1. SOBRE LA MEDIDA DE PODER DE
LOS AMPLIFICADORES DE AUDIO
One of the main advantages of D-Amp Amplifiers
is the possibility to handle in a considerately
more efficient way the musical power with respect to conventional
linear amplifiers, taking in to account
that music average power energy is considerably lower
with respect to continuous sine wave signals of the same
peak level.
In few words the main advantage of D-Amp Amplifiers
is to underperform the continuous signal power output
(unusefull from
the musical point of view) in order to greatly enhance power output
of the useful
musical signals.
Therefore the Audio Power outputs stated in D-Amp Specifications
sheet must be measured in the following conditions:
1. Power RMS x Channel (1kHz, 0.5%THD):
• Maximum
continuous output power delivered to the load for at least
15 minutes, then thermal limiting processor shut down amplifier.
2. Power RMS x Channel in stereo working:
•
Maximum EIAJ standard test output power: average of RMS
output voltage squared divided by load impedance.
• Test signal 1kHz tone burst 8 cycles 0dB, 8 cycles
no signal, THD 1%. If the power measurements will follow
the above conditions there will be founded the power
figures very close to those stated in the
data sheets.
In the case that measurement are done with the non significant
method of continuous sine wave input signals (applied
for more than
15 minute), the system is self-protected from that
unusefull signals, and shut down amplifier.
It is now possible to introduce a new approach in designing
Audio Amplifiers,
especially when a very high audio output power is required.
In effect in the normal operation the amplifier's useful
output music usually is limited by its short term power
capabilities and not by
the heating that results from high continuous power
emission.
Based o the above consideration, it is possible to minimize the non realistic usual
requirement for
continuous power rating, typical of conventional analogue
amplifiers, and to design much more efficient Audio
Amplifiers
increasing their burst power capability with respect
to the continuous power rating.
For the correct design it is moreover necessary to
define as valid for any topologies of music two basic
parameters as: the ratio for
the peak output power to continuous power rating and
the max. burst duration.
About the first parameter from specific research it results that
in the worst case of rock
music compressed for FM broadcast the ratio of r.m.s
to peak power is around 8 dB. This means that if an
amplifiers volume
control is set to place the high peaks at the on set
of clipping, the most severe continuous power demand
is less than 15% (usually
under 10% ) of the amplifier's max. peak power.
About the second parameter - max. burst duration confirm
that for all the music types the burst peak power Is
always reducing with the increasing of the duration
of the bursts.
This general rule is represented by the following expression,
and takes in to account all possible music worst cases:
10 log p/pc =-0.16 Log t
were 't' is the toneburst in milliseconds and ' pc'
is the power level at 0 dB (the clipping point)
This means that the distribution of peak power bursts
in function of duration can be represented in the following
table:
• burst duration max r.m.s level
• 3 ms 0 dB clipping
• 30 ms -2 dB
• 300 ms -3 dB
• 3 sec. -5 dB
• 30 sec. -7dB
Based on the above results D-Amp has been in the position
to define the basic requirements to design of an innovative
very
efficient Audio Professional high power amplifier:
• To obtain extended duration of headroom, able
to delivery burst of 10 sec. or longer at substantially
higher level then normal linear
amplifiers 'continuous power rating.
• To obtain an optimized thermal design suitable
to manage very high r.m.s output power within 3 dB with
respect to the peak power.
This requirement will allows a margin with respect of
to above mentioned experimental results.
• To obtain an automated gain control suitable
to maintain for any input signal level the full dynamic
capability. This requirement in
order to avoid clipping distortion and ensure the nominal
r.m.s power.
The right solution to the above requirements was founded
utilizing digital switching technologies (based on the
principle of PWM
modulation ) with some circuitry topologies solutions.
In effect this PWM technology, through a very high frequency
sampling of audio input signal (over 500 kHz) allows
with the
necessary accuracy to process the signal in digital
form and provides the highest power outputs with extreme
efficiency (near to 97.5 %).
A well designed output filtering and processing solution
provides output capabilities at the highest level of
quality in terms of low
distortion, noise and bandwidth .
Based on the above, D-Amp has developed a new generation
of digital audio amplifiers branded HVI Series.
D-Amp series of Professional Audio Amplifiers is a complete
range of products from 4000 W to 12 000 W on 4 ohms load
in 1 unit 19"
rack size and 8.5 Kg weight.
The global audio result of such new generation of Audio
Amplifiers is that with such innovative design criteria
it was obtained a very
cost-effective product with the best adherence to the
real music professional requirements.
2.Acaso su indicador de limite
representa verdaderamente cliping de salida ?
No, the LED is driven only when the amplifier output
fails to track the input. This condition normally results
only from limited clipping (2%), which occurs when the
power amp reaches either its voltage or current limit.
Limiter LED is red and when light on you are at limit
of clipping. The amplifier have an internal compressor
circuitry to prevent excessive clipping, when the amplifier
clipping reaches the point that the compressor turn
on the limiter (red) and alert the operator that the
input signal is being compressed. 2 Level of limiter
is used, 1 at -2Db before clipping to minimise stress
to loudspeaker (when limiter LED ‘’flick’’
and enable blue LED stay on, and a distortion limiter
when limiter goes on and enable goes off. Limiter limit
to a maximum of 2% absolute amplifier distortion.
3.Es posible de cargar la sensibilidad
de salidaIs it possible dentro de su amplificador ?
In theory, yes, but only by changing certain resistor
values, which requires opening the covers and exposure
to dangerous voltages. This should be done only by qualified
service personnel, or under the guidance of D-Amp Technical
Services. See our support web page for more details
on how to perform this for D-Amp series amplifier.
4.Es posible de inutilizar el
circuito de limite en los amplificadores D-Amp ?
This is not possible due to the philosophy Design.
5.The clip LED’s on my
amplifier flash upon power up before the muting cycle
ends. Is this normal?
During the muting cycle, the "front end" of
the amplifier is internally disconnected from the output
transistors, ensuring that they are fully turned off
in the event of overheating or during routine on/off
muting. When disconnected from the feedback loop, the
front end circuits may have enough stray signal to flash
the Clip LED's. This is perfectly normal, and will stop
as soon as the amp enters the normal "run"
state.
6.Which is the warranty on my
D-Amp amplifiers?
D-Amp provides a 3 year warranty from the date of purchase
of our Distributor. The warranty does not cover failures
due to damage and misuse of the equipment. The customer
is responsible for freight charges to D-Amp will repair
the product under warranty and return it to customer
free of charge.
7.When installing D-Amp amplifiers
in a rack should I leave spaces between ?
La respuesta es Si y No. The airflow technology that
we use in our amplifiers is designed such that it is
best to stack multiple amplifiers on top of each other,
with no space between. The amplifiers draw air into
the back of the amplifier and exhaust it out from the
front panel. If you choose to place the amplifiers with
space between them, then use solid panels between them,
not vented panels. It is not recomended to stack more
than 3 amplifier.
8.Which are loudspeaker protections
on D-Amp amplifiers ?
D-Amp series is equipped with an evaluation / processing
circuitry for output stage behaviour. All signals that
are feed to the load (i.e. loudspeakers ), are subjected
to a pre processing that allows the output stage of
the amplifier to deliver always non distorted and “loudspeaker
safe” signals. This specific feature lead to a
dramatic improvement of reliability of the complete
installed system, reducing loudspeaker failures even
in case of incorrect design. Another circuit track and detect speaker over excurtion and limit the power to avoid to break the speaker.
9.What is mains current requirement
for D-Amp 8000HVI
Mains requirement is defined by the ratio between average
power consumption and mains voltage. For a D-Amp 8000HVI,
power consumption is 1200VA per channel on 1/8 Max power
@ minimum load impedance standard duty program, and
1800VA on ¼ Max power @ minimum load impedance
heavy duty program.
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