David Smith, aka "speaker dave" used a term on the forum that I am not familiar with. The term was "effective array length." I found this JBL doc that covers it, and some other information, and I hadn't seen it before.
This might be some food for thought for those of you working on two or three-way arrays.
http://citeseerx.ist.psu.edu/viewdo...649F17B?doi=10.1.1.114.8971&rep=rep1&type=pdf
This White Paper introduces the principles of JBL’s Vertical Technology™. This
technology comprises a predictive tool, unique electroacoustical elements, and a family of multiway loudspeaker systems. These form JBL’s VERTEC™ system, a next-generation line array product first embodied in the Model VT4889 fullrange system. VERTEC users have access to a design program enabling systems to be arrayed a prioriwith the assurance that array performance will accurately meet the program’s response estimations. In this paper we will:
A. Cover the basics of line array technology from its beginnings to the
present;
B. Dispel much of the mystery surrounding line array technology;
C. Outline in detail the development of a full-range loudspeaker system and
the computer software that optimizes arrays made up of these systems to
produce a desired directional response.
This might be some food for thought for those of you working on two or three-way arrays.
http://citeseerx.ist.psu.edu/viewdo...649F17B?doi=10.1.1.114.8971&rep=rep1&type=pdf
This White Paper introduces the principles of JBL’s Vertical Technology™. This
technology comprises a predictive tool, unique electroacoustical elements, and a family of multiway loudspeaker systems. These form JBL’s VERTEC™ system, a next-generation line array product first embodied in the Model VT4889 fullrange system. VERTEC users have access to a design program enabling systems to be arrayed a prioriwith the assurance that array performance will accurately meet the program’s response estimations. In this paper we will:
A. Cover the basics of line array technology from its beginnings to the
present;
B. Dispel much of the mystery surrounding line array technology;
C. Outline in detail the development of a full-range loudspeaker system and
the computer software that optimizes arrays made up of these systems to
produce a desired directional response.
DL'd & will read later.
Line arrays, like a lot of things in audio, are very scalable. If you create an array with a performance you like then the same array at 1/4th the size will perform the same 2 Octaves higher.
You can make a multiway array or you can actually adjust the size of your array versus frequency. One way to adjust size is to have a progressive rolloff that reduces the high frequencies progressively to outer elements. The rolloff is reducing the "effective array length" and if we kep length proportional to radiated wavelength we will have constant directivity This works for long arrays with one type of driver or symmetrical clusters like the expanding array that ra7 is working on.
Ideally we want to scale continuous source arrays (ribbons, electrostats) but we can do the same thing with multielement arrays as long as we remember that they are sampled arrays with the potential issues that sampling gives. (spatial aliasing: lobes) One smart solution for that is to vary the unit density to have tightly clustered units around the middle and then greater spacing at the ends.
Its all in my paper!
http://www.diyaudio.com/forums/multi-way/243861-floor-ceiling-array-vs-cbt-3.html#post3666436
Regards,
David
You can make a multiway array or you can actually adjust the size of your array versus frequency. One way to adjust size is to have a progressive rolloff that reduces the high frequencies progressively to outer elements. The rolloff is reducing the "effective array length" and if we kep length proportional to radiated wavelength we will have constant directivity This works for long arrays with one type of driver or symmetrical clusters like the expanding array that ra7 is working on.
Ideally we want to scale continuous source arrays (ribbons, electrostats) but we can do the same thing with multielement arrays as long as we remember that they are sampled arrays with the potential issues that sampling gives. (spatial aliasing: lobes) One smart solution for that is to vary the unit density to have tightly clustered units around the middle and then greater spacing at the ends.
Its all in my paper!
http://www.diyaudio.com/forums/multi-way/243861-floor-ceiling-array-vs-cbt-3.html#post3666436
Regards,
David
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