# Need Expert Feedback on Room Response



## DLB (Nov 4, 2008)

I had played around with REW some several years ago. Recently, my Denon 4806ci locked up and I purchased an Onkyo TX-NR3009 to sit in while the Denon gets serviced.

This was a catalyst to get out REW again and take some measurements. I was very curious about the difference between AudysseyXT and XT32.

I am attaching my REW file and would greatly appreciate some expert feedback. It seems that my room is overdamped. Probably not a very common problem.

I do have a couple modes and what appears to be a crossover null around 90 hz that need addressed.

Thanks in advance for you analysis.
DLB


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## DLB (Nov 4, 2008)

How do I know what my real RT60 value is? I am concerned that my room is too dead. In the attached mdat file, the waterfall and RT60 basically shows values above about 90Hz as less than 300ms decay time and above 700Hz as less than 200ms decay time. I am reading that ideal times are more like 300-400ms.

I have a well sound proofed room, but don't have a ton of in-room treatments so i am somewhat surprised by the measurements. I think that surround channels and music could be more lively though.


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## Barleywater (Dec 11, 2011)

IR measurement looks good in terms of signal/noise. Nice.

How do sub with Left or Right measure? HF damping likely comb filter effect, measuring two speakers.

90Hz notch more likely boundary effects than crossover.

Audyssey? 









Above is with:









for IR windows. This gates out most early reflections. Super flat 300Hz-500Hz looks like Audyssey, is this still active with "Pure Direct..."? With gated response comb effect of two speakers plus super early reflections show as droop and notches >5k.


Is sound proofing as treatment of room or for isolation of room/house?

Reverb is hard to remove, but easy to add.

Dayton cal looks like OEM: no correction <20Hz.

Regards,

Andrew


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## DLB (Nov 4, 2008)

Andrew, thank you for taking the time to assist me!

This is with Audyssey disabled using Mains and subwoofer only. There actually 3 subs as configured.

I will have to rerun single channel tonight.

Most sound proofing is isolation. The theater is fully carpetted. There are decorative/ sound panels on walls that should only have minor high frequency absorbtion. Roughly 5/8" fiberglass.

Is there a good place for me to read up on the IR window settings and how this works?

Thanks,
DLB


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## Barleywater (Dec 11, 2011)

In a nutshell: Shorter IR window has higher frequency cutoff, below which information is not useful, and REW tends to display this as in above IR window pic with 125Hz for 2ms/6ms windowing pair. Type of window has effect on how edges taper off.

Best way to learn window behavior is to explore it.

Longer windows show lower frequencies, but integrate more wavelengths of higher frequencies, and it makes seeing comb effects more difficult at the higher frequencies. This applies to single speaker too, in that narrow peaks and dips from similar path length reflections don't stand out with really big windows.

Andrew


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## DLB (Nov 4, 2008)

Barleywater said:


> In a nutshell: Shorter IR window has higher frequency cutoff, below which information is not useful, and REW tends to display this as in above IR window pic with 125Hz for 2ms/6ms windowing pair. Type of window has effect on how edges taper off.
> 
> Best way to learn window behavior is to explore it.
> 
> ...


Thanks Andrew

I took a lot of measurements last night and moved my big sub all over the place looking for the flattest response. I have settled on a new location for now. The bass is much tighter, which seams to reveal more detail in the mids and highs from the short time I listened to it. I need to rerun Audyssey setup and do some more listening and go from there. I wonder if the bass is too tight actually. I was listening to David Gilmour Blu-Ray and I could hear every individual thump of the kick drum, like I was sitting right next to it, only it seemed maybe slightly out of sync with the video. Im guessing due to relocation of the sub. I will post some more measurements in the next day or so. 

Its a busy week at work. 

Thanks,
DLB


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## Barleywater (Dec 11, 2011)

Are you running Audyssey with each sub move? I've seen several threads now with very good sub results using Audyssey. In this regard, keeping sub(s) close to same distance as mains, and as close to mains as is reasonable will likely give most uniform behavior in general listening area.

Andrew


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## DLB (Nov 4, 2008)

Barleywater said:


> Are you running Audyssey with each sub move? I've seen several threads now with very good sub results using Audyssey. In this regard, keeping sub(s) close to same distance as mains, and as close to mains as is reasonable will likely give most uniform behavior in general listening area.
> 
> Andrew


No, I have run Audyssey a number of times with my Denon, before it locked up, and now with my Onkyo with my old Sub location and while it sounded pretty good, never totally impressed me. So my plan was to disable all equalization and find the best location for the sub first and then run Audyssey so that it would have less to correct and hopefully sound better as a result. I have narrowed to two general locations along the longest wall in my room that appear flattest with measurements and I have moved the sub to the most convenient of the two and listened a little and can definitely hear a positive change. Next, I will run Audyssey and then run some after measurements and listen some more and post some results. I am hopeful, that it will sound incredible and the measurements will look the same. If not, then I will look at making some additional changes. Perhaps I will look into a few traps to better attenuate first reflections or perhaps a Feedback Destroyer or both. I have too much money already wrapped up in my Theater to not pull out a few more stops to make it sound the best it can. 

Thanks,
DLB


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## fusseli (May 1, 2007)

What are the dimensions of your room and what is your speaker and sub placement like? I'd agree that shifting stuff around might help the 90Hz null. Might be worth a try. It'd be a quick and easy test to rule out the sub Xover...


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## DLB (Nov 4, 2008)

fusseli said:


> What are the dimensions of your room and what is your speaker and sub placement like? I'd agree that shifting stuff around might help the 90Hz null. Might be worth a try. It'd be a quick and easy test to rule out the sub Xover...


My room is 19'2"L x 14'6"W x 94" high. 

I have a proscenium that is 6" step. I have a riser that is 1' up with my second row of seating. There are 4 seats in each row. There is a 32" walkway around the back and both sides. 

I have a Jamo THX Ultra 2 7.1 setup in THX positioning, all speakers on wall except sub. Also have 2 Definitive Technology mains out in the room about 36" and at screen width that I switch in for music and sometimes use for movies. They each have an integrated powered subwoofer with discreet LFE inputs. 

The sub crossover can be set to Bypass or 120Hz with no change in measurements. 

Thanks, 
DLB


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## DLB (Nov 4, 2008)

I have taken more measurements, and suspect the Pure Direct and Direct modes may not be unfiltered as I previously had assumed. I came up with the idea last night to use the preouts to loop in with my soundcard and see for certain. I haven't actually run the test yet.


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## DLB (Nov 4, 2008)

DLB said:


> I have taken more measurements, and suspect the Pure Direct and Direct modes may not be unfiltered as I previously had assumed. I came up with the idea last night to use the preouts to loop in with my soundcard and see for certain. I haven't actually run the test yet.


So, does anyone know if there would be an impedance matching issue with using a Pre-out vs a line level out like DVRout/TAPEout?


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## fusseli (May 1, 2007)

DLB said:


> Also have 2 Definitive Technology mains out in the room about 36" and at screen width that I switch in for music and sometimes use for movies. They each have an integrated powered subwoofer with discreet LFE inputs.


Were these speakers used in your measurements? If so, I see no coincidence here...

If your measurements are with you on-all speakers, the hunt continues.


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## DLB (Nov 4, 2008)

I am still working through some things in my quest for audio satisfaction. I can confirm that the Direct and Pure Direct modes on the Onkyo attenuate frequencies below 80Hz, even with subwoofer turned off and speakers selected as full range. I also found that the Stereo mode consistently caused some odd issues that showed up as narrow nulls, while the Mono and all channel stereo modes appear to be the best options moving forward for taking measurements for speaker placement. 

I could not successfully manage to use the Pre-out to include the receiver in the loopback calibration. There is a level mismatch or impedance issue. I was able to use the DVRout, but this appears to just mirror the CDinput from my soundcard.

I have moved the sub to the rear center of the theater. It is so big that it just about blocks passage behind the rear seating row, which is not ideal, but the system measures and sounds better. I think I will leave it there for a while and see whether the improvement in sound outweighs the location annoyance.

My THX Ultra 2 Jamo mains measure much flatter than the Def techs, but sound a little confined compared to the Def Techs. The Jamos work great for center and surrounds, but just not ideal for the mains, especially for music.

The Audyssey picks some unexpected settings for speaker distances and associated level adjustments, but it does help widen the sound stage in my opinion.

I have bass set much lower than I used to, so it will probably take a while for my ears to adjust, but I definitely hear a lot more detail in the mids than I used to and is less fatiguing, even at higher volumes.

The other thing I noticed when playing a mp3 that I have listened to dozens of times before, Time by Pink Floyd, is that the noise floor is not as low as my Denon 4806ci was. Now my Denon cost twice as much, so I guess I shouldn't be too surprised. I thought it was a 256bit EAC rip, but certainly didn't sound like it.

Oh, I have had a couple weird HDMI issues, where the center channel wasn't playing when playing a Blu-ray from PS3. I never had this problem with my Denon. I am using a quality cable, so am hoping it won't become a serious problem. I don't want to have to deal with a return.

The GUI is a huge improvement over my older Denon and so is the remote control, although the remote has a few issues.

Well, thats enough for now. When I get a chance, I will post a few pics of my theater and a few more graphs to help illustrate my comments.

I would still like to get some comments regarding RT60 times and the decays time in the waterfall graphs in REW and how different values impact the sound. Thanks!


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## DLB (Nov 4, 2008)

Here is a picture of my theater. The sub in its original position front left. This picture doesn't have the Def Tech fronts which now stand just in front of the proscenium and just to either side of the screen.


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## DLB (Nov 4, 2008)

Here is a photo of the rest of the room showing the seating and surround speakers. Their is a 32" walkway around the rear and sides of the seats. The sub is now sitting behind the second row of seats.


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## EarlK (Jan 1, 2010)

> So, does anyone know if there would be an impedance matching issue with using a Pre-out vs a line level out like DVRout/TAPEout?



-  *Impedance Bridging*  vs  *Impedance Matching* 

- I'm not going to answer your question directly . The posted links & the following info should give you the necessary insights to make your own determination .

- Please study the info in those links and then study the published specs for your particular gear .

- You should find that most solid state electronics rely on on Impedance Bridging for proper signal transfer .

- An old rule of thumb ( that sticks in my brain ) is a 10/1 ratio ( load Z to source Z ) is preferred ( with 5/1 being a bare minimum ) . You should google around to see if these ratios hold any water with current design wisdom .

:sn:


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## DLB (Nov 4, 2008)

EarlK said:


> -  Impedance Bridging  vs  Impedance Matching
> 
> - I'm not going to answer your question directly . The posted links & the following info should give you the necessary insights to make your own determination .
> 
> ...


I have an impedance matching tool that maybe I will dig out and try when I get a chance. Thanks.


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## DLB (Nov 4, 2008)

Well, I have done a fair amount of research. 

I have also played around a little with computer based parametric equalizer and VST Host software and found it cumbersome and don't really want a computer running all the time anyway, but believe that I can get some help from sub equalization from this experience, along with reading countless reviews and watching a few videos.

My biggest problems appears to be one peak and a couple nulls in the base range. I know I need to add some additional first reflection absorption on the side walls and ceiling and on the screen wall. I may also need to add a few base traps. My room is nicely trimmed and I want to be careful not to lose the professional look of my room, and don't want to spend too much additional money either.

I have looked heavily at the parametric EQ hardware from the DSP1124p to the Antimode 2.0 Dual Core and beyond. 

I finally decided that I already have a full range equalizer option with the Audyssey MultEQ XT-32 in my Onkyo TX-NR3009, which is reviewed well by many. Therefore, it's probably unwise to dump more money in another full range equalizer option. 

Since I already have a working REW setup, and I can get a compatible, and highly configurable EQ for about around a $100, I decided to go ahead and give the FBQ1000 a shot. Hopefully, I find that it works well to EQ my main sub. 

I couldn't find a confirmation that it worked via midi with REW, but compared the manual with the DSP1124p and they have identical settings and midi charts so am hopeful this works well. 

I figure that if this solves the peak and nulls reasonably well, but is just noisy or flaky, I can look into higher priced options. If it doesn't work, I'm not out too much and will shift focus to additional acoustic treatments.

I will post some results after I receive the unit and get it set up and working.


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## Barleywater (Dec 11, 2011)

Do you have results for Audyssey MultEQ XT-32? How many calibration points?

Regards

Andrew


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## DLB (Nov 4, 2008)

Andrew,

I have taken before and after measurements, but didn't label them well, so I will take some more when I get a chance. There is definite improvement, but its not a silver bullet.

DLB


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## DLB (Nov 4, 2008)

I received my Behringer FBQ1000 the other day and had a late night last night setting it up and putting it to work! 

First I want to confirm that it works perfectly, as far as I can tell, with REW as a DSP1124p including the MIDI functions!!!

I am going to post several graphs and comments in hopes that the information will be useful to others. I want to be clear that this step is part of a larger process to continually improve my Home Theater and Music listening experience and to learn and have fun doing so. I know I have a lot more to learn and my setup has room for improvement. That's all part of the fun.

All graphs are posted according to BruceK's posting recommendations, except that I didn't see a clear recommendation on smoothing. However, since in his manual measurement recommendations, he recommended measuring at 1/6 octaves, I decided to use that for my smoothing settings. This also made the graphs easy to look at, and the consistency allows easy comparison of before and after graphs.

Here is the response of my Room before any equalization. I used a tape measure to set all the speaker distance settings in my Onkyo TX-NR3009 receiver and used a Radio Shack SPL meter in conjunction with REW and my Dayton EMM-6 with Factory Calibration through my TASCAM US-122MKII to set the Speaker Levels.









Here is the waterfall graph:









Here is the impulse response graph:









And Here is the EQ Filter Response Match Graph:


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## DLB (Nov 4, 2008)

I can't say enough for how well REW has been developed. It is amazing!!! I hooked up the midi cable from the TASCAM to the Behringer and selected the send filter settings to equalizer and a window pops up with step by step help instructions for configuring the Behringer to accept MIDI communications. A few steps later followed by a few seconds of download time and all my filters where auto loaded into the Behringer. I spent the next half hour trying to figure out why the horizontal bars where flashing oddly and assuming I must have done something wrong and fiddling with the various presets. Finally I decided to take a response measurement anyway, and discovered that everything was working well.

Here is a response graph with filters from 10Hz to 120Hz. When comparing to the before response, its obvious that the filters are working to flatten the response on the subwoofer.









Here is a response graph with filters from 10Hz to 250Hz. I wanted to try and clean up the null around 110 Hz, and this did the trick nicely.









Here is the waterfall graph associated with the 10Hz to 250Hz EQ settings. A little ringing at a couple sub-40Hz frequencies, by otherwise looks fairly well behaved to my eye.


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## DLB (Nov 4, 2008)

Now, I decided to run the Audyssey MultEQ XT32 auto calibration on my Onkyo TX-NR3009 receiver. I spent a lot of time looking for real before and after measurements of Audyssey, and only came up with a couple examples that didn't look all that compelling. Now we get to see how my experiment turned out.

I took the minimum of 3 rounds of measurements all at the primary listening and measurement location. This whole experiment optimizes for a single location in my room only.

Here is the response graph after the Audyssey Auto Setup Routine, but with Audyssey disabled and DynamicEQ disabled:









Here is the response graph with Audyssey Music on and DynamicEQ On:









Here is the response graph with Audyssey Music on and DynamicEQ Off. This is the flatest response and so for the purposes of this experiment is what I am referring to as my "After" measurement.









Here is the associated waterfall for my After measurement:









Here is the associated impulse response to my After measurement:


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## DLB (Nov 4, 2008)

Just to show the remaining Audyssey options, I included a few more graphs that I captured.

Here is the response with Audyssey Movie On and DynamicEQ Off:









Here is the response with Audyssey Movie On and DynamicEQ On:









Now the experiment wouldn't be complete without showing an overlay of the "Before" and "After" response graphs. And looking at it below, and understanding a little about what is going on, my opinion is that these results are visually dramatic.


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## DLB (Nov 4, 2008)

Now all this isn't really complete without talking about how it sounds. Getting straight to the point, the room sounds clearly improved at the main listening position in many ways. I will update this section with more detail after I spend more time listening.

For those that want the .mdat file, I'm sorry to say that it is too large to upload at roughly 2.5x the upload limit.

What's next for me? 

1) To understand if and how I can use the same Behringer to also EQ the subs integrated into my Definitive Technology Main L+R speakers. For this experiment, I had to turn them all the way down as they cause bass problems in my room response.

2) To rerun Audyssey with more locations to improve performance at other seating positions. Surround sound in the back row needs improvement as can be expected with how I ran the setup for this experiment.

3) Start experimenting with House Curves.

DLB


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## Barleywater (Dec 11, 2011)

You can save results into multiple mdat files.....

What frequency range was Audyssey set to correct for?

How many microphone positions were used? And at what range of distances from listening position? This has impact on averaging used by Audyssey. Tight grouping of measurement points likely leads to peaky 100Hz-500Hz performance.

Results do look better, and most importantly sound better to you.

Andrew


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## DLB (Nov 4, 2008)

"You can save results into multiple mdat files....."

I will look at breaking them up when I get a chance.


"What frequency range was Audyssey set to correct for?

I don't recall seeing any adjustment settings for Audyssey frequency range, so was assuming full range. Do you know different?


"How many microphone positions were used?"

3 positions


"And at what range of distances from listening position?"

Tightly coupled at main listening location only


"Tight grouping of measurement points likely leads to peaky 100Hz-500Hz performance."

Hmmm. I don't understand why this would be, but good to know. Is there a rule of thumb for smoothest Audyssey results?

Thanks,
DLB


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

DLB said:


> All graphs are posted according to BruceK's posting recommendations, except that I didn't see a clear recommendation on smoothing.


Typically we recommend no smoothing for subwoofer-specific graphs (e.g. upper limit @ ~200 Hz), and smoothing for full range graphs like the ones you presented. Either 1/6- or 1/3-octave smoothing usually works well.

A few other comments: 

*Waterfalls are only useful up to about 300 Hz.
*Lower the graph floor for waterfalls to something closer to your room’s ambient noise floor – probably something like 35 dB.
*The 40 Hz “ringing” your waterfall shows is most likely being generated by some noise source in the room – refrigerator, A/C system, etc. Or possibly some outside noise that’s loud enough to be heard inside the house.

Overall things look great – pretty impressive stuff Audyssey is doing there... :T

Regards, 
Wayne


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## Barleywater (Dec 11, 2011)

Tight grouping of measurement points likely leads to peaky 100Hz-500Hz performance.--

Summed reflections at any single measurement point form specific response, that may contain large peaks and dips that will be compensated for in room correction software. Location of peaks and dips at point 6" away will be quite different at highest frequencies, and very little change for lowest frequencies. 1/4 wave pathlength differences are underlying concept. Multiple measurements distributed about a single sweet spot lead to broadened sweet spot with less perfect correction. For bass and sub in theater setting measurements should be taken across seating area. So with some Audyssey setups it is possible to make preset for single listener discrete stereo+subs that has narrower, well corrected sweet spot, and to make a theater preset that accommodates multiple seats and LFE program content.

Have you looked into having an Audyssey Pro Installer go through your system? As you have obviously spent a lot on your system already, it seems like an option. I think there is also option to purchase pro install license that expands software feature, and number of allowed measurement points.

Personally, I would try a series of different alignment runs with various numbers of correction points, and trying different spreads in microphone locations for each run. Take notes.

Regards,

Andrew


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## DLB (Nov 4, 2008)

I spent some time listening to some music for the last few weekends. I think my system/room sounds pretty good, but could still use some improvement. 

At reference volumes (85-90dB C weighted, slow response), I begin to hear some fatiguing unpleasantness in the mid and high frequencies.

I am not really sure of the source of the problem. I think the problem may also be present at lower volumes, but just becomes more bothersome as the volume is increased, so I don't think it is a speaker cone distortion, or amplifier distortion related to high volume.

I think it may be due to early reflections, so I am thinking about adding sound absorption to the screen wall, ceiling, and more on the side walls at early reflection points.

With my birthday recently passed and Christmas coming, I am due for some toys. 
* I want a new media player and am looking at the Oppo BD103. I connect to digital through my receiver, so don't have a need for the BD105.
* I was thinking that maybe the Onkyo is having difficulty with the 4ohm Jamo's in my system, and was considering a pair of Emotiva XPA-1 monoblocks, or an XPA-2 2-channel amplifier.
* I thought about replacing the Definitive Technology speakers that I also sometimes use for music listening and switch in and out with a pair of Jamo D 7PEX LCRs as my mains.
* But I think what I may really need are some new acoustic panels.

I can't afford them all. I'm a sucker for new electronics, but I think what I most likely need are the acoustic panels. So, I guess I will get some acoustic panels then...


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

DLB said:


> I think it may be due to early reflections, so I am thinking about adding sound absorption to the screen wall, ceiling, and more on the side walls at early reflection points.
> 
> I think what I most likely need are the acoustic panels. So, I guess I will get some acoustic panels then...


Before you go to that expense, you might want to review this article, especially the “Listening Tests” section.

Regards, 
Wayne


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## sfdoddsy (Oct 18, 2007)

Did you run Audyssey after the manual EQ?

If so I'm not convinced it was an improvement. Your last chart before Audyssey was very smooth before some peaks above 250 or so. The chart with Audyssey setup but no EQ was also smooth but with bass boost which could just be the subs too hot.

However, all the Audyssey charts show the introduction of a fairly wide dip just before 200hz that wasn't there before. This is right in the middle of the power range and is likely to result in more clarity, but less weight.

Audyssey has also tipped up the high end to measure flatter. Many people (myself included) find this a bit unnatural. It wouldn't surprise me if this was responsible for the harshness up high you describe.

It should be easy enough to add an HF roll-off with your FBQ, although a DEQ or MiniDSP would be even better. See how that sounds. And try a little tickle for the midbass dip.

Your room is already very dead. I'd be very wary about adding any more treatments.


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## DLB (Nov 4, 2008)

Hi Wayne,

Very interesting article. I will have to also read the others at that site.

My problem is that I don't understand the cause of the problem I am hearing. I suppose I will need to perform some more experimentation to see if I can figure it out before making arbitrary investments.

Thanks,
DLB


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## DLB (Nov 4, 2008)

Hi sfdoddsy,

Thanks for your thoughts! 

Yes, I ran Audyssey after the manual EQ. 

I understand your comments and assumed the issue is related to higher frequencies, maybe 1KHz or several KHz and higher. 

I hear the problem in the PURE mode (No Audyssey) and with the FBQ disabled so do not believe this is the problem. Perhaps I am just overly sensitive to higher frequencies and never noticed it before??? 

I will experiment some more and see if I can isolate the problem or more positively rule out some of the possibilities.

Thanks,
DLB


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## DLB (Nov 4, 2008)

Wayne,

Thinking more about this article, it is supportive of what I have read about Dennis Erskine's approach to home theater acoustics in some respects. He recommends sound absorption below the ear level, which helps with RT, but recommends only very little or no sound absorption at or above ear level, which allows for the advantages of wider soundstage and dynamics.

Thanks,
DLB


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