H8 DSP
Digital Interface Processor
User’s manual
8
8
36
8.11
SET DISTANCE AND DELAY
Fig. 1
Fig. 3
Fig. 2
This setting automatically calculates the time it takes for the speaker sound to reach
the listener’s ear
(Fig. 1)
.
Preliminary Remarks
Sound moves through the air at a speed of 343 mt/sec (1.125 ft/sec) at a
temperature of 20°C (68°F). If you know the distance from the sound emission
point, you can then calculate the time sound takes to reach the listener’s ear.
If you set the distances of the different speakers in your system, the
H8 DSP
will
automatically change them into time (ms - milliseconds). It does not assign a
delay (0.0 ms) to the farthest speaker (usually the Subwoofer) but progressively
growing delays as much as the other speakers get closer to the listening point, in
order for all the emission points to reach the listening point at the same time.
SET DISTANCE
It enables the setting of the distance between the speaker and the listening point.
Choose cm (centimeters) or in (inches). The
Set Distance
boxes can be configured by
using the knobs or by typing the numbers on the keyboard.
DELAY ms/default
It displays the time in ms (milliseconds) calculated according to the distance.
DELAY ms/fine set
The H8 DSP time delays also allows the manual fine-adjustment.
Preliminary Remarks
Fine Set and Phase Delay
Delay assignment according to distance calculation is theoretical. That is, small variations need to be applied due
to small errors in distance measurement, back-wave reflections inside the car compartment and, mainly, the
speaker phase problem.
Two speakers reproducing two areas of frequency close to each other (e.g. Woofer and Midrange) will simultaneously
reproduce in their crossing area, at attenuated level, the same frequencies. Due to the different nature of the
speakers, they will show a difference in phase that, for a short frequency interval, works like a time delay. By using
Fine Set
you can partly correct these problems of
Phase Delay
.
By using
Fine Set
you can change the preset time delay.
This delay adds to (+ x.xx) or is deducted from (- x.xx) the value of the delay
shown in the
Delay / Default
window, and does not change the value
automatically assigned.
If you assign a positive value (+ x.xx) with the “
fine delay
” it will increase
the delay of that speaker taking it at a further distance from the listening
point. Likewise, assigning a negative value (- x.xx) will decrease
the speaker’s delay and therefore bring it closer to the listening point.
For the user to evaluate how much
Fine Set
has been manually changed,
both delay values are shown. To see the result applied to the output,
the values shown in the
Delay / Default and Delay / Fine Set boxes
need to
be added up. A negative value (decreasing the delay) can not be assigned
to the farthest speaker; it can only be assigned to the other speakers as
they are all already delayed compared to the farthest one. If you try and
give a negative value to the farthest speaker, an alert message will appear
(Fig. 2)
. When using
Fine Set
, the letters
Fds
will be shown in green on the
corresponding channel of the
Channel Map
(Fig.3).
