Down or Forward firing Subs

Brian Warren

Stunt Coordinator
Joined
May 5, 2002
Messages
54
My soon to be completed room is 18 x 22 by 20 ft high. carpeted with berber carpet. wired for 7.1 and wired for 2 powered subs. which is better, down or forward firing subs. so far i have seen the JBL PB12 and the velodyne cht 12. will carpeting eat up the bass from the down firing sub? I'm thinking of getting one 12" sub and adding another if need be. any suggestions?
thanks
Brian
 

Chris Tsutsui

Screenwriter
Joined
Feb 1, 2002
Messages
1,865
They perform the same. Not all drivers are DF (down firing) while all drivers can be FF (front firing).

I'd choose DF for the following reasons:

* Lower COG so less likely to fall and crush me

* Air disperses outward in all directions whiles on FF you can face the front in different orientations.

* gravitiy effects the driver uniformly downward.

* Dust doesn't settle on the driver

* The driver stays hidden so when company comes over you tell them that the satellites are making all the noise.

* Even amount of stress on the screws

* Magnets are strenghted with earth's polarity (BS)

* Less likely to get "kicked" in

Come to think of it, maybe DF is better? bah, they're the same.
 

Brook

Agent
Joined
Apr 8, 2002
Messages
38
I am wondering to buy a used subwoofer, it has a 12" Shiva driver and I was wondering if you would recommend buying this or not. It is in a tube and Df.
Brook
 

John Desmond

Stunt Coordinator
Joined
Nov 13, 2000
Messages
90
There are great forward firing subs (like the Aerial) and great downfiring subs, (like REL, ACI, SVS). It is only one aspect of the design. The only advantage forward firing would have sonically would be if using a very high crossover point. Then it is more of a woofer than a sub anyway. Talking about over 100Hz.

Carpet has little or no effect on bass, remember, those bass wavelengths are up to 50 feet long! An inch of carpeting isn't going to do anything with that.
 

Richard_s

Second Unit
Joined
Nov 25, 2000
Messages
267
My room is somewhat similar 16X24 with a 14 foot cathedral. Room carpeted with berber carpet very tight short weave. Obviously there are many factors that affect the overall acoustics but here is what I found in my room. have the subwoofer in the corner (only place I can put it).
Tried a Sony SA-WM40 (front Firing)and got it to balance reasonably well using AVIA. Found I needed more power for HT. For most music it had enough power. I just could not get it to have a "smooth" seamless mixing with my mains (JBL N26's). I tried lots of arrangements in the corner.
Borrowed my sons PSW-110 (also front firing) and this had enough power for HT. Again I could not get a good "smooth" seamless mixing with my mains. NOTE: I originally stated this was a PB10 but paul corrected me below just wanted to make the correction here so as not to confuse. Sorry
I returned the Sony SA-WM40 and Got the PB12 figured I would go for the 250Watt unit and also let me try a downfiring unit. With very little difficulty (maybe I got lucky) this subwoofer balance extremely well (+/-1db at all five channel locations and I could not tell where the subwoofer was). It mixed beautifully and seamlessly with my mains.
Just my experience. I am not comparing apples and apples but the downfiring subwoofer for my room acoustics was clearly the winner. May be it is that the PB12 has more power maybe the difference is the downfiring I don't know but the PB12 was hands down the winner of the three for my room.
BTW: I put my subwoofer onto a piece of plywood never tried it without it but like John states the carpet probably has no effect. I just felt it made sence to do this.
 

Paul Clarke

Supporting Actor
Joined
Jan 29, 2002
Messages
998
Richard,

The PB10 is down-firing. You must have meant another model.

Also, Berber would have less acoustical effect than regular shag pile, whatever density or length. My PB10 on just thick, medium length pile needed to be almost halfway up in volume to reach reference. I placed it on an unused double video cabinet in the exact same location (corner) and the necessary volume reduced appreciably. Instead of 12 o'clock it now sits at 9-9:30 or so. Also the receiver level went down as well. I eventually replaced the cabinet with a nice piece of bluish granite.

Don't ask me why, long waves or no, but it does have an effect. The height of the semi-ball feet of the PB10, the kind and length of carpet pile, whether the room is on a slab or a wooden floor...all of these and more seem to have a substantial influence on the sound in my experience.

My $.02
 

Richard_s

Second Unit
Joined
Nov 25, 2000
Messages
267
Paul:
Correct I meant the PSW-D110 (model that was out before the PB10). The PSW-110 is front firing. Good catch I will edit above.
My PB12 is set at about 1/3 volume with the piece of plywood under it. I don't know if not having the plywood makes a difference.
I don't know but many use spikes to isolate from the floor and this helps the case to have the proper vibrational characteristics. That was the reason I thought it would be best to put the subwoofer up on something so that the carpet would not damp out the case vibrations.
 

Cy Jervis

Agent
Joined
Sep 27, 1999
Messages
28
I had a JBL 10" down firing sub(can't remember the model #) for 3 years before it fried. The sub was O.K. but didn't quite do it for me. I replaced it with the Velodyne CHT 12 and have not regretted it yet. My mother-in-law who lives next door said it rattled her dishes. I say go with watever sounds better to you no matter if it is front or down firing.
 

John F. Palacio

Supporting Actor
Joined
Jan 6, 2002
Messages
575
"My soon to be completed room is 18 x 22 by 20 ft high"
This should be more of a concern than a bottom or side firing sub. Your room is very close to a perfect cube, worse possible scenario for standing waves.
 

Richard_s

Second Unit
Joined
Nov 25, 2000
Messages
267
I am sure his room is vaulted (cathedral) I don't think due to the taper of the ceiling that it will act like a cube causing a standing wave problem.
Brian: BTW are you sure that the ceiling goes to 20 feet or was that a mistake. For standard construction 8 foot ceilings that translates to a 12 foot rise over 11 foot run ( Almost a 12 slope). I have seen rooms like that and they are beautiful many "A-frame" houses are like that. Enjoy your new room
 

John F. Palacio

Supporting Actor
Joined
Jan 6, 2002
Messages
575
"I am sure his room is vaulted (cathedral) I don't think due to the taper of the ceiling that it will act like a cube causing a standing wave problem".
You are right. I assumed it was not vaulted, since he did not mention it was. I have a 16'D x 22'W x 12'H (Non vaulted) that I am still working on improving acoustics!
It was a nightmare when I started now is down to "less than wonderful"
 

Richard_s

Second Unit
Joined
Nov 25, 2000
Messages
267
John:
Did you run a thread of your own on what tricks you might be able to do. This forum or the "Tweak" forum might be a good place.
Have you thought about a suspended ceiling
Just kidding.
 

Brian Warren

Stunt Coordinator
Joined
May 5, 2002
Messages
54
thanks for the info guys. the room is indeed vaulted/slanted with the peak at 20 ft but only for a short distance so its not a cube. we have some very steep and peaked roof lines. I thought 2 subs, one placed left of TV in left front corner and one placed rear right corner would "fill" the room the best, planning 2 12" subs.

I liked the paradime mini monitors and will check B&W's soon. dont know which subs to use. any chance down firing subs would be less likely to fill this volumous room

thanks

brian
 

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