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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.
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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
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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
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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.
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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
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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
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< 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)
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Input THD + noise
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0.0006 percent
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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
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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.
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Power Available (Watts)
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Current @ 2.83V (Amps)
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Audio Interface Output Level (Vrms)
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Output Level (Vpeak)
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SPL Increase over 1 Watt
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Distance to Microphone (meters)
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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
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2.00
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1.000
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0.353
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2.000
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2.83
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+0.0
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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
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0.390
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0.138
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1.250
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1.76
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-4.0
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0.63
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0.250
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0.088
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1.000
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1.41
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-6.0
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0.50
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0.125
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0.044
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0.701
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1.00
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-9.0
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0.35
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Do your research and be very careful when attempting something
like this.
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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
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22.05,
32, 44.1, 48, 96, and 192KHz
24bit
Playback
22.05,
32, 44.1, 48, 96KHz 24bit Recording
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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
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1 x
1/8” TRS unbalanced
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Line-In/Mic-In 3.50mm mini jack
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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
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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
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Input Dynamic range
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114dBA
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145dBA
@ 48KHz
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104 dBA
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Input THD + noise
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-108 dB (0.0004%) @ 1KHz
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-90.9 dBA
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D/A Converters
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AKM AK4396 24-bit/192kHz
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4 x TI Burr-Brown
PCM1796 (123dB SNR, Max. 192kHz/24bit)
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4 x AKM AK-4396 96kHz 24-bit multi-bit DAC
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Output
Op-Amps
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2 x
OPA 2134 & 1 x JRC 5532, (Line Out) All DIP8 Replaceable
2 x
JRC 4580 (Headphone) Soldered In
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JRC
2114D, LM4562
Both
DIP8 Replaceable
unbalanced levels nom -10dBV (max +7dBV)
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TI OPA 2134
National LM4562NA for Front L-R Replaceable
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Analog Outputs
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2 x
unbalanced RCA phono jack
1 x
1/8” TRS Unbalanced (Headphone)
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8 x
unbalanced RCA phono jack
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4
x unbalanced 3.50mm TRS jack
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Output Dynamic range
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110dB
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145dB
@ 48KHz
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120dB
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Output THD + noise
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-92
dBA
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-108 dB (0.0004%) @ 1KHz
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(0.001%) @ 1KHz
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Frequency response
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+0.5dB
10Hz - 15 kHz @ 96KHz sample
rate
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+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
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Optical
S/PDIF digital output following IEC-958C standard
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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
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S/PDIF receiver and transmitter
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Software Compatibility
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Windows 2000/XP/XPx64/Vista/Vistax64
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Windows Vista/XP(32/64bit)/MCE2005
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Microsoft® Windows Vista™ or Windows XP
(Service Pack 2, x64 or Media Center Edition)
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Price
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US$145,
€103
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US$210,
€150
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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 founded in 1997. It is located in Pakenham Ontario which is near Ottawa, Canada. Ottawa is also home to
the National Research Council of Canada's anechoic chamber, a key
facility for acoustics testing. The chamber has been instrumental in the
development of Canadian loudspeakers, hearing aids and microphone arrays.
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News and Events
July 8, 2009: Sonic beacon Version 1.1.0.6 released. Data-Logger
can now save in .FRD and .ZMA file format. Data-Logger and Spectrum
Analyzer can perform .FRD and .ZMA clipboard copy transactions. Signal
generator can output signal complements on each sound card channel to
allow bridging in many consumer audio interfaces. Module status bar shows
current data type, FFT size and sample rate
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