Monacor CAAD 3.0 Handbuch Seite 14

• Electrical Q (Qe): The electrical Q is stated by
GB
losses in the driver resp. the quality of the coil and
the magnet.
Automatically transferred.
• DC resistance (Re) in Ohm: DC resistance of the
coil. Not to be mixed up with the AC or inductivity
resistance of the coil. The last value is usually 20 %
higher.
Automatically transferred.
• Serial resistance (Rs) in Ohm: The serial resis-
tance is a very interesting factor. The value repre-
sents the electrical loss of the speaker wires and the
frequency system in Ohm. As indicated above, it
influences the electrical Q and by this the total Q. If
in case of emergency you do not know the values of
Qms and Qes, do not despair. The solution is uncon-
ventional but it works:
Qts new = Qts old x (Re + Rs/Re) (x means multi-
ply). An inserted serial resistor can slightly increase
a low Qt value of a driver.
Not transferred from the database.
The following parameters depend on the box type to
be calculated.
Closed box
Closed box Q: Here you can insert the desired value
of the closed box Q. The closed box Q is calculated
of driver Q and box Q. Due to natural laws the value
of the closed box Q must be higher than the total Q
of the driver!
Qcb = 0.5 is called "critically attenuated" and gives
a very defined but "thin" bass sound.
Relative sound pressure -6 dB at reson-
ance frequency.
Qcb = 0.7 is an ideal compromise between low-
reaching bass and a good reproduction
of a transient response. Relative sound
pressure -3 dB at rising resonance fre-
quency.
Qcb = 1.0 gives a strong bass but a moderate tran-
sient response. Relative sound pressure
-0 dB at further rising resonance fre-
quency.
Qcb = 1.4 gives a very strong bass, but a poor tran-
sient response. Relative sound pressure
+3 dB at a frequently too high resonance
frequency.
... and so on. But please remember to control the other
parameters and especially the frequency curve (Qcb =
Q closed box).
Alpha (α)
α = (Qcb/Qt)
2 -1
General rule: Low Qcb value = greater box and
Qcb/Qt = fcb/fs
System resonance (fcb) in Hz: The system reson-
ance is fixed by the driver resonance frequency and
the cabinet resonance frequency. Due to natural
laws the system resonance frequency must be high-
er than that for the driver. You will soon find out that
small changes in (fcb) result in great changes in Vb
(box volume).
14
General rule: Low fcb value = greater box
changes with fcb and Qcb are always proportional
Alpha (α):
α = (fcb/fs)
2 -1
Correlation between the equivalent volume of the
driver and the compliance of the box (Vas/Vab). α is
always greater than 0 (zero) and usually lower
than 10.
General rule: Low α-value = greater box
Net box volume (Vb) in l: If you wish to test if the
speakers are suitable for a box: Here you can insert
the net box volume in litres. The frequency curve
and the values of Qcb, fcb, and α show how well
speakers and box match.
Additional volume (Vb+) in l: The additional volume
is composed of the addition of air quantities occu-
pied by driver, crossover, and the bracings (to rein-
force the box). If the final box suggestion is dis-
played by the programme, this volume is considered
and included.
The parameter input for closed box types is finished
here. Please pay attention to possible error messages.
The results of the box calculation are displayed on the
screen at the right. Most parameters should be known.
However, a few must be explained:
The acoustic volume is the inside box volume calculat-
ed by the programme. By dampening material like Acu-
stilux, glass wool, rock wool, sheep wool or similar, the
effective volume of the box is enlarged. The reason for
this is the lower sound speed in the dampening
material. The sound speed can decrease by the factor
1.4 in box types which are dampened very much.
CAAD 3.0 takes this effect into account and assumes
a density factor of 1.2 as a standard value.
The net volume (Vb) is the box volume corrected by
the density factor.
The quotient fs/Qt (EBP = Efficiency Bandwidth Pro-
duct) shows (according to Richard H. Small) if a driver
is suitable for a special box type:
EBP below 50 for transmission line
EBP 50-99 for closed boxes
EBP 100-149 for bass reflex
EBP 150-250 for horn systems
All above-mentioned values are just guidelines and
should not be taken too strictly.
The reference sound pressure (SPL = Sound Pressure
Level) in dB is calculated of the driver data fs, Vas, and
Qe, and can sometimes be slightly lower than stated
by the manufacturer!
With the last parameter CAAD 3.0 gives you dimen-
sions for a speaker box, suitable for the driver inserted.
The additional volume has already been considered
hereby. The data displayed are inside box dimensions.
With closed boxes you can insert your own box dimen-
sions and have the resulting parameters calculated.
For this activate the option field "Set own box dimen-
sions" and change the data in the fields for the box
dimensions. If the option field "Set own box dimen-
sions" is not activated, the inserted data are disregard-
ed and overwritten.