HK Audio CDR 210 F - Manual (Page 50)

Manual
COHEDRA
® & COHEDRA ® Compact
1.2 Remarks on
SPL Calculation in CAPS
For simulation purposes, HK AUDIO ® COHEDRA ®
CAPS and EASE DLL (Version 1.0) use a point
source model that factors the acoustical phase into
the equation. This mathematical model provides
a good approximation of a line array's cylindrical
source up to about 4 kHz. However, the deviations
from actual readings increase markedly above this
frequency. This causes HF interference to appear in
the simulation that does not occur in reality!
To adequately approximate reality, you should
always select an average over three octaves for
frequencies above 4 kHz.
When determining absolute SPL levels, always
use a broadband average; that is, the average
of all calculable frequencies. The reason for this
is because there may be some deviation in the
indication of thirds.
Absolute SPL levels are indicated differently in CAPS
and the EASE-DLL:
1.2.1 CAPS
When Continuous is selected, CAPS computes the
sound pressure level attained at the controller's
input using an EIA-426-B-compliant signal at +6
dBu. Similar to pink noise, the EIA-426-B signal's
spectrum is the averaged result of many different
musical compositions. This input level roughly
corresponds to the limiters' threshold so that these
values are indeed continuous, meaning that they
are attainable over a sustained period using a dense
signal.
Of course, patching higher levels into the
controller's input yields higher output levels. The
Peak calculation option serves this purpose. The
top units are supplied with the maximal permissible
load without taking compression effects and
limiters into account. Accordingly, these values are
attainable for relatively brief periods only.
1.2.2 EASE DLL
SPL calculation in EASE has traditionally been
somewhat different, as it always operates under the
assumption of band-averaged energy distribution.
For this reason, you should only lend credence to
broadband-averaged SPL values; otherwise, the
simulated signals' high-frequency range will be
overemphasized in comparison to actual signals.
Initial SPL values calculated using an EASE DLL are
always peak values! To obtain realistic continuous
levels, the SPL values of all frequencies must be
reduced by at least -6 dB in the Edit Loudspeaker
menu!
The following applies to every simulation
in general:
Computed SPL values can be only reproduced
precisely using the appropriate test signals. In live
musical applications, differences occur naturally
as a result of the different spectra and crest factors.
However, computed values may certainly be
considered conservative, and their accuracy
has been verified in countless analyses.
Acoustic simulation for COHEDRA ®
CAPS EASE DLL
Runs on all Win xx platforms Dynamic Link Library plug-in for EASE 4.0
2D cut model 3D volume model
Direct sound calculation Calculation of all simulations:
direct sound, ALCons, RaSTI, ray tracing, auralization
Application: Day-to-day use when touring Application: Precision simulations for fixed installations
Data import