# ALMFamily Theater Room Measurements



## ALMFamily (Oct 19, 2011)

Good afternoon all!

I have reached the point where I am trying to determine if the bass trapping I have done to this point is not enough / sufficient / too much and then continue on to full room response.

I have been moving subs and mains around to determine best possible locations and I hit a point with a question.

Here is the response I had with the 2 subs:









With that steep of a drop in SPL after around 50 Hz, am I looking at an example of too much trapping? I am not certain if the amount of trapping I have done has deadened the room or if I have something else going on. I have front corner super traps and the soffits were built to absorb from 20-200 Hz. The crossover is set in the AVR for 80 on both the mains and CC and the LPF of LFE is set to 120 Hz.

I attached the mdat file for the sub measurement. Any suggestions / constructive criticism welcome! :bigsmile:

Thanks!

Joe


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## Dale Rasco (Apr 11, 2009)

Checking the file now. Hold please sir...


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## Dale Rasco (Apr 11, 2009)

Couple of questions Joe. 

What mic are you using? 
Did you calibrate the sound card?
What sub are you using? Is it ported?


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## fusseli (May 1, 2007)

How big is your room? Is that sub-only with or without LPF?


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## ALMFamily (Oct 19, 2011)

Dale Rasco said:


> Couple of questions Joe.
> 
> What mic are you using?
> Did you calibrate the sound card?
> What sub are you using? Is it ported?


Dale,

I am using the CM-140 for a mic and I did do the sound card calibration. I have 2 of the SVSOUND PB-13 Ultras and both are ported. I have not plugged any of the ports and have the setting on 20 Hz.



fusseli said:


> How big is your room? Is that sub-only with or without LPF?


The room is roughly 14' wide by 19' long with a height of just under 7.5'. If you mean the LPF setting on the AVR, I have that set to 120. On the subs, I have the crossover turned off.

Thank you both for your help. If it helps, I can post that graph with the sound card cal on......


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## Dale Rasco (Apr 11, 2009)

have you tried flipping the phase on one to 90 or 180?


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## ALMFamily (Oct 19, 2011)

I did Dale, and I came out with huge dips. I spent a hour moving them around a bit more tonight before the Packer game, and got some different results. I will post up a new graph tomorrow - thanks so much again for helping me out with this.


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## fusseli (May 1, 2007)

Your room isn't that big and with a low ceiling it isn't a huge volume, I'm wondering if your room contribution is dominating your response. Unless the subs are out into the room and not in the corners, the room interaction shouldn't be making anything dip. Can you block the ports on your PB13s (if they are meant to do that) and repeat measurements? Your room might do best with sealed subs...


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## ALMFamily (Oct 19, 2011)

I can do that - I will get the plugs out and give that a go tomorrow. Thanks for the suggestion!


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## ALMFamily (Oct 19, 2011)

Got some time today to do more measurements!

First thing I did was to plug ports and retest (after changing the setting on the back) sealing it, then removing one plug at a time. I saw a drop in SPL, but the overall pattern of the response was the same.

So, I started really moving them around and taking measurements. Let me say - REW is a wonderful thing!

I made it to this point - I got one in the middle of the front wall and one toward the front corner where my sump pump closet dips out (I will try to get a photo up later to give a visual). Here is what I ended up with for a response:









I am by no means an expert, but that does not look half bad. This is only with the two subs - I have not done the mains as of yet (well, I did them by themselves but not with the subs) but this looks like something I could work with on the ydp2206 EQ. 

What do you guys think?

View attachment 12-10 two subs mids.mdat


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## fusseli (May 1, 2007)

That looks much better! I'm surprised that plugging the ports didn't make a bigger difference. Since it didn't, you might leave them plugged since you apparently don't need the extra LF. You can verify from the waterfall, the persistence below 30Hz could all be the room... I'd set your LPF at 80-90Hz and give the system a listen and see how you like it?


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## ALMFamily (Oct 19, 2011)

Spent a few more hours doing measurements - I moved the mains around and incorporated them as well as the CC - both are crossed over at 80 Hz. Here is the response I came up with:









As I have no point of context, I am not sure if this is bad or good. I think it looks pretty good (before EQing) but would love to hear other people's opinions.

I am including the waterfall - except for 60 Hz and below @25 Hz, it looks like I have sufficient trapping if I am reading it correctly. Does that look correct?









As always, I am attaching the .mdat files and thanks for any assistance!

Joe


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## ALMFamily (Oct 19, 2011)

fusseli said:


> That looks much better! I'm surprised that plugging the ports didn't make a bigger difference. Since it didn't, you might leave them plugged since you apparently don't need the extra LF. You can verify from the waterfall, the persistence below 30Hz could all be the room... I'd set your LPF at 80-90Hz and give the system a listen and see how you like it?


Ha! You snuck a post in on me! 

I forgot - in the measurements I just posted up - I did find that plugging one of the ports on the front sub gave me a bit more even response @20 Hz so I left it plugged for that measurement.

I never considered if plugging the ports would tame some of that persistance below 30 Hz - I will plugs the ports tomorrow and see what happens. I am actually going to be adding a 3rd sub in the room and locating it in the rear corner of the room - I was able to talk my wife into getting me a PSA XS30 for Christmas. :devil: With that being the case, I will probably plug them when I incorporate it.

Now, I just need to read through the documentation on the ydp2206 EQ and see if I cannot try to do a house curve. I got 2 of them used so it is worth a shot.....


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## ALMFamily (Oct 19, 2011)

Finally got a chance to do some measurements experimenting with plugging ports. I found that plugging all ports on both subs really tamed that persistance below 30 Hz - good call mate! 

So, prior to adding the 3rd sub, here is the response I think I will be going into EQ with:









Here is the associated waterfall:









Will be trying my hand at full range measurements next......

View attachment 12-13 l-c-r subs sealed.mdat


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## Todd Anderson (Jul 24, 2009)

Did you try placing them on the center (mid points) of your side walls?


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## ALMFamily (Oct 19, 2011)

The sub in the front of the room is pretty much exactly in the middle of the wall. The one on the side wall is closer to the end where the sump pump is. 

I noticed when I was moving the side wall one around that the further I moved it from that corner, the more dips I saw.

Really anxious to get the XS30 in here and move them around a bit again to see how much better I can get it. Plus, I have only measured from the main LP to this point. When I get time, I will take measurements from the other listening spots and see what kind of response I have there. As I will always be sitting in the main LP, that was the one that was important! :bigsmile:


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## Todd Anderson (Jul 24, 2009)

Interesting... Pretty cool how optimal sub placement varies so widely from room to room...


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## ALMFamily (Oct 19, 2011)

Exactly what I thought - I started off in the middle of that side wall because I thought that would be the best location as you suggested. But, it just kept getting better as it moved closer to the corner!

I have ordered the Master Handbook of Acoustics - it just bugs me to look at results and not know if it is a good response or not! Hopefully, I can at least get to a point where I will not need to post every graph and ask how it looks.... :R


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## ALMFamily (Oct 19, 2011)

Now that I received the XS30 and I am nearing the end of the construction road, I will be getting back on the REW wagon! I started taking measurements and finding the best locations for the mains. Placement is very limited so I am going to have to accept some shortcomings, but I hope to smooth everything over with the 3 subs.

More to come.....


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## ALMFamily (Oct 19, 2011)

So, after a few hours of moving subs and mains around, I got to this point:









I was really happy with the way it came out - it looked like a great starting point for a house curve.

Then, I ran Audyssey thinking it would dial it in further. Here is the post Audyssey REW result:









I was astounded - I made an assumption (and probably a bad one) that Audyssey would only make it better. So, I turned Audyssey off and thought "no problem, I will just turn it off and be good to go". No such luck:









Of course, I foolishly did not write down pre-Audyssey settings so I could not get back to where I was. So, I am in the process of trying to get close to where I was before.... more to come!


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## kadijk (Jan 23, 2011)

Pre audyssey results were looking awesome Joe. My question is how did it sound? Or did you get to listen to anything at that point? I also love your cheeky assumption that the primary listening position will be yours-all the time...I once thought that way too. It's rare that I sit there. Actually, with teen aged kids, it's rare that I use the room at all. I almost have to book myself in


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## ALMFamily (Oct 19, 2011)

kadijk said:


> Pre audyssey results were looking awesome Joe. My question is how did it sound? Or did you get to listen to anything at that point? I also love your cheeky assumption that the primary listening position will be yours-all the time...I once thought that way too. It's rare that I sit there. Actually, with teen aged kids, it's rare that I use the room at all. I almost have to book myself in


I did not get a chance to listen to anything. And, I probably should have stopped right there and done that, but after reading through several threads, I figured it could only get better.

I fell prey to the 3rd greatest blunder - do not just look at test results, listen!

The good thing for me is that my oldest is 12. By the time they hit the teenage years, I will have them trained to different seats! :bigsmile:

Plus, there is no game console in there....


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## ALMFamily (Oct 19, 2011)

OK, I spent more time today tweaking and moving things a bit. Here is the resulting FR:









I am going to listen to this a bit - and re-read (for the umpteenth time  Wayne's excellent house curve articles. It looks like I really just have some peaks to worry about......


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## Todd Anderson (Jul 24, 2009)

Since you have 3 subs, I would take measurements at your primary seat... And then the extremes. I did this when I was dialing in my duals. Helped me find the sub positions that gave me the most even response across my seats... It's amazing how you can get great results at the primary spot for several configurations, but different results at the extremes.

Does Audyssey allow you to EQ manually? I've never used Audyssey, but MCaCC let's me tweak everything manually (down to 120hz of course)... Perhaps there's a way to get in the final settings and tweak?

A BFD can be had for cheap... $70 on eBay. That would definitely give you ultimate control. I've found mine easy to program in conjunction with REW and have had awesome results.


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## ALMFamily (Oct 19, 2011)

27dnast said:


> Since you have 3 subs, I would take measurements at your primary seat... And then the extremes. I did this when I was dialing in my duals. Helped me find the sub positions that gave me the most even response across my seats... It's amazing how you can get great results at the primary spot for several configurations, but different results at the extremes.
> 
> Does Audyssey allow you to EQ manually? I've never used Audyssey, but MCaCC let's me tweak everything manually (down to 120hz of course)... Perhaps there's a way to get in the final settings and tweak?
> 
> A BFD can be had for cheap... $70 on eBay. That would definitely give you ultimate control. I've found mine easy to program in conjunction with REW and have had awesome results.


I took measurements in two locations - middle of front row and middle of back row. I am the only one in my family that cares about the sound quality :yikes: and those are the two seats I have the possibility of sitting in. The middle of the back row was not quite as good of course, but it was still workable.

It does not - I believe you need Audessey Pro for that but I could be wrong. I actually have 2 Yamaha YDP2206 PEQs that I can use - I am gong to use one for the SVS subs and the other for the mains initially - unless one of you good fellows talks me into just doing all 3 subs.


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

Typically you want to EQ all subs all at once (since that’s the way you hear them) with single set of filters. That said, you might take individual measurements to see of one of them has a drastic problem that you might want to deal with separately.

BTW, excellent choice on the YDP2006 for the main channels. If you haven’t seen it, here’s a post I made a while back that contains snippets from a review on it that I never got around to finishing.

Regards, 
Wayne


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## ALMFamily (Oct 19, 2011)

Thanks for the link Wayne - I will check that out now.

Is there a better device for EQing 3+ subs than the Yamaha?


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## Dale Rasco (Apr 11, 2009)

Normally when I EQ multiple subs I do them all at once as well. I believe I read that somewhere... Oh yeah, Wayne's thread!


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## ALMFamily (Oct 19, 2011)

Dale Rasco said:


> Normally when I EQ multiple subs I do them all at once as well. I believe I read that somewhere... Oh yeah, Wayne's thread!


In order to do that, would you not need to split the EQd signal out multiple times? In my case, wouldn't I need 2 splitters and if so, is there a signal loss involved?


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## Dale Rasco (Apr 11, 2009)

So when I used to run three subs I split it at the behringer once and then split one of the lines at the subs. The fronts I think.


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## ALMFamily (Oct 19, 2011)

I will not be able to split at the subs as mine are all in different parts of the room. Guess I will just have to split them after the 2206. Thanks for the feedback on EQing them together guys!


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## NBPk402 (Feb 21, 2012)

ALMFamily said:


> I will not be able to split at the subs as mine are all in different parts of the room. Guess I will just have to split them after the 2206. Thanks for the feedback on EQing them together guys!


Why not disconnect all the subs except for one and then EQ and set the level on that one... disconnect the EQ'd one and hook up another, etc. until you have EQ'd them all. At that point hook them all up and set your sub level.


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

Dale Rasco said:


> Normally when I EQ multiple subs I do them all at once as well. I believe I read that somewhere... Oh yeah, Wayne's thread!


Thanks for the kind words Dale! To be fair I think it was Sonnie who originally came up with the “EQ ‘em all as one” idea. :T




ALMFamily said:


> Is there a better device for EQing 3+ subs than the Yamaha?


The BFD is actually better for subs, as it has something like 60 center frequency selections per octave, while the Yamaha only has about 25, IIR. The BFD also has more available bandwidth settings than the Yamaha. So, you can achieve more precise equalization with the BFD. 

That said, I’ve never had a problem getting what I needed for the subs from the Yamaha. In reality, if a filter’s frequency setting is off a few Hz from the center of a peak or null, or doesn’t quite “fit” its width, it’s not going to make an audible difference.

The Yamaha mainly excels as a full-range equalizer for the main channels, and for most people (not obsessed with picture-perfect waterfall graphs) it’s acceptable for subs as well. And lest we forget, the YDP2006 really excels in the “doesn’t look like bling” department. 

One advantage the YDP200 does have over the BFD is individual delay adjustments for each channel. Naturally, this might require an EQ channel for each subwoofer if you have them spread around the room, even if you did use matching filters for them.




ALMFamily said:


> In order to do that, would you not need to split the EQd signal out multiple times? In my case, wouldn't I need 2 splitters and if so, is there a signal loss involved?


You can split the signal after the EQ, or before (e.g. if you wanted to send the signal to both channels of the EQ). Signal loss isn’t a concern. If it happens, all you have to do is boost the level on the sub amplifier. That’s what it’s there for.  




ellisr63 said:


> Why not disconnect all the subs except for one and then EQ and set the level on that one... disconnect the EQ'd one and hook up another, etc. until you have EQ'd them all. At that point hook them all up and set your sub level.


That means separate equalization for each sub, which isn’t what we’re after. We want to equalize them all with a single set of filters.

Regards, 
Wayne


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## ALMFamily (Oct 19, 2011)

Thanks for the response Wayne. I think I will just go ahead and use one of the YDPs for subs and the other for mains. While I would like to get the sound dialed in as much as possible, I am probably not in the picture perfect graph camp. 

I will swap them over to EQ them all as one -well, I will probably use both inputs as I do have one splitter already and I can just set them to EQ for both channels the same - and then I will post the results.


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## bkeeler10 (Mar 26, 2008)

Okay, so I just stumbled upon this thread and read it with great interest. But it's been a while since you've written an update. How did the EQ go and what did the results look like?


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## ALMFamily (Oct 19, 2011)

Sad to say that the 4520 that I am going to be running the room with is defective and I am working with Denon now to get it exchanged. Once I have the unit back, I will be getting back on this.


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## ALMFamily (Oct 19, 2011)

Ok, I have the 4520 back in the fold so I will be getting back to business on this. I took an initial measurement of the two SVS subs which are both plugged into one of the two outputs on the YDP2206 without Audyssey engaged. I will post that up later.

I did a quick measurement before I had to get the kids adding in the 3rd sub, and it introduced some dips at its current location. I am going to do a measurement with just the 3rd sub from its current location, and then move it around some to see what happens. More to come.....


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## NBPk402 (Feb 21, 2012)

Is the replacement 4520 fixed? What is the manufacturer date on the new one? I can live with my HDMI problem until I can afford a new projector and confirm that it is the Denon... Until then I am going to assume it is a faulty projector.


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## ALMFamily (Oct 19, 2011)

ellisr63 said:


> Is the replacement 4520 fixed? What is the manufacturer date on the new one? I can live with my HDMI problem until I can afford a new projector and confirm that it is the Denon... Until then I am going to assume it is a faulty projector.


It is - unfortunately, I am not sure what the date is. I will try to remember to look at the unit to see if I can find it when I pull the rack out.


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## ALMFamily (Oct 19, 2011)

In a never-ending quest to find the best place for the subs, I starting moving them around - again.  I ended up by moving the 2nd PB-13 to the front wall with this response:










So, I started moving the 3rd sub around, and ended up putting it in the spot vacated by the PB-13 in front of the sump pump entry closet. This was the associated response:









Once I got that done, I ran Audyssey to set the associated distances, and then shut Audyssey off.

This looked like an excellent starting point to attempt a hard knee house curve...


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## ALMFamily (Oct 19, 2011)

So, next I started applying filters to set the curve. Here is where I ended up:









I used 3 filters to get to this point - one at 30 Hz, one at 50 Hz, and one at 55 Hz.

Next, I added in the mains and took another measurement:









Again, this is with Audyssey off. I then added the rest of the channels and took one more:









Next up, running Audyssey....


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## ALMFamily (Oct 19, 2011)

After running Audyssey, I took one last measurement:









Not bad at all....

Now, I did not do any EQ on the mains (and I have a 2206 to be able to do that) so obviously I missed a step before running Audyssey, but this has really become a continual learning experience so I will likely re-read a few articles (thanks again Wayne!) and start the process from the beginning once again. Fortunately, I have a good starting point...


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## ALMFamily (Oct 19, 2011)

So, I am hoping you guys can shoot holes in my logic and point out any mistakes I made...


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## bkeeler10 (Mar 26, 2008)

Not an expert on house curves, (I'll have to re-read Wayne's article too), but things are looking quite smooth, even if there is an emphasis in the bottom octave-and-a-half or so. But this is usually the goal when developing a house curve, right? I guess I would've expected Audyssey to flatten out that bottom end. Anyway, what's the crossover frequency between subs and LR?


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## ALMFamily (Oct 19, 2011)

bkeeler10 said:


> Not an expert on house curves, (I'll have to re-read Wayne's article too), but things are looking quite smooth, even if there is an emphasis in the bottom octave-and-a-half or so. But this is usually the goal when developing a house curve, right? I guess I would've expected Audyssey to flatten out that bottom end. Anyway, what's the crossover frequency between subs and LR?


The crossovers are all set to 80 - I did play with them a bit to see if going lower or running full band made any improvement. and it did not.

If I am understanding correctly, you are indeed correct - that is the purpose of the house curve.


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