# Help for muddy speech



## Wewill

Hello,

This is my first post on this forum, so I hope I have followed all of the posting rules. Sorry my first post is so long, but I have tried to include all of the necessary information.

I would appreciate some help with a problem I am having with dialog intelligibility in my home theater.

I recently bought a Denon X4200W AVR and have calibrated my theater using the Audyssey XT32 that was included with the AVR. The new AVR is used in my theater with a 7.1 setup.

In general, I am enjoying the Denon and have used it for playback of both music and Blu-ray movies. However, I have noticed the vocals in music and the dialog in movies are often slightly muffled and, at times, are difficult to understand with the Audyssey calibration turned on. With Audyssey turned off, the system playback, as a whole, is not as pleasing; but, the dialog clarity improves.

To tackle this problem, I first searched this forum and others for posts dealing with “intelligibility.” The following steps are my take on the advice given to others with this issue.

First, I used this problem as an excuse to buy a new center speaker (an RBH 661C/R). The RBH 661 is recommended by RBH to use with the RBH 61C/R’s I use for front left and right speakers. Overall, the new center speaker sounds better than the one it replaced, but the vocal/dialog issue is still degraded with Audyssey engaged.

I finally decided it was time to break out my UMIK-1 and use REW (Ver. 15.14) to try to find the cause of the intelligibility problem. Details of my test technique are included at the bottom of this post.

This graph is for the center speaker with all other speakers turned off (1/6-Octave smoothing). The purple trace is the recorded response with Audyssey turned on (Dynamic EQ turned off) and the green trace is with the Audyssey turned off.









Here is a graph (actually a photo of my plasma TV) presented by the AVR of the Audyssey calibration of the center speaker:










My interpretation of these graphs is that the Audyssey calibration greatly reduced the mode at about 130Hz and smoothed out the null at about 300Hz. 

However, the REW graph with Audyssey turned on, compared to the calibration turned off, seems to have significantly reduced the SPL between about 1.3kHz and 2.7kHz. My research found that this band (1.3 to 2.7kHz) is right in the middle of the intelligibility frequency spectrum of the human voice!

In case this will be of value, here is a graph of my left front speaker with Audyssey turned on and off (1/6-octave smoothing; Purple is Audyssey off).









Here is a graph of my right front speaker with Audyssey turned on and off (1/6-Octave smoothing; Green is Audyssey off).









So, my first question is if I am analyzing these graphs correctly (i.e., Audyssey’s calibration is degrading the vocals). Or do the graphs show another anomaly that can account for the speech-clarity issue?

If I have found the problem, is there any alternative other than manually EQing the room?

DATA GENERATING TECHNIQUE

I located the UMIK-1 at my primary listening position, a leather reclining chair, using a mic boom and tripod. To reduce some of the reflections from the reclining chair, I covered it with a thick blanket. The mic was positioned pointing toward the ceiling and the calibration file for 90 degrees was used in REW. Each measurement in the graph is the average of 3 mic positions – all at my usual ear level, but the first measurement was located at the center position, then the second measurement was 6 inches to the left (parallel to the head rest) and the third measurement was 6 inches to the right of the center position (also parallel to the head rest). Using REW, I averaged the 3 readings and then displayed them with 1/6-octave smoothing.

Thanks for your help.[/SIZE]


----------



## tonyvdb

What centre channel are you using? May we see a picture of your center channel speaker location as well as the front of the room? Placement and type of center channel speaker can dramatically change what you hear.


----------



## Wewill

I took a few quick photos of the front of my home theater.

These two wide-shots show my RBH SX-61/R left and right speakers, my RBH 661C/R center speaker and two Velodyne DD-18 subwoofers. You can also see the two corner bass traps, and the panels for absorption of reflections. Not shown is the absorption panel mounted on the ceiling between the center speaker and the primary listening position.


















Here is a close-up of the center speaker, under my Panasonic plasma TV, and between my subwoofers. As you can see in the photos, I didn't have much choice in the location of the center speaker.










I hope these are useful.


----------



## Wayne A. Pflughaupt

First, welcome to the Forum!

As I see it, there are two primary issues affecting vocal clarity. One is the loss in the 2 kHz area (as you noted). The other is the roll-out of the high frequencies, where the sibilants are.

For the latter, you might try taking measurements with a 0° calibration file and the mic pointed directly at the speaker. Since you have absorption on the ceiling, it’s possible the lack of overhead reflections arriving at the mic are causing the high end portion of the graph to look worse than it really is.

There are a couple of things you can try. If you’re running Audyssey with the normal recommendation of analyzing multiple positions (i.e. putting the mic in various locations all over the room), try instead analyzing only at the primary listening position, or in locations only a few inches varying from that. Our very own AudiocRaver has performed evaluations and written some pieces showing that single-mic analysis typically gets the best results. 

Alternately, bypassing Audyssey for manual EQ is a good option, assuming your receiver has built-in equalization that is flexible enough.

Regards, 
Wayne


----------



## lcaillo

I agree with Wayne (both of them) with regard to using only measurements at the primary listening position. I would also try moving the center, left, and right speakers out toward the listening position.


----------



## willis7469

+3 I think getting the speakers out into the room would help in a number of ways. 


Sent from my iPhone using Tapatalk


----------



## Wewill

Thanks for all of the suggestions.

Regarding my procedure for Audyssey measurements, I was fortunate to have read and followed the directions of Wayne Myers (“AudiocRaver”) in making the Audyssey tests in my first post. (I even took his advice and bought a Bosch laser distance meter—a great gadget!) I have reread his extensive posts and followed his procedure in the reconfiguration described below.

The REW measurements and photos I have previously posted were based on the following speaker configuration:

OLD:

Left and Right Front speakers: (1) Distance from front of each tweeter to front wall: 2’ 7”; (2) Distance from front of each tweeter to side wall: 2’4”; (3) Distance from center of Left Front tweeter to Right Front tweeter: 8’6”; (4) Distance from center of tweeter for both Left and Right Front speakers to Primary Listening Position (“PLP”): 8’6”.

Center speaker: (1) Distance from front of tweeter to front wall: 1’10”; (2) Distance from center of tweeter to both side walls: 6’8”; (3) Distance from center of tweeter to Primary Listening Position (“PLP”): 8’1”.

Today, I moved the Left, Center and Right speakers further away from the front wall. I also moved the Left and Right speakers further away from the side walls. Here are their new measurements:

NEW:

Left and Right Front speakers: (1) Distance from front of each tweeter to front wall: 3’ 0”; (2) Distance from front of each tweeter to side wall: 2’9”; (3) Distance from center of Left Front tweeter to Right Front tweeter: 8’1”; (4) Distance from center of tweeter for both Left and Right Front speakers to PLP: 8’1”.

Center speaker: (1) Distance from front of tweeter to front wall: 2’8”; (2) Distance from center of tweeter to both side walls: 6’8”; (3) Distance from center of tweeter to Primary Listening Position (“PLP”): 7’3”.

Here is a graph of the Center speaker in the new position with Audyssey off (green) and on (gold)(The measurement procedure was the same as in my first post:










Audyssey is clearly decreasing the major excursions from a smooth response, but is still putting a "hole" in the important vocal frequencies.

Here is a graph of the Center speaker in the new position, with the mic aimed at the speaker, with Audyssey on (green)and off (red):









Comparing the traces for the vertical vs the horizontal mic orientation, there seems to be better response in the upper frequencies. Wayne suggests this may be due to the reflection absorption panel attached to the ceiling between the center speaker and the PLP. But, I'm not sure what to make of this -- is the absorption panel helping or hurting?

This is the measured response (mic back to vertical) of the Left speaker with Audyssey on and off:









Here is a graph of the response (mic still vertical) of the Right speaker with Audyssey on and off:









This graph is a comparison of the Center speaker's response, with Audyssey ON in both traces, with the difference being the speaker location. Clearly, moving the speaker further into the room has flattened the response in the 200Hz -- 1kHz range and from 2.5 -- 5kHz.









I welcome additional comments and suggestions. However, it seems moving the front and center speakers further into the room may provide additional improvement.


----------



## b bos37

Have you tried the dialogue enhancing feature on the Denon ?


----------



## Wewill

b bos37 said:


> Have you tried the dialogue enhancing feature on the Denon ?


Thanks for the suggestion.

Yes, I have tried that feature. According to the menu, it increases the dialogue by 2.5 dB. So, when the enhance feature is engaged, the distorted audio is louder than when it is not engaged. I am able to understand slightly more of the vocals, but the distortion is just louder.

However, I am hopeful about a technique I discovered tonight that is available on my Denon AVR. I can copy the Audyssey EQ settings (or at least the Audyssey level settings) to a manual EQ. Then, I can adjust the manual EQ levels from -6 to +6 (I'm not sure if these numbers are dB or just relative settings). After increasing the levels in the 1.5 to 2.5kHz range, the vocals sound better. Tomorrow, I will run some REW scans with the higher manual EQ levels and see if the measurements correspond to my perception.


----------



## Goozoo

If I may chime in on this....other owner of Dennons have had similar complaints on other sites about their center channels as well (as have Marantz owners). Aside from tweaking with EQ (which I am a fan of), you may try adding another speaker from above the screen to have dual center channels. Alternatively, you may want to look at a different center channel altogether that will still blend well with your mains but has a different tweeter design for more intelligible voice output. Both of these solutions worked for me and others facing similar issues. I am now running 2 centers and one of them a different speaker design than the rest. Best of luck and welcome to the Shack.


----------



## AudiocRaver

I skimmed through the previous posts, beg pardon if someone else already suggested this.

The calibration mic pattern you have used probably ended up showing Audyssey a peak in the 1.5 to 2.5 kHz range, and Audyssey has compensated for it with the dip you are hearing and measuring.

Precisely what calibration pattern are you using with Audyssey?


----------



## jtalden

> Audyssey 'Reference' setting includes a 3dB dip around 2kHz. Audyssey 'Flat' does not have this dip. 
> The Denon center 'channel level' can be increased as needed manually if the 'dialog level adjust' is not enough.

I didn't see these other 2 options mentioned above, but I may have missed them.


----------



## Wewill

Goozoo said:


> ....other owner of Dennons have had similar complaints on other sites about their center channels as well (as have Marantz owners). .


Thank you so much for this information. Since I have been compulsively testing, changing speaker locations, and modifying acoustical treatment in my home theater for days, I can’t tell you how relieved I am to know that perhaps my problem is in the Denon AVR.

Frankly, I have always assumed the problems that are so evident in the vocal playback, as confirmed by my many REW scans, were my fault (i.e., poor speaker selection, poor speaker location, improper acoustical treatment, improper test technique, etc., etc.)

Before I consider buying yet another center speaker, either to replace my new one, or to supplement my current speaker, I am going to try to further isolate the problem.

Perhaps my problem is in the audio amplifier section of the AVR. To check this, I am going to connect the “pre/out” signal from the AVR’s center channel to a separate Rotel amp. After adjusting the levels, and re-running the Audyssey program, it will be very interesting to see if the problem is improved.

Thanks again, and stay tuned ….


----------



## Wewill

jtalden said:


> > Audyssey 'Reference' setting includes a 3dB dip around 2kHz. Audyssey 'Flat' does not have this dip.
> 
> Thank you for the reminder about Flat vs Reference. I will make sure to always use the Flat Audssey setting.
> 
> > The Denon center 'channel level' can be increased as needed manually if the 'dialog level adjust' is not enough.
> 
> I didn't see these other 2 options mentioned above, but I may have missed them.


That's a great idea to use the "channel level" to supplement the "dialog adjust." I tried that technique last night while watching a movie. Unfortunately, it made the vocal distortion more pronounced. With no "dialog adjust" or increased "chanel level," I had to reduce the volume just to understand what was being said!

If you get a chance, please read my next post where I propose a new theory for this distortion problem.


----------



## Wewill

AudiocRaver said:


> I skimmed through the previous posts, beg pardon if someone else already suggested this.
> 
> The calibration mic pattern you have used probably ended up showing Audyssey a peak in the 1.5 to 2.5 kHz range, and Audyssey has compensated for it with the dip you are hearing and measuring.
> 
> Precisely what calibration pattern are you using with Audyssey?


Thank you for taking an interest in my problem. I really appreciate all of the work you put into your post on how to properly calibrate using Audyssey.

I will be more specific in my description of the mic positions used during Audyssey MultEQ XT32 calibration. I am using the following pattern (taken from your post):

"8-Point Basic Setup Mic Pattern - MultEQ XT32, MultEQ XT, MultEQ (6 pts). Use for step 2 of this Process. All dimensions are relative to PLP Center (PLPC):
1.	PLPC
2.	3 inches forward
3.	3 inches up
4.	3 inches up & 3 inches forward
5.	3 inches left
6.	3 inches right
7.	6 inches left
8.	6 inches right"

Please take a look at the following REW scans showing the Center speaker with Audyssey (Flat) On and Off. The way I interpret these results is the relocation of the center channel further into the room has virtually eliminated the cut in the 1.5kHz to 2.5kHz range. However, please notice the roll-off of the frequency response from about 2kHz upward. While Audyssey improves this roll-off, it is still far from ideal.









This post is getting long, so I will start another post with my new theory of the cause of my distorted audio coming from my Center speaker.


----------



## b bos37

If you don't mind can you let me know what type of stand are you using for the center speaker ?


----------



## MatrixDweller

Is it muddy sound or just low volume?

*If it's low volume*
Another thing to consider is that Audyssey may have reduced the level of your center speaker compared to the other speakers in your system. Wayne's point about running Audyssey from just one listening position and moving the mic only slightly has some merit. I have an older Denon 4311ci and I do find the center channel's volume is low after running Audyssey. If I break out my SPL meter my fronts tend to be in and around 75dB and my center is 73dB from my main seating position. Going around the speakers and bumping up/down the channel levels makes a huge difference.

*If it's muddy sound:*
The 2D graphs don't take in to account the time domain, ie: reverberation or transient decay time (RT60). Looking at the pictures of the room there is a lot of absorbers on your front wall but it's hard to tell how thick they are. So I have lots of questions.
How thick are the absorbers and what material are they made of? 
Do you also have them on the first reflection points on your side walls? 
What other room treatments do you have? 
Is your room in your basement? 
If so:
Do you have a subfloor with insulation or is it carpet with underpad over concrete? 
Are your walls stuffed with insulation from floor to ceiling? 

What I'm thinking is that your RT60 over the frequency spectrum may be uneven. High at some frequencies and low at others. You might also have reflected sound reaching your ears from first or second reflection points (but not at all frequencies) smearing the sound. If you do a waterfall graph in REW it will give you a better understanding.


----------



## Wewill

For days now, I have been racking my brain, and my back muscles, in trying to eliminate the distorted audio I am hearing from my new center speaker connected to my new Denon AVR. I tried to watch a new Blu-ray movie last night, but I couldn’t get into the film because the vocals from the center speaker were so distorted – and the volume of the AVR was set at about -20dB!

Due to some great advice I received on this forum, I have improved the frequency response of the Center channel in a previously depressed range from about 1.5kHz to 2.5kHz. However, with the Audyssey calibration On or Off, the frequency response I am measuring at my PLP rolls-off almost linearly from about 2kHz on up. (B/T/W, Wayne noticed this in a very early post on this thread, but I failed to fully appreciate his insight.)

My first thought was my Umic-1 was not responding appropriately in the higher frequencies. Fortunately, I have a second Umic-1 and was able to compare the two. While I was very impressed by how closely they tracked in response to the same audio signal, my theory was shot down. I concluded there is nothing wrong with the mic I am using.

My next thought was to suspect the acoustic treatment I have in my home theater. Until yesterday afternoon, I had a 4’ by 8’ acoustic absorption panel at the first reflection points on both side walls and on the ceiling. I also had much thicker absorption across the back wall. With some significant effort, and some back sprain, those panels are now removed. But, removing those panels had no effect on the high frequency roll-off, as can be seen in the following REW scans:









My next idea was to apply some manual EQ to the system to supplement what the Audyssey calibration was doing. Instead of starting with a fresh manual equalizer with all of the settings at 0dB, I was able to use the copy feature of my AVR to transfer the Audyssey EQ boost/cut levels to the manual equalizer. My plan was to modify the manual EQ to try to have a more flat frequency response in the mid and high frequency ranges.
When I opened the manual EQ, with the copied Audyssey settings, I was very surprised to see Audyssey was already boosting the frequencies from 2kHz on up. Here is a photo of the manual EQ from the Denon AVR as displayed on my plasma TV:









And, here is a close up view of the same image:









As you can see, the Audyssey is already boosting the following frequency bands by the maximum of 6dB:2--16kHz. It has been my understanding that applying an EQ, especially in the mid and high frequencies, should be limited to cutting, not boosting (although, I have read a few authors who don’t think a judicious boost of up to 3dB is that bad). If my math is correct, a 3dB boost requires a doubling of audio output power, so 6d6B requires a factor of 4 increase in power.

So, my current theory is some vocal distortion is caused by the diminished mid and high frequency levels. But, I think asking the AVR to boost a broad band of frequencies by 6dB may be resulting in clipping by the AVR’s amp (especially if there is a large demand for power by other channels, and the center channel vocals are loud). Perhaps it is clipping that is the major cause of the distortion.

My next step is to take the Center channel pre-out signal and run it through a separate audio power amplifier. I will post again once this has been done.

Thanks for sticking with me through my own “odyssey.” As usual, your thoughts, ideas and suggestions are most welcome.


----------



## jtalden

Possibly the CC tweeter is bad? You could place the mic about 18" in front of the CC. If the HF response still rolls off >5dB with Audyssey turned off then the tweeter is bad. 


You can also look at your current CC data on the REW 'distortion' chart to see if the distortion is really high at some frequencies. If you post an .mdat file of the CC we could take a look also. Maybe there is a hint there.


----------



## Wewill

b bos37 said:


> If you don't mind can you let me know what type of stand are you using for the center speaker ?


Thanks for your interest. Then center speaker stand is Sonus model number SFC18.

Please let me know if you have any other questions.


----------



## Wewill

MatrixDweller said:


> Is it muddy sound or just low volume?
> 
> *If it's low volume*
> Another thing to consider is that Audyssey may have reduced the level of your center speaker compared to the other speakers in your system. Wayne's point about running Audyssey from just one listening position and moving the mic only slightly has some merit. I have an older Denon 4311ci and I do find the center channel's volume is low after running Audyssey. If I break out my SPL meter my fronts tend to be in and around 75dB and my center is 73dB from my main seating position. Going around the speakers and bumping up/down the channel levels makes a huge difference.
> 
> Thanks for your interest in my garbled vocal sound problem from my center speaker. I'm very confident the issue is not low volume. In fact, increasing the volume results in more distortion. However, once this issue is resolved, I will use my RadioShack SPL meter to verify the center channel level is the same as the other channels.
> 
> *If it's muddy sound:*
> The 2D graphs don't take in to account the time domain, ie: reverberation or transient decay time (RT60). Looking at the pictures of the room there is a lot of absorbers on your front wall but it's hard to tell how thick they are. So I have lots of questions.
> How thick are the absorbers and what material are they made of?
> Do you also have them on the first reflection points on your side walls?
> What other room treatments do you have?
> Is your room in your basement?
> If so:
> Do you have a subfloor with insulation or is it carpet with underpad over concrete?
> Are your walls stuffed with insulation from floor to ceiling?
> 
> What I'm thinking is that your RT60 over the frequency spectrum may be uneven. High at some frequencies and low at others. You might also have reflected sound reaching your ears from first or second reflection points (but not at all frequencies) smearing the sound. If you do a waterfall graph in REW it will give you a better understanding.


I appreciate your interest in the acoustic treatment in my home theater. 

It is located on the second floor of our home. The walls and ceiling are 5/8" drywall, and the cavities between the studs are filled with fiberglass. There are no windows, and I had the original hollow-core doors replaced with solid-core doors with weather tight seals. The wooden floor is covered with extra thick wall to wall carpet and a thick carpet pad.

All of the panels are made by GIK Acoustics; they don't make public the exact material they use in their products, but I wouldn't be surprised if it is similar to Owens Corning 703. Other than the corner bass traps, each panel is 2" thick and custom framed with wood trim. By design, the wood trim moves each panel an additional 2" from the wall on which it is mounted (thus extending the absorption to lower frequencies). If you look at the independent test data on the GIK website, you will see the absorption of these panels is relatively uniform from about 2kHz and up. 

Working closely with the folks at GIK, I have, on the front wall, 5 of the GIK panels. In the corners of the front of the room, there are floor-to-ceiling GIK Tri-Trap bass absorbers. 

Before I removed them a few days ago, there was a panel on both of the side walls and the ceiling, between the speakers and the PLP. As you know, those panels were primarily for absorbing the first reflections from the speakers and the walls.

Across the back wall were 3 panels of the GIK panels that were framed with wood trim to move them 10" away from the wall and thereby increase their bass absorption.

I was also concerned that my acoustic panels may have resulted in the excessive absorption of the high frequency range of the audio. So, I have removed all of the panels, other than those on the front wall. Unfortunately, there was no impact on the high frequency roll off or the distorted vocal reproduction. 

Please let me know if you have further questions about the acoustic treatment of my room; I find the subject fascinating!


----------



## Wewill

I think I found the cause of my high-frequency response problem!

As I previously posted, my next step in trying to solve this mystery of the missing high frequencies was to substitute a separate amp for the center channel amp in my Denon AVR. To begin to make this swap, I went into the closet in my home theater where all of my equipment is located. I found the center channel speaker wire and took it off the Denon CC speaker binding posts.

To clear the path for the speaker wire to the substitute amp, I noticed that during my most recent installation I had coiled the excess speaker wire (about 20 feet) into a neat, small circular loop. The many turns of the loop were held together tightly in several places with cable-ties.

Seeing this configuration, and from the far distant past, I remembered something from my Electrical Engineering education. If you coil a wire into closely held multiple loops, at some range of AC frequencies, the coil can act like an inductor (i.e., a “choke;” an impedance that opposes the flow of high-frequency AC current-- the higher the frequency, the higher the impedance). Hoping this was the source of my problem (actually, grasping at straws!) I quickly cut the cable ties and let the speaker cable loose from its coiled configuration.

Next, I hooked the loose speaker wire to the Rotel substitute amp and turned everything on. 

After performing an REW sweep, I knew I was on to the problem.

For the sake of comparison, here is an earlier scan with the coiled speaker wire and Audyssey Off & ON:









Here is a scan of the center channel without the coil and Audyssey Off:









Feeling confident, for the first time in many days that my system was working properly, I did another Audyssey calibration. Here is a scan showing the frequency response with the Audyssey turned On:









Most importantly, I played the Blu-ray video that had the badly distorted vocal-audio, and found the distortion in the vocals was gone or at least 90 percent better (since this is a new center speaker and a new AVR, I have to gain some more experience to know what to expect). The speech reproduction was now clear and easy to understand.

So, to sum up this misadventure, it was my compulsive behavior that resulted in wasting many hours.

Lessons learned: 1. Don’t be so compulsive about the appearance of wire that no one will see; 2. Audyssey is not “plug-in-play.” You need to perform an REW scan before and after the application of Audyssey calibration; 3. Trust your ears – if something doesn’t sound right, it probably isn’t.

Next steps: I am still troubled by Audyssey applying nearly 6dB of gain in some of the frequency bands. So, I am going to compare the audio response (especially the distortion) with Audyssey On, and 1.with the substitute Rotel amp and 2. With the Denon internal center channel amp.

I would appreciate hearing any comments and suggestions.


----------



## AudiocRaver

Wewill said:


> Seeing this configuration, and from the far distant past, I remembered something from my Electrical Engineering education. If you coil a wire into closely held multiple loops, at some range of AC frequencies, the coil can act like an inductor (i.e., a “choke;” an impedance that opposes the flow of high-frequency AC current-- the higher the frequency, the higher the impedance). Hoping this was the source of my problem (actually, grasping at straws!) I quickly cut the cable ties and let the speaker cable loose from its coiled configuration.


Not arguing with your results, but your coil is a real inductive coil with a single-conductor wire. With speaker wire, two conductors are packaged together side by side, and the "coil/inductor" effect is negated. It cancels out. That's the theory anyway. What type of cable have you used?



> Lessons learned: 1. Don’t be so compulsive about the appearance of wire that no one will see; 2. Audyssey is not “plug-in-play.” You need to perform an REW scan before and after the application of Audyssey calibration; 3. Trust your ears – if something doesn’t sound right, it probably isn’t.


All true.



> Next steps: I am still troubled by Audyssey applying nearly 6dB of gain in some of the frequency bands. So, I am going to compare the audio response (especially the distortion) with Audyssey On, and 1.with the substitute Rotel amp and 2. With the Denon internal center channel amp.
> 
> I would appreciate hearing any comments and suggestions.


A 6 dB of boost at mid or high frequencies creates an opportunity for boost if those frequencies are present in the program material. Usually, that material will account for a small percentage of the total power, so increasing that band of frequencies 6 dB ends up increasing total power by a fraction of that amount. To play it safe, though, go ahead and be careful, just not quite as conservatively as you have.

I still think that the mic calibration pattern could be troublesome. If you are happy, fantastic! Next time you run a calibration, try this mic pattern, in part two of post #1. It is better at ignoring the bounce off of a chair back that can lead to the dip that has been bothering you.

Not suggesting you do all the work over, if you are happy you are happy. Just something to think about for the future.


----------



## Wewill

Thanks for your comments and suggestion.



AudiocRaver said:


> Not arguing with your results, but your coil is a real inductive coil with a single-conductor wire. With speaker wire, two conductors are packaged together side by side, and the "coil/inductor" effect is negated. It cancels out. That's the theory anyway. What type of cable have you used?
> 
> 
> I still think that the mic calibration pattern could be troublesome. If you are happy, fantastic! Next time you run a calibration, try this mic pattern, in part two of post #1. It is better at ignoring the bounce off of a chair back that can lead to the dip that has been bothering you.
> 
> Not suggesting you do all the work over, if you are happy you are happy. Just something to think about for the future.


*SPEAKER WIRE ISSUE:*

For speaker cable I am using simple, generic, 12 AWG, copper stranded wire. This choice is not due to cost, but the careful consideration of the effectiveness of more costly alternatives.

When I recently replaced the center speaker, I also replaced the center speaker cable. To feed the cable through the small opening into the equipment room, I had to separate the two conductors (i.e., “unzip” them from each other) and feed the individual conductors into the room, one at a time. So, I had two lengths of single conductor wire inside the equipment room; it was those single conductor wires that I neatly wound into coils. That is why the inductance was not canceled out by an opposing electro-magnetic field in an immediately adjacent wire.

*TRIANGULAR/PLANAR MIC POSITIONS:*

I took your suggestion and recalibrated Audyssey with the goal of using the mic pattern in part two of your post #1. With the one exception noted below, I tried very carefully to follow your directions for positioning the mic at the eight points you described in a triangular/planar mic pattern. (In addition, I included 2 layers of blanket draped over the chair and headrest.)

However, contrary to your diagram, I purposely did not place my mic tripod on the chair (please see my concern addressed below). Instead, I located my mic stand on the floor, between the back of the chair and the back wall. After elevating the height of the stand well above the head rest of the chair, I rotated the mic-end of the boom toward the front of the room, and downward to about 120-degrees from a fully vertical position. In this orientation, the stand and mic were mechanically and thus sonically isolated from the chair for all eight measurements.

The first measurement was taken with the mic located between where my ears are normally positioned, which is a few inches below the top of the headrest (the Primary Listening Position or PLP). Next, I raised the height of the boom, without changing the approximate 120-degree angle, so the mic was just above the headrest. This was the position for measurement number two.

For measurements three through eight, the mic stand height remained constant, only the length of the boom was increased. I used a ruler to ensure the eighth mic position was 12-inches forward from the first mic position, but was at the same vertical elevation as the first position.

Thus, all of the mic positions were in a vertical and right-triangular plane that was orthogonal to the headrest. The 90-degree vertex of the right triangle was midway between my ears in the PLP. The apex of the triangle was about eight inches above the first mic position. The remaining positions followed an imaginary line (the hypotenuse of the triangle) that connected the apex and a vertex 12 inches in front of, but at the same elevation as my PLP.

Please let me know if I did not follow your mic pattern.

(F/Y/I, when I followed the link in your post, none of the images or scans in your article were visible, even after clicking on them. Fortunately, in one of the responses to your article, your diagram of the triangular/planar mic pattern was reproduced. The diagram made the mic pattern much more comprehensible.) 

*FR COMPARISON -- TRIANGULAR VS OLD AUDYSSEY:*

Here is a graph showing the FR of the center speaker before and after the triangular/planar Audyssey calibration. I have set up this graph so the two scans do not overlap for easier comparison. PLEASE NOTE: The blue trace is with the triangular/planar Audyssey; The red trace is the older calibration (the title of the graph is reversed).









Comparing the before and after scans, in the FR from 100 Hz to 20 kHz, the before scan is linear plus or minus 6dB. The after scan is linear, in the same frequency range, to plus or minus 4dB. So, that is a nice improvement.

*SPEECH INTELLIGIBILITY -- IMPORTANT FREQUENCIES*

Here is a chart of the importance of certain frequency bands to the intelligibility of speech (from: http://www.dpamicrophones.com/mic-university/facts-about-speech-intelligibility):










With this chart in mind, the new frequency response in the range of 2 kHz to 4.5 kHz seems to be depressed compared to the old response. 

This is an overlay of the FR of the two previous scans, but limited to the frequency range of 600Hz to 6kHz. This overlay makes clear the cut in gain, resulting from the triangular/planar calibration from 2kHz to 5kHz, ranging from 0 to a maximum of 9dB at 2.8kHz (the cursor location):









It seems the notch I have been trying to eliminate since my first post has reappeared. Albeit subjective, the vocals have a more “hollow” timbre with the new Audyssey calibration
*
DENNON AVR EQ SETTINGS, BEFORE AND AFTER*

Here is a photo of the EQ settings before I ran the most recent Audyssey calibration:









Here is a photo of the EQ settings after I ran the Audyssey triangular/planar calibration:









Extracting the gain or boost setting from both photos, we can see:

FREQ BEFORE	AFTER
63Hz.... +3... +3
125Hz... -4... -4
250Hz... +4... 0
500Hz... +2... 0
1kHz.... +2... 0
2kHz.... -2... -2
4kHz.... +4... +4
8kHz.... +3... +3
16kHz... +3... +2

Of course, the boost and gain settings are just a partial view of the EQ since we have no way of knowing, from the information my Denon AVR provides, what the Q is associated with each setting.

I do have a question regarding the methodology you used in optimizing the mic positions during Audyssey calibration. It appears you made your measurements with the tripod for the mic sitting on the seat of your PLP. Did you consider the possibility of coupling the sound waves from the speaker to the chair, through the tripod, and then to the mic?

Thanks again for your suggestions. Your help, and the help provided by those who have posted replies, has guided me in greatly improving the vocal clarity from my center channel.

Additional comments and ideas from everyone who reads this post would be greatly appreciated.


----------



## FargateOne

Thanks for sharing. Very interesting


----------



## AudiocRaver

Wewill said:


> Thanks for your comments and suggestion.
> 
> 
> 
> *SPEAKER WIRE ISSUE:*
> 
> For speaker cable I am using simple, generic, 12 AWG, copper stranded wire. This choice is not due to cost, but the careful consideration of the effectiveness of more costly alternatives.
> 
> When I recently replaced the center speaker, I also replaced the center speaker cable. To feed the cable through the small opening into the equipment room, I had to separate the two conductors (i.e., “unzip” them from each other) and feed the individual conductors into the room, one at a time. So, I had two lengths of single conductor wire inside the equipment room; it was those single conductor wires that I neatly wound into coils. That is why the inductance was not canceled out by an opposing electro-magnetic field in an immediately adjacent wire.
> 
> *TRIANGULAR/PLANAR MIC POSITIONS:*
> 
> I took your suggestion and recalibrated Audyssey with the goal of using the mic pattern in part two of your post #1. With the one exception noted below, I tried very carefully to follow your directions for positioning the mic at the eight points you described in a triangular/planar mic pattern. (In addition, I included 2 layers of blanket draped over the chair and headrest.)
> 
> However, contrary to your diagram, I purposely did not place my mic tripod on the chair (please see my concern addressed below). Instead, I located my mic stand on the floor, between the back of the chair and the back wall. After elevating the height of the stand well above the head rest of the chair, I rotated the mic-end of the boom toward the front of the room, and downward to about 120-degrees from a fully vertical position. In this orientation, the stand and mic were mechanically and thus sonically isolated from the chair for all eight measurements.
> 
> The first measurement was taken with the mic located between where my ears are normally positioned, which is a few inches below the top of the headrest (the Primary Listening Position or PLP). Next, I raised the height of the boom, without changing the approximate 120-degree angle, so the mic was just above the headrest. This was the position for measurement number two.
> 
> For measurements three through eight, the mic stand height remained constant, only the length of the boom was increased. I used a ruler to ensure the eighth mic position was 12-inches forward from the first mic position, but was at the same vertical elevation as the first position.
> 
> Thus, all of the mic positions were in a vertical and right-triangular plane that was orthogonal to the headrest. The 90-degree vertex of the right triangle was midway between my ears in the PLP. The apex of the triangle was about eight inches above the first mic position. The remaining positions followed an imaginary line (the hypotenuse of the triangle) that connected the apex and a vertex 12 inches in front of, but at the same elevation as my PLP.
> 
> Please let me know if I did not follow your mic pattern.
> 
> (F/Y/I, when I followed the link in your post, none of the images or scans in your article were visible, even after clicking on them. Fortunately, in one of the responses to your article, your diagram of the triangular/planar mic pattern was reproduced. The diagram made the mic pattern much more comprehensible.)
> 
> *FR COMPARISON -- TRIANGULAR VS OLD AUDYSSEY:*
> 
> Here is a graph showing the FR of the center speaker before and after the triangular/planar Audyssey calibration. I have set up this graph so the two scans do not overlap for easier comparison. PLEASE NOTE: The blue trace is with the triangular/planar Audyssey; The red trace is the older calibration (the title of the graph is reversed).
> 
> View attachment 120409
> 
> 
> Comparing the before and after scans, in the FR from 100 Hz to 20 kHz, the before scan is linear plus or minus 6dB. The after scan is linear, in the same frequency range, to plus or minus 4dB. So, that is a nice improvement.
> 
> *SPEECH INTELLIGIBILITY -- IMPORTANT FREQUENCIES*
> 
> Here is a chart of the importance of certain frequency bands to the intelligibility of speech (from: http://www.dpamicrophones.com/mic-university/facts-about-speech-intelligibility):
> 
> 
> View attachment 120433
> 
> 
> With this chart in mind, the new frequency response in the range of 2 kHz to 4.5 kHz seems to be depressed compared to the old response.
> 
> This is an overlay of the FR of the two previous scans, but limited to the frequency range of 600Hz to 6kHz. This overlay makes clear the cut in gain, resulting from the triangular/planar calibration from 2kHz to 5kHz, ranging from 0 to a maximum of 9dB at 2.8kHz (the cursor location):
> 
> View attachment 120441
> 
> 
> It seems the notch I have been trying to eliminate since my first post has reappeared. Albeit subjective, the vocals have a more “hollow” timbre with the new Audyssey calibration
> *
> DENNON AVR EQ SETTINGS, BEFORE AND AFTER*
> 
> Here is a photo of the EQ settings before I ran the most recent Audyssey calibration:
> 
> View attachment 120417
> 
> 
> Here is a photo of the EQ settings after I ran the Audyssey triangular/planar calibration:
> 
> View attachment 120425
> 
> 
> Extracting the gain or boost setting from both photos, we can see:
> 
> FREQ BEFORE	AFTER
> 63Hz.... +3... +3
> 125Hz... -4... -4
> 250Hz... +4... 0
> 500Hz... +2... 0
> 1kHz.... +2... 0
> 2kHz.... -2... -2
> 4kHz.... +4... +4
> 8kHz.... +3... +3
> 16kHz... +3... +2
> 
> Of course, the boost and gain settings are just a partial view of the EQ since we have no way of knowing, from the information my Denon AVR provides, what the Q is associated with each setting.
> 
> I do have a question regarding the methodology you used in optimizing the mic positions during Audyssey calibration. It appears you made your measurements with the tripod for the mic sitting on the seat of your PLP. Did you consider the possibility of coupling the sound waves from the speaker to the chair, through the tripod, and then to the mic?
> 
> Thanks again for your suggestions. Your help, and the help provided by those who have posted replies, has guided me in greatly improving the vocal clarity from my center channel.
> 
> Additional comments and ideas from everyone who reads this post would be greatly appreciated.


First, I appreciate the detail of your posts, it is much easier to try to help someone who communicates those details so clearly.

Second, the attempt to follow my most recently suggested mic setup pattern has given the opposite of the result I hoped it would in the 2 kHz range. All I can say is...:dontknow: (that's the shrug that our teenagers often give us when we want an explanation, along with a monosyllabic u-u-uuh, their abbreviation for _I don't know._ Do not, repeat DO NOT try that one on your spousal unit.)

Part of the exercise I went through in determining that pattern was to take measurement each of the points of the pattern with REW and see if any of them have a peak (or dip) in the critical 1 to 3 kHz range. A cumulative peak there will lead to REW compensating in the opposite direction. If any of your measurements give a peak in that range, do not use that position. That is my suggestion for determining how that setup pattern might be affecting your result. Also, it is possible that the mic setup pattern is doing exactly what it was intended to and then Audyssey is adding that dip at 2 kHz by its own design.

Also, the pattern is meant to simplify the Audyssey setup process. No critical measurements after the first point, no L or R positions (which tend to only reinforce a peak measurement problem if it exists) and gives the best soundstage and imaging (SS&I) that I have been able to get from Audyssey.

Your point about placing the mic stand on the floor is a good one, next time I am doing work around the chair I will try it out. Generally I do not place the stand on the chair, it was part of the effort to come up with the simplified pattern and an easy way to accomplish it.

Edit; And thanks for the explanation on the coils of wire, now it makes perfect sense.


----------



## manish.rana

Some wrote a piece about this.


https://www.thedebuguy.com/blog/zkje5z0tjqj4ali1j42xfew05abk8w


----------

