# Ideal room response



## DanTheMan (Oct 12, 2009)

I've been doing some experimenting today. When I turned my subs by ear listening to music I got this:








which looks like this when I did a FR sweep:








The bass is 5 positions across my listening couch.

I did a little fiddling to get flat and got this:









Is there a balance that is preferred or recommended for HT? Sorry I forgot to format these for the forum, but a deleted the data and can't quickly redo them.

Thanks, 

Dan


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## glaufman (Nov 25, 2007)

Not sure exactly what you're asking, but some people like to see a flat response for HT, some like to have it bass heavy.


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## DanTheMan (Oct 12, 2009)

So there's no THX guidelines or anything? I looked on their site but didn't see anything.

Thanks Gregg! Your always helpful,

Dan


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## glaufman (Nov 25, 2007)

Hi Dan-
I believe THX would say a flat response is ideal for reproducing the creative intent.


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## laser188139 (Sep 19, 2009)

Hi Dan,

I agree with Greg, that what THX recommends is flat when listening at theater level volumes, 105dB peaks and ~75dB voice levels. Since most of us listen at softer levels in our homes, some adjustment is needed to maintain the same perceptual intensity. Audyssey builds this in with their DynamicEQ, so I can target my curve to flat and let it introduce adjustments later. As I understand it, the same idea is behind the definition of a house curve with REW, to listen to test tones at your normal listening level to determine what sounds even, and then use this as your equalization target. 

If I did not have Audyssey and wanted a scientific approach, I might pick a level for the average sub content, relative to the 115dB LFE peak, and look that up on the ISO equal loudness curve at some sub frequency. Then, if I typically listen to films with the volume control set -20dB from reference, I would look at the equal loudness curve 20dB lower, see what value that has at the same chosen sub frequency. Calculate the difference, and use that as the amount of boost. 

Bill


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## lsiberian (Mar 24, 2009)

I think that last graph has a room gain bump. Is the sub near a corner?


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## DanTheMan (Oct 12, 2009)

OK, Thanks again Gregg.

Got it Bill. Thank you very much. That's my plan now. It is sounding good as is, but I'm a nutty OCD type.

Thanks Isiberian. Pretty much everything below 200Hz is dominated by the room in my graphs. My subs are both away from the corner, but it almost seems that any usable place(meaning they stay out of floor space) seems to have that 30Hz bump. I just can't get rid of it, but I also don't mind it. It's the 50-200 range that I want to get as right as possible and w/o a DEQX I'm not sure it's really possible. Audyssey would be nice, but I just have a stereo receiver. If the subs go more towards the corner I get something more like this:









Te 50Hz notch moves to a 40Hz, but still the double peak thing.

This is one sub in the corner, one seven feet away down the long wall:









Room acoustics!:doh: That might actually be a better place for this question, but I think I got it licked anyway thanks to you guys.

Dan


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## lsiberian (Mar 24, 2009)

DanTheMan said:


> OK, Thanks again Gregg.
> 
> Got it Bill. Thank you very much. That's my plan now. It is sounding good as is, but I'm a nutty OCD type.
> 
> ...


You could probably eq it down and get some nice results. It would increase your overall sub headroom by a 10db with a -10db filter. This is a good problem to have IMO.:R


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## DanTheMan (Oct 12, 2009)

An EQ is in my future. I'm hoping to get an analog one once I figure out what's best placement for the room.

Dan


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## glaufman (Nov 25, 2007)

laser188139 said:


> 105dB peaks and ~85dB voice levels.


Actually, the last I saw from THX for home use was 75dB at "reference level," which I believe is supposed to be voice levels, and in any case should be the level the AVR puts out when using it's internally generated test tones or from a calibration disk. This is different than for commercial theaters, which use the levels Bill quoted. The rationale behind the difference if I understand correctly is 85dB is just too loud in the smaller spaces in homes. Since many here have said that 85db is not too loud in home spaces *that have been properly treated acoustically* I believe THX made a compromise here and assumed that most home users wouldn't tame their reverberation times, and compromised to 75dB to compensate. This is just conjecture on my part.


DanTheMan said:


> but it almost seems that any usable place(meaning they stay out of floor space) seems to have that 30Hz bump.


This might mean that you should consider moving your listening position, which is as important as the sub's position.


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## laser188139 (Sep 19, 2009)

glaufman said:


> Actually, the last I saw from THX for home use was 75dB at "reference level," ...


Actually, Greg, you are probably right and it was I who was confusing test signal levels with normal levels. As I recall now, the Dolby dialnorm is based on a normal voice level of -31dbFS, so I should have written 75dB. 

Thanks for the correction,
Bill


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