[djn]

Why is that.  I've read the the baffle should be 2 times the diamiter of the driver and centered on the baffle, and I've read (and built) speakers where the baffle is large and the driver offset.  I am new to OB and trying to understand all this....NOT to start anything: I just want to learn.

[opnly bafld]

I've read the the baffle should be 2 times the diamiter of the driver and centered on the baffle..............

I think this has been recommended as a maximum width.

Lin

[ga foo 88]

I think 2.2 x diameter of the driver is whats recommended for the baffle width.  Or max baffle width, I can't recall.

[mcgsxr]

I recall seeing recommendations that the baffle not be larger than 2x the width of the baffle.

I believe that offset on a baffle is a good thing - it helps ensure that there are differences in effective baffle length to the driver.

There is also the school of thought that very little if any baffle is good, depending on the implementation.

Lots of ways to skin the audio cat.

[djn]

A friend and I were talking about this.  We've both read the narrow and wide baffle threories.  Maybe in a week or two, we can find a good OB driver and do some narrow and wide baffles, with the same driver, and take some measurements. 

When I built my OBs, I used the EDGE program and ended up with a 2' wide x 4' tall baffle with 8 4" drivers for the flattest responce.  I tried the 2.2 times the driver width and the responce curve was just a peak.

[Rudolf]

djn,

it doesn't make sense to look into this small-or-no-baffle thing, if we haven't looked into concepts like "constant directivity" and "power response" first. If you feel that those latter aspects are of no concern for you, it would be a waste of time and energy to give it a trial.

A second aspect: The advantages of a small baffle (if there are any) can be best recognized in the off-axis response. You really need to compare horizontal simulations at 30°, 45° and 60° (to both sides) with your 0° sim for both cases to understand. And yes, this small baffle act will need heavy EQ. If it doesn't, something would be wrong.

Rudolf

Just two quotes from Floyd Toole:
"In a small listening room we are in a transitional sound field, consisting of the direct sound, several strong early reflections, and a much diminished late reflected sound field. What we hear is dominated by the directional characteristics of the loudspeakers and the acoustic behavior of the room boundaries at the locations of the strong early reflections." (page 457)

"Important for localization, and very interesting from the perspective of sound reproduction, is the observation that the precedence effect appears to be most effective when the spectra of the direct and reflected sounds are similar [4], [18], [20]. This appears to be an argument for constant-directivity loudspeakers and frequency-independent (that is, broad-band) reflectors, absorbers, and diffusers. (page 458)

Both from http://www.harman.com/EN-US/OurCompany/Technologyleadership/Documents/Scientific%20Publications/13686.pdf

[djn]

Thanks Rudolf, I have to read this paper a couple times before it will even begin to set in, but I think I understand what you are saying.  I have a stack of thick stiff corrigated cardboard and want to play with this concept a bit.  I do know that my Wolverine 8" sounds way better in a 2' wide by 3' tall baffle with the driver offset than it does in a 1' wide board.  I tried that today just for kicks and in the board it was just one big peak.

My room is 6142 cubic feet and there are not many reflective surfaces....unless I pull the drapes open.

I only sit in one position, unles someone is visiting just to listen so the off axis responce does not matter to me.  I will have to read up on Constant Directivity and power response to understand what you mean.

[Rudolf]

I only sit in one position, unles someone is visiting just to listen so the off axis responce does not matter to me.

Man, you are really funny!

Let's assume that you sit 2 m from your loudspeakers. Let us further assume that your head has the same surface area as a 8" cone. Now we look at your loudspeakers radiating evenly into a 180° forward hemisphere (which they should do up to 1 kHz at least). At 2 m radius (where you are sitting) the surface area of this hemisphere is 628 times bigger than your head area. 627 of 628 parts of the radiated acoustical energy are coming as off axis response to you. Don't try to tell me that you can mask that out. You don't have cat's ears. 

For sure we can discuss how much the off axis radiation is attenuated in your room before it is reflected back to you. And you could argue that you are sitting in the near field and the off axis radiation gets lost in the depth of your (sorta big) living room. But in general off axis response has to be considered.

How much effort and how much expense everybody is willing to spend to get the off-axis-response "right" to what degree - that's a question which has to be answered individually. But we should know a problem before we decide that it is no issue for us.

Rudolf

BTW: When Toole is talking about "small" listening rooms, he means "small" in comparison to concert halls or stadiums. Any room length below 40 feet would be considered "small".

[djn]

OK, I get it now.  I was thinking of the tern "off Axis" as it relates to imaging from a horn.  I think I will do some more reading and try to understand this better.

[canzld]

for slightly less dense reading (and very well explained) try Toole's

Sound Reproduction: The Acoustics and Psychoacoustics of Loudspeakers and Rooms . My public library had it.

And yes, this small baffle act will need heavy EQ.

or crossing to an appropriate driver not on the small baffle