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Discussion Starter · #1 · (Edited)
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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Discussion Starter · #2 · (Edited)
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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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?

Text Line Plot Font Slope


Above is with:

Text Font Line


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.:D

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

Regards,

Andrew
 

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Discussion Starter · #4 ·
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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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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Discussion Starter · #6 ·
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.

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
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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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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Discussion Starter · #8 ·
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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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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Discussion Starter · #10 ·
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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Discussion Starter · #11 ·
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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Discussion Starter · #12 ·
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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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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Discussion Starter · #14 ·
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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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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Discussion Starter · #18 ·
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 .

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

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Discussion Starter · #19 ·
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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