Audio wave question??????

[JimShaw]

I am considering adding two more speakers to my surround sound.

Because all my speakers are in-ceiling, I am not able to test to make sure there are problems.

I want to add a left and right speaker. The sound wave of both speakers will intersect and cross through other speaker sound waves in the system.

Do audio waves crossing through each other create any problems with the sound/wave, any distortions?????

I don't think it will but before spending $$$ and cutting holes in the ceiling, I want other's opinions that know more about this than I do.

Thanks



m

[Jim Hawkins]

Originally Posted by JimShaw

I am considering adding two more speakers to my surround sound.

Because all my speakers are in-ceiling, I am not able to test to make sure there are problems.

I want to add a left and right speaker. The sound wave of both speakers will intersect and cross through other speaker sound waves in the system.

Do audio waves crossing through each other create any problems with the sound/wave, any distortions?????

I don't think it will but before spending $$$ and cutting holes in the ceiling, I want other's opinions that know more about this than I do.

Thanks



m

Normally I would just say "do it" but since you have such nice equipment I am assuming that these worries may matter.

I think the best way is to borrow some cabinet speakers and temporarily hang them from the ceiling? See what that sounds like? Course each speaker sounds different but this may help you get a better idea.

Just my two cents.

[JimShaw]

Originally Posted by Jim Hawkins

Normally I would just say "do it" but since you have such nice equipment I am assuming that these worries may matter.

I think the best way is to borrow some cabinet speakers and temporarily hang them from the ceiling? See what that sounds like? Course each speaker sounds different but this may help you get a better idea.

Just my two cents.

When I first read your post, I thought that is something I might try. Then, I thought more and decided that it might not work.

Yes, you are correct. Different speakers would definitely sound different. Probably so much so, that I don't think I would be able to tell if it was the difference in speakers or a collision of sound waves.

[JimShaw]

I have read a lot of sound wave web sites yesterday. Here is some information

-------------------------------

It is the nature of waves in any medium to pass through each other without disrupting each other. If you picture intersecting hallways with a 1 khz wave (Freq 1) going South and a 2 khz wave (Freq 2) gong East, each wave will reach its listener with no disruption. If Listener A could only hear at 1 khz and Listener B could only hear at 2 khz, neither would even have a way of knowing that the other wave crossing through his own wave existed. There would be no loss or distortion resulting from the superposition of the waves at the intersection.



At the intersection of the hallways, a microphone would let you see how the sound pressures of the two waves combine as they pass through each other. You would get a different measurement for every position of the microphone at the intersection. If Freq 2 was switched to 1 khz and both waves were the same amplitude, then there would be complete cancellations at some points in the intersection. At other points the waves would add together and the amplitude would be doubled. Still, each listener would hear his own wave with no disruption by the other.

There are real world situations where we ignore this out of practicality. A concert PA system will have flying left and right speaker columns both running the same signal during the concert, but because of the reverberant acoustics of the arena, with reflections all over the place, there are so many intersecting waves at any one point that the result is mostly additive with very little cancellation taking place. In our listening rooms it can be a problem.

-------------------------------------

From the above it sounds like if two sound waves cross path and they are the same sound wave, they will cancel each out, a collision, a distortion. But because the waves that cross each other are different sound waves, there isn't any collision or distortion.

This is my understanding from the above excerpt from an article.

You agree?


m

[JimShaw]

Here is an excerpt from a physic forum talking about sound waves that pass through each other

Interestingly, the meeting of two waves along a medium does not alter the individual waves or even deviate them from their path. This only becomes an astounding behavior when it is compared to what happens when two billiard balls meet or two football players meet. Billiard balls might crash and bounce off each other and football players might crash and come to a stop. Yet two waves will meet, produce a net resulting shape of the medium, and then continue on doing what they were doing before the interference.

It seems from the above that meeting waves pass through each other, changes the shape of both waves and then once through, the wave reverts back to the original shape and path.

This is my understanding, yours also?



m

[Blu-Dog]

Originally Posted by JimShaw

It seems from the above that meeting waves pass through each other, changes the shape of both waves and then once through, the wave reverts back to the original shape and path.

This is my understanding, yours also?

There are multiple factors in sound wave propagation, as with any wave. These are:

• Frequency
• Volume or Amplitude
• Direction
• Reflection
• Conducting Medium (environment)

Waves will not "revert to the original shape and path". They are either affected by the above mentioned factors, or they are not. Waves are either sympathetic to other waves, or conflicting, and all are affected by the factors above.

When you're listening to reproduced sounds from speakers, the seating position is most important, since the sound is affected using delays in output, or volume changes, or frequency shifts, which all affect the sound. The clearest sound is achieved with headphones, where all factors are minimized. In any room environment, changes in those factors are affected by innumberable factors, and can change simply by rearranging the furniture.

Even more odd, you may have exactly the same setup in Death Valley (280 feet below sea level) as you do in Colorado Springs (6,000 feet above sea level), and see slight differences in sound.

Once affected, a wave is changed permanently. It takes a lot to change a sound wave, such as canceling it out, or giving a perceived increase in sound. Conditions rarely change the wave - the differences are in how the sound reaches the listener, such as distance, or more importantly, direction of the speakers or reflections from other objects.

You have built-in speakers, flat to the ceiling (or walls, I'm not sure), so the subtlety in what you're hearing will be affected by directionality, reflections from the furniture and flooring, and some very sensitive changes in how the sound amplifier outputs the sound. Delays, "voids", and changes in frequency and volume will have very significant effects, where wave conflicts probably couldn't be detected by any human ear.

[JimShaw]

Originally Posted by Blu-Dog

There are multiple factors in sound wave propagation, as with any wave. These are:

• Frequency
• Volume or Amplitude
• Direction
• Reflection
• Conducting Medium (environment)

Waves will not "revert to the original shape and path". They are either affected by the above mentioned factors, or they are not. Waves are either sympathetic to other waves, or conflicting, and all are affected by the factors above.

When you're listening to reproduced sounds from speakers, the seating position is most important, since the sound is affected using delays in output, or volume changes, or frequency shifts, which all affect the sound. The clearest sound is achieved with headphones, where all factors are minimized. In any room environment, changes in those factors are affected by innumberable factors, and can change simply by rearranging the furniture.

Even more odd, you may have exactly the same setup in Death Valley (280 feet below sea level) as you do in Colorado Springs (6,000 feet above sea level), and see slight differences in sound.

Once affected, a wave is changed permanently. It takes a lot to change a sound wave, such as canceling it out, or giving a perceived increase in sound. Conditions rarely change the wave - the differences are in how the sound reaches the listener, such as distance, or more importantly, direction of the speakers or reflections from other objects.

You have built-in speakers, flat to the ceiling (or walls, I'm not sure), so the subtlety in what you're hearing will be affected by directionality, reflections from the furniture and flooring, and some very sensitive changes in how the sound amplifier outputs the sound. Delays, "voids", and changes in frequency and volume will have very significant effects, where wave conflicts probably couldn't be detected by any human ear.

Once affected, a wave is changed permanently. That is what I thought but was surprised by the comment from the article...about keeping the same path and reverting back

You have built-in speakers, flat to the ceiling, YES

you're hearing will be affected by directionality, reflections from the furniture and flooring, and some very sensitive changes in how the sound amplifier outputs the sound. Delays, "voids", and changes in frequency and volume will have very significant effects. Yes, I agree and Audyssey's XT32 does help in that area.

where wave conflicts probably couldn't be detected by any human ear. That has been my thinking in that even if there might be a change, I would probably never notice it being that it will only be used as a surround and a surround back with a 6.1 or a 7.1 source.

Do you agree??

m

[JimShaw]

Originally Posted by Blu-Dog

There are multiple factors in sound wave propagation, as with any wave. These are:

• Frequency
• Volume or Amplitude
• Direction
• Reflection
• Conducting Medium (environment)

Waves will not "revert to the original shape and path". They are either affected by the above mentioned factors, or they are not. Waves are either sympathetic to other waves, or conflicting, and all are affected by the factors above.

When you're listening to reproduced sounds from speakers, the seating position is most important, since the sound is affected using delays in output, or volume changes, or frequency shifts, which all affect the sound. The clearest sound is achieved with headphones, where all factors are minimized. In any room environment, changes in those factors are affected by innumberable factors, and can change simply by rearranging the furniture.

Even more odd, you may have exactly the same setup in Death Valley (280 feet below sea level) as you do in Colorado Springs (6,000 feet above sea level), and see slight differences in sound.

Once affected, a wave is changed permanently. It takes a lot to change a sound wave, such as canceling it out, or giving a perceived increase in sound. Conditions rarely change the wave - the differences are in how the sound reaches the listener, such as distance, or more importantly, direction of the speakers or reflections from other objects.

You have built-in speakers, flat to the ceiling (or walls, I'm not sure), so the subtlety in what you're hearing will be affected by directionality, reflections from the furniture and flooring, and some very sensitive changes in how the sound amplifier outputs the sound. Delays, "voids", and changes in frequency and volume will have very significant effects, where wave conflicts probably couldn't be detected by any human ear.

Once affected, a wave is changed permanently. That is what I thought but was surprised by the comment from the article about keeping the same path and reverting its shape back. Or at least that was my understanding.

You have built-in speakers, flat to the ceiling, YES

you're hearing will be affected by directionality, reflections from the furniture and flooring, and some very sensitive changes in how the sound amplifier outputs the sound. Delays, "voids", and changes in frequency and volume will have very significant effects. Yes, I agree and Audyssey's XT32 does help in that area.

where wave conflicts probably couldn't be detected by any human ear. That has been my thinking in that even if there might be a change, I would probably never notice it being that it will only be used as a surround and a surround back with a 6.1 or a 7.1 source.

Do you agree??

m

[Blu-Dog]

Originally Posted by JimShaw

Once affected, a wave is changed permanently. That is what I thought but was surprised by the comment from the article...about keeping the same path and reverting back

You have built-in speakers, flat to the ceiling, YES

you're hearing will be affected by directionality, reflections from the furniture and flooring, and some very sensitive changes in how the sound amplifier outputs the sound. Delays, "voids", and changes in frequency and volume will have very significant effects. Yes, I agree and Audyssey's XT32 does help in that area.

where wave conflicts probably couldn't be detected by any human ear. That has been my thinking in that even if there might be a change, I would probably never notice it being that it will only be used as a surround and a surround back with a 6.1 or a 7.1 source.

Do you agree??

Yes. 7.1 is usually overrated - the studios generally matrix a 5.1 source to make 7.1, so there's not much source difference, though it fills in the sound more completely. My main theater is 7.1 - though I have three other viewing/listening areas, all with 5.1, and there's not an appreciable difference if the speakers are correctly placed.

The 6.1 offerings on The Incredibles and the Star Wars films aren't much different, either. I use the direct source, unprocessed, on my Pioneer receivers, so I get discrete 7.1 when it's available, but I don't notice any changes listening to 5.1 sources (even though with the receiver's processing, I could turn it into 7.1 output).

On the "wave change" issue, there might be some kind of debate, but it wouldn't be reasonable. I was raised on radar, and specialized in several Electronic Counter Measure (ECM and ECCM )tricks. It turns out that the effect on "changing waves" is a combination of both altering wave dynamics, and fooling the detector. You can alter a wave with either sympathetic or conflicting information, and the detector won't know the difference, or thinks it does, and tries to compensate.

In home stereo, you are the detector, which is the reason perfectionist slobs like myself crawl around pushing subwoofers while the wife supervises and says things like, "I'm not sure...try it in that first spot again" and refuses to go buy more beer until we're done, even if I'm sweating like a man running past a pack of wolves, whilst carrying a pork chop. It's all about what the detector receives, and the other factors involved.

The real shifts are in the variance from the source - nothing stays the same, so the dynamics are always changing. It's not like you're listening to a white noise pattern, or a single, unchanging frequency generator playing the same note. It's hard to figure out, and even worse when the wife cheerfully says, "I can help!"

[JimShaw]

Originally Posted by Blu-Dog

Yes. 7.1 is usually overrated - the studios generally matrix a 5.1 source to make 7.1, so there's not much source difference, though it fills in the sound more completely. My main theater is 7.1 - though I have three other viewing/listening areas, all with 5.1, and there's not an appreciable difference if the speakers are correctly placed.

The 6.1 offerings on The Incredibles and the Star Wars films aren't much different, either. I use the direct source, unprocessed, on my Pioneer receivers, so I get discrete 7.1 when it's available, but I don't notice any changes listening to 5.1 sources (even though with the receiver's processing, I could turn it into 7.1 output).

On the "wave change" issue, there might be some kind of debate, but it wouldn't be reasonable. I was raised on radar, and specialized in several Electronic Counter Measure (ECM and ECCM )tricks. It turns out that the effect on "changing waves" is a combination of both altering wave dynamics, and fooling the detector. You can alter a wave with either sympathetic or conflicting information, and the detector won't know the difference, or thinks it does, and tries to compensate.

In home stereo, you are the detector, which is the reason perfectionist slobs like myself crawl around pushing subwoofers while the wife supervises and says things like, "I'm not sure...try it in that first spot again" and refuses to go buy more beer until we're done, even if I'm sweating like a man running past a pack of wolves, whilst carrying a pork chop. It's all about what the detector receives, and the other factors involved.

The real shifts are in the variance from the source - nothing stays the same, so the dynamics are always changing. It's not like you're listening to a white noise pattern, or a single, unchanging frequency generator playing the same note. It's hard to figure out, and even worse when the wife cheerfully says, "I can help!"

even worse when the wife cheerfully says, "I can help! That brought laughter to this old body

Sounds like it might be a big waste to add the surround backs especially the way I have to do it.

I have to turn the surrounds into MIDS by moving them about four feet from where they were and put the surround backs into the spot originally occupied by the surrounds.

I guess this might not be that good of an idea.

I so wanted to add two more speakers. I could then say my system is a 9.3. It's like saying mine is bigger than yours.




m

[Blu-Dog]

Originally Posted by JimShaw

even worse when the wife cheerfully says, "I can help! That brought laughter to this old body

Sounds like it might be a big waste to add the surround backs especially the way I have to do it.

I have to turn the surrounds into MIDS by moving them about four feet from where they were and put the surround backs into the spot originally occupied by the surrounds.

I guess this might not be that good of an idea.

I so wanted to add two more speakers. I could then say my system is a 9.3. It's like saying mine is bigger than yours.

Basically, my advice is, don't mess with it. After looking for pristine sound, I got it - and it wasn't light years away from what I had with more basic stuff. The truth is, I like some of it ear-splitting loud, and the stuff I used to have as my "best" equipment sounded almost as nice. Just not as loud.

So I used to have a 10" JBL subwoofer with a 100 watt amplifier, which pooped out, but sounded OK. I moved to dual Polk home-builts, a bit better. Now I have a JBL Fathom 13", two JBL W3's in a single enclosure, and two subs built into Definitive Mythos ST's - all in the same room. You can inhale between explosions, fairly easily, most times. But does it sound "better"? Not when an assassin is sneaking through a room and steps on a squeaky floorboard, or Pavarotti is singing.

The source is the key. If it is mixed well, and you're not trying to make the neighbors think that World War III has just broken out, very modest expenditure - and reasonably careful placement - can bring outstanding results. There is a lower limit, but wisdom and care trumps wallet-waving and bragadoccio every time.

[JimShaw]

Originally Posted by Blu-Dog

Basically, my advice is, don't mess with it. After looking for pristine sound, I got it - and it wasn't light years away from what I had with more basic stuff. The truth is, I like some of it ear-splitting loud, and the stuff I used to have as my "best" equipment sounded almost as nice. Just not as loud.

So I used to have a 10" JBL subwoofer with a 100 watt amplifier, which pooped out, but sounded OK. I moved to dual Polk home-builts, a bit better. Now I have a JBL Fathom 13", two JBL W3's in a single enclosure, and two subs built into Definitive Mythos ST's - all in the same room. You can inhale between explosions, fairly easily, most times. But does it sound "better"? Not when an assassin is sneaking through a room and steps on a squeaky floorboard, or Pavarotti is singing.

The source is the key. If it is mixed well, and you're not trying to make the neighbors think that World War III has just broken out, very modest expenditure - and reasonably careful placement - can bring outstanding results. There is a lower limit, but wisdom and care trumps wallet-waving and bragadoccio every time.

Good advice.

I just watch a great movie with great sound. My system is, in my view point, perfect as in-ceiling speakers can get. I have them backed up with two 13" HSU mid base modules and an SVS PB13-Ultra.

I have just decided that I am not going to take a chance, spend a lot of money, only to find it has not accomplished anything.

As you mentioned: There is a lower limit, but wisdom and care trumps wallet-waving and bragadoccio every time. Wise beyond your years.

Thanks

m

[JimShaw]

My decision has been made. What helped was the price I was able to get two AIM8 Fives. Best Buy's price after a special order would be $1794.75.

I was able to find two new speakers shipped for $615.16.

For that price, I will be happy to test. If good, great. If not, I'll sell and probably make a profit.

I'll let you know.




m