Stacking a LOT of 3" speakers?

[Mikael Abdellah]

What happens to the frequency response when you mount a LOT of small speakers tightly together? I tried searching for stacking etc. here in the forum but I could find a suitable thread. Is it called something else than "stacking"?

 

[richie00boy]

Line array, there's loads of info on it. What you are worried about is comb filtering.

 

[Mikael Abdellah]

I'm not sure line array is the same. I will be putting all drivers in a big sqaure. Will this configuration behave differently from a line array or is the theory the same?

 

[zobsky]

I'm not sure line array is the same. I will be putting all drivers in a big sqaure. Will this configuration behave differently from a line array or is the theory the same?

bessel array ?

 

[Scottmoose]

Completely differently (to a line-source). Have a search of the older audio books from the 1950s - early 1960s and you'll see that speakers, admittedly not using 3in drivers, but similar in concept, were quite popular once upon a time. This might interest you, particularly the Sweet Sixteen section: http://www.roger-russell.com/columns/columns.htm

 

[69stingray]

Do you mean something like this:

An externally hosted image should be here but it was not working when we last tested it.

Helix from Legacy Audio

 

[Mikael Abdellah]

here are some pictures of the progress of my new project. the first one shows what I came home with from the wood shop.

 

[Mikael Abdellah]

here is the basic layout of the full (low mid to high) range from the side. no glue yet, just carefully placed the parts the way they are supposed to be when its finished.

 

[Mikael Abdellah]

and here is the side view of the sub. there will be 2 per side

 

[Mikael Abdellah]

one front baffle finished. 3 to go.

 

[Mikael Abdellah]

i think its more holes than board now

 

[Mikael Abdellah]

after some sanding all speakers fit nicely

 

[neutron7]

i hope it doesnt sound like a guitar flanger when you walk around!

 

[ocool_15]

What is the intended purpose of this design? What frequencies to you intend to have the "stack" cover.

 

[Mikael Abdellah]

It is going to be a small, cheap and easy to DIY PA-system. Not sure about the crossover points yet, but I will run the stack of 3" drivers as low as possible.

 

[maghen]

I was really into that idea too, before I decided to go the "line array way" instead.
The problem that talked me out of it was the cancellations that will occur. I have no idea how serious this problem will be in practice , but theoretically it doesn't sound very good...

 

[Mikael Abdellah]

As long as this one plays loud (and I do mean LOUD) I don't really care.

 

[Mikael Abdellah]

more progress. i have today finished the 2nd of the 4 bass boxes.

 

[bjorno]

…What happens to the frequency response when you mount a LOT of small speakers tightly together…

Hi,
You may find some useful answers here:

http://www.diyaudio.com/forums/showthread.php?postid=1215500#post1215500

Your short array is a small square and thus what is considered for the vertical dispersion will also apply for the horizontal, see the first picture.

Stacking several vertical line arrays made with point sources horizontally makes a plane source array to a certain extent, see the second picture where a T-line array is suggested as a complement.

The normal line array SPL/distance plot can be extended with a short ‘Close field’ region depending on the horizontal length (width) of the array where the SPL versus distance is constant(0 dB/ octave) and that extends to about the array-length/ 3.14 where the Nearfield (3 dB/ octave) takes over as can be seen in Jim Griffins papers: http://www.audiodiycentral.com/resource/pdf/nflawp.pdf

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[bjorno]

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