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post #1 of 40 Old 09-22-2012, 07:12 PM - Thread Starter
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Hi folks!

I've watched one too many movies thinking I should turn the subtitles on to understanding half of what the actors are saying. It's all a garble and a mumble. Music is great, no problems there, and I'm quite picky, been an audiophile for 20 years.

I've been living with this situation for many years and have not had the time or money to address it. Perhaps it's time to take action. smile.gif

Here's the room (run, it's a square!): 11.5' x 11.5' with one corner cut off for the doorway. The ceiling has a fan/light that takes over a large area. Wall to wall pile carpet with pad. The room is also an office, so the walls are lined with desks and monitors, racks, etc. There is a window with wooden louvers at the opposite side from the LCR speakers, and a pair of the typical glass closet sliding doors on the the side wall.

Here's the gear:

Speakers: DIY left, right with high dollar Scandinavian drivers and massive cabinets. I know a thing or two about building speakers, at least I used to when I had more time. Center channel: Dynaudio C120+. Cost $700 plus tax. This is a horizontal MTM and it is sitting underneath a large projection screen on top of a solid wooden cabinet with drawers.

Electronics: Panasonic SA-XR57. This replaced a Denon AVR-5700 and high end Adcom amp. Sounds about the same, maybe a little more detail on the Panny, even though it cost me a small fraction of what I paid for the older gear (bought long ago when these pieces were current, not second hand). Dialog problem remains unsolved. Source: HDMI output from a computer running XBMC. Speaker cables are DIY 12 GA OFC with gold plated connectors. Pretty sure based on experimentation over the years that cables are cables.

I've read on and off over the years about using things like convolver and REW, etc., to test a room and establish a filter. That's all well and good, but how to practically apply the equalization to 6 speakers? The solutions I've seen only work with a subwoofer. And, if that were to be addressed, how to practically use the filter with modern DVD/Blu-ray playback software assuming a software solution?

The Audyssey system looks interesting, but I'm not convinced based on many expert opinions that it is more or less just a gimmick.

So, room treatments for first reflection points are probably a good option, but the fan/light fixture is probably in the way. I have not actually done the mirror test though, but it's likely. And the side walls are pretty much covered with miscellaneous objects as mentioned previously, none of which would be suitable to stick a treatment onto.

Please share your thoughts and suggestions. smile.gif

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post #2 of 40 Old 09-22-2012, 07:58 PM
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Quote:
Originally Posted by Ben_Tech View Post

Hi folks!
The Audessey system looks interesting, but I'm not convinced based on many expert opinions that it is more or less just a gimmick.

Dialog in Films Unintelligible, I too with many cable tv shows and movies shown on cable, have the same problem at times, poor dialog, it just doesn't project into the room with power. The only way for me to fix this problem in the most cost effective way is just to turn off audessey. Audessey can make some source material better and some worse, thats why is has a on/off mode button..
Audessey may just help you since your not happy with the way your HT sounds without Audessey. If you were happy with the way it sounds than Audessey may ruin it for you. Audessey removes the peaks and dips, I love the imperfections with my HT, thats why it sounds better than most.....
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post #3 of 40 Old 09-22-2012, 11:35 PM - Thread Starter
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Thanks for your reply. The Denon 1713 is not out of the question to replace the Panny. However, I'd like to investigate some other options if at all possible as I think, generally, that any properly functioning and electrically adequate amplifier sounds much the same as any other..... a shame to spend that much on a cheap DSP chip when my receiver works fine. smile.gif (As mentioned, I had expensive receiver / amp in the past and it sounds about the same.)

I should also mention that I have a radio shack SPL meter that I use at the primary listening position to set the levels of each channel and carefully measure and set the distance delays... I have always done this, but the problem persists. smile.gif So, I am hoping to learn to become more sophisticated with my approach.

I have tried setting the center channel approximately 2-3 dB hotter than the LR. I believe I have tried that in the past and it did not help much, but I'll give it another shot.

Looking forward to further discussion about my options.

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post #4 of 40 Old 09-23-2012, 08:44 AM
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Quote:
Originally Posted by Ben_Tech View Post

Henter channel: Dynaudio C120+. Cost $700 plus tax. This is a horizontal MTM and it is sitting underneath a large projection screen on top of a solid wooden cabinet with drawers.

Please share your thoughts and suggestions. smile.gif

Hi Ben_Tech,

Although you have described the position of the Center speaker, here are some questions:

- is the Center speaker tilted to face seated ear hight at the MLP?

- is the Center speaker nudged off the top of the cabinet 1 inch minimum in order to minimize first reflections or is it sitting way inside on the top?

- is the Center speaker visible from the MLP or blocked by a coffee table or else?
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post #5 of 40 Old 09-23-2012, 09:23 AM
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You can try reversing the phase of the center speaker by rewiring. Just let your ears be the judge. If your Xover for the center is 80hz or higher,, phasing for lowend output won't be the big issue, just use what sounds best to you..
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post #6 of 40 Old 09-23-2012, 10:52 AM
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Quote:
Originally Posted by Ben_Tech View Post

Hi folks!
I've watched one too many movies thinking I should turn the subtitles on to understanding half of what the actors are saying. It's all a garble and a mumble. Music is great, no problems there, and I'm quite picky, been an audiophile for 20 years.
I've been living with this situation for many years and have not had the time or money to address it. Perhaps it's time to take action. smile.gif
Here's the room (run, it's a square!): 11.5' x 11.5' with one corner cut off for the doorway. The ceiling has a fan/light that takes over a large area. Wall to wall pile carpet with pad. The room is also an office, so the walls are lined with desks and monitors, racks, etc. There is a window with wooden louvers at the opposite side from the LCR speakers, and a pair of the typical glass closet sliding doors on the the side wall.
Here's the gear:
Speakers: DIY left, right with high dollar Scandinavian drivers and massive cabinets. I know a thing or two about building speakers, at least I used to when I had more time. Center channel: Dynaudio C120+. Cost $700 plus tax. This is a horizontal MTM and it is sitting underneath a large projection screen on top of a solid wooden cabinet with drawers.
Electronics: Panasonic SA-XR57. This replaced a Denon AVR-5700 and high end Adcom amp. Sounds about the same, maybe a little more detail on the Panny, even though it cost me a small fraction of what I paid for the older gear (bought long ago when these pieces were current, not second hand). Dialog problem remains unsolved. Source: HDMI output from a computer running XBMC. Speaker cables are DIY 12 GA OFC with gold plated connectors. Pretty sure based on experimentation over the years that cables are cables.
I've read on and off over the years about using things like convolver and REW, etc., to test a room and establish a filter. That's all well and good, but how to practically apply the equalization to 6 speakers? The solutions I've seen only work with a subwoofer. And, if that were to be addressed, how to practically use the filter with modern DVD/Blu-ray playback software assuming a software solution?
The Audyssey system looks interesting, but I'm not convinced based on many expert opinions that it is more or less just a gimmick.
So, room treatments for first reflection points are probably a good option, but the fan/light fixture is probably in the way. I have not actually done the mirror test though, but it's likely. And the side walls are pretty much covered with miscellaneous objects as mentioned previously, none of which would be suitable to stick a treatment onto.
Please share your thoughts and suggestions. smile.gif

1. Your room sounds like an acoustic nightmare, which can certainly cause loss of dialogue intelligibility. Reflections off all the hard surfaces can cause comb filtering that reduces dialogue intelligibility. Room treatments can help.

2. Placement of the CC on top of a wooden cabinet can cause serious comb filtering, especially if the CC is placed well back from the front edge of the cabinet. The early reflections off the surface of the cabinet combine constructively and destructively to cause the comb filtering. Moving it to the front edge of the cabinet can help.

3. Try using a "phantom" center. In the receiver's setup menu, set the CC to Off or None. The receiver will then re-route the CC info to the L/R speakers. When you sit in the middle, between the L/R speakers, you should hear the CC info in the center. If dialogue intelligibility improves, you can be assured that the problem is the placement of your CC speaker.

4. Audyssey could help. It's not a gimmick.

Craig

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post #7 of 40 Old 09-23-2012, 01:15 PM - Thread Starter
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Originally Posted by mogorf View Post

Hi Ben_Tech,
Although you have described the position of the Center speaker, here are some questions:
- is the Center speaker tilted to face seated ear hight at the MLP?
- is the Center speaker nudged off the top of the cabinet 1 inch minimum in order to minimize first reflections or is it sitting way inside on the top?
- is the Center speaker visible from the MLP or blocked by a coffee table or else?

Thanks for your reply!

Answers:

1) No, it is aimed at the chest rather than the head. I could tilt it. It would depend on the height and/or position of the viewer though as that tends to vary. I already tried placing very thick wool felt in between the cabinet and the speaker as a decoupling method, I can just move a piece of that underneath to tilt it if it would help.

2) It is nudged off the edge.

3) Clearly visible with no obstructions.

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post #8 of 40 Old 09-23-2012, 01:31 PM
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Originally Posted by Ben_Tech View Post

Thanks for your reply!
Answers:
1) No, it is aimed at the chest rather than the head. I could tilt it. It would depend on the height and/or position of the viewer though as that tends to vary. I already tried placing very thick wool felt in between the cabinet and the speaker as a decoupling method, I can just move a piece of that underneath to tilt it if it would help.
2) It is nudged off the edge.
3) Clearly visible with no obstructions.

So far so good! smile.gif

Sorry to ask the obvious, but did you/ could you check whether all 3 drivers (2 woofers and 1 tweeter) are intact in your Center speaker. This to make sure none of them are blown out.

P.S. +1 to Craig, Audyssey is not a gimmick, I also have excellent results in my living room setup with an Audyssey enabled AVR. smile.gif Please feel free to visit my setup (link in my sig).
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post #9 of 40 Old 09-23-2012, 01:45 PM - Thread Starter
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Originally Posted by craig john View Post

1. Your room sounds like an acoustic nightmare, which can certainly cause loss of dialogue intelligibility. Reflections off all the hard surfaces can cause comb filtering that reduces dialogue intelligibility. Room treatments can help.
2. Placement of the CC on top of a wooden cabinet can cause serious comb filtering, especially if the CC is placed well back from the front edge of the cabinet. The early reflections off the surface of the cabinet combine constructively and destructively to cause the comb filtering. Moving it to the front edge of the cabinet can help.
3. Try using a "phantom" center. In the receiver's setup menu, set the CC to Off or None. The receiver will then re-route the CC info to the L/R speakers. When you sit in the middle, between the L/R speakers, you should hear the CC info in the center. If dialogue intelligibility improves, you can be assured that the problem is the placement of your CC speaker.
4. Audyssey could help. It's not a gimmick.
Craig

Hi Craig, thanks for your reply.

1) Yes, it is. I wish I had space on the walls and ceiling for treatments. I could perhaps place small treatments around the light/fan fixture if that would help. One wall is done in high end wallpaper which is off limits in terms of putting holes in. I could perhaps put something over the glass closet doors if that would help but I don't think the glass is a first reflection point where it is. Suggestions appreciated?
2) It is placed about 1" off the edge of the cabinet as I was aware of that issue.
3) I have tried that in the past and my vague impression was that it might have helped a little bit. I'll give it another try sometime soon.
4) Thank you for your opinion on that.

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post #10 of 40 Old 09-23-2012, 01:52 PM - Thread Starter
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Originally Posted by joehonest View Post

You can try reversing the phase of the center speaker by rewiring. Just let your ears be the judge. If your Xover for the center is 80hz or higher,, phasing for lowend output won't be the big issue, just use what sounds best to you..

Thanks for that. I could try reversing the banana plugs on the center channel. Adding it to my list of things to try sometime soon.

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post #11 of 40 Old 09-23-2012, 02:00 PM - Thread Starter
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Sorry to ask the obvious, but did you/ could you check whether all 3 drivers (2 woofers and 1 tweeter) are intact in your Center speaker. This to make sure none of them are blown out.

I checked it when I purchased it. I bought it new in a sealed box from an authorized dealer. It has not been driven hard..... OK just checked again - even took a photo:


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post #12 of 40 Old 09-23-2012, 02:00 PM
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I have no knowledge of your AVR but I think at times we are all subject to this. I have what I would consider pretty nice speakers and separates. I have all speakers set with a radio shack SPL meter.

I have been doing more Netflix downloads lately. Dialog from the center has been hard to hear at times with these downloads. I finally adjusted the trim to the center by 1.5 positive and some of these subpar downloads are finally audible via the center.

Are you able to adjust your trim levels on the fly via your AVR? NAD was always sweet as they have volume adjustments for each channel via the remote and would return to original settings at power off.

Are you sure you don't just need to adjust your center volume?

Good Luck...

Rick

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post #13 of 40 Old 09-23-2012, 02:09 PM - Thread Starter
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I have no knowledge of your AVR but I think at times we are all subject to this. I have what I would consider pretty nice speakers and separates. I have all speakers set with a radio shack SPL meter.
I have been doing more Netflix downloads lately. Dialog from the center has been hard to hear at times with these downloads. I finally adjusted the trim to the center by 1.5 positive and some of these subpar downloads are finally audible via the center.
Are you able to adjust your trim levels on the fly via your AVR? NAD was always sweet as they have volume adjustments for each channel via the remote and would return to original settings at power off.
Are you sure you don't just need to adjust your center volume?
Good Luck...
Rick

Thanks Rick - I have raised the volume of the center a bit (about +2-3 dB). We will see how that goes. The Panny does have an adjustment for the center, surrounds and sub without going into the menu, however, you have to cycle through the three choices as they are all on one button on the remote rather than having a button for each. The Panny is a fine amp within its ability to drive the connected loudspeakers. So, for a small room, it sounds the same as my former $4500 amplification setup. I thought why not, as I was able to actually make money on selling my old gear and buying this one. Plus the lights don't dim when I turn it on like they did with the old boat anchors.......

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post #14 of 40 Old 09-23-2012, 03:08 PM
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I checked it when I purchased it. I bought it new in a sealed box from an authorized dealer. It has not been driven hard..... OK just checked again - even took a photo:

A photo doesn't show a blown out speaker. Can you go up front and listen to each driver with your ear at very cloce proximity to each membrane?
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post #15 of 40 Old 09-23-2012, 03:30 PM - Thread Starter
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A photo doesn't show a blown out speaker. Can you go up front and listen to each driver with your ear at very cloce proximity to each membrane?

Done - no issues detected. I played pink noise and all drivers hum and hiss just like they are supposed to. By blown out I assumed you meant physically damaged, i.e., pieces of the surround missing, etc. smile.gif But, I suppose the spider could become disconnected from the cone and not be visible.

I once bought a brand new pair of high end speakers and one of the drivers was not working, but it was easily corrected by the dealer by re-soldering the connection. It seems a wire came loose during shipping. These things happen, but this particular center speaker is in perfect working order.

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post #16 of 40 Old 09-24-2012, 11:40 AM
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but this particular center speaker is in perfect working order.

Then the next step is to investigate your room acoustics. I'm sure a few well-placed absorbers at reflection points will do wonders for increasing clarity.

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post #17 of 40 Old 09-24-2012, 12:40 PM - Thread Starter
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Then the next step is to investigate your room acoustics. I'm sure a few well-placed absorbers at reflection points will do wonders for increasing clarity.
--Ethan

Hi Ethan - thanks for your reply. I was thinking about that. As I mentioned above there is a very nice wallpapered wall that is off limits in terms of putting holes into. However, I could possibly hang something from the ceiling in front of the wall. Do you think that would work? I'm sure there is a first reflection point along there. Any affordable products or DIY construction tips that you have perhaps seen? I'm sure you have read and/or done more in this area than I. The wooden frames I have seen built are fairly heavy which is why I'm asking if there is anything lighter that is just as effective. Also, I am concerned that fiberglass bat may be an airborne allergen source (in very minute quantities but still) as I am quite sensitive to allergens. Thanks! smile.gif

PS Would it also be good to treat or replace those glass sliding closet doors?

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post #18 of 40 Old 09-24-2012, 01:20 PM
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Without seeing a photo of your setup it's difficult to comment on what to put where. As a test, start by hanging thick doubled-up bath towels at the side-wall reflection points using masking tape. If that helps, then you can look into proper acoustic panels either hung from the ceiling on wires or on stands. Fiberglass is not a health problem if it's properly covered, and rigid fiberglass sheds even less.

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post #19 of 40 Old 09-24-2012, 04:33 PM
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We run into this problem a lot on sound reinforcement systems. An individual may have voice tonalities that are just hard to understand.
The power in a voice comes with the Vowels and that is in a frequency range below 1000 Hz. Speech intelligibility comes from the consonants and that is above 1000 Hz.
Typically if we have someone that is difficult to understand, we tweek the response up right around 1800 Hz and their voice comes through much clearer.
Some people already have a peak in their voice in that range and may need to be tweeked down to keep it from being overbearing.
Telephones for instance have a boosted response in the 1500-2500 Hz range.

With modern receivers, you can often set the response for an individual input. You may be able to manually tweek the response to boost it in the 1800 hz range by a few db.

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With modern receivers, you can often set the response for an individual input. You may be able to manually tweek the response to boost it in the 1800 hz range by a few db.

Hi DoyleS,

I doubt that that would be the general solution to the OP's problem on dialog intelligibility. The secret lies somewhere else. As Ethan has already asked, a couple of photos may be required to reveal some of the hidden burdens the OP is experiencing in his room setup. Let's see!
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post #21 of 40 Old 09-24-2012, 05:44 PM
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I checked it when I purchased it. I bought it new in a sealed box from an authorized dealer. It has not been driven hard..... OK just checked again - even took a photo:
MTM speakers in horizontal configuration are a bad idea. They have really bad off-axis response due to interference pattern between the woofers. In the center channel configuration, the side reflections are at very large angles. So having good off-axis response is very important. Here are the directivity Index (difference between on and off-axis) for MTM (left) and with the addition of a mid-range driver (right):

i-Jg5gZ4X-L.gif

You see the very jagged and rough DI for the MTM on the left. The addition of mid-range turns that bad situation into an excellent one. Also note that the problem areas are between 500 and 3000 Hz which is important area for voice. I suggest replacing that speaker with 3-way configuration. Once there, side reflections can actually be useful in spreading the apparent image, matching it better to your screen which is likely wider than your center speaker. Reflections can also help in dialog ineligibility. Here is a reference from the book, Sound Reproduction: The Acoustics and Psychoacoustics of Loudspeakers and Rooms (section 10.3, MULTIPLE REFLECTIONS, NOISE, AND SPEECH INTELLIGIBILITY)

"Following the pattern set by studies involving single reflections, Lochner and Burger (1958), Soulodre et al. (1989), and Bradley et al. (2003) found that multiple reflections also contribute to improved speech intelligibility."

The research paper referenced above is by Bradley, J.S., Sato, H., and Picard, M. (2003) and the title is “On the Importance of Early Reflections for Speech in Rooms,” published in the Journal of Acoust. Soc. Am., 113, pp. 3233–3244. You can find online copies if you like to read more. It shows that we can gain up to 9 db in dialog intelligibility by having reflections/comb filtering than not!

So do what you can to improve the off-axis response. Other things to do:

1. Make sure you room is not too live. Put a person where the center speaker is and sit where you normally sit. Have them speak in normal voice. If you have trouble understanding them, then your room is too live (too much reflections). Add more furnishings to it. Curtains, furniture, bookshelves, etc. all help to reduce that. If you are technical, measure RT60 and aim for 0.4 seconds or so. Typical modern living room with lots of hard surfaces can be well above 2 second! Here are actual measurements of an empty room improving with addition of everyday furnishings:

i-jjWhnJp-XL.png

So do not feel compelled to use commercial acoustic products.

2. Get the low frequencies to be smooth. It may not make sense why this would help voices. But when you have peaks in low frequencies, in time domain they translate into ringing, i.e. the notes lasting a while. This long decay will tend to mask the higher frequency notes such as speech.

3. Make sure the center level is set correctly.

Good luck smile.gif.

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post #22 of 40 Old 09-24-2012, 06:06 PM - Thread Starter
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Thank you everyone and particularly Amir for that detailed analysis. I am familiar with the advantages of three-way center channel loudspeakers and actually purchased drivers in the past to build my own, paying particular attention to the soft dome midrange driver. I selected a unit that can reproduce a very wide band so there would not be a crossover point in the vocal range. If I can come up with a crossover design that I am happy with I might just finally get around to building it. smile.gif

Additionally, the room is very full of furnishings, wooden window treatments, racks, equipment, hardwood drawers and bookcases, desks, monitors, you name it. That's why it would be hard to locate treatments, too much in there. Plus wall-to-wall carpets. So it would not be a live room. smile.gif

I'll consider posting photos if I can de-clutter it slightly, it might be embarrassing as it is!

One question...
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2. Get the low frequencies to be smooth. It may not make sense why this would help voices. But when you have peaks in low frequencies, in time domain they translate into ringing, i.e. the notes lasting a while. This long decay will tend to mask the higher frequency notes such as speech.

Do you mean use REW and set up a Behringer DSP1124P or something like that to just correct the subwoofer in-room response?

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post #23 of 40 Old 09-24-2012, 08:44 PM
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Originally Posted by Ben_Tech View Post

Do you mean use REW and set up a Behringer DSP1124P or something like that to just correct the subwoofer in-room response?
Yes, that's it! Use it to pull down any peaks you see in the measurement. Seems like you know the subject well smile.gif. But just in case, here is a more detailed write-up: http://www.madronadigital.com/Library/BassOptimization.html. It shows how you can optimize bass without any acoustic material which should fit nicely with your family needs smile.gif.

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post #24 of 40 Old 09-25-2012, 11:46 AM
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Originally Posted by amirm View Post

MTM speakers in horizontal configuration are a bad idea. They have really bad off-axis response due to interference pattern between the woofers. In the center channel configuration, the side reflections are at very large angles. So having good off-axis response is very important. Here are the directivity Index (difference between on and off-axis) for MTM (left) and with the addition of a mid-range driver (right):
i-Jg5gZ4X-L.gif
You see the very jagged and rough DI for the MTM on the left. The addition of mid-range turns that bad situation into an excellent one. Also note that the problem areas are between 500 and 3000 Hz which is important area for voice. I suggest replacing that speaker with 3-way configuration. Once there, side reflections can actually be useful in spreading the apparent image, matching it better to your screen which is likely wider than your center speaker. Reflections can also help in dialog ineligibility. Here is a reference from the book, Sound Reproduction: The Acoustics and Psychoacoustics of Loudspeakers and Rooms (section 10.3, MULTIPLE REFLECTIONS, NOISE, AND SPEECH INTELLIGIBILITY)
"Following the pattern set by studies involving single reflections, Lochner and Burger (1958), Soulodre et al. (1989), and Bradley et al. (2003) found that multiple reflections also contribute to improved speech intelligibility."
The research paper referenced above is by Bradley, J.S., Sato, H., and Picard, M. (2003) and the title is “On the Importance of Early Reflections for Speech in Rooms,” published in the Journal of Acoust. Soc. Am., 113, pp. 3233–3244. You can find online copies if you like to read more. It shows that we can gain up to 9 db in dialog intelligibility by having reflections/comb filtering than not!
So do what you can to improve the off-axis response. Other things to do:
1. Make sure you room is not too live. Put a person where the center speaker is and sit where you normally sit. Have them speak in normal voice. If you have trouble understanding them, then your room is too live (too much reflections). Add more furnishings to it. Curtains, furniture, bookshelves, etc. all help to reduce that. If you are technical, measure RT60 and aim for 0.4 seconds or so. Typical modern living room with lots of hard surfaces can be well above 2 second! Here are actual measurements of an empty room improving with addition of everyday furnishings:
i-jjWhnJp-XL.png
So do not feel compelled to use commercial acoustic products.
2. Get the low frequencies to be smooth. It may not make sense why this would help voices. But when you have peaks in low frequencies, in time domain they translate into ringing, i.e. the notes lasting a while. This long decay will tend to mask the higher frequency notes such as speech.
3. Make sure the center level is set correctly.
Good luck smile.gif.

+1 to just about everything. This is an excellent reply with pertinent examples where needed. Well said!

But, "MTM speakers in horizontal configuration are a bad idea" when they are designed with large driver separation (I estimate 10-11" c-c spacing) and high crossover point (2510Hz, or a 5.4" wavelength) so off-axis lobing is present from 500Hz through about 3000Hz, as in your Dynaudio C120+.

A proper MTM CC has a c-c spacing that's less than 1 wavelength at the crossover frequency. This requires a very small, very capable tweeter, and the result is very good dialog intelligibility. Note that 1KHz is light blue; the heavily lobed contour is 15KHz... ModulaIV2PLR1SS.jpg 76k .jpg file

Have fun,
Frank
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post #25 of 40 Old 09-25-2012, 07:27 PM - Thread Starter
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I ran a couple of tests with REW on the subwoofer only (through the receiver) and averaged them. Please see the following image for the in-room response. You can click it to see it full size.



I know I ran the test higher than necessary for a sub, but I wanted to see what it was doing in the lower mids so I ran it up to 500 Hz.

What do you fellows think?

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post #26 of 40 Old 09-25-2012, 07:46 PM - Thread Starter
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As a follow-up, here's a reading with no audio playing. Just 'listening to the room,' as it were.



I think everything under 20 Hz is probably mostly the soundcard/SPL meter just being non-linear, because I did a test without the SPL meter even turned on and it read quite a bit of activity down below 20 Hz. However, the readings over 20 Hz are probably 'real,' perhaps I have a noisy room - computer fans, etc.?

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post #27 of 40 Old 09-26-2012, 10:36 AM
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^^^ It's not clear what your graphs show. What's your crossover frequency? And do you really have that much background noise in the room? Some of that noise looks like hum. Do you hear hum?

While you're at it, go ahead and post an REW graph of RT60 versus frequency. biggrin.gif

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post #28 of 40 Old 09-26-2012, 12:31 PM - Thread Starter
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Hi Ethan, Thanks for your reply! My understanding is that, for PCM sources such as REW, my receiver will send bass to the subwoofer even when the mains are set to large. However, it is likely it has a low pass filter on it of some type. The manual does not say, but I'd guess 100 Hz based on the measurement. Yes, I hear some hum from computer fans in the room. It's not that bad, but the measurements seem to pick it up quite strongly. At least I'm guessing that's what all that noise is in the 200 - 500 Hz range. I'll post that graph you asked for later on. smile.gif Thanks again.

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post #29 of 40 Old 09-26-2012, 12:56 PM - Thread Starter
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Here's a couple of different RT60 graphs as the measurement tends to vary a bit each pass. I don't see a way to average them.





Let me know if this is what you want to see, or if there is a better way to do it in REW. smile.gif

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post #30 of 40 Old 09-27-2012, 12:30 PM
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Quote:
Originally Posted by Ben_Tech View Post

My understanding is that, for PCM sources such as REW, my receiver will send bass to the subwoofer even when the mains are set to large.

That doesn't sound right. Unless I'm missing something. Do you have a sub with the receiver set for large mains anyway? Do you get anything from the sub?

When I asked to see an RT60 I meant the full range 20-20K, and I should have specified to display it as 1/3 octave. Then set the upper bound to 1 or 2 seconds, to better see the data rather than all scrunched up at the bottom.

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