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TIP: It's a good idea to experiment with different loudspeaker locations by conducting
listening tests before you finalize the locations (this is especially important in permanent
installations). Make sure to use live microphones and live instruments (if applicable), as
well as track playback. Choosing the physical location of the loudspeakers in the room is
always the most important part of any successful system installation.
Further notes on polarity: In some acoustical environments, the system may sound better
when the polarity relationship is technically non-optimal, resulting in a dip or attenuation at
crossover, compared to optimal polarity where the crossover region is accentuated by the
overlap of the subwoofer and the full-range speaker(s). However, this is not the best way to
achieve the sound quality that you're seeking. The proper course of action is to establish
relative polarity that accentuates the overlap that's causing the peak at crossover, and then
equalize (EQ) the peak with a parametric equalizer until the response is flat, or until you've
achieved the tonal response you desire (we'll explain why below).
Alternatively, you might insert a high-pass filter in the full-range system (typically at 80 – 100
Hz with a 12dB/octave slope), so that the overlap with the subwoofer is reduced in magnitude.
A third technique is to increase the slope of the crossover to 24 dB per octave or 48 dB per
octave, if the crossover has such capability, thereby reducing the bandwidth of the spectrum
in which the two sources overlap.
There's an important reason for taking one or more of the measures discussed above. If that
nice-sounding response dip at crossover is in fact due to phase cancellation, it means that the
drivers and amplifiers will be working harder than they should to produce less sound pressure
level than they are capable of, due to the acoustic cancellation taking place. All that cancelled
energy uses power unnecessarily!
Instead of putting the two systems out-of-phase to get the sound you want, if you attenuate
the peak at crossover with any of the methods described above
that's required to obtain a given sound pressure level. This will result in more available power,
more headroom and less demand on the drivers and amplifiers, thereby lowering the potential
for distortion and damage under high power conditions.
Now that you've chosen the final physical locations for your full-range loudspeakers and
subwoofers, established their optimum phase relationship, and brilliantly EQ'd any crossover
peaks, you're almost ready to permanently wire the system. But first read the section below
on "Choosing Appropriate Loudspeaker Models and Appropriate Signal Processors."
CHOOSING APPROPRIATE LOUDSPEAKER MODELS
AND APPROPRIATE SIGNAL PROCESSORS
In order to design, install, and operate a highly successful sound system, the initial product
selection must be carefully considered. Loudspeakers, amplifiers, and processing electronics
must be appropriately scaled to handle the job that will be required of them.
Choose VERIS 2 models with high enough maximum power to provide the needed SPL at
the farthest listener - with attention paid to maintaining appropriate headroom. Typical
headroom factors are at least 6 dB for voice paging, at least 10 dB for voice
reinforcement, and as much as 20 dB for music reinforcement.
Select VERIS 2 models with the right frequency response for the application. Voice-only
systems do not need extended low frequency response, but music systems usually do
(depending on the style of music). Acoustic guitars do not require the same LF response
as dance music.
Subwoofers will improve the sound quality of a music reinforcement system, but may
reduce intelligibility in a voice-only system in a reverberant space.
2
The three corrective methods referred to; i.e. equalizing, high-passing, and increasing the slope of the crossover,
are all various implementations of equalization.
VERIS 2 – Operation Manual - Page 26
2
, you are reducing the power
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