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and speech. Since the beginning of the decade, those early sound boards have blossomed into an array of powerful, high-fidelity sound products, capable of duplicating voice, or-chestral soundtracks, and real-life sounds with uncanny realism (Fig. 41-1). Not only havesound products helped the game industry to mature, but they have been instrumental in thedevelopment of multimedia technology (the integration of sound and picture), as well asInternet Web phones and other communication tools. This chapter is intended to explainthe essential ideas and operations of a contemporary sound board, and show you how toisolate a defective sound board when problems arise.

Understanding Sound BoardsBefore you attempt to troubleshoot a problem with a sound board, you should have an un-derstanding of how the board works and what it must accomplish. This type of back-ground helps you when recommending a sound board to a customer or choosing acompatible card as a replacement. If you already have a strong background in digitalsound concepts and software, feel free to skip directly to the troubleshooting portion of this chapter.

THE RECORDING PROCESS

All sound starts as pressure variations traveling through the air. Sound can come from al-

most anywherea barking dog, a laughing child, a fire engines siren, a person speaking.You get the idea. The process of recording sound to a hard drive requires sound to be car-ried through several manipulations (Fig. 41-2). First, sound must be translated from

pressure variations in the air to analog electrical signals. This is accomplished by a mi-crophone. These analog signals are amplified by the sound card, then digitized (converted to a series of representative digital words each taken at a fixed time interval). The result-ing stream of data is processed and organized through the use of software, which places the

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FIGURE 41-1 A Logitech SoundMan Wave sound board. Copyright 1995 Logitech Corporation


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data (as well as any overhead or housekeeping data) into a standard file format. The file issaved to the drive of choice (typically, a hard drive).

THE PLAYBACK PROCESS

Simply speaking, the playback process is virtually the reverse of recording (Fig. 41-3). Asoftware application opens a sound file on the hard drive, then passes the digital data back to the sound card. Data is translated back into equivalent analog levelsideally, the re-constructed shape of the analog signal closely mimics the original digitized signal. Theanalog signal is amplified, then passed to a speaker. If the sound was recorded in stereo,the data is divided into two channels that are separately converted back to analog signals,amplified, and sent to their corresponding speakers. Speakers convert the analog signal

back into traveling pressure waves that you can hear.

THE CONCEPT OF SAMPLING

To appreciate the intricacies of a sound cards operation, you must understand the conceptof digitization (otherwise known as sampling ). In principle, sampling is a very straight-forward concept; an analog signal is measured periodically, and its voltage at each point in

1194 SOUND BOARDS

Sound

Mic Analogsignal

Digitalsignal

Softwaredriver

Storagedevice

(hard drive)

Sound board hardware

FIGURE 41-2 The sound-board recording process.

Softwaredriver

Storagedevice

(hard drive)

Analogsignal

Digitalsignal

Lspkr.

Rspkr.


FIGURE 41-3 The sound-board playback process.


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time is converted to a digital number. The device that performs this conversion is known

as an Analog-to-Digital Converter (ADC) . It sounds simple enough in principle, but it hassome important wrinkles.The problem with sampling is that a digitizer circuit has to capture enough points of an

analog waveform to reproduce it faithfully. The example in Fig. 41-4 illustrates the impor-tance of sampling rate. Waveforms A and B represent the same original signal. WaveformA is sampled at a relatively slow rateonly a few samples are taken. The problem comeswhen the signal is reconstructed with a Digital-to-Analog Converter (DAC) . As you see,there are not enough sample points to reconstruct the original signal. As a result, some of the information in the original signal is lost. This form of distortion is known as aliasing .Waveform B is the same signal, but it is sampled at a much higher rate. When that data isreconstructed, the resulting signal is a much more faithful reproduction of the original.

As a rule, a signal should be sampled at least twice as fast as the highest frequency con-tained in the signalthis is known as Nyquists Sampling Theorem . The lowest standard

sampling rate used with todays sound boards is 11kHzthis allows fair reproduction of normal speech and vocalization (up to about 5.5kHz). However, most low-end sound

boards can digitize signals up to 22kHz. Unfortunately, the human range of hearing isabout 22kHz. To capture sounds reasonably well throughout the entire range of hearing,you would need a sampling rate of 44kHzoften known as CD-quality sampling becauseit is the same rate used to record audio on CDs. The disadvantage to high sampling ratesis disk space (and sound file size). Each sample is a piece of data, so the more samplestaken each second, the larger and faster a file grows.

DATA BITS VS. SOUND QUALITY

Not only does the number of samples affect sound quality, but also the precision (or number of bits) of each sample. Suppose that each sample is converted to a 4-bit number. Thatmeans each point can be represented by a number from 0 to 15not much precision there.


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Waveform A: reconstructed Waveform B: reconstructed

Waveform A: original Waveform B: original

FIGURE 41-4 The concept of sampling rate .


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If 8 bits are used for each sample, 256 discrete levels can be supported. But the most pop-

ular configuration is 16-bit conversion, which allows a sample to be represented by one of 65,536 levels. At that level of resolution, samples form a very close replica of the originalsignal. Many of todays sound boards are 16-bit.

THE ROLE OF MIDI

Although the majority of a sound card is geared toward handling the recording and playback of sound files, the Musical Instrument Digital Interface (MIDI) port has become aninexpensive and popular addition to many sound-card designs. The MIDI standard is de-fined by hardware, software, and electrical interconnections. At the core of a MIDI inter-face is a synthesizer IC. Unlike a sound file, which basically contains the digitalequivalent of an analog waveform, a MIDI file is a set of instructions for playing musicalnotes. Each note is sent to the synthesizer, along with duration, pitch, and timing specifi-cations. The synthesizer can be made to replicate a variety of musical instruments, such asa piano, guitar, harmonica, fluteyou name it. The high-end sound boards are capable of synthesizing a small orchestra. Because most synthesizers can process several channelssimultaneously, the MIDI standard supports playing a number of instruments (or voices)at the same time. Thus, very high-quality music can be produced with MIDI on a PC. Thetwo most common synthesizer types are FM and Wavetable.

Figure 41-5 illustrates the kinds of things that MIDI is capable of. Pre-recorded MIDIfiles can be read from a storage device, such as a hard-drive file, or from CD-ROM (manygames include an orchestral-quality MIDI soundtrack on the CD). The MIDI data is

passed through to the sound boards synthesizer which reproduces the sound, and out tothe amplified speakers. If you plan to compose music yourself, you can interface a MIDIinstrument to the sound boards MIDI port. Using MIDI sequencer software, the notes

played on the instrument will be heard through the speaker, as well as recorded to theMIDI file on the hard drive. Notice that you do not need a MIDI instrument to playback aMIDI file, but you need an instrument and sequencer software to create a MIDI file. Also,

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Harddrive

MIDIport Synthesizer

Speakers

MIDI instrumentSequencersoftware


FIGURE 41-5 The path of MIDI signals through the PC.


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because MIDI is not sound (but rather sound blueprints), the same MIDI compositionentered on a keyboard can be played back as a harp, or a guitar, or a flute.

INSIDE A SOUND BOARD

Now that you are aware of the major functions a sound board must perform, you can see

those functions in the context of a complete board. Figure 41-6 shows a simplified block diagram of a sound board. It is important that your own particular sound board might dif-fer somewhat, but all contemporary boards should contain these subsections.

The core element of a sound board is the Digital Signal Processor (DSP) . A DSP is avariation of a microprocessor that is specially designed to manipulate large volumes of digital data. Like all processor components, the DSP requires memory. A ROM containsall of the instructions needed to operate the DSP and direct the boards major operations.A small quantity of RAM serves two purposes: it provides a scratch pad area for theDSPs calculations and it serves as a buffer for data traveling to or from the PC bus.

Signals entering the sound board are passed through an amplifier stage and provided toan A/D converter. When recording occurs, the DSP runs the A/D converter and acceptsthe resulting conversions for processing and storage. Signals delivered by a microphoneare typically quite faint, so they are amplified significantly. Signals delivered to the lineinput are often much stronger (such as the output from a CD player or stereo preamp), soit receives less amplification.

For signals leaving the sound board, the first (and often most important) stop is themixer . The mixer combines CD-audio, DSP sound output, and synthesizer output into asingle analog channel. Because most sound boards now operate in a stereo mode, mosthave two mixer channels and amplifier stages. The audio amplifier stage(s) boost the


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PC bus

MIDI/ joystickinterface

RAM Digitalsignal

processor(DSP)

Synthesizer

Mic. in

Bus interface circuits

ROM

ADCAudio

amp

Line in

CD audio

Speakerout

Lineout

MIDIinstrum.

or joystick

Mixer/ filter

Audioamp

FIGURE 41-6 Simplified block diagram of a sound board.


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analogs signal for delivery to stereo speakers. If the sound will be driving a stereo system,

a line output provides a separate output. Amplifier output can be adjusted by a singlemaster volume control located on the rear of the board.Finally, a MIDI controller is provided to accommodate the interface of a MIDI instru-

ment to the sound board. In many cases, the interface can be jumpered to switch the con-troller to serve as a joystick port. That way, the sound board can support a single joystick if the MIDI instrument will not be used. MIDI information processed by the DSP will beoutput to the on-board synthesizer.

Knowing the BenchmarksAn important aspect of sound boards is their audio benchmarks. Unlike logic and pro-cessing circuitry, which is measured in terms of millions of operations per second, the

benchmarks that define a sound card are very much analog. If you are an audiophile, manyof the following terms might already be familiar. If most of your experience has been withlogic systems, however, these concepts will appear very different than many of the other sections in this book.

DECIBELS

No discussion of sound concepts is complete without an understanding of the decibel (dB) .Decibels are used because they are logarithmic. Human hearing is not a linear response.If you increase the power of your stereo output from 4 W to 16 W, the sound is not 4 timeslouderit is only twice as loud. If you increase the power from 4 W to 64 W, the sound is only three times as loud. In human terms, amplitude perception is measured logarith-

mically. As a result, very small decibel values actually relate to substantial amounts of power. The accepted formula for decibels is:

gain (in dB) = 10 log10

Dont worry if this formula looks intimidating. Chances are that you will not need to useit, but consider what happens when output power is greater than input power. Suppose thata 1-mW signal is applied to a circuit and a 2-mW signal leaves. The circuit provides a gainof +3 dB. Suppose that the situation was reversed, where a 2-mW signal is applied to thecircuit and a 1-mW signal leaves it. The circuit would then have a gain of -3 dB. Nega-tive gain is a loss, also called attenuation . As you see, a small dB number represents alarge change in signal levels.

FREQUENCY RESPONSE

Expressed simply, the frequency response of a sound board is the range of frequencies thatthe board will handle uniformly. Examine the sample graph of Fig. 41-7. Ideally, a sound

board should be able to produce the same amount of power (0 dB) across the entire work-

P out Pin

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ing frequency range (usually 20Hz to 20kHz). This would show up as a flat line across the

graph. In actuality, however, this is not practical; invariably a rolloff of signal strengthwill be at both ends of the operating range. A good-quality sound board will demonstratesharp, steep rolloffs. As the rolloffs get longer and more shallow at high and low fre-quencies, the board has difficulty producing sound power at those frequencies. The resultis that bass and treble ranges might sound weak, which affects the sounds overall fidelity.By looking at a frequency-response curve, you can anticipate the frequency ranges wherea sound board might sound weak.

SIGNAL-TO-NOISE RATIO

The signal-to-noise ratio (SNR) of a sound board is basically the ratio of maximum undis-torted signal power to the accompanying electronic noise being generated by the board (primarily hum and hiss), expressed in decibels. Ideally, this will be a very large dB num-

ber, which would indicate that the output signal is so much stronger than the noise signalthat for all intents and purposes the noise is imperceptible. In actuality, a good-qualitysound board will enjoy an SNR of 85 dB or higherbut these are difficult to find. For most current sound boards with SNR levels below 75 dB, hum and hiss are audible duringsilent periods, as well as a certain amount of sound grit underlying sound and music re-

production. Some very inexpensive sound boards are on the market with SNR levels aslow as 41 dB (noise might be noticeable and actually annoying).

You might also find the SNR value expressed as an A-weighted decibel number. Thereason for this is that human hearing is not equal at all frequencies, so we cannot hear allnoise equally. The process of A-weighting emphasizes the noise levels at frequenciesthat we are most sensitive to. Resulting SNR values are often several dB higher (better)than non-weighted SNR values. Be careful here; a sound board with a low SNR might usethe A-weighted value in the specification sheet. If this is the case, subtract about 3 or 4 dBfor the actual SNR figure.

TOTAL HARMONIC DISTORTION

Sound and music are rich in harmonics (overtones) that are basically integer multiples of anoriginal frequency signal (although at much lower levels). As a consequence, harmonics

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dB

0.01 0.1 1.0 10.0 100.0

Ideal response

Satisfactoryresponse

Poor response

kHz

6

4

2

0

2

4

6

FIGURE 41-7 A sample sound board frequency-response curve.


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are a valuable attribute of sound. The number and amplitude of harmonics provide the

sound characteristics that allow you to distinguish between a guitar, flute, piano, or anyother musical instrument played at the same notewithout harmonics, every instrumentwould just produce flat tones, and every instrument would sound exactly the same.

However, when sound is produced in an electronic circuit, other unwanted harmonics aregenerated that can alter the sound of the music being produced (thus the term harmonicdistortion ). The total harmonic distortion (THD) of a sound board is the root-mean

squared (RMS) sum of all unwanted harmonic frequencies produced, expressed as a per-centage of the total undistorted output signal level. In many cases, the RMS value of noiseis added to THD (expressed as THD+N ). The lower this percentage is, the better. THD+N values over 0.1% can often be heard, and suggest a less-than-adequate sound-board design.

INTERMODULATION DISTORTION

This figure is related to harmonics. When two or more tones are generated together, am- plifiers create harmonics, as well as tone combinations. For example, if a 1kHz and 60Hztone are mixed together, intermodulation harmonics will be generated (e.g., 940Hz,880Hz, 1060Hz, 1120Hz, etc.). This intermodulation gives sound a harsh overtone. Be-cause intermodulation is not related to sound quality, it is a form of distortion that should

be kept to a very low level. Like THD, Intermodulation Distortion (IMD) is the RMS sumof all unwanted harmonic frequencies expressed as a percentage of the total undistorted output signal level. IMD should be under 0.1% on a well-designed board.

SENSITIVITY

Although it does not directly affect the fidelity of sound reproduction, sensitivity can be animportant specification. Sensitivity is basically the amplitude of an input signal (such as amicrophone signal) that will produce the maximum undistorted signal at the output(s) withvolume at maximum.

GAIN

By itself, sensitivity is hard to apply to a sound board, but if you consider the boards output power versus its input signal power and express the ratio as a decibel, you would havethe gain of the sound board. Many sound boards offer a potential gain of up to 6dB. How-ever, it is important that not all sound boards provide positive gainsome boards actuallyattenuate the signal even with the volume at maximum. In practical terms, this usuallyforces you to keep the volume control at maximum.

Using MicrophonesAn ever-growing number of sound card owners are using their sound cards to record sound or broadcast sound over the Internet through such applications as WebPhone. Sound recording demands the use of microphones, and not all microphones work properly withevery sound board. Often, the user mistakes a poor microphone response as being a prob-

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lem with the sound card. This part of the chapter looks at some important considerations

for choosing and using a microphone.

MICROPHONE TYPES

The three types of microphones are: dynamic, condenser, and electret condenser. All threemicrophone types are available for sound boards:

s Dynamic Dynamic microphones are typically hand-held or desktop units. They have alarger response range and usually sound better than condenser microphones. A dy-namic microphone does not require phantom power because the diaphragm element inthe microphone can create enough electric current for the sound board to use.

s Condenser Condenser microphones are the small multimedia microphones that aretypically sold with computers. When you open a new sound board and take the micro-

phone out of the box, it is almost always a condenser microphone. They do not have asgood a response range as dynamic microphones, and they also have a smaller di-aphragmthis demands phantom power from the sound board.

s Electret condenser Electret condenser microphones are basically condenser microphones with a built-in battery for power. They have the same response as a condenser microphone, but they do not require phantom power to operate. Some electret con-denser microphones will allow you to remove this internal battery. With the battery notinstalled, phantom power would be required.

PHANTOM POWER

The next question is What is phantom power? Phantom power is simply a small, low-current power supply on the sound board, which is used to power some microphones. Such

devices as dynamic microphones can produce enough current on their own to avoid the useof phantom power, but condenser microphones demand phantom power as a current source.

Heres the main problem with todays sound boardsnot all of them provide switchable phantom power. Ideally, sound boards (such as the Ensoniq Soundscape) would provide phantom power and allow you to jumper the phantom power on or off, depending on whichmicrophone you plan to use. If you use a dynamic microphone, youd switch phantom

power off. If you use a condenser microphone, youd switch phantom power on. If a sound board does not provide phantom power at all, youre stuck using a dynamic microphone or a powered electret condenser microphone. If a sound board provides full-time phantom

power (and you cannot turn it off), youll need to stay with a condenser microphone.You can probably see the potential for trouble here. If you use a condenser microphone

on an unpowered sound board, the microphone will not work at all (or generate little morethan faint noise). On the other hand, plugging a dynamic or electret microphone into a

powered sound board will usually result in severe clippingonce again, youll capture lit-tle more than noise.

CHOOSING A MICROPHONE

Whether youre choosing a microphone for yourself or recommending one to someoneelse, remember some considerations. Perhaps the most important issue is the application.

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If you just need a basic, inexpensive microphone to record a few simple voice notes, a con-

denser or electret microphone would work just fine and your sound board will require a phantom power supply. If you want to record more professional vocals or if you are preparing a presentation, a dynamic microphone will generally provide the best results(and no phantom power is needed).

Troubleshooting a Sound Board Traditionally, sound boards use many of the same chipsets and basic components, but be-cause each board is designed a bit differently, it is very difficult for commercial diagnos-tic products to identify failed IC functions. For the most part, commercial and sharewarediagnostics can only identify whether a brand-compatible board is responding or not. Asa result, this chapter will take the sub-assembly replacement approach. When a sound

board is judged to be defective, it should be replaced outright. This part of the chapter re-views the problems and solutions for sound boards under both DOS and Windows. Thefollowing tips might help you nail down a sound problem most efficiently:

s Check to see that your speakers are connected, powered, and turned on.s Check that the speaker volume and sound card master volume are turned up.s Check to see that the mixer volume and master volume are set properly.s Be sure that the music or sound file(s) are installed properly.s Check that all sound card and multimedia drivers are installed.s Be sure that the drivers are up to date.s Check for resource conflicts between the sound card and other devices in the system.s Be sure that the sound card is selected and configured properly (especially for DOS

apps).s The sound device should be enabled and configured under CMOS (for sound functionsincorporated on the motherboard).

DRIVERS AND DRIVER ORDER

Unlike most other expansion devices that are driven by system or supplemental BIOS,sound boards use small device drivers to set up their operations. These drivers are gener-ally included in CONFIG.SYS and AUTOEXEC.BAT, and are called when the system isfirst initialized. Most sound-board drivers are only used to initialize and set up the board,so they do not remain residentthis is good because it would reduce the load on conven-tional and upper memory. However, these initialization routines vary from board to board.For example, the files installed for a Creative Labs Sound Blaster will not support a Tur-

tle Beach MultiSound board. If you elect to replace a sound board, you must also disableany current sound-board drivers, and include any new supporting driver files. The processis not difficultjust follow the installation instructions for the board. But the softwareconsideration does add another wrinkle to the replacement process.

When there are problems installing or upgrading a sound board, one of the first issues tosuspect is the driver loading order. Sound boards are typically multi-function devices thatrequire several drivers in CONFIG.SYS and AUTOEXEC.BAT. If the drivers are in-

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stalled in the wrong order, the sound board (or other features of the board) might not function.

As a rule, the drivers should be loaded in the following order after your memory managers:s The sound boards device driver:

DEVICE=C:.SYS /A:220

s The CD-ROM port setup driver (if the sound board is equipped):

DEVICE=C:.SYS /P:340

s The CD-ROM driver (if the sound board is equipped):

DEVICE=C:.SYS /D:MSCD001 /P:340 /A:0 /T:5 /I:11

FULL-DUPLEX DRIVERS

Many current sound boards are compatible with multimedia communication technolo-gies, such as Internet Phone, Webphone, and communication tools. These tools requirefull-duplex operation; that is, sound is digitized with the microphone and received sound is played through the speakers simultaneously. This demands full-duplex drivers. If you

plan to use communication tools, youll need to install full-duplex sound-card drivers thatare appropriate for your particular sound board and operating system. For example, theCreative Labs SB32, AWE32, and AWE64 require the Windows 95 full-duplex driver file(SBW95UP.EXE) available from the Creative Labs Web site ( http:\www.creaf.com ). Touse those same devices for full-duplex under Windows NT 4.0, youd need theAWENT40.EXE driver file. As a rule, always check with the sound board maker for cur-

rent full-duplex drivers.

.WAV PLAYBACK PROBLEMS UNDER WINDOWS 95

Of all the sound-board problems reported, perhaps the most common is the failure to playwave files (ordinary sound files with the .WAV extension) under Windows 95. This prob-lem usually manifests itself during the Windows startup or shutdown when the accompa-nying sounds are not played. A variety of issues can prevent .WAV files from playing.

Program-specific problems If you cannot play .WAV files from a specific programthat you use in Windows 95, check to see if the same problem occurs when you play thefile from another program. If the problem occurs only with one particular program, thefiles associated with that program might be damaged or that program might not be config-ured correctly under Windows 95. If you cannot get .WAV files to play under any appli-cation, chances are that another issue is responsible.

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You might find that full-duplex drivers are not available for older sound boards orsound boards running under OS/2 and Windows NT. In that case, you cannot supportfull-duplex applications.


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Sound device is not configured properly If you cannot play any .WAV files in

Windows 95 (or if .WAV files are not played at the proper volume), you might not have asound device selected or the sound device that you have selected might not be configured properly. To select and configure a sound device in Windows 95:

s Open the Control panel and doubleclick the Multimedia icon.s In the Playback area under the Audio tab (Fig. 41-8), click the playback device that you

want to use in the Preferred device list, then move the Volume slider to the value youwant (usually 50 to 75% volume is adequate).

s In the Recording area under the Audio tab, click the playback device that you want touse in the Preferred device list, then move the Volume slider to the value you want.

s Be sure that the speakers are properly connected to the sound card and that the speak-ers are turned on.

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FIGURE 41-8 The Audio tab under the Multimedia properties dialog.


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Mixer settings are not configured properly If you cannot play any .WAV filesunder Windows 95 (or if .WAV files are not played at the proper volume), the mixer con-trol settings might not be configured properly. You can use the mixer-control program in-cluded with Windows 95 to adjust the volume for playback, recording, and voicecommands. To configure mixer control settings for Windows 95:

s Click the Start button, point to Programs , point to Accessories , point to Multimedia ,then click Volume control (Fig. 41-9).

s Be sure that the Mute all check box below the Volume control slider and the Mutecheck box below the Wave slider are not selected, and that the Balance sliders for Vol-ume control and Wave are in the center of the scale.

s Move the Volume control and Wave sliders at least halfway to the top of the scale. Youmight need to adjust the current Volume control or Wave settings to play .WAV files atthe volume level you want.

The sound hardware is not configured properly It is possible that your sound card might not be compatible with the type of .WAV file you are attempting to play, or aresource conflict might be between your sound card and another device installed in your computer. Check the Device manager to see if your sound board has any resource con-flicts. To determine whether your sound card supports the .WAV file format you are at-tempting to play, contact the sound cards manufacturer.


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FIGURE 41-9 The multimediaVolume control applet.

If the Volume control and Wave sliders do not appear, click Properties on the Options menu, then click the Volume control and Wave check boxes in the Show the followingvolume controls box to select them.


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The sound files are damaged If you cannot play certain .WAV files in Windows 95

(or if the .WAV files are not played properly), the .WAV files themselves might be dam-aged. To check if a .WAV file is damaged, use the right mouse button to click the .WAVfile in Windows Explorer, click Properties on the menu, then click the Details tab. The

Audio format line should contain information about the type of compression used to com- press the file, the sound quality of the file, and whether or not the file is in stereo. If thisinformation is missing, the .WAV file is probably damaged and should be reinstalled or re-copied to the drive.

Compression-related problems Windows 95 includes 32-bit versions of severalcommon CODECS including Adaptive Delta Pulse Code Modulation (ADPCM) , Interac-tive Multimedia Association (IMA) ADPCM , Group Special Mobile (GSM) 6.10, Consul-tative Committee for International Telephone and Telegraph (CCITT) G.711 A-Law and u-Law, and Truespeech from DSP. These 32-bit CODECS are installed by default duringWindows 95 setup, and are used by multimedia programseven if a 16-bit version of thesame CODEC is available. Be sure that .WAV file format is supported by an availableCODEC. Otherwise, you might need to install an appropriate CODEC.

SYMPTOMS

Symptom 41-1. A noticeable buzz or hum is being produced in one or both

speakers Low-cost speakers use unshielded cables. Unfortunately, strong signals fromac cords and other signal-carrying conductors can easily induce interference in the speaker wires. Try rerouting speaker cables clear of other cables in the system. If problems per-sist, try using higher-quality speakers with shielded cables and enclosures. In most cases,that should resolve everyday noise problems. If the noise continues, regardless of whatyou do, the fault might be in the sound-board amplifier. Try moving the sound board toanother bus slot away from other boards or the power supply. If that does not resolve the

problem, try a new sound board.

Symptom 41-2. No sound is produced by the speaker(s) The lack of sound from a sound board can be caused by any one of a wide range of potential problems. If thesound board works with some applications, but not with others, it is likely that the problemis caused by an improperly installed or configured application. See that the offending appli-

cation is set up properly (and be sure it is even capable of using the sound card). Also check that the proper sound driver files (if any) are loaded into CONFIG.SYS and AU-TOEXEC.BAT, as required. In many cases, one or two sound-related environment variablesthat are set in AUTOEXEC.BAT. Be sure that your startup files are configured properly.

Check your speakers next. See that they are turned on and set to a normal volume level.The speakers should be receiving adequate power and should be plugged properly into thecorrect output jackif speakers have been plugged into the wrong jack, no sound will be

1206 SOUND BOARDS

If you can play other .WAV files of a similar format, chances are good that the suspectfile is indeed damaged. If you can play .WAV files of different formats, but not .WAV filesof a particular format, it might be that your sound board does not support the particularformat.


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produced. If the cable is broken or questionable, try a new set of speakers. Also see that

the master volume control on the sound board is turned up most (or all) of the way.If problems continue, a resource conflict might be occurring between the sound board and another device in the system. Examine the IRQ, DMA, and I/O settings of each de-vice in the system. Be sure that no two devices are using the same resources. You mightlike to use the PC Configuration Form at the end of this book to record your settings. If

problems persist, and no conflict is present, try another sound board.

Symptom 41-3. CD audio will not play through the sound card This problemcan occur under both DOS and Windows. First, be sure that the sound board is actually ca-

pable of playing CD audio (older boards might not be compatible). If the sound card is play-ing sound files, but is not playing CD audio, check several things. First, open the PC and besure that the CD-audio cable (a thin, 4-wire cable) is attached from the CD-ROM drive to thesound board. If this cable is broken, disconnected, or absent, CD audio will not be passed to

the sound board. If the cable is intact, be sure that the CD audio player is configured prop-erly for the sound board you are using, and check the startup files to see that any drivers and environment variables needed by CONFIG.SYS and AUTOEXEC.BAT are available. If CD audio fails to play under Windows, be sure that an MCI (Multimedia Control Interface)CD Audio driver is included in the Drivers dialog box under Windows Control panel .

Symptom 41-4. An error, such as No interrupt vector available appearsThe DOS interrupt vectors used by the sound boards setup drivers (usually INT 80h toBFh) are being used by one or more other drivers in the system. As a consequence, thereis a software conflict. Try disabling other drivers in the system one at a time until you seethe conflict disappear. Once you have isolated the offending driver(s), you can leave themdisabled, or (if possible) alter their command-line settings so that they no longer conflictwith the sound boards software.

Symptom 41-5. It has no MIDI output Be sure that the file you are trying to playis a valid MIDI file (usually with a .MID extension). In most cases, you will find that the

MIDI mapper under Windows is not set up properly for the sound board. Load the Win-dows MIDI mapper applet from the Control panel , and set it properly to accommodateyour sound board.

Symptom 41-6. Sound play is jerky Choppy or jerky sound playback is typicallythe result of a hard drive problemmore specifically, the drive cannot read the sound fileto a buffer fast enough. In most cases, the reason for this slow drive performance is ex-cessive disk fragmentation. Under DOS, the sound file(s) might be highly fragmented.Under Windows, the permanent or temporary swap files might be highly fragmented. Ineither case, use a reliable DOS defragmenter, such as PC Tools or Norton Utilities (leaveWindows before defragmenting the disk), and defragment the disk thoroughly.

Symptom 41-7. An error, such as Out of environment space appearsThe system is out of environment space. You will need to increase the systems environ-ment space by adding the following line to your CONFIG.SYS file:

shell=c:.com /E:512 /P


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This command line sets the environment space to 512 bytes. If you still encounter the er-

ror message, change the E entry to 1024.

Symptom 41-8. Regular clicks, stutters, or hiccups occur during theplayback of speech This might also be heard as a garbled sound in speech or sound effects. In virtually all cases, the system CPU is simply not fast enough to permit buffer-ing without dropping sound data. Systems with i286 and slower i386 CPUs typically suf-fer with this kind of problem. This is often compounded by insufficient memory(especially under Windows), which automatically resorts to virtual memory. Because vir-tual memory is delivered by the hard drive and the hard drive is much slower than RAManyway, the hard drive simply cant provide data fast enough. Unfortunately, little can bedone in this kind of situation (aside from adding RAM, upgrading the CPU, or changingthe motherboard). If it is possible to shut off various sound features (i.e., music, voice, ef-fects, etc.), try shutting down any extra sound features that you can live without. Be sure

that no TSRs or other applications are running in the background.

Symptom 41-9. The joystick is not working or is not working properly onall systems This problem only applies to sound boards with a multi-function MIDI/joy-stick port being used in the joystick mode. Chances are that the joystick is conflicting withanother joystick port in the system. Disable the original joystick port or the new joystick

portonly one joystick port (game adapter) can be active at any one time in the system.Because joystick performance depends on CPU speed, the CPU might actually be too fastfor the joystick port. Disable the joystick port or try slowing the CPU down.

Symptom 41-10. The sound board is installed and everything works prop-erly, but now the printer does not seem to work An interrupt conflict is be-tween the sound board and an IRQ line used by the printer. Although parallel printers areoften polled, they can also be driven by an IRQ line (IRQ5 or IRQ7). If the sound board is using either one of these interrupts, try changing to an alternative IRQ line. Whenchanging an IRQ line, be sure to reflect the changes in any sound board files called byCONFIG.SYS or AUTOEXEC.BAT.

Symptom 41-11. The following error message appears: Error MMSYS-TEM 337: The specified MIDI device is already in use This problem often oc-curs with high-end sound boards, such as the Creative Labs AWE64. This error is oftencaused by having the sound boards mixer display on with the wavetable synthesizer se-lected (i.e., the LED display in the Creative Mixer turned on and Creative Wave Synthe-sizer selected as the MIDI playback device). You can usually correct the problem byturning the mixer display off.

Symptom 41-12. The following error message appears: Error: Wave de-vice already in use when trying to play wave files while a MIDI file is play-ing This problem often occurs with high-end sound boards, such as the Creative LabsAWE64, and it is usually the result of a device configuration problem. If full-duplex isturned on and you try to play a .WAV file and a MIDI file at the same time with thewavetable synthesizer (e.g., the Creative Wave Synthesizer) selected as the MIDI play-

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back device, an error will occur. To resolve this problem, you need to turn off the full-du-

plex mode:s Hold down key and doubleclick on My computer .s Select the Device manager tab. A listing for Sound, video, game controllers should be

included in the Device manager , doubleclick on the listing to expand it.s You should now see a listing for the sound board (e.g., Creative AWE32 16-Bit Audio).

Doubleclick on the listing, then select the Settings tab. Un-check the box labeled Allow full-duplex operation . Click OK until you are back to the Control panel .

s Now try to play a .WAV and MIDI file at the same time.

Symptom 41-13. You hear pops and clicks when recording sound underWindows 95 Cache is insufficient to adequately support the recording process (or cacheis improperly configured). Try the following procedure to alter the way cache is allocated:

s Open Notepad and load SYSTEM.INIs Locate the area of SYSTEM.INI labeled [vcache].s Add the following line [vcache]:

maxfilecache=2048

s Save your changes to the SYSTEM.INI file.s From the desktop, right-click on My computer , then select Properties .s Select the Performance page, then click on File system .s Find the slider marked Read-ahead optimization , then pull the slider to None .s Save your changes and restart Windows 95.

Symptom 41-14. You notice high frequency distortion in one or possiblyin both channels In many cases, the AT bus clock is set faster than 8MHz and data is

being randomly lost. This problem usually occurs in very fast systems using an ISA sound board. Enter the systems CMOS setup and check the AT bus clock under the Advanced chipset setup area. See that the bus clock is set as close as possible to 8MHz. If the busclock is derived as a divisor of the CPU clock, you might see an entry, such as /4. Be surethat divisor results in a clock speed as close to 8MHz as possible. If problems still persist,try increasing the divisor to drop the bus speed below 8MHz (this might have an adverseeffect on other ISA peripherals).

Symptom 41-15. You hear pops and clicks when playing back pre-recorded files under Windows 95 An excessive processing load is on the system,which is often caused by virtual memory and/or 32-bit access. Start by disabling virtualmemory: Open the Control panel and doubleclick on the System icon. Select the Perfor-mance page and click on Virtual memory . Set the swap file to None and save your changes. Try the file playback again. If problems persist, try disabling 32-bit file access.If that still does not resolve the problem, try disabling 32-bit disk access.

Symptom 41-16. Pops and clicks are audible on new recordings only,pre-existing files sound clean This is often caused by issues with software caching.


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If you are using DOS or Windows 3.1, disable SmartDrive from both CONFIG.SYS and

AUTOEXEC.BAT, then restart the computer for your changes to take effect. If problemscontinue (or you are using Windows 95), an excessive processing load on the systemmight be caused by virtual memory or 32-bit access. Follow the recommendations under Symptom 41-15.

Symptom 41-17. Pops and clicks occur when playing back or record-ing any sound file In most cases, there is a wiring problem with the speaker system.Check all of your cabling between the sound board and speakers. If the speakers are pow-ered by ac, be sure that the power jack is inserted properly. If the speakers are powered by

battery, be sure that the batteries are fresh. Check for loose connections. If you cannot re-solve the problem, try some new speakers. If the problem persists, replace the sound board.

Symptom 41-18. The sound board plays back fine, but it will not record

The board probably records fine in DOS, but not in Windows. If the sound board is using16-bit DMA transfer (typical under Windows), two DMA channels are in use. Chancesare that one of those two DMA channels are conflicting with another device in the system.Determine the DMA channels being used under Windows, then check other devices for DMA conflicts. If you are using Windows 95, check the Device manager and look for en-tries marked with a yellow icon.

Symptom 41-19. A DMA error is produced when using a sound board withan Adaptec 2842 controller in the system This is a known problem with the Dig-ital Audio Labs DOC product and the Adaptec 2842. You will need to alter the con-trollers FIFO buffer. Go in the controllers Setup by hitting + Open prompted during system startup. Select the Advanced Configuration option, then select the FIFOthresholdchances are that it will be set to 100%. Try setting the FIFO threshold to 0%and see if this makes a difference.

Symptom 41-20. A DMA error is produced when using a sound board withan Adaptec 1542 controller in the system This is a known problem with the Dig-ital Audio Labs DOC sound product and the Adaptec 1542. The problem can usually beresolved by rearranging the DMA channels. Place the Adaptec controller on DMA 7, then

place the sound board on DMA 5 for playback and DMA 6 for recording.

Symptom 41-21. The sound card will not play or recordthe system justlocks up when either is attempted The board will probably not play in either DOSor Windows, but might run fine on other systems. This is a problem that has been identi-fied with some sound boards and ATI video boards. ATI video boards use unusual addressranges, which sometimes overlap the I/O address used by the sound board. Change thesound board to another I/O address.

Symptom 41-22. The sound card will record, but will not playback As-suming that the sound board and its drivers are installed and configured properly, chancesare that a playback oscillator on the sound board has failed. Try replacing the sound board outright.

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Symptom 41-23. The sound application or editor produces a significant

number of DMA errors This type of problem is known to occur frequently when us-ing the standard VGA driver that accompanies Windowsthe driver is poorly written and cannot keep up with screen draws. Try updating your video driver to a later, more efficientversion. If the driver is known to contain bugs, try using a generic video driver that is writ-ten for the video boards chipset.

Symptom 41-24. The sound board will not record in DOS Several possible problems can account for this behavior. First, suspect a hardware conflict between thesound board and other devices in the system. Be sure that the IRQs, DMA channels, and I/O port addresses used by the sound board are not used by other devices.

If the hardware setup appears correct, suspect a problem between DOS drivers. Try aclean boot of the system (with no CONFIG.SYS or AUTOEXEC.BAT). If sound can berun properly now, there is a driver conflict. Examine your entries in CONFIG.SYS or AU-

TOEXEC.BAT for possible conflicts or for older drivers that might still be loading to support hardware that is no longer in the system.

Finally, suspect the hard-drive controller. Try setting up a RAM drive with RAM-DRIVE.SYS. You can install a RAMdrive on your system by adding the line:

device=c:.sys /e 8000

The 8000 is for 8MB worth of RAMbe sure that enough RAM is in the PC. Once theRAMdrive is setup, try recording and playing from the RAMdrive (you might have tospecify a new path in the sound-recorder program). If that works, the hard-drive controller might simply be too slow to support the sound board, and you might need to consider up-grading the drive system.

Symptom 41-25. When recording sound, the system locks up if a keyother than the recorders hot-keys are pushed This is a frequent problem un-der Windows 3.1x. The system sounds (generated under Windows) might be interferingwith the sound recorder. Try turning off system sounds. Go to the Main icon, choose theControl panel , then select Sounds . A box will appear in the lower left corner marked En-able system sounds . Click on this box to remove the check mark, then click OK .

Symptom 41-26. After the sound-board driver is loaded, Windows locksup when starting or exiting In virtually all cases, you have a hardware conflict

between the sound board and another device in the system. Be sure that the IRQs,DMA channels, and I/O port addressed used by the sound board are not used by other devices.

Symptom 41-27. When using Windows sound-editing software, the soundboard refuses to enter the digital modealways switching back to theanalog mode Generally speaking, this is a software-configuration issue. Be sure thatyour editing (or other sound) software is set for the correct type of sound board (i.e., anAWE32 instead of a Sound Blaster 16/Pro). If problems persist, the issue is with your sound drivers. Check the [drivers] section of the Windows SYSTEM.INI file for your


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sound-board driver entries. If more than one entry is listed, you might need to disable the

competing driver. This is a known problem with the Digital Audio Labs CardDplus, and it is caused by incorrect driver listings. For example, the proper CardDplus driver must beentered as:

Wave=cardp.drv

and the companion driver must be listed as:

Wave1=tahiti.drv

You will need to be sure that the proper driver(s) for your sound board are entered in SYS-TEM.INI. You might also need to restart the system after making any changes.

Symptom 41-28. The microphone records at very low levels (or not at all)Suspect that the problem is in your microphone. Most sound boards demand the use of agood-quality dynamic microphone. Also, Creative Labs and Labtec microphones are notalways compatible with sound boards from other manufacturers. Try a generic dynamicmicrophone. If problems persist, chances are that your recording software is not config-ured properly for the microphone input. Try the following procedure to set up the record-ing application properly under Windows 95:

s Open your Control panel and doubleclick on the Multimedia icon.s The Multimedia properties dialog will open. Select the Audio page.s In the Recording area, be sure to set the Volume slider all the way up.s Also see that the Preferred device and Preferred quality settings are correct.s Save your changes and try the microphone again.

Symptom 41-29. The sound card isnt working in full-duplex mode Virtu-ally all current sound boards are capable of full-duplex operation for such applications asInternet phones. Check the specifications for your sound board and see that the board is,in fact, capable of full-duplex operation. If it is, and full-duplex isnt working, your audio

properties might be set up incorrectly:

s Open your Control panel and doubleclick on the Multimedia icon.s The Multimedia properties dialog will open. Select the Audio page.s If the Playback device and the Record device are set to the same I/O address, this is

only half duplex.s Change the Playback device I/O address, so it is different from the Record device.s Hit the Apply button, then hit the OK button.s You should now be in Full duplex mode.

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Some of the very latest sound boards (such as the Ensoniq SoundscapeVIVO 90) willcarry full duplex operation with the same Playback and Record device selected.


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Symptom 41-30. DMA errors occur using an older sound board and an

Adaptec 1542 In many cases, you can clear DMA issues by slowing down the 1542 usingthe /n switch. Add the /n switch to the ASPI4DOS command line in CONFIG.SYS, such as:

device=c:.sys /n2

If slowing the 1542 down with an /n2 switch doesnt fix the problem, then you should strongly consider upgrading the sound board. This is a known problem with the older Dig-ital Audio Labs CardD sound board.

Symptom 41-31. Hard-disk recording problems occur under Windows 95Recorded audio is saved to your hard drive. For most systems, sound data can be trans-ferred to the HDD fast enough to avoid any problemsif data transfer is interrupted,your recorded sound might pop or break up. Many factors affect HDD data-transfer

speed. The following sections outline a number of procedures that might help you op-timize a system for sound recording. First, try disabling the CD auto insert notificationfeature:

s Go to the Device managers Open the CD-ROM entrys Select your CD-ROM drive, and click Propertiess Go to the Settings pages Uncheck the Auto insert notification boxs Select OK

Next, try turning down the level of graphics acceleration:

s Right-click on the My computer icons Left-click on Propertiess Select the Performance pages Select the button labeled Graphicss Start by turning down the acceleration one notch (you can return later to turn it down

further if more performance is required)s Select OK

It might also be necessary to adjust the size of your virtual memory swap file:

s Right-click on the My computer icons Left-click on Properties

s Select the Performance pages Select the button labeled Virtual memorys Choose Let me specify my own virtual memory settingss If your PC has 16MB of RAM, set the minimum and maximum at 40MB. If you have

32MB of RAM, set the minimum and maximum at 64MB.s Select OK


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Try removing any active items from your Startup group:

s Click the Start buttons Go to the Programs menu, then select Startup . If you see anything here, it might be

hurting your system performance. Eliminate anything that is not absolutely necessary.s To remove items, click the Start button, go to Settings , then select Taskbars Choose the page labeled Start menu programss Click the Remove buttons Open the Startup group by doubleclicking its Remove any items that you feel are not necessary and are wasting resourcess Select the Close button when finished

Clear any indexes of the Find Fast utility:

s Click the Start buttons Go to Settings , then choose the Control panel s Open the Find Fast utilitys Go to the Index menus Select Delete indexs Select an index in the In and below drop boxs Select the OK buttons Repeat steps 5 through 7 until all indexes are removed

Try defragmenting the hard drive:

s Click the Start buttons Go to Programs , Accessories , and System toolss Choose Disk defragmenters Select the drive to defragment and click OK s Click the Start button to begin defragmentation

Finally, you might want to suspend the System Agent (if installed):

s If System Agent is installed, open it by doubleclicking its icon in the taskbar s Go to the Advanced menus Choose Suspend system agent s Close the System agent window.

Symptom 41-32. The microphone records only at very low levels or not atall Check your phantom power settings first. In many cases, the microphones gain is settoo low in the sound boards mixer applet. Start the sound boards mixer, be sure that themicrophone input is turned on, then raise the microphones level control. Remember tosave the mixer settings before exiting the mixer. You should not have to restart the system.

Symptom 41-33. The dynamic microphone clips terribly, and recordingsare noisy and faint This is probably caused by phantom power being switched on in

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your sound board. Try turning the phantom power off. If you cannot turn phantom power

off, try plugging the dynamic microphone into the sound board line input jack. Remem- ber to start the sound board mixer applet and set the line input level properly.

Symptom 41-34. Trouble occurs when using Creative Labs or Labtec mi-crophones with your (non-Creative Labs) sound board This is a common com-

plaint among Ensoniq sound board users. It turns out that Ensoniq sound boards are notcompatible with Creative Labs or Labtec microphones. Try a generic microphone instead.

Symptom 41-35. Static is at the remote end when talking through a voiceapplication, such as WebPhone Noise is occurring at the line input or microphoneinput, which is being transmitted to the remote listener. Check the line input signal. Youmight try reducing or turning off the line input mixer level. If the problem persists, check your phantom power setting and your microphone. Try reducing the microphone level in

the sound boards mixer. Try a different microphone.

Further StudyThis concludes the material for Chapter 41. Be sure to review the glossary and chapter questions on the accompanying CD. If you have access to the Internet, take a look at someof these sound-board resources:

Creative Labs: http://www.creaf.com

Turtle Beach: http://www.tbeach.com/

Frontier Design Group: http://www.frontierdesign.com/Ensoniq: http://www.ensoniq.com

SIC Resource: http://www.sicresource.com/

Star Multimedia: http://www.starusa.com/

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sound boards

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