Effect of Surround Back distance

[Highlander]

All,

Image a square or approximately square room. The system comprises Centre and Front, Surround and Surround Back left and right speakers. In this imaginary room the speakers are all approximately equidistant from the listening position as per the attached thumbnail.

Now imagine a pronounced rectangular room so that the Surround Back speakers are much further from the listening position even though the other speakers retain their previous distances.

In the second example the receiver, upon setup, will faithfully increase the level and distance settings of the Surround Backs over and above the other speakers that are much closer to the listening position.

My question is, what effect will distance of the Surround Backs from the listening position have upon sound quality? Will it be better when they're distant because they'll have the distance to develop a full sound field of their own, or will it be worse simply because they are further away?

 

[mtrycrafts]

All,

Image a square or approximately square room. The system comprises Centre and Front, Surround and Surround Back left and right speakers. In this imaginary room the speakers are all approximately equidistant from the listening position as per the attached thumbnail.

Now imagine a pronounced rectangular room so that the Surround Back speakers are much further from the listening position even though the other speakers retain their previous distances.

In the second example the receiver, upon setup, will faithfully increase the level and distance settings of the Surround Backs over and above the other speakers that are much closer to the listening position.

My question is, what effect will distance of the Surround Backs from the listening position have upon sound quality? Will it be better when they're distant because they'll have the distance to develop a full sound field of their own, or will it be worse simply because they are further away?

I don't see an issue either way, not if the delay times are levels are properly set up. By the way, what would the new distance be to those rears, or rather the distance incremental increase over the square room?
Going from a square room to a rectangle will have an overall effect, so that would mask anything else.

 

[Highlander]

By the way, what would the new distance be to those rears, or rather the distance incremental increase over the square room?

Mtrycrafts you're a gem. It's a theoretical question, there are no distances!

Going from a square room to a rectangle will have an overall effect, so that would mask anything else.

Okay, to get around that imagine the room is rectangular in both cases but that in the first case the Surround Backs are positioned 'into the room' whereas in the second case they're at the rear wall.

 

[Buckeye_Nut]

Ditto...

Providing the delays and SPL are adjusted accordingly, the net result should be the same.

On the other hand...... room acoustic issues should be addressed in every room to truly achieve the best sound reproduction possible with any given setup.

 

[Highlander]

Ditto...Providing the delays and SPL are adjusted accordingly, the net result should be the same.

I'm not so sure Buckeye Nut (and Mtrycrafts). My gut's telling me that even if the loudness and delay are correct via the receiver's level and distance settings respectively, that the 'spread' of sound will be different in the two cases and that the ear will pick it up. As to which would acoustically be considered better, that I don't know.

That's what my gut's telling me. Could be complete rubbish I'm spouting for all I know though.

 

[mtrycrafts]

Okay, to get around that imagine the room is rectangular in both cases but that in the first case the Surround Backs are positioned 'into the room' whereas in the second case they're at the rear wall.

In your picture you have a 7.1 setup. Are you asking this question as a 5.1 setup?

If so, the side mounted surrounds vs only the rears will give some differences about the rear hemisphere sound filed perception. Early on in this game, Dolby had the surrounds on the back wall. With more channels, that expanded for a better surround envelopment as your picture shows. Not sure which you would like more, on the side wall or the rear wall. However, all 4 rear speakers in a space as you described would be a better option.

 

[MDS]

When you calibrate each channel the receiver will ensure that the delay is set appropriately so that the sounds from each channel reach your ears at the same time. However, that isn't the whole story and I'd think that having the rear surrounds farther back will produce a more enveloping sound due to all the reflections you will get after the the direct sound reaches your ears.

 

[jimfitz]

When you calibrate each channel the receiver will ensure that the delay is set appropriately so that the sounds from each channel reach your ears at the same time. However, that isn't the whole story and I'd think that having the rear surrounds farther back will produce a more enveloping sound due to all the reflections you will get after the the direct sound reaches your ears.

I agree...

 

[Highlander]

In your picture you have a 7.1 setup. Are you asking this question as a 5.1 setup?

R e a d T h e Q u e s t i o n. Having Surround Backs compels a 7.? setup.

...I'd think that having the rear surrounds farther back will produce a more enveloping sound due to all the reflections you will get after the the direct sound reaches your ears.

I agree...

Me too. I just wanted to see what others felt about it.

 

[bass addict]

My question is, what effect will distance of the Surround Backs from the listening position have upon sound quality? Will it be better when they're distant because they'll have the distance to develop a full sound field of their own, or will it be worse simply because they are further away?

In my imaginary room, are my surrounds direct radiating, bipolar or quadpolar?

 

[Highlander]

In my imaginary room, are my surrounds direct radiating, bipolar or quadpolar?

Free your imagination. Let it run wild.

I had direct radiating speakers in mind when I formed the thread.

 

[bass addict]

Free your imagination. Let it run wild.

I had direct radiating speakers in mind when I formed the thread.

I ran both and this is what I ran into IME. A direct radiating speaker is better used when you have some distance between you and the speaker. I ran a 6.1 setup in my old house before moving and building a dedicated room. The rear speaker was about 1.5 ft behind me. It was very distracting in movies and the sound sounded like it was coming from right behind my head (not very natural at all). I then switched to a QS8 and the realism greatly improved. The quadpolar speakers diffuse the sound enough that even when they are close to you it sounds more realistic. YMMV

 

[bpape]

Farther back in the room, the specific location of the rears would be less localizable allowing more of a similar 'stereo image' full left to right similar to what the front 2 are doing for you.

Also, being farther away and assuming the same height, you're also sitting closer to on axis angle wise in relation to the tweeter so you're not going to experience the severe off axis tweeter response anomolies as if you were sitting closer.

Bryan