What is the ideal directivity pattern for stereo speakers?

Status
Not open for further replies.
Hello dewardh

Draw the room.

OK

Draw the desired listening area within that room.

How do you now it's optimal?

Draw the loudspeaker placement and polar that will uniformly illuminate that listening area with both direct and reflected sound.

Same as before.

Draw the loudspeaker placement and polar that will uniformly illuminate that listening area with both direct and reflected sound.

How are you going to know what it will sound like?

Size drivers to give the desired maximum SPL in the listening area.

Build enclosures that give the desired polar with those drivers.

The rest is trivial.

Max SPL makes sense but no measurements?? How do you even know what you have of where your issues are?? Are you considering the measurements as trivial??


Hello Simon

I have a couple of systems and in my HT my mains are fullrange and do act as distributed subs in line with a pair of LFE subs. What you are saying makes sense as long as you can get the imaging and placement you want along with good LF placement.

Hello Earl

You use your own room optimization software. Is there anything similar out there along the same lines. I have used a room mode calculator that was effective and did a good job at predicting where problem placements for both speakers and the listening position. That's old school, anything new out there??

Rob🙂
 
I don't like headphone much either, but the DTS demo changed my mind. It's the poor man's Smyth Realizer. I thought for sure they were cheating the demo with a sub blended in. Nope, all in the headphones.

I've yet to hear the Smyth, but a few confirmed headphone haters I know have, and fell in love.
 
How do you now it's optimal?
You don't, and it doesn't matter . . . the room was the "given", and odds are that the "listening area" will be determined by a) the spouse, and b) placement of the television.

How are you going to know what it will sound like?
It will sound like you make it sound . . . that's the "do it" in "do it yourself".

Are you considering the measurements as trivial?
Pretty much. Whole measurement systems cost only a few hundred dollars now, and some (like the Sound Easy UE) are so automated that they will even design and tweak the crossovers for you, while others (like REW) will address final equalization.

If the driver choices and radiation pattern are good (appropriate to the room) the rest falls easily into place. The problem comes when one designs some sort of "optimum" box and then tries to shoehorn it into an inappropriate position in a room where it cannot possibly work well. That's the "mass production" route, and the result will be a lot of wasted effort and a result no better than buying a "system" from some big-box retailer would get you.

Since the end goal is good sound at a particular location in a particular room that is where good design starts. You work back from there to get it. Of course there will always be some final "adjustments" . . . no design ever makes it from paper to product without. But no amount of "measurement" and "correction" is going to fix a design that is simply wrong for the application from the outset.
 
While in ear earphones or headphones can produce very smooth and extended bass free of room effects they're never going to have the same dynamic impact or realism as speakers in the bass region because only the ear drum is stimulated while speakers vibrate your entire body in a more natural way.

I hear that a lot but actually nobody ever tried it. Once the sound is fully externalized (due to binaural processing) I doubt that much is missing that can't be recreated with bass shakers.
 
You don't, and it doesn't matter . . . the room was the "given", and odds are that the "listening area" will be determined by a) the spouse, and b) placement of the television.

Hello dewardh

I am talking about a fixed room, I didn't say placement was fixed. It makes no sense to put speakers in the worst room positions and then rely on EQ to "fix" them. You want to get it right as best you can with placement and use the "fix" tools as little as possible.

So how do you predict best placement in a given room without the old tried and true way of moving them around a half a dozen times.

This is getting off the track of what I asked Earl.

Rob🙂
 
Rob

The math behind room modes calculation is certainly not new, but I have not seen a piece of software that does what I look for, namely drag and drop movement of mains and multiple subs (with real acoustics and amp parameters), with five listener locations, variable wall damping on each set of walls, the statistics (frequency variance at each listener and the total spatial variance) all in real time with instant updating.

If there is a program out there that does this, I haven't seen it.
 
So how do you predict best placement in a given room
It depends on the room, and the designated listening area within that room. There is no general, or "one size fits all", answer. A quick sketchup of the primary room modes will give a good hint of where and at what frequencies your "problems" will be, and that in turn will lead to possible placements (and other techniques) that minimize those problems. But what works best in a small and highly reflective room may not work (or even be necessary) in a large and lossy room.
 
Hello Earl

I didn't think so thanks. Your software sounds impressive.

Hello Markus

When my HT is going I get quite a bit of furniture shake so to speak, I would have to say the demo was too high. But still no pressurization pants flapping or the growl in your chest.

Rob 🙂
 
Status
Not open for further replies.