all right I'm Dave Rat and today I'm going to talk about line arrays versus
point source systems and why line arrays have become so popular and what problems
they have and have not solved and what they've done that is absolutely unique
to their design so let's take a look at this stuff what I've got is a bunch of
these speakers here that I made their little 3-inch speakers they're nothing
special there just utilitarian utilitarian testing devices for me to
demonstrate and test various sound concepts I've got a little 8 channel app
here I'm using a couple channels I've got two speakers that can go on each
channel I have a little peak noise generator
we're actually using white noise for this so we can hear the high-frequency
interactions so the first thing we will do is to start off with a point source system
and we will plug in a single speaker here
I recommend you wear headphones while listening to this
because I am going to use headphones and you can hear what I am hearing
So, I've got a microphone here
and we can point it at this little point source
I am going to move it side to side
you should be able to hear it
Kind of fade off a little bit when I am not centered on it
I can do the same thing with the speaker
And they are fairly directional
So a point source system
has its coverage whatever it is, these aren't very wide but whatever the
coverage is and there is no horizontal or vertical
for the most part, you have a single speaker there are no issues or interaction between
speakers but typically or often a single speaker is not enough to cover a venue
or we need more control over the horizontal or vertical dispersion so we
start adding additional speakers to the mix here
Let's go ahead and do that and we will plug in a second speaker
Now with two speakers
when I go side to side you hear
A phasing issue
That has to do with the difference of arrival times
of one speaker versus the other
we can spread these apart and splay them a bit and tray and reduce that build up in the middle
Lets push them farther
put them tighter
And with a well designed system those interactive issues can be reduced but
not eliminated we can go bigger and we can add in another couple speakers here
and now we have four
but vertically
let me take the mic out
vertically
so with a point source or a splayed system we might make these trapezoidal we might
have perfect horns to get in there and get this stuff all dialed in and no
matter what we do when we're standing there listening to this those
center points, the alignments between now
let's go ahead and
take this and
and turn the line array to a vertical line array instead of
a horizontal line, now we haven't changed anything
we still have all these issues
and we have the lack of issues
in the horizontal domain
by creating a line array, a well-designed horizontal splayed system
or a well-designed multi source point, multi speaker point source system will have
multiple interactions between boxes in the horizontal domain whereas a line
array well-designed line array has piled all of those up into the vertical domain
and the reason that's so interesting is we have ears on the side of our heads
and as humans we are extremely perceptive in differentials of time
arrival in the horizontal domain and not only that we're constantly moving our
head we have a hundred and eighty degree motion from left to right and with the
ear on each side we almost have a 360-degree horizontal listening range or
domain in the vertical we have a much more limited ability to hear vertical
and altitude differentials and we were basically relying on
the shape of our ears rather than the two differential and the points so since
we're very very acute horizontally and somewhat diminished vertically by taking
all of these unavoidable issues of having multiple speakers and piling them
all up in the vertical domain where we as humans are less able to hear them and
creating a horizontal domain a horizontal field that is almost free of
any of those aberrations we haven't made the problems go away we've just made them
much less audible to us as human beings and hence this is a an advantage that is
human and you can measure a point-source system with all the measurement
equipment you can measure a line array with the all this measurement equipment
and you can get similar or better or worse results but unless you take into
account the human factor of what we hear how we
perceive at how our heads move during a show, are you running up and down the
stairs? are you doing jumping jacks and burpees? well then the horizontal, uh,
the vertical issues may come into play but if you're staying reasonably at the
same altitude but you're moving your head side to side the horizontal issues
are going to be more of a concern for us so I just thought wasn't thought that is
a interesting perspective on line arrays versus point source arrays with all
other things being equal there is a definitely a human factor to take into
account all right hope that's interesting and I'll be back with more
videos soon