# my Room, my REW measures, my cry for Help



## GuitarCry (Dec 14, 2008)

What a great software REW is. Thank you *JohnM*. I'll definitively leave a donation after my room project.
And what a hard project it's going to be!...

I'm stuck with every audio enthusiast's nightmare: a 44m3, *almost cube*, room.
It's purpose is for stereo music listening.



Lots of listenable room modes and too lively.

*Audio system*: Monitor Audio BR2 powered by Cambridge Audio 740A
*Measurement system*: Behringer ECM8000 (at listening position, vertical with 15º tilt forward), Behringer UB802 mixing table and Creative Labs USB Sound Blaster Live!​
These are my first measurements with the wonderful REW. Could please help me interpret them?

































A *long way* from the House curve ideal right!?
After these results I tried to move the speakers *30cm forward from their standard position*, to evaluate speaker position impact: Unfortunately, due to room size, they cannot be greatly moved from the standard position.



















Could you help me out on what probably are the changeable variables in my room that will yield the greater improvement?

Recently I've been building 6 skyline diffusers, 48x48cm, out of extruded polystyrene, for ceiling sound dissipation on the 525Hz-4290Hz range.
Think this will help? Any suggestion on what placement should I try?










An Alleluia to this wonderful community.

Cheers


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## gperkins_1973 (Aug 25, 2008)

That's a nice extension on the BR2's. I have the RS6's and they roll off at about 50hz which is a bit wierd to be honest as I thought they extended to about 35hz.

cheers

Graham


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## GuitarCry (Dec 14, 2008)

Yeah, it's weird because the BR2 specifications state 42Hz – 30kHz range, which do not concur with my measurements. Althought the soundcad does not go beyond 20KHz, I can actually ear 16Hz from them, using REW, wich is kind of weird. But that measurement below 3Hz... that's impossible. It must be some kind of environment noise, right!?

I'll check that out tonight by measuring the room noise.

Cheers


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## gperkins_1973 (Aug 25, 2008)

I would be very surprised you can hear or even feel 16hz at that level. It would take alot off amplification and woofers to hear that low. I have my crossover on my onkyo set to 100hz for the speakers and 100hz for the sub which may be causing the to roll off like that. If I cross them lower I get a big dip between 70 and 120hz. 

cheers

Graham


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

Hello GuitarCry,

Despite your “problem” room, your graphs look really good to me. It looks like you have some treatments that are cutting down on comb filtering – carpeted floors perhaps?

The only problems in response I see is a fairly deep depression between ~3 kHz and 8 kHz. With the speakers in the original position you also had a depression between 90-180 Hz.

Moving the speakers improved the 3-8 kHz depression, but the bass depression moved downstream to 50-120 Hz.

Aside from full-range equalization, there isn’t much you can do except experiment with placement locations. It might be easier to utilize REW’s RTA feature for that. Then you can see the changes in response instantaneously, as opposed to stopping to make another sweep.

Regards,
Wayne


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## GuitarCry (Dec 14, 2008)

It's kind of weird that these monitors have such power at 40Hz. I believe it's the room singing... Am I wrong?



> Despite your “problem” room, your graphs look really good to me. It looks like you have some treatments that are cutting down on comb filtering – carpeted floors perhaps?
> 
> Read more: Home Theater Forum and Systems - HomeTheaterShack.com - Reply to Topic


Good? Really? that's nice to know, but I do feel the room needs lots of work due to liveliness. Don't you think the decay times are a bit too long?

I don't know what you mean by comb filtering, but besides the 1.5m2 carpet in the room diagram, the floor is flat wood.



> Aside from full-range equalization, there isn’t much you can do except experiment with placement locations.


 I've done just that, and following these advices, repositioned my speakers and listening position. I've also redone the measurements. What kind of changes in REW’s RTA diagram should I be looking for when moving the speakers around?

New Measurements with 8 sweeps and new speaker and listening position:










* Same Graph with 1/6 octave smoothing*









* Same Graph for the Bass frequencies* 































































So Wayne, do you recommend no Bass-traps and other acoustic treatments for me at this point? I still feel a lot of Boomyness in my room though.
Thank you so much


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

> What kind of changes in REW’s RTA diagram should I be looking for when moving the speakers around?


Improved (flatter) frequency response. Like that big hole between 50-120 Hz “filling up,” for example. Or not so much roll-off of the high end (comparing your first yellow graph to your later red ones).



> Good? Really? that's nice to know, but I do feel the room needs lots of work due to liveliness. Don't you think the decay times are a bit too long?


I’m not really big on that stuff. If I don’t hear any flutter or reverb from a hand clap, I’m happy with the acoustics. Our Moderators over at our Acoustics Forum can tell you what your decay numbers should look like, and what you can do to get them there.



> So Wayne, do you recommend no Bass-traps and other acoustic treatments for me at this point? I still feel a lot of Boomyness in my room though.


 There are two primary causes to explain a perception of “boominess.” One is a nasty peak in bass response. I’m not really seeing that in your frequency response graphs. The other is excessive decay times of the bass signal (aka “ringing”). Your waterfall shows that may be an issue in the 50-60 Hz range. Bass traps can help there, if you can get some that work at frequencies that low, and if you have the space in your room for as many as you’ll need.

An alternate solution that might be more effective, economical and (especially) use-of-space-efficient, would be to get a subwoofer for the bass, and use parametric EQ to tame any peaks.

Regards,
Wayne


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## GuitarCry (Dec 14, 2008)

@Wayne: Thank you so much for your help on this. Certainly bass traps for 50Hz-60Hz will be very difficult to obtain, especially in my small room and the constant WAF to attend. Yes, I do hear my handclaps reverb and flutter.

I'll look into the sub-woofer and EQ parametric control. Any recommended start-up reading on this subject?

Best regards


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

To learn about subwoofers, we have a couple of Forums dedicated to that, on manufactured and DIY subs. For equalization, you’re already in the right place. Just poke around this REW Forum. The threads with the paperclip icon means graphs have been attached. Many of those threads will contain “before and after” graphs for people who’s sub response went from this...







​

...to this.







​

Regards,
Wayne


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## GuitarCry (Dec 14, 2008)

Wow. That's a remarkable improvement. I'll definitively look into your suggestions. Thanks


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