Antex electronics SX-7 User manual

1
SX-7 SX-9 SX-11 SX-12a
SX-20 SX-22 SX-23e SX-26
Digital Audio Adapter
User's Manual
For DOS
and Windows
January 25, 1996
ANTEX ELECTRONICS CORPORATION
16100 SOUTH FIGUEROA STREET
GARDENA, CALIFORNIA 90248
9000-2347-7006

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TABLE OF CONTENTS
INTRODUCTION..........................................................................4
ABOUT DIGITAL AUDIO .............................................................4
MINIMUM HARDWARE RECOMMENDED ................................7
ADAPTER INSTALLATION .........................................................7
JUMPER SETTINGS .......................................................7
I/O ADDRESSES AND INTERRUPTS............................7
SX-12a, SX-20 .................................................................8
SX-7..................................................................................8
SX-9, SX-11 .....................................................................10
SX-22, SX-23e, SX-26.....................................................11
DRIVER INSTALLATION.............................................................16
DISKS...............................................................................16
WINDOWS DRIVER INSTALLATION .............................16
WINDOWS DRIVER CONFIGURATION ........................17
DOS DRIVER INSTALLATION........................................17
USING DOS DEMONSTRATION SOFTWARE..........................19
PROBLEMS RUNNING THE DEMO...............................23
USING WINDOWS DEMONSTRATION SOFTWARE................24
ANTEX MIXER.............................................................................27
MIXER BUSES.................................................................27
RECORD MODE..............................................................27
PLAY MODE (Feedthrough)............................................28
MIXER DEVICES.............................................................28
UTILIZING DIGITAL AUDIO COMPRESSION UNDER WINDOWS
......................................................................................................29
ISO/MPEG-1 BITRATES & FORMAT EXTENSIONS.................31

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FIGURES
Figure 1: Analog-to-Digital Conversion........................................5
Figure 2: Digital-to-Analog Conversion........................................6
Figure 3: SX-12a, SX-20 Connector Locations...........................8
Figure 4: SX-7 Connector Locations ..........................................9
Figure 5: SX-9 and 11 Connector Locations ..............................11
Figure 6: SX-22, 23e and 26 Connector Locations....................13
Figure 7: SX-22, 23e and 26 Balanced Connectors...................14
Figure 8: SX-22, 23e and 26 Digital Connectors........................15
Figure 9: DOS Demo Environment..............................................20
Figure 10: The Antex Demo Window...........................................24
Figure 11: Message Box reporting an unavailable compression
format or an invalid sample rate...........................................24
Figure 12: File Open dialog box. .................................................25
Figure 13: Antex Mixer................................................................27

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INTRODUCTION
The Series 2 Digital Audio Adapters are IBM AT compatible add-on boards which convert high fidelity
analog signals to digital data for storage to, and retrieval from, disk.
The Series 2 adapters sample two channels of audio from 6.25 kHz to 50kHz with 16 bit resolution. They
incorporate Sigma Delta technology with 64 times oversampling, providing superior fidelity at greater
than 90 dB signal-to-noise ratio.
ABOUT DIGITAL AUDIO
In professional circles, digital audio has been with us for over 10 years. With the advent of the compact
disk in 1983, digital audio has become commonplace as a consumer item. Few will argue that digital
audio has afforded an order of magnitude improvement in overall sound quality and signal-to-noise ratio
over the best analog systems which preceded them. But just what is digital audio, and where and how is
it used?
It is possible to use digital data transmission techniques to transmit digital audio signals by wire or radio.
However, this practice has not yet become common due to the extremely wide signal bandwidth required
to transmit real-time digital audio signals. For the present, digital audio techniques seem largely confined
to the recording and playback of music and other audio signals where, in a few short years, digital audio
technology has all but replaced the previous analog record/playback techniques. In the present decade
we will see digital audio technology replace analog technology in most signal processing functions in
both the professional and consumer markets. It is also likely, particularly with the advent of fiber optic
cables, that digital audio technology will be utilized in the transmission of real-time audio signals on a
widespread basis.
But what is digital audio?
In essence, digital audio is a technological process whereby an analog audio signal (produced when
sound waves in the air excite a microphone) is first converted into a continuous stream of numbers (or
digits). Once in digital form, the signal is extremely immune to degradation caused by system noise or
defects in the storage or transmission medium (unlike previous analog systems). The digitized audio
signal is easily recorded onto a variety of optical or magnetic media, where it can be stored indefinitely
without loss. The digitized signal is then reconverted to an analog signal by reversing the digitizing pro-
cess. In digital audio record/playback systems, each of these two functions is performed separately. In
digital audio signal processing systems (where no record/playback function occurs) both analog-to-digital
and digital-to-analog conversion processes occur simultaneously. A variety of techniques are possible,
but the most common method by which audio signals are processed digitally is known as linear pulse
code modulation, or PCM. Let's take a brief look at how PCM works.
Converting an analog signal to digital is a two-stage process, sampling and quantization. This is
illustrated in Figure 1. At regular intervals, a sample-and-hold circuit instantaneously freezes the audio
waveform voltage and holds it steady while the quantizing circuit selects the binary code which most
closely represents the sampled voltage. Most digital audio is based on a 16-bit PCM system. This means
that the quantizer has 65,536 (216) possible signal values to choose from, each represented by a unique
sequence of the ones and zeroes which make up the individual code "bits" of the digital signal.

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The number of these bits generated each second is a function of sampling rate. At a relatively low
sampling rate of 8 kHz (suitable for voice) far fewer code bits are produced each second than, for exam-
ple, at the 44.1 kHz sampling rate used for commercial compact disks. For a two-channel stereo signal at
a 44.1 kHz sampling rate, some 1.4 million bits are generated each second. That's about five billion bits
per hour,which is why you'll need at least an 800 Megabyte hard disk to record an hour of compact disk
quality music.
To visualize the analog-to-digital conversion process, refer to Figure 1. At the top is one cycle of an
analog input signal wave. We've used a simple sine wave to make visualization easier. In this example,
the signal has a peak-to-peak amplitude of 20 units, measured by the scale on the left. The sampling
frequency is many times higher than the signal being sampled and is shown along the bottom of Figure
1. Once for each cycle of the sampling frequency, the sample-and-hold circuit "slices" the input signal,
allowing the quantizing circuit to generate a (digital) number equal to the closest (of the 65,536 possible
discrete values) quantization value of the input signal at the time the sample is taken. This repeats for
each successive cycle of the sampling frequency and the quantizer generates a continuous "bit stream"
which represents the quantized signal. The continuous stream of digital audio information is converted
into a digitally modulated signal using a technique known as linear pulse code modulation.
Digital-to-analog conversion (used in playback) is the exact opposite of the analog-to digital conversion
process and is illustrated in Figure 2.
In digital-to-analog conversion, the PCM bitstream is converted at the sampling frequency to a
continuously changing series of quantization levels which are individual "steps" of discrete voltage equal
to the quantization levels in the analog-to-digital process. The shape of this continuously changing
stream of quantization levels approximates the shape of the original wave. This is shown in the top half
Figure 1: Analog-to-Digital Conversion

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of Figure 2. This signal is then passed through a low-pass filter, which removes the digital "switching
noise." The end result, shown in the bottom half of Figure 2 is an analog output signal whose waveshape
is a very close approximation of the original analog input signal. The foregoing is a very brief and, of
necessity, oversimplified explanation of how digital audio works. For the interested reader, the book
Principles of Digital Audio by Ken C. Pohlmann, copyright 1985 by Howard W. Sams, is highly
recommended.
Figure 2: Digital-to-Analog
Conversion

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MINIMUM HARDWARE RECOMMENDED
Ÿ16 MHz 386-SX or compatible
Ÿ28 mSec average access hard disk
Ÿ1:1 Interleave hard disk controller
ŸMouse
ŸVGA display
ADAPTER INSTALLATION
Make sure the main power to your computer is OFF. You will need a full-size, 16 bit/AT slot. If you are
unfamiliar with the internal design of your computer see its "Guide to Operations" manual for step by step
installation procedures.
Read JUMPER SETTINGS and for information about configuring the adapter before plugging it into the
slot.
JUMPER SETTINGS
These SX series adapters have four hardware jumpers. They are JP1, JP2, JP3 and JP4, which are
used for multiple board operation. JP1 should be installed for a single board system.
NOTE: On the SX-7, jumper JP2 serves as the adapter selection jumper. Adapter 1 is at the top, with
adapter 4 at the bottom.
1
2
3
4
PLACE JUMPER HERE IF YOU HAVE ONLY ONE
ADAPTER
I/O ADDRESSES AND INTERRUPTS
The valid I/O addresses for the SX7, SX9, SX11, SX-12a, SX20, SX22, SX23e and SX26 are:
180h, 22h, 280h, 300h, 320h and 380h
The valid interrupts are:
2, 3, 4, 5, 10, 11 and 12

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SX-12a, SX-20
There are 5 external connections located on the front surface of the audio board's metal bracket (Fig. 3).
Audio Input:
Line: RCA jacks, 2VRMS/+6dBV max (digital clipping), with an impedance pf 20 k ohms
Audio Output:
Headphone: 1/4" stereo phone jack, 0.5 VRMS into 8 ohms
Line: RCA jacks, 2VRMS/+6dBV max (digital clipping), with an impedance of 470 ohms and a
load impedance of >10k ohms
SX-7
There are four external connectors located on the SX-7 audio board's metal mounting bracket. See
Figure 4. There is also one three pin header (JP1) for an optional user-supplied headphone connection,
which would allow for a front panel headphone jack.
Figure 3: SX-12a, SX-20 Connector Locations
RIGHT LINE IN
LEFT LINE IN
HEADPHONE OUTPUT *
RIGHT LINE OUTPUT
LEFT LINE OUTPUT
* Stereo Headphones
SX-12a/SX-20

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Figure 4: SX-7 Connector Locations
Headphones
DB-9 Balanced Out
Unbalanced Right
Unbalanced Left
SX-7
JP1
1LEFT
RIGHT
GND
Pin Assignment
1 Gnd
2
3nc
4 Right Out -
5 Left Out -
6nc
7nc
8 Right Out +
9 Left Out +
DB-9
Female
Balanced Analog I /O Connector
12345
6789

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Audio Output:
Line:
Unbalanced - RCA jacks, 2VRMS/+6dBV max (digital clipping), with an impedance of 470 ohms
and a load impedance of > 10 k ohms
Balanced - Nine pin D connector, -16 dBm maximum, with an impedance of 47 ohms and a load
impedance of 600 ohms
Headphone:
1/4" Stereo Phone Jack, 0.5 VRMS into eight ohms
SX-9, SX-11
There are 5 connectors located on the SX-9/SX-11 audio board's metal mounting bracket. See Figure 5,
7 & 8. for more information on the SX-9/SX-11 connectors.
Audio Output:
Line:
Balanced - Nine pin D connector 0 to +26dBu(digital clipping) - software selectable with 1dBu
resolution, with an impedance of 50 ohms and a load impedance of 600 ohms
Unbalanced - 1/8Ó stereo mini jack 2VRMS/+6dBV max (digital clipping), with an impedance of
470 ohms and a load impedance of 10k ohms
DB-9
Female
Balanced Analog I /O Connector
12345
6789
Pin Assignment
1 Gnd
2nc
3nc
4 Right Out -
5 Left Out -
6nc
7nc
8 Right Out +
9 Left Out +

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Figure 5: SX-9 and 11 Connector Locations
AES/EBU Digital:
7 pin Mini DIN jack. Professional AES/EBU: EIAJ CP-340 Type I / IEC-958 Pro or Consumer
S/PDIF: EIAJ CP-340 Type II / IEC-958 Consumer
SX-22, SX-23e, SX-26
There are 5 external connectors located on the SX-22 audio board's metal mounting bracket. There are
7 external connectors on the SX-23e/SX-26. See Figure 6, 7 & 8 for more information on the SX-22/SX-
23e/SX-26 connectors.
Audio Input:
Line:
SX-22:
Balanced - Nine pin D connector (-10dBu, +4dBu and +16dBu - software selectable) with an
impedance of 20k ohms.
Pin Assignment
1 Ground
2nc
3 Out - AES/EBU+ or S/PDIF+
4nc
5 Out - AES/EBU - or S/PDIF-
6nc
7 AES/SPDIF sense - This line
should be connected to Ground for
AES/EBU operation and left
floating for S/PDIF
1
3
5
2
4
6
7 pin Mini DIN Female
7
Stereo Mini Headphones
DB-9 Balanced Out
Unbalanced Right
Unbalanced Left
SX-9/SX-11
Adapter # Jumper Block
AES/EBU, S/PDIF Digital Out
Balanced Analog Header
nnnnnnnnnnnnnnnnnnnn
nnnnnnnnnnnnnnnnnnnn
SP-100 Header
SP-100
apt-X adapter

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The SX-22 balanced analog I/O levels are specified in dBu, where 0 dBu is 0.775 Vrms or
2.19Vpp for a sinewave. If an I/O is connected as unbalanced then the level is 1/2 the balanced
I/O. The adjustable level is referred to as Trim. The following Trim settings are available on the
SX-22.
VdBu VRMS VPP VRMS-if connected as
unbalanced
-10 0.245 0.693 0.12
+4 1.23 3.47 0.6
+16 4.89 13.8 2.4 -(approx the same as
SX12a/20 unbalanced I/O)
The input and output trims may be adjusted separately, but both input or both output channels
must have the same setting.
SX-23e/SX-26:
Balanced - Nine pin D connector 0 to +26dBu (digital clipping) - software selectable with 1dBu
resolution, with an impedance of 20k ohms
Unbalanced - 1/8Ó stereo mini jack 2VRMS/+6dBV max (digital clipping), with an impedance of
20k ohms and a load impedance of 10k ohms
AES/EBU Digital (SX-22, SX-23e & SX-26):
7 pin Mini DIN jack. Professional AES/EBU: EIAJ CP-340 Type I / IEC-958 Pro or Consumer
S/PDIF: EIAJ CP-340 Type II / IEC-958 Consumer
Audio Output
Line:
SX-22:
Balanced - Nine pin D connector (-10dBu, +4dBu and +16dBu - software selectable) with an
impedance of 20k ohms.
SX-23e/SX-26:
Balanced - Nine pin D connector 0 to +26dBu(digital clipping) - software selectable with an
impedance of 50 ohms and a load impedance of 600 ohms or greater.
Unbalanced - 1/8Ó stereo mini jack 2VRMS/+6dBV max (digital clipping), with an impedance of
470 ohms and a load impedance of 10k ohms

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Headphone (SX-22, SX-23e & SX-26):
1/4" stereo phone jack, 0.5 VRMS into 600 ohms or greater.
AES/EBU Digital (SX-22, SX-23e & SX-26):
7 pin Mini DIN jack. Professional AES/EBU: EIAJ CP-340 Type I / IEC-958 Pro or Consumer
S/PDIF: EIAJ CP-340 Type II / IEC-958 Consumer
Headphones
Adapter# Jumper Block
Balanced I/O
Digital AES/EBU I/O
SX-22
Balanced AnalogHeader
DigitalHeader
Headphones
Adapter# Jumper Block
Balanced I/O
Digital AES/EBU I/O
SX-23e/SX-26
Balanced AnalogHeader
DigitalHeader
Unbalanced In
Unbalanced Out
nnnnnnnnnnnnnnnnnnnn
nnnnnnnnnnnnnnnnnnnn
S P - 1 00 H ea d er
SP-100
apt-X adapter
Figure 6: SX-22, 23e and 26 Connector Locations
Pin Assignment
1 Ground
2 Right In -
3 Left In-
4 Right Out -
5 Left Out -
6 Right In +
7 Left In +
8 Right Out +
9 Left Out +
DB-9
Female
B
a
l
ance
d A
na
l
og
I /O C
onnec
t
or
12345
6789

14
SX22 Balanced I/O to XLR
12345
6789
B
a
l
ance
d I
n -
XLR
ma
l
e s
h
e
ll
,
f
ema
l
e p
i
ns
Left
Right
1
- 2
+ 3
GND
Right
Balanced Out - XLR female shell, male pins
1
1
1
+ 3
Left
- 2
- 2
+ 3
- 2
+ 3
SX22 Unbalanced I/O to RCA
12345
6789
Left
Unbalanced Out - Female RCA
Right
Left
Right
Unbalanced In - Female RCA
n
n
n
n
n
n
n
n
n
n
n
n
n
n
n
n
246810121416
13579111315
B
a
l
ance
d A
na
l
og
H
ea
d
er
Figure 7: SX-22, 23e and 26 Balanced Connectors
Pin Assignment Pin Assignment
1 Right In + 2 Ground
3 Right In - 4 Ground
5 Left In + 6 Ground
7 Left In- 8 Ground
9 Right Out + 10 Ground
11 Right Out - 12 Ground
13 Left Out + 14 Ground
15 Left Out - 16 Ground

15
7
p
i
n
Mi
n
i DIN F
ema
l
e
1
3
5
2
4
67
Digital I/O header - JP7
n
n
n
n
n
n
n
n
1
3
5
7
2
4
6
8 (nc)
Pin Assignment
1 Ground
2 In - AES/EBU -
3 Out - AES/EBU+ or S/PDIF+
4 In - AES/EBU +
5 Out - AES/EBU - or S/PDIF-
6 In - S/PDIF+
7 AES/SPDIF sense - This line should be
connected to Ground for AES/EBU
operation and left floating for S/PDIF
Figure 8: SX-22, 23e and 26 Digital
Connectors
SX22 S/PDIF cable wiring diagram
1
3
5
2
4
6
7 pin Mini DIN Male Plug
7
Back view of plug
S/PDIF In
S/PDIF Out
Female RCA jacks 7 pin Mini DIN Male Plug
1
3
5
2
4
67
SX22 AES/EBU cable wiring diagram
Back view of plug
1
2
3
12
3
GND
AES/EBU In
XLR Female pins,
Male shell
AES/EBU Output
XLR Male pins,
Female shell

16
DRIVER INSTALLATION
DISKS
Disk 1. The "WINDOWS DRIVERS" disk contains Windows drivers and applications (Note: The
DOS 3.2/Windows 2.0 drivers continue to come on a single disk):
·ANTEXWAV.DRV - Windows Wave Driver for SX3, SX5e, SX7, SX9, SX11, SX12a, SX20,
SX22, SX23e, SX26, SX33, SX33e, Z1, Z1e
·SAPIZ1.DRV - OPL3 FM Synthesizer for Z1 and Z1e
·VAPIZ1.DRV - YM3802 MIDI driver for Z1 and Z1e
·MIDIMAP.CFG - MidiMapper config file with Z1 and Z1e specific maps
·ANTEXMIX.EXE, MMMIXER.DLL - Antex Mixer Applet and DLL
·ANTEXDEM.EXE - Antex Demo
·OEMSETUP.INF - Windows definition file for manual driver installation
·SETUP.EXE and supporting files - Windows driver installation utility
·README.TXT (optional) - Windows information
Disk 2. The "DOS DRIVERS" disk contains DOS drivers and applications:
·SX25.EXE - DOS V3.3 TSR driver for the SX7, SX9, SX11 SX-12a, SX20, SX22, SX23e and
SX26
·Z1.EXE - DOS V3.3 TSR driver for the Z1, Z1e, SX3, SX33, SX33e
·SX5E.EXE - DOS V3.3 TSR driver for the SX5e
·ADG.EXE - Digital audio player/recorder
·README.TXT (optional) - Additional information
WINDOWS DRIVER INSTALLATION
1. Insert the DRIVERS disk into your floppy drive (assumed to be A:)
2. Start Windows

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3. In Program Manager, click on File then Run..
4. Enter A:SETUP in the command line box, then press OK.
5. When the driver installation is complete, Windows should restart automatically. If not, exit then restart
Windows manually.
WINDOWS DRIVER CONFIGURATION
To change the adapter type, I/O address and interrupt settings of the Windows driver:
1. Select Control Panel in the Main group of the Program Manager. Then select Drivers.
2. Select "Antex Audio Driver for Windows" from the list of installed drivers. Click on Setup.
3. To set adapter type:
"Antex Audio Driver Setup" displays the adapter types assigned to adapters 1-4. Change the type by
using the drop down menus for each adapter. Information about the number of devices, I/O address,
and interrupt number are displayed to the right of each adapter.
4. To set the number of devices, I/O address, or interrupt number:
Select Advanced in "Antex Audio Driver Setup". Select an adapter to reconfigure.
Change the number of devices, I/O address, or interrupt number by selecting the appropriate buttons.
Invalid choices are displayed in gray.
Test new settings by selecting Test.
NOTE: The driver version number and date displayed in the middle left of the "Antex Advanced Setup"
screen. Refer to this information when reporting problems to Antex Technical Support.

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DOS DRIVER INSTALLATION
1. Insert the DRIVERS disk into your floppy drive (assumed to be A:)
2. Type A:
3. Type INSTALL driveletter:\path to copy all files from the disk to a subdirectory on your hard disk.
ex. INSTALL C:\ANTEX
REMEMBER: When the Windows driver installation is complete, Windows should restart automatically. If
not, exit then restart Windows manually, or your changes will not be implemented.

19
USING DOS DEMONSTRATION SOFTWARE
On the enclosed disk is the demonstration software for the SX-7, SX-9, SX-11, SX-12a, SX-20, SX-22,
SX-23e and SX-26 boards. Filenames are as follows:
Driver Program
SX25.EXE
DOS Demonstration Program
ADG.EXE
To run the Demonstration Software:
1. Load the disk files into their own directory on your hard disk using the DOS copy command (all files
must be in the same directory).
2. Install your mouse driver
3. Install the driver by running SX25.EXE
4. Run the demo ADG.EXE A=(I/O Address) I=(Interrupt)
ex. C>ADG A=280 I=2 (This is the default setting.)
5. At this point there should be a short pause as the board initializes, then the demo environment should
appear(Fig. 9).
Note: The left button of your mouse is to execute a command, the right is to escape. You may also use
the highlighted letter of the command to access it directly from the keyboard.

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KEY COMMANDS:
Q-Quit
Quits the demo program and returns to DOS.
C-Channels
Allows choice of channel configuration.
MONO-Single channel record/play.
STEREO-Dual channel record/play.
T-Format
The format for encoding or decoding audio data:
PCM16 - 16 Bit Pulse Code Modulation, uncompressed.
PCM8 - 8 Bit Pulse Code Modulation, uncompressed.
PCMU8 - 8 Bit Pulse Code Modulation, uncompressed. This format is compatible with
Microsoft 8 Bit WAV format.
ADPCM1 - Series 1 compatible Adaptive Differential Pulse Code Modulation
compression.
ADPCME - Enhanced Adaptive Differential Pulse Code Modulation compression, DVI
compatible.
Figure 9: DOS Demo Environment