Pioneer Reference Series DEX-P9R - Manual (Page 10)

class-D amplifiers
60
for full specifications please see next page.
Pure intensity comes charging out of Pioneer’s first Class-D amplifier, the GM-D500M. With a
sizzling 1000 W of maximum output power, the sound is overwhelmingly crisp thanks to the
digital processing. Class-D amps require less electrical current which means less
distorting heat throughout the system without bulky heat sink surfaces. With its
powerful design and Pioneer technology, this compact amp fuels your subs and
speakers for hyper-clean sound without distortion — at power levels
which have to be experienced to be believed.
CLASS-D AMPLIFIER
• Max. output power: 1 x 1000 W (2 Ω) or 1 x 600 W (4 Ω)
• Continuous output power (14.4 V): 1 x 500 W (20 – 240 kHz/2 Ω),
1 x 300 W (20 – 240 kHz/4 Ω)
• 1 x 490 W (4 Ω) or 1 x 630 W (2 Ω) (DIN 45324, +B = 14.4 V)
• 2 Ω stable operation
• Variable LPF (Low Pass Filter) (40 – 240 Hz, -24 dB/oct.)
• PWM Regulated MOSFET power supply
• Bass Level control (-22 – +12 dB)
• High Voltage Input capability (125 mV – 6.5 V)
• Low load impedance capability (2 – 8 Ω)
• Large power/ground terminals (screw-type)
• RCA input terminals
• Chassis size (mm): 268 x 52 x 250
❚ Technology Class-D Amplifiers
Class-D amplifiers overcome the inefficiencies of traditional Class-A or AB
amplifiers. Pioneer’s GM-D500M and GM-D505 Class-D amps transform very
little power into heat while a very high percentage of the power supply (67 %) is
transferred into the load. This results in a very compact amp which needs little
input power to produce very high output power.
CURRENTVS. POWER
Power Output (Watt — 4 Ω)
0 50 100 200 300 400 500
Curr
ent
(A)
50
40
30
20
10
0
The Class-D amplifier’s PWM (Pulse Width Modulator) modulates the original
audio input signal with another signal which has a much higher fixed frequency.
The result is a digital signal which contains the input signal and a band of
frequency components around the modulation frequency. A LPF (Low Pass Filter)
will then filter out the 350 kHz frequency pulses and the resulting amplified
output signal is then sent to the subwoofer and/or speakers.
The advantage of this amplification is that the power output FETs operate like a
switch that is ‘on’ or ‘off’: when ‘on’, the FET acts like a closed switch, no voltage
runs through its terminals, and no wasted power is transformed into heat.
This is why Pioneer’s Class-D amp’s heat sink can be kept very small, and a stable
load can be pumped into your subs and speakers to create a maximum of
undistorted, clear sound.
High current Front or rear
speaker
Subwoofer
Front or rear
speaker
Subwoofer
Low current
BTT
+
The high amplifier power required to drive a subwoofer causes unstable current and
voltage, which not only goes to the subwoofer but also to the front and rear speakers. As a
result, the sound quality is affected and distorted.
A Class-D amplifier needs only 2/3 of the current of a conventional amplifier, so the power
supply to both subwoofer and front and rear speakers is more stable. As a result, the
sound quality will not be affected, so you can enjoy a very clean sound output without
distortion.
PULSE WIDTH MODULATOR METHOD
Input signal
Output signal Pulse Width Modulation
Circuit
A LPF (Low Pass Filter) cuts
off the high frequency
Signal amplitude
transfer to Pulse
Width
+V
-V
0
+ Amp
- Amp
Class-D
Class-AB
1 x 1000 W (2 Ω)
1 x 600 W (4 Ω)
Max.
GM-D500M NEW
BTT
+