Pioneer SC-LX901 Product Reference Manual page 11

Audio Technologies
Advanced Sound Retriever
LX901 LX801 LX701 LX502
The Advanced Sound Retriever restores the output
of compressed audio—such as WMA, AAC, and
MP3—to the level of CD sound. The technology
creates new signals to restore the minor details left out during
the compression process.
Advanced Sound Retriever
Restoration Image
Restoration of lost music cadence
Sound Retriever ON
CD sound Compressed Restored
sound sound
Time Time
Restoration of lost music cadence
Sound Retriever ON
Restored
CD sound Compressed
sound sound
Low Middle High Frequency Low Middle High Frequency Low Middle High
Auto Sound Retriever
LX901 LX801 LX701
Since the Advanced Sound Retriever is designed with
an algorithm optimised to process 128 kbps signal, it
did not work well with 8-15 kHz high frequencies in 64
kbps signal, which is the bit rate for quite a few internet stations. The
newly developed Auto Sound Retriever automatically determines the
audio signal's bit rate, and interpolates the data lost during compression.
It is especially effective for improving the sound quality of low bit rate
content—an ideal feature when switching between internet radio
stations with different bit rates.
Playback Upper Limit Frequency by Bit Rate
25
20
15
10
5
64 96 128 160
Bit rate (kbps)
Current Sound Retriever Upper limit for
unable to play 8-15 kHz playback differs
range for MP3's 64 kbps by frequency
Auto Sound Retriever
Compressed Sound
Improvement for S/N Ratio
-80
-100
dB
-120
1k
Hz
Advanced Sound Retriever
Compensation Effect
+0
-20
-40
-60
-80
Time
-100
-120
-140
0 5k 10k 15k 20k Hz
Original Sound
Advanced Sound Retriever ON
Advanced Sound Retriever OFF
Frequency
MP3
WMA
AAC
192 256 320
Current Sound Retriever
optimised for
128 kbps bit rate
Restored Sound
14.5dB
: OFF
: ON
20k
Jitterless Transmission for Various Sources
LX901 LX801 LX701
PQLS with HDMI
With the precision quartz controller on the AV receiver, Precision
Quartz Lock System (PQLS) eliminates distortion caused by timing
errors. It controls the amount of audio signals from the AV receiver
to the compatible Blu-ray Disc player, giving the best possible
digital-to-analogue conversion. PQLS Bit-stream is available on the
AV receivers for CD/DVD/BD playback.
For PQLS to be effective, Control with HDMI needs to be on, and
PQLS setting needs to be set to Auto.
Jitterless Transmission (PQLS)
Blu-ray Disc Player
Servo
HDMI
Circuit
IN/OUT
A/V decoder
Audio signal with jitter
PQFA for USB/Network Audio
The previous D/A conversion process used the clock from the input
stage, which generated jitter along the way. With PQFA (Precision
Quartz File-based Audio), the clock is supplied for each stage of input,
digital signal processing, and D/A conversion, and the shorter path
prevents jitter occurrence. Additionally, a high-precision clock IC (OSC)
is used to realise D/A conversion with much less jitter. You can enjoy
USB and network audio sources in higher quality sound.
PQFA System Comparison
USB In
DSP
Network Module
Non PQFA System: The clock crystal originally has a lot of
Standard
jitter and the noise affects the circuit, and more jitter occurs
Clocking Crystal
due to long clock path.
USB In
DSP
Network Module
PQFA System: The ultra-high precision clock crystal has little jitter, and a clock
is supplied for each stage via a short path. This eliminates jitter occurrence,
and PQFA realises clean D/A conversion.
Jitter Occurrence in Network
Time
Audio system with no PQFA
High-Precision OSC for 48/96/192 kHz (right), for 44.1/88.2/176.4 kHz (left)
11
AV RECEIVERS REFERENCE GUIDE
AV Receiver
Control Data
Transfer PLL
Clocking
HDMI
Data
Crystal
IN/OUT
Transfer
AUDIO DATA DATA
DAC
AUDIO CLOCK MEMORY
CONTROL DATA
Jitterless signal via PQLS
DAC
Audio signal with jitter
DAC
Jitterless signal
Ultra-High Precision
Clocking Crystal
AUDIO DATA AUDIO CLOCK
Time
Audio system with PQFA