i can feel it in my body not my ears. It has been in that position for about 3 months now. My room is solid wood throughout, no windows and solid 2x6 boarded ceiling "very efficient". I think that the VTF-15 even when calibrated is too much for my 15x25 solid box. but i tamed it!
All of that extra energy just needed to be directed the right way!

I'm glad you got it figured out. But what I'm saying is that you really needed a down firing sub but you bought one that was designed as front firing.
 

·
Registered
Joined
·
1,724 Posts
I'm fairly new to all this sub theory stuff but I can attest to the fact that when I took Bill's advise and turned my Rythmik FV15HP around firing towards the corner, it helped flatten my frequency curve in the all important below 80hz area. The 30,40 and 50hz frequencies saw the greatest improvement with a 5, 7 and 10db increase respectively at my listening position in a 24x24x10 foot room. 60hz actually saw a 4db drop and now my curve has a total peak to null difference of 7db across the frequency range which I guess isn't bad for a room this size with little in the way of bass traps. The sub driver is about 3 feet out from the corner and I actually like having the plate amp facing me as it makes it easier to access for adjustments when I feel like doing so.
 

·
Registered
Joined
·
1,399 Posts
My Klipsch RW-12d manual sez put it in the corner about a foot away from the wall, facing out at a 45 degree angle.


OK, the manual doesn't say that. I read the picture.
 

·
Banned
Joined
·
15,491 Posts

Quote:
Originally Posted by wvu80  /t/1469035/placement-of-a-forward-firing-subwoofer#post_23230063


My Klipsch RW-12d manual sez put it in the corner about a foot away from the wall, facing out at a 45 degree angle.


OK, the manual doesn't say that. I read the picture.
The problem with manuals is that they tend to be written by marketing departments, not engineering departments. There is nothing to be gained by facing the sub out, nor is there anything to be gained by having it a foot away or facing it at a 45 degree angle. If an engineer wrote the manual it would show at least six possible placements, along with instructions on how to determine which is the best for your particular room.
 

·
Registered
Joined
·
344 Posts

Quote:
Originally Posted by Prime316  /t/1469035/placement-of-a-forward-firing-subwoofer#post_23229317


I'm glad you got it figured out. But what I'm saying is that you really needed a down firing sub but you bought one that was designed as front firing.

Yup, my room seems to like the down firing subs better. Some of the subs that i have owned were the PB13, MK2.3 & Epik Empire. Funny thing about the Empire is that it also liked my room maybe because of the dual opposing drivers??? It played nice in my room just like the down firing HSU MK 2.3. Looking back i should of also have turned the SVS PB13 facing downwards to see if it also would of sounded better.
Oh yea...the WORST position was with the drivers facing upwards toward the ceiling! Yea, subs ARE directional to a certain point!
 

·
Registered
Joined
·
919 Posts

Quote:
Originally Posted by Bill Fitzmaurice  /t/1469035/placement-of-a-forward-firing-subwoofer#post_23231302


If an engineer wrote the manual it would show at least six possible placements, along with instructions on how to determine which is the best for your particular room.

I hate to ask Bill, but if you had the time to very briefly state the six most likely placements, with a one or two sentence summary on what each room condition each might be best suited for, that would be a hugely useful learning experience for many. Otherwise, many of us are left looking at the marketing departments' sketches.
 

·
Registered
Joined
·
1,519 Posts

Quote:
Originally Posted by mogrub  /t/1469035/placement-of-a-forward-firing-subwoofer#post_23355285


I hate to ask Bill, but if you had the time to very briefly state the six most likely placements, with a one or two sentence summary on what each room condition each might be best suited for, that would be a hugely useful learning experience for many. Otherwise, many of us are left looking at the marketing departments' sketches.
+1
 

·
Banned
Joined
·
15,491 Posts

Quote:
Originally Posted by mogrub  /t/1469035/placement-of-a-forward-firing-subwoofer#post_23355285


I hate to ask Bill, but if you had the time to very briefly state the six most likely placements, with a one or two sentence summary on what each room condition each might be best suited for, that would be a hugely useful learning experience for many. Otherwise, many of us are left looking at the marketing departments' sketches.
This is a bit too power pointey for my taste, but it eventually gets to the meat of sub placement:
http://www.harman.com/EN-US/OurCompany/Innovation/Documents/White%20Papers/multsubs.pdf
 
1 - 20 of 40 Posts
Top