Sub in corner + parametric EQ = No more muddy sound?

[Muzikal-JRNE]

My current sub placement has 3ft of space from the corner of my room, and is against the front wall. The sub dimensions are 15"x15"x15". After doing several crawl tests with the sub in my main listening position, this produces the best sound. If it is placed in the corner the bass levels are higher, but the sound is muddy and boomy.

Well... I am thinking about building my first DIY sub for my home and it has the possibility of being be considerably larger. If I do this the sub will have to go in the front corner of my room. I plan on using a Behringer BFD parametric equalizer with REW software to tune the sub to the room.

Will I be able to equalize out the muddy sound from the corner placement with this setup? Am I better off going with a smaller sub that will allow me to place it in a more optimal starting location? Sound quality more important to me than raw SPL output, but I will take as much of both as I can get


PS. HomeTheaterShack is the [Best / most helpful / least drama] forum that I have used, for any subject!!!
I look forward to being a helpful contributing member.


Cheers, Joe

[brucek]

Will I be able to equalize out the muddy sound from the corner placement with this setup?

I would say so - yes. Quite a bit of gain is realized in a corner, and sometimes it needs to be lowered with EQ.

brucek

[Wayne A. Pflughaupt]

Welcome to the Forum, Joe!

First, the floor-crawling technique is a pretty primitive way to determine placement when we have stuff like REW available to us. On top of that it’s not terribly reliable, as most program sources don’t carry a wide range of bass notes (i.e., from the lowest to the highest). At best the crawl method will help you minimize peaks, but depressions in response will probably escape unnoticed, since they aren’t inherently offensive.

The muddy sound you’re getting in the corner is most likely certain frequencies that are overemphasized. Fortunately, those are the easiest problems for an equalizer to deal with. However, before you commit to your big new sub that will have limited placement options, it would be best to take some preliminary readings with REW. A graph will show for sure if the response at the corner will be “equalizable.”

Regards,
Wayne

[Muzikal-JRNE]

Wayne A. Pflughaupt wrote:

Welcome to the Forum, Joe!

First, the floor-crawling technique is a pretty primitive way to determine placement when we have stuff like REW available to us. On top of that it’s not terribly reliable, as most program sources don’t carry a wide range of bass notes (i.e., from the lowest to the highest). At best the crawl method will help you minimize peaks, but depressions in response will probably escape unnoticed, since they aren’t inherently offensive.

The muddy sound you’re getting in the corner is most likely certain frequencies that are overemphasized. Fortunately, those are the easiest problems for an equalizer to deal with. However, before you commit to your big new sub that will have limited placement options, it would be best to take some preliminary readings with REW. A graph will show for sure if the response at the corner will be “equalizable.”

Regards,
Wayne

Thanks Wayne, that's a good idea. If I am going to take measurements from REW with my existing sub to see room mode patterns, how far do you think I should move the subs between measurements? 2"? 6"? 12"?

Cheers, Joe

[Wayne A. Pflughaupt]

Measure at any and all positions that you think you might be able to locate the sub.

Regards,
Wayne

[brucek]

how far do you think I should move the subs between measurements?

Why not just place the sub at your listening positions and just move the mic around while running the RTA in REW.

brucek

[Muzikal-JRNE]

brucek wrote:

Why not just place the sub at your listening positions and just move the mic around while running the RTA in REW.

brucek

Another good idea! Why didn't I think of that.
I'm guessing you just place the mic at the center of where the driver face would be?

Cheers, Joe

[brucek]

I'm guessing you just place the mic at the center of where the driver face would be?

Yeah it's not that critical, as the large peak and valley locations are revealed pretty quick with the RTA. I did this at one time in my room and simply placed the sub on the floor in front of the couch (since getting it up on the coach was not an easy task). Then when you move the mic around the room you can get a good picture where the best spots are. Then you place the sub there and fine tune the position with regular measurements.

brucek

[snowmanick]

Joe, as mentioned measure the difference first. EQ's can make a large impact but they are not capable of fixing everything. In my experience sub placement and room layout make a larger difference than what is easily obtainable from an EQ.

brucek wrote:

Yeah it's not that critical, as the large peak and valley locations are revealed pretty quick with the RTA. I did this at one time in my room and simply placed the sub on the floor in front of the couch (since getting it up on the coach was not an easy task). Then when you move the mic around the room you can get a good picture where the best spots are. Then you place the sub there and fine tune the position with regular measurements.

brucek

That is a great idea that would have saved me a lot of lifting and shuffling. Oh well.

Question on this method though, how does the mic position account for driver orientation? I noticed awhile back that rotating my sub by 90 degrees created measurable (and in at least one instance clearly audible) differences. The mic though is somewhat omni-directional. Would there be a way to compensate for that or am I back to moving the sub in each location with the mic at the primary LP?

[brucek]

I noticed awhile back that rotating my sub by 90 degrees created measurable (and in at least one instance clearly audible) differences.

Given the low frequencies, the peaks and dips should be wide enough to allow the RTA method to give a good approximation for the subs location. But, you would definitely have to fine tune with the sub in that location.

brucek

[snowmanick]

brucek wrote:

Given the low frequencies, the peaks and dips should be wide enough to allow the RTA method to give a good approximation for the subs location. But, you would definitely have to fine tune with the sub in that location.

brucek

That makes sense, thanks brucek. Using your method will still cut huge chunks of time and effort off the initial lug and measure process.

[Ayreonaut]

I have to emphatically say no. Placing the sub in a corner will cause it to excite most of your room resonances. This results in frequency response that varies wildly from seat to seat. You might be able to equalize an acceptable response for your primary listening position, but other seats might experience a horribly different response. And I think that the transient response at the primary listening position suffers too. This is from my personal experience, with measurements, not conjecture.

Place the sub in a better position out of the corner. If your room is rectangular these locations can be predicted. If it isn't a rectangle, the best location might be harder to predict. But if there is more than one seat in your HT, it is essential that you listen and make measurements at all of the important seats. Try to find a location for the sub that gives you more consistent results at all seats. If there are a few peaks in the FR that show up at all seats, you can tame those with EQ.

[Muzikal-JRNE]

Ayreonaut wrote:

I have to emphatically say no. Placing the sub in a corner will cause it to excite most of your room resonances. This results in frequency response that varies wildly from seat to seat. You might be able to equalize an acceptable response for your primary listening position, but other seats might experience a horribly different response. And I think that the transient response at the primary listening position suffers too. This is from my personal experience, with measurements, not conjecture.

Place the sub in a better position out of the corner. If your room is rectangular these locations can be predicted. If it isn't a rectangle, the best location might be harder to predict. But if there is more than one seat in your HT, it is essential that you listen and make measurements at all of the important seats. Try to find a location for the sub that gives you more consistent results at all seats. If there are a few peaks in the FR that show up at all seats, you can tame those with EQ.

Thanks for your reply, it was very helpful.

Cheers, Joe

[Wayne A. Pflughaupt]

Ayreonaut wrote:

I have to emphatically say no. Placing the sub in a corner will cause it to excite most of your room resonances. This results in frequency response that varies wildly from seat to seat.

That will depend on the room. I EQ'd at the sweet spot, and response at other locations ranges from excellent to acceptable.

Regards,
Wayne

[millerwill]

Ayreonaut wrote:

I have to emphatically say no. Placing the sub in a corner will cause it to excite most of your room resonances. This results in frequency response that varies wildly from seat to seat. You might be able to equalize an acceptable response for your primary listening position, but other seats might experience a horribly different response. And I think that the transient response at the primary listening position suffers too. This is from my personal experience, with measurements, not conjecture.

Place the sub in a better position out of the corner. If your room is rectangular these locations can be predicted. If it isn't a rectangle, the best location might be harder to predict. But if there is more than one seat in your HT, it is essential that you listen and make measurements at all of the important seats. Try to find a location for the sub that gives you more consistent results at all seats. If there are a few peaks in the FR that show up at all seats, you can tame those with EQ.

Can you give me the formula, or refer me to one, that gives the best location for one sub in a rectangular room?

[Ayreonaut]

I like locating 25% of the room length and 25% of the room width if the width and length of your room differ significantly. This avoids placing the sub in any peaks of the first three axial room modes for length and width. Contrast this to corner placement which places the sub at the peaks of all axial room modes.

Of course a room which is not a rectangle with closed doors on every opening has an unpredictable response, so you'll want to experiment. But one thing is guaranteed: Placing the sub hard in a corner is the one place that will excite all of the modes the most.

Check this link for info on placing multiple subs:

http://www.harman.com/wp/pdf/multsubs.pdf

[millerwill]

Ayreonaut wrote:

I like locating 25% of the room length and 25% of the room width if the width and length of your room differ significantly. This avoids placing the sub in any peaks of the first three axial room modes for length and width. Contrast this to corner placement which places the sub at the peaks of all axial room modes.

Of course a room which is not a rectangle with closed doors on every opening has an unpredictable response, so you'll want to experiment. But one thing is guaranteed: Placing the sub hard in a corner is the one place that will excite all of the modes the most.

Check this link for info on placing multiple subs:

(I can't copy the ref.)

Thanks much. (The ref is interesting reading, though it's mainly focused on multiple subs, which is not relevant for me.) My room is 17x14 (and 8.3 ft high), but I don't quite understand: if the (one) sub is 25% of the L and W, then it will be out in the room, right, not along any wall? That just won't work in my situation.

I'm in the process of replacing my SVS PB10 by a Mark Seaton SubMersive (arriving next week), and have also ordered a Velodyne SMS-1 for eq. I suppose I'll just play with moving the new sub around in all the possible locations, using the SMS-1 to detect the one that gives the smoothest spectrum, and then go from there.

[Mika75]

Adding another sub will do alot more than any eq.

edit: I should have also said running them in stereo also

[Ayreonaut]

millerwill wrote:

...I suppose I'll just play with moving the new sub around in all the possible locations, using the SMS-1 to detect the one that gives the smoothest spectrum, and then go from there.

Good idea. A much better approach than shoving it in a corner and trying to correct all the problems that usually creates.

It is absolutely essential that you take measurements in all of the listening seats. Your primary listening location might measure OK, while another seat might sound horrible. I made this mistake and my wife was very uncomfortable.

When you equalize, you should do it for the average response with cuts only. I figured this out the hard way shortly before I obtained Audyssey which makes this easy.

[duwdu]

millerwill wrote:

Thanks much. (The ref is interesting reading, though it's mainly focused on multiple subs, which is not relevant for me.) My room is 17x14 (and 8.3 ft high), but I don't quite understand: if the (one) sub is 25% of the L and W, then it will be out in the room, right, not along any wall? That just won't work in my situation.

I'm in the process of replacing my SVS PB10 by a Mark Seaton SubMersive (arriving next week), and have also ordered a Velodyne SMS-1 for eq. I suppose I'll just play with moving the new sub around in all the possible locations, using the SMS-1 to detect the one that gives the smoothest spectrum, and then go from there.

Hi millerwill,

Sorry if I've missed it, but do you have a thread on here on the submersive? If so please provide me with the link.

Thanks.

duwdu

[millerwill]

duwdu wrote:

Hi millerwill,

Sorry if I've missed it, but do you have a thread on here on the submersive? If so please provide me with the link.

Thanks.

duwdu

This is a good start: www.avsforum.com/avs-vb/showthread.php?t=759877

[Massael]

The SubMersive is a really amazing sub - also seems like the built-in curve is meant to account for some average room modes.