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PCI Sound Cards with Extended Frequency Response
An audio codec is
responsible for the A/D and D/A conversion of the audio signals in sound
cards. Although many audio codecs have responses from DC to 100KHz usually
their frequency response is rolled off at both the low and high ends by
the electronic hardware surrounding the codec.
Low cost cards roll off at
the low end to increase dynamic headroom/reduce clipping problems on the
little pc speakers which usually aren't equipped to handle low
frequencies anyway. Sometimes unintentional bass attenuation is caused
just because the analogue design has been made to be as cheap as possible
and uses too small signal coupling capacitors.
Almost all older low cost
sound cards roll off at 24KHz or below just because their maximum
sampling rate is 48KHz.
In order to measure
frequency response of an audio component a sound card with relatively
flat frequency response of 20Hz to 20KHz is required. In order to measure
ultra-sonic signal even higher upper frequency response is required.
The following table compares
three PCI sound cards with balanced inputs/outputs and frequency
responses extending from at least 20Hz to beyond 22KHz.
|
Parameter
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M Audio Audiophile 192
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ESI Juli@
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Lynx 22
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Sample rates
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44.1, 48, 88.2, 96, 176.4 and 192 kHz from
internal clock
|
44.1, 48, 88.2, 96, 176.4 and 192 kHz from
internal clock
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8 kHz to 200 kHz, including all
standard rates with variable adjustment
|
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Analogue I/O
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two inputs and two outputs,
balanced/unbalanced quarter-inch jack sockets, maximum input level
+14.2dBu
|
two of each, either balanced
quarter-inch jack sockets at +4dBu sensitivity, or unbalanced phono
sockets at -10dBV sensitivity
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two inputs / two outputs
Electronically balanced or unbalanced, XLR connectors on L2Audio Cable
+4 dBu nominal /+20dBu max. or -10dBV nominal / +6dBV max., software
selectable in channel pairs
|
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Digital I/O
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S/PDIF in and out on phono co-axial, sync'able
to external sample rates from 32kHz to 192kHz, supporting AC3 and DTS
pass-through, plus MIDI In and Out.
|
S/PDIF in and out on phono co-axial,
additional S/PDIF optical out, MIDI In and Out
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one input and one output
AES/EBU or S/P DIF format, transformer coupled, XLR connectors on
L2Sync cable
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Converters:
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AKM 5385A dual-bit delta-sigma
24-bit/192kHz (A-D), AKM 4358 multi-bit 24-bit/192kHz (D-A).
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AKM5385A dual-bit delta-sigma
24-bit/192kHz (ADC), AKM4358 multi-bit 24-bit/192kHz (DAC)
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24-bit, multi-level, delta-sigma
|
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Input Dynamic range
|
113dBA (ADC)
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114dBA (ADC)
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117 dB, A-wtd specs measured at 44.1 kHz sample rate, 24-bit, card
installed in computer
|
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Output Dynamic range
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109dBA (DAC)
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112dBA (DAC)
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117 dB, A-wtd. specs measured at 44.1 kHz sample rate, 24-bit, card
installed in computer
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Frequency response
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±0.5dB, 20Hz to 80kHz at 192kHz
sample rate
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±0.5dB, 20Hz to 40kHz at 192kHz
sample rate
|
< 10Hz - 92 kHz @ 200 kHz sample
rate
< 10Hz - 46 kHz @ 96 kHz sample rate
< 10Hz - 23 kHz @ 48 kHz sample rate
(analog input to analog output)
|
|
Input THD + noise
|
0.0006 percent
|
0.0006 %
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-108 dB (0.0004%) @ -1 dBFS
-104 dB (0.0006%) @ -8 dBFS
1 kHz signal, 22Hz - 22kHz BW
|
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Output THD + noise
|
0.0023 percent
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0.0006 %
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-97 dB
(0.0014%) @ -1 dBFS
-104 dB (0.0006%) @ -8 dBFS
1 kHz signal, 22Hz - 22kHz BW
|
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Software Compatibility
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Windows XP/2000/Vista, Mac OS X 10.1
and newer compatible
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Windows 98SE/ME/XP/2000/Vista, Mac OS
X 10.1 and newer, Linux (ALSA) compatible
EWDM driver: MME, DirectSound, ASIO
2.0 and GSIF 2.0 support
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Windows 2000/XP/XPx64/Vista/Vistax64,
Macintosh OSX: CoreAudio (10.4), Linux, FreeBSD compatible
MME, ASIO 2.0, WDM, DirectSound, Direct Kernel Streaming
and GSIF support
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Price
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US$180, €116
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US$190, €119
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US$925, €596
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PCI Sound Cards with Replaceable Op-Amps
The sound cards shown below have swappable op-amps in common
8-Pin Dip packages (as below) configured in a balanced configuration on
their line outputs.
You could use a SO-8 to
8-pin DIP adaptor such as the Brown Dog 970601 to replace the op-amp in
your sound card with a high current SOIC op-amp such as the LMH6672. This
amp can drive +4.8Vpeak into 25 ohms (200mA or 960mW) with a +6V supply.
In a bridged configuration this would translate to +3.2V into 8 ohms or
640mW. In this case the distance from the loudspeaker to the measurement
microphone could be reduced so that a lower audio interface output level
can be used to drive the loudspeaker and still produce results that can
be traced back to the 1Watt at 1 meter loudspeaker measurement standard.
For a loudspeaker in a box, sound pressure level (SPL) increases 6dB each
time the distance between the source and the measurement microphone is
halved. The table below shows six possible scenarios. If your sound card
can drive 640mW into an 8 ohm load reduce its input level so that it
drives 500mW into the speaker and set the distance from the microphone to
the driver to 0.71 meters. Reducing the distance between the driver and
microphone too much reduces the time of arrival of the first floor
reflection effectively cutting off the low frequency response of the
measurement.
|
Power Available (Watts)
|
Current @ 2.83V (Amps)
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Audio Interface Output Level (Vrms)
|
Output Level (Vpeak)
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SPL Increase over 1 Watt
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Distance to Microphone (meters)
|
|
2.000
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0.706
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4.000
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5.66
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+6.0
|
2.00
|
|
1.000
|
0.353
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2.000
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2.83
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+0.0
|
1.00
|
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0.500
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0.177
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1.414
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2.00
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-3.0
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0.71
|
|
0.390
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0.138
|
1.250
|
1.76
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-4.0
|
0.63
|
|
0.250
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0.088
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1.000
|
1.41
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-6.0
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0.50
|
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0.125
|
0.044
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0.701
|
1.00
|
-9.0
|
0.35
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Do your research and be very careful when attempting
something like this.
|
Parameter
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AudioTrak Prodigy HD2
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Xonar HDAV 1.3 Deluxe
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Auzentech X-Fi Prelude 7.1
|
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Sample rates
|
22.05,
32, 44.1, 48, 96, and 192KHz
24bit
Playback
22.05,
32, 44.1, 48, 96KHz 24bit Recording
|
44.1K/48K/96K/192KHz @ 16/24bit
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192
KHz @ 16/24 bit Playback
32,
44.1, 48 and 96kHz @ 16/24 bit Recording
|
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Analog Inputs
|
1
x 1/8” TRS unbalanced
|
Line-In/Mic-In 3.50mm mini jack
|
1 x MIC IN (mono)
unbalanced 3.50mm TRS jack
1 X LINE IN unbalanced 3.50mm
TRS jack
|
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Input
Op-Amps
|
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TI
RC4580, NJM5532
Both
DMP8 Not replaceable
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TI
OPA2134 SOIC Soldered In
|
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A/D Converters
|
AKM AK5353 24-bit, multi-level,
delta-sigma
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1 x Cirrus-Logic CS5381
(120dB SNR, Max. 192kHz/24bit)
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1
x AKM-5394 high resolution 24/192 ∆Σ ADC
|
|
Input Dynamic range
|
114dBA
|
145dBA
@ 48KHz
|
104
dBA
|
|
Input THD + noise
|
|
-108 dB (0.0004%) @ 1KHz
|
-90.9
dBA
|
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D/A Converters
|
AKM
AK4396 24-bit/192kHz
|
4 x TI Burr-Brown
PCM1796 (123dB SNR, Max. 192kHz/24bit)
|
4
x AKM AK-4396 96kHz 24-bit multi-bit DAC
|
|
Output
Op-Amps
|
2
x OPA 2134 & 1 x JRC 5532, (Line Out) All DIP8 Replaceable
2
x JRC 4580 (Headphone) Soldered In
|
JRC
2114D, LM4562
Both
DIP8 Replaceable
unbalanced levels nom -10dBV (max +7dBV)
|
TI OPA 2134
National
LM4562NA for Front L-R Replaceable
|
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Analog Outputs
|
2
x unbalanced RCA phono jack
1
x 1/8” TRS Unbalanced (Headphone)
|
8
x unbalanced RCA phono jack
|
4 x unbalanced 3.50mm TRS jack
|
|
Output Dynamic range
|
110dB
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145dB
@ 48KHz
|
120dB
|
|
Output THD + noise
|
-92
dBA
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-108 dB (0.0004%) @ 1KHz
|
(0.001%) @ 1KHz
|
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Frequency response
|
+0.5dB 10Hz
- 15 kHz @ 96KHz sample rate
|
+0.5dB 10Hz - 30 kHz @ 96KHz sample rate
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+0.05dB
10Hz - 20 kHz @ 192KHz sample rate 24 bit
|
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Digital I/O
|
Optical
S/PDIF digital output following IEC-958C standard
|
Coaxial
and High-bandwidth Optical Combo Output Connector. Supports
192KHz/24bit
Coaxial and High-bandwidth Optical Combo Input Connector. Supports
192KHz/24bit (Shared with Line/Mic In). HDMI1.3 - In/Out Type A *1
|
S/PDIF
receiver and transmitter
|
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Software Compatibility
|
Windows
2000/XP/XPx64/Vista/Vistax64
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Windows Vista/XP(32/64bit)/MCE2005
|
Microsoft® Windows Vista™ or
Windows XP (Service Pack 2, x64 or Media Center Edition)
|
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Price
|
US$145,
€103
|
US$210,
€150
|
US$199,
€142
|
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What We Do
Sonic beacon produces
electrical and acoustical data acquisition and analysis software for the
Windows operating system.
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About Us
Sonic beacon is a Canadian organization that provides a free
set of virtual instruments that are useful for measuring the time and
frequency domain responses of audio components using a personal computer.
It is located in Pakenham Ontario which is near Ottawa, Canada.
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News and Events
March 23, 2014: 32 and 64 Bit Versions
of sonic beacon (1.1.0.9) released. Tested on Microsoft Windows 8 (64
Bit), Microsoft Window 7 Home Premium (64 Bit) and Windows XP 32 Bit
Professional.
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