Which came first... the seating or the sub?

[elee532]

Given that listener location and sub location interact with each other, how do I go about determining the best location for my listening chair and the best location for my sub? Most of the guides I have seen for subwoofer setup assume that the listening location is already chosen.

Thanks.

[DrWho]

Place the subwoofer in the corner and then walk around the room to find a good listening position. Moving the subwoofer around is only going to shift where peaks occur....the nulls should be close to the same for a given listening position.

[tcarcio]

You could try putting the sub where your seat will be, also known as the sweet spot, Then crawl, yes crawl, around the room until you find the spot where the bass sounds best and then put the sub there. You can do that for the spots that you are thinking of putting the seats and then you will at least have starting positions for the sub no matter where you decide to sit.

[tonyvdb]

tcarcio wrote:

You could try putting the sub where your seat will be, also known as the sweet spot, Then crawl, yes crawl, around the room until you find the spot where the bass sounds best and then put the sub there.

Yes, this is correct. This is the best way to find a proper placement for a sub in any room.

[elee532]

tcarcio wrote:
You could try putting the sub where your seat will be, also known as the sweet spot, Then crawl, yes crawl, around the room until you find the spot where the bass sounds best and then put the sub there.

tonyvdb wrote:
Yes, this is correct. This is the best way to find a proper placement for a sub in any room.

What if I don't yet have a seating location picked out? I gues my question was... how do I go about picking a seating location AND a sub location? Which comes first?

DrWho wrote:

Place the subwoofer in the corner and then walk around the room to find a good listening position.

Does it matter which corner I use? Does sub placement matter in relation to where I have bass traps located?

DrWho wrote:

Moving the subwoofer around is only going to shift where peaks occur....the nulls should be close to the same for a given listening position.

Can you explain the second part of this statement to me? I think I understand what you are saying about peaks. I'm not clear what you mean in your statement about nulls. Sorry, I'm a total amateur at this sound physics stuff.

Thanks all for the replies thus far!

[salvasol]

elee532 wrote:

What if I don't yet have a seating location picked out? I gues my question was... how do I go about picking a seating location AND a sub location? Which comes first?

If it were me.....I start picking the seating location first (use the 38% rule as a starting point; that means place your seat 38% of the lenght of the room from the back wall or 62% from front wall; example: lenght is 20ft, this will mean your seat will be 7.60feet from back wall or 12.40 feet from front wall).

Then, use the crawling method suggested by TCarcio.

Does it matter which corner I use? Does sub placement matter in relation to where I have bass traps located?

I don't think so, bass traps need to be placed everywhere two walls meet (specially front and back walls)

Can you explain the second part of this statement to me? I think I understand what you are saying about peaks. I'm not clear what you mean in your statement about nulls. Sorry, I'm a total amateur at this sound physics stuff.

Have you downloaded REW????....is a great tool to compare the frequency response on every spot you choose to place the subwoofer

[elee532]

Thanks salvasol. I do have, and am starting to understand, REW. In fact, it's kind of what led me to start this thread. I was doing some testing this weekend with the REW spectrum feature. I put the sub 38% from the back of the room, and then started moving the SPL meter into the different locations I had in mind for the sub. I could see lots of change as a I moved, but there were certain nulls that never seemed to get any better. I then randomly moved the sub into a different seating location and one of the nulls disappeared.

Of course, there are many more combinations of sub and seating location thus leading me to wonder if there is a standard process when both of these two variables need to be calculated. Unfortunately, it seems there isn't :-)

BTW, if you have any interest in the specifics of my situation, I have a thread going on here. The first set of graphs is my seating at 38% from back wall.

Thanks for your help!

[salvasol]

elee532 wrote:

... I could see lots of change as a I moved, but there were certain nulls that never seemed to get any better. I then randomly moved the sub into a different seating location and one of the nulls disappeared.

That's true, some are room related

Remember that to get a good response you need to take advantage from room, placement, EQ'ing and accoustic treatment (basstraps and acoustic panels)...you'll get there little by little

[elee532]

...acoustical treatments are done (probably covered about 60% of room corners with superchunk traps). No EQ until I my Emotiva UMC-1 shows up. So, just wracking my brain (and driving my wife crazy) trying to find the right room placement for seats and sub right now. :-)

[DrWho]

If your room is a perfect rectangle then it's quite easy to identify where to put the listening position and subwoofers for the optimum bass performance. The problem is that any room irregularities dramatically complicate the acoustical scenario to the point of being practically unsolveable. Temperature and humidity play a role too.

I would also argue that a room with parallel walls is not at all conducive to a good sounding system so we shouldn't build a room to have parallel walls for the sake of making the acoustics predictable.

I guess what I should have said about room modes is that moving the sub and listening position around doesn't change the frequency of the problem....and the problem is really one of resonance. If you're not in a null, then you're sitting in a spot that is ringing. The modes are a function of the room's geometry so moving the subwoofer doesn't really change the ringing behavior. Think of subwoofer position in terms of wavelength....if your wavelength is 30ft, then moving the sub even 5ft isn't a very big change in phase.

I personally feel the ideal scenario is to always put the subwoofer in the corner to take advantage of the boundary gain and ultimately lower the distortion of the system. The room modes would then need to be addressed with the acoustical construction of the room...easy to say, but almost always impractical.