Subwoofer Placement Advice

[digitalwhispers]

Okay, so I'm running a pair of Samson Resolv 80a's and I just added a Resolv 120a subwoofer. Assuming I know nothing, how is the best way to set it up and where should I begin with the placement experiments? Any advice is welcome.

[mshilarious]

http://www.abluesky.com/p_s_gb/p5s8.html

[digitalwhispers]

Thanks! Any other resources?

[COOLCAT]

I have an old Mix magazine,1997 by Bob Hodas.. with a Woof or not to Woof article.

It says symetrically in the center goes the sub if you only have one.

It also mentions the old wives tale that bass is omnidirectional, and said the old laquer masters for vinyl combined 200hz and below to mono for phase problems..out phase made the cutting lathe jump..but now we can have stereo bass.

The exercise to prove this was to put the sub off to one side of your room and see if you could hear it, proving its not omindirectional.

strongly recommended using a good analyzer too to set up the sub-woofer.

suggestion to lift the sub off the ground too was mentioned.

I have a cheap RTA setup and you can sure see the bass. The volume on my sub was near zero volume too, post setup...but it showed on the graph.

[TonyBelmont]

Down and dirty solution is to put the sub at your mixing position (where you typically sit), and walk around the room with a radio shack SPL meter... Put the sub where you get the best levels on the meter...

[pingu]

Hi Tony, good to see you here.

[TonyBelmont]

Originally Posted by pingu

Hi Tony, good to see you here.

Hey pingu, how are things down under?

[pingu]

We could do with a decent audio store.


Apart from that is all good man.

[seriousfun]

Originally Posted by COOLCAT

I have an old Mix magazine,1997 by Bob Hodas.. with a Woof or not to Woof article.

It says symetrically in the center goes the sub if you only have one.

It also mentions the old wives tale that bass is omnidirectional, and said the old laquer masters for vinyl combined 200hz and below to mono for phase problems..out phase made the cutting lathe jump..but now we can have stereo bass.

The exercise to prove this was to put the sub off to one side of your room and see if you could hear it, proving its not omindirectional.

strongly recommended using a good analyzer too to set up the sub-woofer.

suggestion to lift the sub off the ground too was mentioned.

I have a cheap RTA setup and you can sure see the bass. The volume on my sub was near zero volume too, post setup...but it showed on the graph.

A 1/3 Octave Real Time Analyzer is useless for deterimining flat response from a subwoofer (1/12 Octave is minimum spacing between EQ/Analysis bands to find dips in frequency response caused by room modes - Bob Hodas uses a 1/24 Octave analyzer/EQ).

Subwoofer placement 1/2 (or 1/4 or other even divisions) wall is wrong - this will nearly guarantee some kind of cancellation of an important fundamental frequency. Experimentation is the key to proper subwoofer placement, and most likely 1/3 across a wall, or in a corner is the result. My first two rules of subwoofer placement are: if you choose in advance where the subwoofer will go, it will be wrong - and wherever the subwoofer measures best will end up in a doorway, walkway, or somewhere the wife doesn't approve!

Bass does radiate omnidirectionally, and in a small room (under 12,000 cf) fundamental tones below 100 Hz are not localizable. Subwoofers play harmonic content as well as fundamental tones, so subwoofers may or may not be localizable even if their fundamental tones might not be. Ported subwoofers are almost always localizable. In many cases, a localizable subwoofer delivering flat bass response is preferable to a non-localizable subwoofer playing bad frequency response due to improper placement.

Carpet, spikes, platforms, feet...none of these, or raising a subwoofer a few inches off the floor, have an effect on the FR of the subwoofer unless it is engaging different room modes by the location change.

1. Place the sub after analysis and listening for flattest frequency response
2. calibrate your system according to the Blue Sky instructions, using their test tones
3. Make sure the subwoofer is in-phase with your mains
4. Listen and enjoy!

[COOLCAT]

I've a question on the "octaves" in articles concerning subwoofers.

I have the Allen Heath, software. Its only $10.
If it isn't telling me the correct info,
and a better resolution 1/24 package is recommended often for subs....

So why does it graph the lower frequencys as I increase the subwoofer volume, either up or down? It seems its working or in other words following the sub-woofer freq's vs volume?

Here's the article by Bob Hodas. (gotta love the Smithsonian-internet.)
It disagrees with some of what your saying I think.

http://www.bobhodas.com/publications.html

[SouthSIDE Glen]

Originally Posted by seriousfun

My first two rules of subwoofer placement are: if you choose in advance where the subwoofer will go, it will be wrong - and wherever the subwoofer measures best will end up in a doorway, walkway, or somewhere the wife doesn't approve!

Now THOSE are the kind of real-life rules that I love .

Great post all around. One question though. While I am no expert on subwoofers, I was always of the belief that the main idea of raising a sub (or any loudspeaker with bass response, really) off the floor was to decouple it from the floor in order to reduce unwanted distortion caused by the vibrations transferring to the floor and essentialy making the floor an extended driver membrane.

Of course the key word here would be decouple. Setting the driver on a stand that does not provide actual vibrational or shock isolation would serve little use. Also, if it's a high-mass floor such as basement concrete or something like that, such de-coupling would not be so necessary.

Is there anything to this in your view or not?

G.