# Which location?



## Peter De Smidt (Dec 22, 2006)

First off, the new REQW is outstanding! Second, I've been playing around with some location choices. Here are the graphs for two options. Which location would you recommend?


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## brucek (Apr 11, 2006)

Not a lot of difference, but I guess I choose #2......


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## Peter De Smidt (Dec 22, 2006)

Thanks Bruce! I'll give that a try. 

Regarding filters, I should definitely lower the peak at about 41 hz. (I found out that I have to cross over to my mains at 120hz. If I don't, I can't lower the 40hz ish peak much because there's still enough output from the mains--Polk LSI15s-- to cause a problem.) So should I lower humps at 65 to 85 hz and 100 to about 150hz to get them as close to ideal response as possible? Any other suggestions?


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## brucek (Apr 11, 2006)

> I found out that I have to cross over to my mains at 120hz.


Yet, you're showing an 80Hz crossover in your graph?

Wouldn't 120Hz cause a lot of localization of the sub and somewhat lessen your soundstage?



> So should I lower humps at 65 to 85 hz and 100 to about 150hz to get them as close to ideal response as possible?


Well, I'd like to see what the plot looks like when you use your 120Hz crossover and set REW to match that target first. But, the higher you move along the target, the less effect removing peaks will have because the mains begin to take over (as you've noticed already). EQ'ing a sub at 150Hz when you use a 80Hz crossover is a bit of a waste usually. The telltale of how it all worked out is to add the mains after equalizing and then take a look at the overall plot...

brucek


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## Peter De Smidt (Dec 22, 2006)

So here's a result after quite a bit of futzing. This is with both fronts and the sub working, with a Behringer mic at the listening position. 1/3 octave smoothing has been applied. The jaggedness of the response is a little disheartening! It sounds pretty good, though. The sub is a DIY that I built about 14 years ago. It has two Audio Concepts DV12 woofers firing down in an isobaric configuration, and there's two 12" slaps passive radiators on either end. It definitely needs upgrading, hopefully to an IB. I ended up using about about 6 filters on the BFD.


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## cyberbri (Apr 27, 2006)

How accurate is the mic above the bass region?


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## brucek (Apr 11, 2006)

> I ended up using about about 6 filters on the BFD.


There appears to still be a lot of peaks in with the sub. Since the sub is the only device we can equalize, forget about the mains for now.

I'd like to see a before and after eq of the sub alone from 15Hz to 200Hz. To me, it doesn't look like your filters are doing anything.

brucek


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## Peter De Smidt (Dec 22, 2006)

Thanks guys, I'll do some more measurements today. I don't know how accurate the mic is. It's a Behringer ECM8000, and I'm using Sonnie's calibration file. After things settle down here a bit, I'll send it off to be calibrated.


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## lovingdvd (Jan 23, 2007)

As far as which location goes - one suggestion is to pick location A, fully tweak the filters and see how good you can get it and how it sounds. Then repeat for location B. Decide which location to use permanently based on which location it best calibrations in, how it sounds in each spot, and also weigh in convenience and aesthetics (i.e. if there's only a slight advantage in one spot but ideally be suited in the other location I'd probably go with the most convenient location).


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## Peter De Smidt (Dec 22, 2006)

Here are measurements with just the sub going. I've changed the crossover to 80, and moved the mains to minimize their 40hz peak. The first one is without BFD. The second is with the BFD.


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## brucek (Apr 11, 2006)

I think that looks pretty good except for that pesky dip at ~45Hz. Sometimes moving the sub a bit can help a lot. 
Now when you add in your mains, you'll have to see if they can help with the dip at ~80Hz. The phase switch on the sub may help there with any negative interaction.

brucek


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## Kendle (Aug 31, 2006)

I have an almost identical dip in my subs response; no matter how much EQ is applied the dip will not go away. This is very detrimental on the low end impact. Moving it around has very little effect, unless I move it to the othe corner, then the dip moves to the 50Hz region.
Is there any way to get rid of this dip?

Ken


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## Peter De Smidt (Dec 22, 2006)

Unfortunately, there aren't that many locations available. Down the road, I'll work on some bass traps...but I'd better finish the upstairs bathroom, or I'll be in real trouble! :surrender: I wonder if the 45hz dip has to do with the construction of my sub. The active woofers are down firing, and there's about a three inch space from the bottom baffle to the floor. Maybe that space is acting like a bandpass filter. I'll try flipping the sub upside down and see what happens. I really appreciate all of the help!


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## brucek (Apr 11, 2006)

> Maybe that space is acting like a bandpass filter.


No, the dip will be a room issue. 

brucek


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## Peter De Smidt (Dec 22, 2006)

Here are the combined responses of the front and subwoofer. The first is with the sub in phase, and the second is with the phase reversed. What distance from a wall would cause of 45hz dip?


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## Chrisbee (Apr 20, 2006)

I hate holes in the information provided because one can never take anything for granted in sub testing: 

Somebody has to ask: 

Is your mike at ear height at the listening position?

While moving the sub is one option. Another is moving yourself.

Try moving the mike backwards or forwards a foot or so to see if it affects that 45Hz trough.

What is your room size? Room modes can be calculated:

http://www.mcsquared.com/modecalc.htm


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## Peter De Smidt (Dec 22, 2006)

Yes, the mic is at ear level. It's a 100 year old house with plaster walls. The listening room is the living room. Ceilings are 9 ft high, and there are two large (7ft tall) arched entry ways into the living room. I move one of the chairs to the indicated position for serious listening.


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## Chrisbee (Apr 20, 2006)

That's very good. You seem to have plenty of flexibility as to listening position.

I would try a few test sweeps in front and behind your chair in the hope of losing that trough.

The trough can't exist over the whole room because the room dimensions don't allow for it as obvious room modes.

It's lucky you have a hall or you would have a coincidence of factors in the 9' and 18' dimensions. 

Your large room size is excellent for avoiding serious audible peaks in the upper bass. You should become a classical organ enthusiast at once! 

Despite the large room you appear to have a very compact listening triangle. Is this the result of furniture layout?

Your rear surrounds are so far away that they must surely need serious boost to be heard? Can't you bring them forwards to just behind the two sentinel chairs? 

There appears to be two solid but narrow walls just there in the entrance to the dining area.

Do you have any flexibility in subwoofer position? I'm wondering if it can be moved further to the right? '
This might be worth a try if listening position adjustments fail.

At present that trough would probably take some of the power and excitement out of music and film.


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## Peter De Smidt (Dec 22, 2006)

Ok, so I just spent a half hour typing in some stuff, and when I went to add an attachment, IE crashed. More analysis/info will have to wait for tomorrow! Whatever I do, though, has to take into account the following factors:









Sure, she looks all cute, but she's just about to start throwing ornaments like dodge balls. Additionally, there's this:









The closer the speaker gets to the door, which is in the hall on the same wall as the TV, the more likely it is to get knocked over.


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## Wayne A. Pflughaupt (Apr 13, 2006)

Nice photography there, Pete. :clap:


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