speaker vs tv placement for better acoustics

[ryanosaur]

Having a hard time finding an answer to this. I know TVs are bad for acoustics. My rig is mixed usage, but I'm primarily audio, say 80%.
What placement guidelines should I employ to remove the TV from the equation as much as possible... just short of removing the TV? (...As it applies to front speaker placement, including Center, I should clarify, as I am interested in exploring 5-channel audio, too.)
I've seen this hinted at before... most recently by @Matthew J Poes in his thread introducing the article about hearing and microphones.
My space is a little tight: roughly 11.5x16', 2000'3 volume. right now, speakers are about 3' on center from side wall, about 1' from front wall (rear ports), and TV is recessed back about 7" from fronts and sides of the speaker cabinets. Center channel is same, except the bottom of the TV is almost kissing the top of the cabinet. Speakers are about 5.5' apart on center, LP is about 6.5' back.
Thanks!

 

[snakeeyes]

Having a hard time finding an answer to this. I know TVs are bad for acoustics. My rig is mixed usage, but I'm primarily audio, say 80%.
What placement guidelines should I employ to remove the TV from the equation as much as possible... just short of removing the TV? (...As it applies to front speaker placement, including Center, I should clarify, as I am interested in exploring 5-channel audio, too.)
I've seen this hinted at before... most recently by @Matthew J Poes in his thread introducing the article about hearing and microphones.
My space is a little tight: roughly 11.5x16', 2000'3 volume. right now, speakers are about 3' on center from side wall, about 1' from front wall (rear ports), and TV is recessed back about 7" from fronts and sides of the speaker cabinets. Center channel is same, except the bottom of the TV is almost kissing the top of the cabinet. Speakers are about 5.5' apart on center, LP is about 6.5' back.
Thanks!

Does Marantz have a center lift feature like Yamaha? Basically allowing the mains to lift the dialog up to the middle of the screen.

 

[ryanosaur]

Does Marantz have a center lift feature like Yamaha? Basically allowing the mains to lift the dialog up to the middle of the screen.

Marantz has something that uses the C to enhance the L/R stereo field, but not what you describe (as best I can tell... which would be similar in some ways, but by using the L/R to enhance the C) But dialog isn't my curiosity here.

 

[Verdinut]

Does Marantz have a center lift feature like Yamaha? Basically allowing the mains to lift the dialog up to the middle of the screen.

I don't know which AVR ryanosaur has, but my SR5010 has a dialogue enhancing control for exactly boosting the center channel output up to 12dB.

 

[Verdinut]

Marantz has something that uses the C to enhance the L/R stereo field, but not what you describe (as best I can tell... which would be similar in some ways, but by using the L/R to enhance the C) But dialog isn't my curiosity here.

My SR5010 has a Dialogue Level Adjust setting in the Audio section. I figure that yours would have it too.

 

[ryanosaur]

I don't know which AVR ryanosaur has, but my SR5010 has a dialogue enhancing control for exactly boosting the center channel output.

I did find that, now, BTW... I'm on an SR6012...

 

[ryanosaur]

Hi Verdinut! Yes, but that's not what I'm inquiring about.

I want to learn more about minimizing the acoustic impact the TV itself has on Audio performance.

 

[Verdinut]

On my SR5010, I cannot access the Dialogue Level Adjust setting. It says that it can't be set in the current sound mode.

I changed the sound mode in the music mode setting as well as in the movie sound mode setting, but it doesn't work. I was able to set it before though. Why don't they clearly specify in what sound mode I can access it? Is the AVR defective? Does anyone have a clue about what is the problem?

The manual doesn't provide more info either.

EDIT: I found the answer by putting a Blu-ray film in the OPPO and I could access to this setting. Marantz could have specified either on the display or at least in the owner's manual the condition for getting to it instead of mentioning that I can't access it!

So it seems that some design engineers figure that anyone knows but they don't put themselves in a layman's shoes. If they are not responsible for important omissions, then the marketing people are the ones.

 

[Verdinut]

Hi Verdinut! Yes, but that's not what I'm inquiring about.

I want to learn more about minimizing the acoustic impact the TV itself has on Audio performance.

Are you referring to the reflection of the sound by the TV screen? We have no option here except perhaps changing the angle of the screen.

 

[Trell]

I don't know which AVR ryanosaur has, but my SR5010 has a dialogue enhancing control for exactly boosting the center channel output.

That is just to increase the centre volume level. The top Denon models has a "Dialogue enhancer" option that increase frequencies in the 1k to 3k range that still works with Audyssey, while lower models version just increase the level, which sucks as everything coming from the centre channel is louder.

 

[snakeeyes]

Marantz has something that uses the C to enhance the L/R stereo field, but not what you describe (as best I can tell... which would be similar in some ways, but by using the L/R to enhance the C) But dialog isn't my curiosity here.

Okay ya that’s good to know.

 

[lovinthehd]

Maybe a nice thick absorptive cover for the tv when not in use?

 

[ryanosaur]

Maybe a nice thick absorptive cover for the tv when not in use?

Right? Obviously its a sound reflective surface, which also obstruct reflections from the wall behind..

More specifically: how do sound waves emanate from the front baffle of the speaker cabinet that makes having the TV screen level with the baffles very bad?
But given that, how much space is needed to minimize the effect?

 

[Matthew J Poes]

Having a hard time finding an answer to this. I know TVs are bad for acoustics. My rig is mixed usage, but I'm primarily audio, say 80%.
What placement guidelines should I employ to remove the TV from the equation as much as possible... just short of removing the TV? (...As it applies to front speaker placement, including Center, I should clarify, as I am interested in exploring 5-channel audio, too.)
I've seen this hinted at before... most recently by @Matthew J Poes in his thread introducing the article about hearing and microphones.
My space is a little tight: roughly 11.5x16', 2000'3 volume. right now, speakers are about 3' on center from side wall, about 1' from front wall (rear ports),and TV is recessed back about 7" from fronts and sides of the speaker cabinets. Center channel is same, except the bottom of the TV is almost kissing the top of the cabinet. Speakers are about 5.5' apart on center, LP is about 6.5' back.
Thanks!

Certainly removing all sources of diffraction is best accomplished by completely removing the object from the equation. It’s obviously unrealistic for most, so what you do is seek to mitigate.

Diffraction is caused by sound waves bending around objects and so the more irregularities around a speaker the more diffraction. Geddes showed that diffraction can be perceived similar to non-linear distortion (it becomes more objectionable the louder the sound gets). He did this for waveguides but the test was with test signals over headphones, meaning it applies to all diffraction of this nature.

Beyond complete elimination of diffraction sources, the best thing to do is ensure the speakers are well forward or the tv. Where that is not possible, ensuring there is good distance between the speaker and tv is best. Where that is not possible you can add absorption around the areas that cause diffraction. Where that is not possible, you live with it knowing that this compromise exists.

Having heard the isolated effects of this kind of diffraction via the test signals mentioned earlier, it’s a subtle but noticeable objectionable quality that I suspect many wouldn’t care that much about. If we create percentages out of dimensions of sound quality, this is part of that last 5%.

Note that while I have ultra low diffraction speakers, I necessarily added diffraction sources back into my home theater front stage in order to create the screen wall. The best solution for me is to build a THX style baffle wall as that eliminates the diffraction. Since that is exceedingly difficult for me to do in my setup and supreme laziness and lack of handiness, I have acoustic insulation around the support beams were diffraction is possible.

 

[ryanosaur]

Cool, Matthew. And thank you! I've been digging reading your posts!

As you said, its a compromise. What is your best guess on TV-distance-from-speaker for minimizing the acoustic impact? And that would be back, away from the speaker fronts, correct? What about distance between speaker and TV, please?

Cheers!

 

[Matthew J Poes]

Cool, Matthew. And thank you! I've been digging reading your posts!

As you said, its a compromise. What is your best guess on TV-distance-from-speaker for minimizing the acoustic impact? And that would be back, away from the speaker fronts, correct? What about distance between speaker and TV, please?

Cheers!

Thanks!

There are no hard and fast rules for distance and diffraction that would apply to this scenario. The distance would depend on things like the shape of the doffeacting object, wavelength, and dispersion of the speaker. A speaker with wide dispersion will more readily diffract off nearby objects. A speaker with narrower dispersion has less sound radiating to the sides and so it will diffract less readily.

Additionally, diffraction depends on frequency. At mid to high frequencies, where it is most notably a detriment, small objects near by are a bigger problem than large objects far away.

If I had to just place a guess, I would say the speakers should be at least 6” to a foot in front of the tv and any cabinets. Should be at least a foot to either side, but farther away is preferred. This doesn’t eliminate the diffraction but helps further delay it. The goal is to get them delayed sufficiently that the brain can sort them out from the actual direct sound. Like noted in my article, we are taking advantage of what we know of psychoacoustics. Toole talks quite a bit about the notion that we needent be too concerned with reflections because a) they have some benefit, and b) the brain does a good job sorting out the direct call reflected sound. As long as it’s sufficiently delayed. If it is too close in time to the direct sound, the sound mixes and the brain can’t sort it out (but it’s stilk a kind of distortion with a certain level of delay). As Geddes points out, this leads to a perception of non-linear distortion.

And it’s a perfect example of something that would look like comb filtering or just garbage in the measurements of the steady state response, be difficult to disentangle in the time domain graphs, cannot be eqed, but is known to be readily audible. This is why we have to go back to psychoacoustics to look for the best solutions. Work with the problem instead of against it.

 

[Danzilla31]

Cool, Matthew. And thank you! I've been digging reading your posts!

As you said, its a compromise. What is your best guess on TV-distance-from-speaker for minimizing the acoustic impact? And that would be back, away from the speaker fronts, correct? What about distance between speaker and TV, please?

Cheers!

Can you notice an issue with it or are you like me just OCDing every last angle to improve your room? Lol.

Like Matthew stated it may not be enough of a noticeable level in real life to even worry about it.

It's too bad you can't just do a projector and use a flat screen against the wall. My towers are 2 feet in front of that and I don't believe this is an issue for me because of this

Or if it is I just can't tell! Lol

 

[snakeeyes]

Can you notice an issue with it or are you like me just OCDing every last angle to improve your room? Lol.

Like Matthew stated it may not be enough of a noticeable level in real life to even worry about it.

It's too bad you can't just do a projector and use a flat screen against the wall. My towers are 2 feet in front of that and I don't believe this is an issue for me because of this

Or if it is I just can't tell! Lol

Just imagining him in a tin foil hat like on the movie Signs. LOL

 

[ryanosaur]

Just imagining him in a tin foil hat like on the movie Signs. LOL

 

[ryanosaur]

Can you notice an issue with it or are you like me just OCDing every last angle to improve your room? Lol.

Like Matthew stated it may not be enough of a noticeable level in real life to even worry about it.

It's too bad you can't just do a projector and use a flat screen against the wall. My towers are 2 feet in front of that and I don't believe this is an issue for me because of this

Or if it is I just can't tell! Lol

No... no issues, but since I wiped my old room and have an almost-blank slate to work with, I want to do it as best I can.

Plus learning about the details of how our equipment works, why, and how it all interacts is a big part of my journey!