[philba]

I am putting together a 5.1 speaker system and my current thinking is to use dipole surrounds. As I understand it, the ideal mount should be high (2-3' above the listener's ears) and slightly behind the sweetspot. Unfortunately, my room (20x12 - screen on the short wall) has a door and window making it impossible to have this exact placement. So, I have several options and would really appreciate any feedback. I will have a second row of seating available behind the sweetspot.


I will start out with 5.1 with the thought of moving to 7.1 as more material becomes available in that format. But I'll worry about that later.


Options:

1) place surrounds low (2-3 ft off floor) but slightly behind the sweetspot. (preserve distance from fronts)


2) place surrounds at proper height but 3 feet behind sweetspot (preserve height)


which compromises on the quality the least? I suspect that option 2 (preserve height) is the best but am no expert. Or is there yet another possibility?


Also, would it make sense to bag the dipoles and go to a simple monopole bookshelf speaker? The dolby page on placement has some alternates for monopoles. It certainly saves money.


Thanks in advance

Phil

 

[sdurani]

Hi Phil,
Quote:

As I understand it, the ideal mount should be high (2-3' above the listener's ears) and slightly behind the sweetspot.

Because dipole speakers have a null in their dispersion pattern, they should be placed directly to the sides of the listeners. Placing them slightly behind the sweetspot will put listeners outside the null, thereby reducing (more likely eliminating) the specific effect that dipoles are used for. Having them 2-3' above the listener's ears will add a little more envelopment.


Best,

Sanjay

 

[philba]

Thanks.


How tight is the typical dipole null? Can I have 2 rows of chairs with dipoles or will one row get a worse experience than than the other? I didn't realize dipoles were that finicky.


I think you are saying that for my application, I shouldn't get dipoles. right?


Phil

 

[sdurani]

Phil,
Quote:

How tight is the typical dipole null?

In my experience, pretty damn tight. You have to be right down the middle axis of the speaker to stay in the acoustic null. This way, you get the desired effect of hearing only reflected sounds and nothing directly from the speaker. If you haven't done so already, you ought to go to an A/V store and check out some dipoles; walk around them so you get a good sense of what it sounds like to be in the nulls and how wide they are.
Quote:

Can I have 2 rows of chairs with dipoles or will one row get a worse experience than the other?

Whether the experience will be "better" or "worse" is a subjective call, one that you'll have to make by listening from both rows. Suffice it to say that only one row will get the ambient envelopment of the dipole surrounds; listeners in the other row won't be in the null and therefore will easily be able to locate where the surrounds are. Placing the dipoles between the rows will kill the effect for all listeners.


You may also want to look into other choices for your surrounds. The "dipoles" from some manufacturers are pseudo-dipoles. You've probably seen them: the drivers are at 90 degree angles instead of on opposite sides of the speaker cabinet; these may work out better for you than traditional dipoles. There are also bipole and tripole surrounds, which provide a fairly even dispersion pattern all the way around the speakers; the sound is pretty omni-directional with no nulls. There are even "switch-able" speakers that let you switch between dipole and bipole by flipping a toggle or changing jumpers.


Like I said earlier, take a listen to the variety of surround speakers that are out there so you can choose what works best in your particular system.


Good Luck,

Sanjay