Void Bias V3 User Manual - page 29
Section area
(mm
2
- AWG)
Nominal
resistance
Length
(ms)
Resistance
(ohm)
2 x 1.5 - 16 AWG
R = 12 Ω/km
5
0,12
10
0,24
20
0,48
2 x 2.5 - 13 AWG R = 7.4 Ω/km
5
0,07
10
0,15
20
0,30
2 x 4 - 11 AWG
R = 4.5 Ω/km
5
0,05
10
0,09
20
0,18
TABLE 10: Typical speaker cabling resistance.
Average power/
rated power
Power
compression
Equivalent series
resistance
to a 8 Ω driver
10%
1.4 dB
1.0 Ω
20%
2.0 dB
1.4 Ω
50%
2.8 dB
2.1 Ω
100%
4.5 dB
3.8 Ω
TABLE 11: Typical resistance increase
due to voice coil heating.
On TABLE 11 notice the exceptionally high value (3.8 ohm)
when the driver reaches it thermal limit.
Another advantage offered by the damping control feature is
that in adding the series equivalent output resistance to the
amplifier chain, the variation of the voice coil resistance due
to heating can be taken into account. This allows to obtain a
correctly damped bass response at average working condi-
tion, where the voice coils is subject to heating due to the
passage of current.
For example, if the subwoofers are going to work at close to
full power, an additional negative resistance of 1 to 2 Ohms
should be added to compensate the high resistance gener-
ated by the heated voice coils to obtain a correctly damped
response. On the other hand, if the same subwoofers are
working at low power, a smaller negative resistance should
be added: in this case the cooler voice coil presents a
smaller series resistance to be compensated.
Leaving too high an equivalent series resistance results in an
overdamped system.
9.12 DSP Settings: Channel setup
9.12.1 Auxiliary delay
This delay is a further input delay: it acts before the input EQ
and is independent from the input EQ stage.
9.12.2 Diagnostics
The diagnostics tool allows the user to program and test the
integrity of the input and/or output line.
•
The input test is based on the detection of a pure tone
(generated by an external tone generator) on any input
line.
•
The output test relies on the measurement of the im-
pedance at a well defined frequency: the amplifier can
generate a pure tone and measure the voltage and
current at the generated tone frequency. It is therefore
possible to recalculate the impedance at that specific
frequency.
When an alarm condition is met, the user can be informed of
the event via software or directly from the amplifier.
9.12.2.1 Tone in alarm
The tone in alarm can measure the integrity of any input line
feeding signal into the amplifier. This detector can measure
a tone applied by an external generator.
•
Tone in alarm: enable/disable the input tone detection
•
Tone in freq: the frequency of the tone that has to be
detected (range 20 Hz - 24 kHz, step of 10 Hz).
•
Tone in Vmin: the minimum threshold value that has
been detected (range 0 V
rms
- 4 V
rms
, step of 10 mV
rms
).
•
Tone in Vmax: the maximum threshold value that has
been detected (range 0 V
rms
- 4 V
rms
, step of 10 mV
rms
).
9.12.2.2 Tone out gen
The inner tone generator allows the user to generate a tone
that can be used to check the integrity of the output line. This
tone should be used outside of the frequency bandwidth of
the driven speaker to avoid can be listen.
•
Tone out gen: enable/disable the internal generator.
•
Tone out ampl: the output voltage of the generator
(range 0 V
rms
- 20 V
rms
, step of 1 V
rms
).
•
Tone out freq: the frequency of the tone that has to be
generated and eventually detected (range 20 Hz - 24
kHz, step of 10 Hz).
9.12.2.3 Tone out alarm
The output tone detection can measure the presence of a
tone generated by an external or internal generator.
•
Tone out alarm: enable/disable the output tone
detection.
•
Tone out Vmin: the minimum detected threshold voltage
value (range 0 V
rms
- 20 V
rms
, step of 1 V
rms
).
•
Tone out Vmax: the maximum detected threshold volt-
age value (range 0 V
rms
- 20 V
rms
, step of 1 V
rms
).
Bias Series User Guide V1.0
Page 23