Operating instructions

R.5-MAX, R2-MAX Page 13 Installation and Operation Manual
R-MAX SPEC SHEET PROCESSING DETAILS
COMMUNITY LOUDSPEAKER DATA: “TRUE TO SPECIFICATION”
Ever since Community pioneered the measurement and publication of detailed loudspeaker specifications in 1976, we
have striven to present the most relevant, useful, and technically correct loudspeaker data to our customers. Community
believes that our customers are best served by having published data and specifications that accurately depict the real world
performance of our loudspeaker systems and work properly with computer-based loudspeaker modeling software.
In the beginning, this was an easy task. Community’s engineers provided the data and we published it with no modifications. As
time progressed, however, other loudspeaker manufacturers’ marketing departments began to evaluate their specifications
prior to publication to make sure that their loudspeakers were presented in the best possible way. This often meant omitting
specifications that were not flattering in competitive comparisons. Some manufacturers have now taken these marketing
specs to extremes, while others simply leave out important details needed to convey the full loudspeaker performance
characteristics.
In contrast, Community continues to present its data in a “full-disclosure”, detailed engineering format. Professional
designers and end users appreciate this approach, but some customers may not have the time or expertise to compare
spec sheets, validate the numbers, and then sit back and ask themselves, “Did what I just read make sense? Does it all add
up?” Unfortunately, when this happens, the manufacturer with the most inflated, unrealistic numbers and the most highly
smoothed (and sometimes DSP processed without annotation) frequency responses may appear to be the best choice. That
is, until the loudspeakers are installed in the field and don’t meet expectations.
Thus, for Community’s R-MAX loudspeaker product line, we chose the approach that allows us to present our specifications
in the traditional “full-disclosure” format while also providing them in a more competitive format that allows our products to
be directly compared to other manufacturers.
EQUALIZED VS. UN-EQUALIZED OUTPUT SPL
Here’s an example. As shown in Figure 8, R-MAX spec sheets include Maximum Output SPL for each model with and without
equalization.
Maximum Output
2
without EQ
3
:
with EQ
4
:
133 dB (139 dB Peak)
132 dB (138 dB Peak)
Figure 8. R2-64MAX “Maximum System Output” ratings from the spec sheet
In contrast, most manufacturers provide only the Maximum Output SPL without EQ. This is a glaring omission because,
once the loudspeaker has been equalized, its Maximum Output SPL can only be as high as the output of its least powerful
component (transducer). For example, in a 3-way loudspeaker, the passive MF/HF Maximum Output SPL may be stated as
“134 dB”. But, if the MF is 10 dB higher in output than the HF, the equalized Maximum Output SPL may be 5-10 dB lower than
this single number. In many cases the LF output is a few dB lower still, reducing the loudspeaker’s overall equalized Maximum
Output SPL even further.
Community purposely designed the R-MAX series with drivers that have well-matched outputs. Thus, R-MAX models do not
require excessive equalization and that means the overall Maximum Output SPL of an equalized vs. un-equalized R-MAX
loudspeaker does not change by more than a dB for any model. This is an important dierentiating feature of R-MAX Series
specifications – the Maximum Output SPL that is achievable in the real world before and after processing is clearly stated
on the spec sheet. Designers will not have to piece together data from multiple documents to tell their customers what kind
of performance to expect. Community has made it clear and unambiguous. But this is not the only type of equalization that
reduces Maximum Output SPL and becomes a hidden omission on some spec sheets.
LOW FREQUENCY “BOOST” EFFECT ON OUTPUT SPL
In many cases, the equalized loudspeaker response shown on a spec sheet includes significant boost applied to the low-
frequency driver to increase LF extension. However, every dB of LF boost reduces the loudspeaker’s overall Maximum Output
SPL by approximately the same amount. This means that the LF driver is likely to reach its excursion limit (and/or activate the
system limiter) before the loudspeaker’s specified maximum power level has been applied.
For example, consider a loudspeaker system with the following LF driver parameters: 97 dB 1W/1m sensitivity, 2000 watts
(63V @ 2 Ohms) maximum input and a calculated Maximum Output SPL of 130 dB SPL. While not explicitly stated on the spec
sheet, the processor settings downloaded from the manufacturer’s website specify a +6 dB boost at 70 Hz, via a parametric
EQ (PEQ) filter, to achieve the LF response shown in the spec sheet’s frequency response graph.