Audio Control SA-3055 Owner's Manual

SA-3055

Competition Autosound

Analyzer/SPL Meter

Operation Manual

22410 70th Avenue West • Mountlake T errace, WA 98043

Phone 425-775-8461 • Fax 425-778-3166 • Internet http://www.audiocontrol.com

P/N 9021100

SA-3055 Owner’s Manual

Table of Contents

About This Manual .................................................... i

Notational Conventions.............................................. i

Notes, Cautions, and Warnings .................................. ii

Chapter 1 Introduction

Test Instruments vs. To ys ........................................... 1-1

ANSI Filter Design .................................................... 1-2

Applications ............................................................... 1-3

Accessory Information................................................ 1-3

Chapter 2 SA-3055 Front and Rear Panel Features

Front Panel ................................................................. 2-1

Rear Panel .................................................................. 2-4

Chapter 3 Operation

Quick-Start Information ............................................. 3-1

Using The SA-3055's Functions................................. 3-1

Storing and Recalling a Response Curve .................. 3-1

Averaging Several Readings ...................................... 3-2

Peak-Hold; RTA and Digital SPL .............................. 3-2

Clearing the Internal Memories ................................. 3-2

Printer Operation ........................................................ 3-2

Printers Supported ...................................................... 3-2

Connector Pin Designations....................................... 3-3

Battery Operation ....................................................... 3-4

A and C Weighted Measurements ............................. 3-5

Getting extreme at 175dB SPL .................................. 3-6

Chapter 4 Acoustical Testing with the SA-3055

Overview .................................................................... 4-1

Basic Procedure.......................................................... 4-2

Body Effects ............................................................... 4-3

Sound Pressure Level and Hearing Loss ................... 4-3

Chapter 5 A Primer on Car Acoustics ...................................... 5 -1

Chapter 6 Getting the Last ¼ dB

Getting the Last 1/4 db .................................................6-1

Setting Gain Levels ................................................... 6-12

Chapter 7 Contest Scoring

IASCA Scoring ........................................................... 7-1

USAC Scoring ............................................................ 7-1

Chapter 8 Other SA-3055 Applications

Sound System Equalization ....................................... 8-1

Hi-Fi Equalization ...................................................... 8-1

Component Checkout ................................................. 8-4

Sound and Music Monitoring .................................... 8-6

Crossover Testing....................................................... 8-7

Chapter 9 Theory of Operation

Input Circuitry ............................................................ 9-1

One-Third Octave Filters ........................................... 9-1

Signal Multiplexing & Analog to Digital Conversion 9-1

Microprocessor Circuitry ........................................... 9-2

LED Display............................................................... 9-2

Pink Noise Generator ................................................. 9-2

Chapter 10 Warranty

Legalese.....................................................................10-1

Service Information ...................................................10-1

Chapter 11 Specifications ...........................................................11-1

SA-3055 Owner’s Manual

About This Manual

This manual describes the AudioControl SA-3055 and a few of its audio applications.

The manual is divided into several major sections. Chapter 1. Introduction is an overview of the SA-3055 and to this manual.

Chapter 2. SA-3055 Front and Rear Panel Featur es describes the physical features

found on the front and rear panels of the SA-3055. Chapter 3. Operation describes how to use the various functions of the SA-3055 Chapter 4. Acoustical Testing with the SA-3055 has procedures for using the

SA-3055 for sound system equalization and analysis. Chapter 5. Car Acoustics looks at the research and specifics of automobile

acoustics. Chapter 6. Last ¼ dB describes some advanced topics. Chapter 7. Contest Scoring explains the special programming built into the SA-3055

for car stereo contests. Chapter 8. SA-3055 Applications describes a few other applications for the

SA-3055 besides equalizing sound systems. Chapter 9. Theory of Operation, for terminally curious technoids only , is a descrip-

tion of what goes on inside the confines of the box. Chapter 10. Warranty Information describes the SA-3055 warranty and tells how to

obtain service for the SA-3055. We trust that you'll never need to use

this section. Chapter 11. Specifications lists the SA-3055's specifications.

SA-3055 Owner’s Manual

Notational Conventions

Within this manual, several different notation conventions are used to indicate various

facets of the SA-3055's features.

SMALL CAPS Indicate a marked feature on the unit, like a control or a connector.

They are also used within procedures to identify controls and switches by function.

Italics Are used for emphasis. Words printed in boldface convey more emphasis and boldface than those printed in italics.

Notes, Cautions, and Warnings

Some of the text in this manual is set apart by the headings: Note, Caution, or Warn-

ing.

These terms are used to denote varying degrees of awareness required by the user

during installation, operation, or maintenance of the SA-3055.

NOTE conveys information that may be helpful to the user. A note is similar to an aside during a conversation.

CAUTION indicates a potential danger to the instrument. WARNING indicates a potential hazard to the operator.

SA-3055 Owner’s Manual

Chapter 1 - Introduction

Introduction

Congratulations on purchasing one of the world's most popular audio analyzers. The AudioControl SA-3055 is an affordable, measurement-grade, one-third octave real-time analyzer designed for audio signal analysis. Previous analyzer designs were either too costly for the average professional or too inaccurate for serious use. The SA-3055 overcomes these inadequacies by combining a state-of-the-art microprocessor-based design with modern electronic manufacturing techniques. The result is a very accurate, quick and easy to use instrument, self contained in one box.

The SA-3055 includes the following features:

• Car stereo contest scoring

• Portable battery operation

• Parallel printer port

• Completely self contained opeating system and programing

• 30 one-third octave bandwidth filters

• Fourth-order filters conform to ANSI S1.11-1986 standards

• Laboratory-grade calibrated measurement microphone

• Internal digital pink noise source

• 36 dB display window

• 9 x 30 large-format LED display matrix

• Full-screen digital SPL readout with 1/10th dB resolution

• Six non-volatile memories with lithium battery backup

• Frequency response averaging for up to six stored response curves

• 20 second temporal averaging

• Peak-hold

• Balanced XLR microphone, balanced TRS ¼" phone jack and unbalanced RCA connector inputs

• 175 dB sound pressure level measurement (optional)

Test Instruments vs. Toys

There is a fundamental difference between the many real-time analyzers currently available on the market today . That difference is one of calibration. An instrument that is calibrated is capable of making measurements based on some absolute reference (absolute measurement).

An instrument that isn't calibrated can only make comparisons against a relative reference (relative measurement). For example, someone asks you, "How hot is it today?" If you step outside for a moment and reply, "Oh, a bit hotter than yesterday ," that's a relative measurement. On the other hand, if you step outside and consult a certified laboratory thermometer and say "85 degrees F," you've made a measurement against an absolute reference.

The SA-3055 was calibrated at the factory to meet or exceed its published specifications. You can make a measurement with the SA-3055 and compare it with a measurement made by any other measurement-grade instrument and know that you are comparing apples with apples.

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Chapter 1 - Introduction

ANSI Filter Design

A real-time analyzer works by dividing the audio spectrum up into equal bandwidth parts using a set of calibrated (usually) bandpass filters. Then the output of each filter is displayed on some sort of level indicator: LED matrix, V ideo display, LCD, etc.

The American National Standards Institute (ANSI) oversees the establishment and maintenance of various engineering standards in conjunction with the International Standards Organization (ISO) in Europe. These two standards organizations have established standards for the performance of the bandpass filters used for acoustical measurement purposes.

For one-third octave analyzers, there are two classes of filters allowed by ANSI. These are Class II, and Class III. Class I is reserved for octave bandwidth analyzers. Class III filters are the hardest to design and manufacture and are usually only found on the most expensive (read unaffordable) analyzers. Class II filters, are easier (not easy , just easier) to design and manufacture than Class III filters. Any real-time analyzer intended for serious measurement work will use filters that at least meet Class II standards.

The filters used in the SA-3055 analyzer meet or exceed the standards specified by ANSI for a Class II, T ype E filter set. Simply, they are very, very good but still affordable.

Figures 1.1 and 1.2 show two different one-third octave filters. Figure 1.1 is representative of those found in most analyzers. Figure 1.2 is an actual filter used in the SA-3055. Note the difference in the response away from the center frequency . The inferior filter's broad response characteristic translates to potential measurement errors at frequencies removed from the band-center and undesirable interaction between adjacent frequency bands.

Figure 1.1. A non-measurement quality one-third octave filter

1-2

Figure 1.2. A measurement quality one-third octave filter

SA-3055 Owner’s Manual

Chapter 1 - Introduction

Applications

The SA-3055 is well-suited to many audio applications including but not limited to:

• Acoustical analysis for sound reinforcement or recording studios

• Equalizer adjustment and setup

• Crossover level setting and verification of frequency

• Gain matching and setting at various stages of the signal chain

• Movie theater system setup and alignment

• Tape recorder setup

• Industrial noise measurement

Special Features

Rechargeable Internal Battery Pack

The rechargeable battery option allows the SA-3055 to be used independent of AC mains power. The batteries install within the instrument and provide up to 4

hours of operation on a full charge.

The batteries are recharged by plugging the instrument into a source of AC mains power and leaving the front panel P hours. When charging, the power light glows red. When fully charged the red power light flashes occasionally .

OWER switch set to OFF for a period of 9 to 10

Printer Output

The printer output option provides a Centronics parallel interface for a PC compatible printer (not provided). The analyzer-to-printer cable is a standard PC-type parallel printer cable (also not provided).

The printed output is a form with suitable blank spaces for recording the time and place of the measurement and other data, followed by the a printed representation of the real-time spectrum display on the analyzer .

On-screen score display

For quick check-ups in the shop when you don’t have a printer handy , the SA-3055 will display the frequency response score on the screen. Of course if you do have a printer, the SA-3055 provides complete information about the individual response deviations on a special printout.

Automatic SPL judging

Forget about finding your stopwatch. Forget about disputes over SPL scores. The SA-3055 automatically times 30 seconds and holds the loudest SPL peak during the count-down. An LED bar ticks off the seconds for great crowd appeal.

No computer required

The SA-3055 works directly with your PC-compatible printer . A separate computer is not required. Just plug your printer into the SA-3055 and you’re ready to go.

SC-10 Soft Carrying Case

The optional soft carrying case protects the SA-3055 from the ravages of portable operation. It includes a large pocket to carry the mike and cables. There is also a

hatch on the bottom of the case to allow access to the power cord connection.

SA-3055 Owner’s Manual

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Chapter 1 - Introduction

Options

Customized Printout

The CP-10 option customizes the printer output form to include six lines of data for

your business name, address, and other data. Since this data is only factory

installed, it has the additional benefit of “branding” your analyzer in case someonewan-

ders off with your prize analyzer .

AC-10 A- and C-weighting Filter

The AC-10 A/C weighting filter is a compact plug-in module designed to be

inserted inline with the microphone. The AC-10 applies the standard A- or C-

weighting function to the microphone signal.

Very High SPL option

The high SPL option allows sound pressure level measurements over 170 dB. This

option includes a high SPL microphone and software upgrades.

External SPL Display

Designed for SPL contests, this option includes a large, very bright SPL display which

connects to the SA-3055. The output is in big, bold numbers, which are easily readable by

the contest crowd. T wo analyzers and displays may be started simultaneously by a single

simulstart button (SS-10).

1-4

SA-3055 Owner’s Manual

Chapter 2 - SA-3055 Front and Rear Panel Features

Figure 2.1. SA-3055 Front Panel

Front Panel

LED DISPLAY

The left portion of the display shows the one-third octave energy content of the input signal from 25 Hz to 20kHz. Each column within the display represents a single one-third octave band. The band centers are marked on the bottom of the screen.

The right-hand end of the display indicates the setting of the DB switch, and conse-

quently the amount of change in the input signal that each LED on the left- hand side of the display represents.

The far right portion of the display indicates the sound pressure level (SPL), relative

to the settings of the DB switch and control.

POWER SWITCH

Depressing the POWER switch to the right turns the SA-3055 on. Pressing it to the left turns it off.

LOW BATT/POWER/CHARGE LED

The LOW BATT/POWER indicator illuminates solid green during normal operation of the SA-3055. When operating the SA-3055 on the optional internal rechargeable batteries, a flashing green LED indicates that the batteries need recharging. Once the Low Batt LED has begun flashing, there is approximately ½ hour of battery life remaining.

The SA-3055 has a sense circuit that prevents operation of the instrument below critical battery cell voltage. This prevents total battery discharge, which shortens the cell life.

To continue operation, the SA-3055 may be operated from the AC power line. The batteries may be recharged by plugging the SA-3055 into a suitable source of AC power , with the front panel POWER switch set to the OFF position for a period of 9 to 10 hours. The power LED will glow red while the batteries are charging. The minimum recharge time from the voltage-cutout state is around 2 hours, which will then operate the instrument for around one hour. Completely rechar ging the batteries from a dischar ged state (instrument dead) requires 9 to 10 hours (2 times the discharge time).

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Chapter 2 - SA-3055 Front and Rear Panel Features

SPL

Momentarily pressing the SPL push-button switch toggles the SPL bargraph at the right side of the display window on and off. Pressing and holding the SPL push-button activates the full-screen digital SPL display . Momentarily pressing the SPL switch again restores normal analyzer operation. The associated LED indicator indicates the status of the SPL switch. The SPL bargraph display scaling is always 4 dB/step, regardless of the setting of the dB switch. The SPL switch works regardless of the setting of the RECALL/RTA switch. This means that you can switch the SPL bargraph on and off even with a stored display .

ISPLAY SPEED

The display speed push-button switch is located underneath the SPL switch and to the left of the FAST, MED and SLOW LEDs.

The lighted LEDs to the right of the switch indicate the response time of the display . Press the button to change the decay time of the display . The Fast setting is optimized for looking at transients in conjunction with peak hold, the Med setting is useful for program monitoring, and the Slow setting averages 20 samples over a ½ second period. This works well for measurements using pink noise. A fourth display speed is a 20 second time average. It is indicated by the SLOW LED flashing. During the first 20 seconds as the average is accumulating, the Slow LED will flash 2 times per second. Once the accumulator is full, the flashing will slow down to 1 flash per second.

MEMORY

The SA-3055 can store up to six different frequency response curves (including the SPL bar graph display) in its internal non-volatile memory . These memories are stored at the highest resolution of the SA-3055, so you can scale the display with the DB/STEP switch during memory recall. Any combination of the memories can also be averaged. Look in the Operation section of this manual for further information.

An internal back-up battery maintains the contents of the memory for periods of up to one year, even with the AC power supply disconnected. This feature allows the unit to “remember” a standard curve that may be recalled each time that the SA-3055 is used.

PINK NOISE

The internal pink-noise generator is an accurate, digital, laboratory-grade test source. The pink noise output is accurate throughout the measurement range to within 0.25dB.

The maximum output provided at the ¼" tip-sleeve phone jack is 1 volt into a 600 load (unbalanced, ring and sleeve grounded), or 150 mW into a 4 ohm load.

The signal level at this connector is controlled by the knob to its immediate left.

The pink noise generator has sufficient output to drive virtually any speaker or crossover directly .

DB PER STEP

This switch sets the resolution of the spectrum analyzer portion of the display . The setting represents the value of each LED in the display . Thus, a setting of 1dB per step causes each LED in the display to represent a 1dB change. At this setting, the overall range of the display is 9dB. At the 4-dB-per-step setting, each LED in the display represents a change of 4dB, with a 36dB overall display range.

When using the SA-3055 for sound system equalization, start with the 4 dB/step

2-2

SA-3055 Owner’s Manual

Chapter 2 - SA-3055 Front and Rear Panel Features

setting and progressively decrease the setting of the DB PER STEP switch as the equalization process progresses. For program monitoring, the 4dB position works well because it displays the widest dynamic range.

Memorized response curves are always stored at 1-dB-per-step-resolution, regardless of the setting of the front panel switch. You can select whatever resolution you wish for a stored display when it is displayed and know that it is accurate. The same holds true for displays dumped to the printer output.

DB INPUT SENSITIVITY

The DB INPUT SENSITIVITY control and switch select the reference level of the curve

shown in the display window . The control to the right of the input selector switch is a fine adjustment and alters the range selected by the switch over a range of ±10 dB. The normal setting for this control is the detented (click-stopped) center position.

The reference level of the display is shown on the display window by the light gray

horizontal line. The actual reference level of the reference line corresponds to the dB level setting of the DB/SPL switch.

For example, the DB/SPL switch (coarse adjustment) is set to 90dB. The light gray

line on the display window represents a sound pressure level of 90dB if the 10dB control (fine adjustment) is set at the center-detented position.

INPUT 3

A ¼" tip-ring-sleeve phone jack is used for connecting to balanced and unbalanced sources. Connect unbalanced sources by using a tip-sleeve (2 conductor) plug inserted into this jack.

This input has an impedance of 10 kohms and is suitable for signal levels from -56dBu to +36dBu. An input signal of 0dBu represents 100dB SPL.

INPUT 2

This is a standard audio (RCA) connector with an input impedance of 1 Mohm in parallel with 30 pF . The particular combination of resistance and capacitance allows connecting almost any audio source to this input.

This input is suitable for signal levels from -56dBu to +36dBu. An input signal of 0dBu represents 100dBSPL.

INPUT 1

This is a standard +12 volt, phantom-powered, balanced microphone input. The phantom power supply is intended for the AudioControl CM-10 or High SPL measurement microphones.

Ordinary dynamic microphones may also be connected directly to this input providing that they have a balanced output. Unbalanced microphones may not be used. This input is suitable for acoustical levels at the microphone ranging from 44dB SPL to 136dB SPL. The SPL display is only accurate if the AudioControl CM-10 microphone is used, or if the external microphone matches the sensitivity of the CM-10 microphone.

CAUTION: A microphone with an unbalanced output may be damaged if connected to this input. AudioControl assumes no responsibility for microphones damaged in this manner. Connect microphones with ¼" phone plug connectors to the Balanced Input 3 connector.

SA-3055 Owner’s Manual

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Chapter 2 - SA-3055 Front and Rear Panel Features

Figure 2.2. SA-3055 Rear Panel

Rear Panel

AC Mains power input receptacle

An IEC 3-prong receptacle provides the connection for AC power input to the

SA-3055.

The SA-3055 is factory supplied to operate at one of the following AC power supply voltages. The supplied configuration is marked on the rear panel of the unit. Consult the AudioControl factory for power supply conversion information.

I 120 VAC, 60 Hz I 220-240 VAC, 50/60 Hz

Power Fuse

The correct fuse is listed next to the power input receptacle.

Printer Interface

This is a female 25-pin connector (DB-25F) used for connection to an external PCtype printer (not supplied). The connector is wired for a parallel interface printer . A description of the pin connections can be found on page 3-5.

This momentary-contact switch is used to print the contents of the display onto an external printer.

2-4

SA-3055 Owner’s Manual

Chapter 3 - Operation

Using the SA-3055 is simple and straightforward. This section describes the basic

procedures for using the SA-3055.

Quick-Start Information

1. Connect the SA-3055 to a suitable source of AC power. If your instrument is equipped with the battery option, the batteries must be charged before use. The correct AC power configuration is marked on the rear panel of the instrument.

2. Connect the input signal source to the appropriate input on the front panel of the instrument.

3. If you are using the internal pink noise source, connect the PINK NOISE output of the analyzer to the amplifier or sound system line input. The PINK NOISE output has sufficient power capacity to directly drive a loudspeaker to modest levels.

4. Set the DB INPUT switch so that signal peaks reach the upper third of the display. Adjust the gray line dividing the display represents the SPL setting of the

represents the value of each LED in the display . A scale is printed on the right-hand side of the display window .

DB INPUT control as needed. If the variable ±10 dB control is centered, then the

DB SWITCH.

5. Select the display resolution using the DB PER STEP switch. The switch setting

6. Select the decay time of the display by pressing the push-button switch adjacent to the FAST, MED, or SLOW LEDs. The Fast setting is suitable for viewing transients. The Med setting is suited to signal monitoring and the Slow setting works well for pink noise measurements.

7. You can determine the sound pressure level at the microphone by pressing and holding the SPL push-button for one second until the display changes to the digital mode. This will display the sound pressure level in 1/10th dB (centibel) resolution. The SPL bargraph is always 4dB per step, regardless of the setting of the DB PER STEP switch.

Using The SA-3055's Functions

Storing a Response Curve

1. Press the STORE/FREEZE button. The display is now frozen and ready to be stored.

2. Pressing the MEMORY button again steps through the six memories in sequence. The display shows the contents of each memory as it is selected.

3. The RECALL and RTA LEDs are not illuminated. This indicates that the SA-3055 is ready to store the display .

4. Pressing the STORE/FREEZE button again stores the contents of the display into the selected memory . The associated LED indicators display which memory is currently active.

5. The yellow RECALL LED illuminates to indicate that you are now in recall mode. You can recall any other memory for comparison purposes by selecting that memory by repeatedly pressing the Memory button.

6. Press the RECALL/RTA button to return to real-time mode.

SA-3055 Owner’s Manual

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Chapter 3 - Operation

Recalling a Response Curve

1. Press the RECALL/RTA button until the RECALL LED is illuminated.

2. Press the MEMORY push-button to successively view the contents of the six memo-

ries.

3. Pressing the RECALL/RTA button again returns the SA-3055 to the RTA mode.

Averaging Several Readings

The averaging mode allows up to 256 previously stored readings to be averaged

together. The averaged result is stored in memory number six, replacing its contents.

1. Acquire and store up to six response curves.

2. Press and hold the S

TORE/FREEZE button for one second. The yellow MEMORY 6

LED is now flashing, indicating the initiation of the averaging mode.

3. Select the first memory for averaging using the M

EMORY button. Touch the

STORE/FREEZE button once.

4. Select the next memory for averaging using the MEMORY button. Touch the

STORE/FREEZE button once. Repeat this step for each additional memory to be averaged.

You can weight a specific memory by selecting it more than once.

5. After selecting the memory locations to be averaged, press and hold the STORE/

FREEZE button for one second. The MEMORY 6 LED will come on solid and the average will be displayed on the screen and written into memory location 6.

6. The contents of memory location 6 are lost when the average is calculated. The

result of the averaging operation is overwritten into memory location 6.

Peak-Hold

The Peak-Hold mode allows you to accumulate the highest peak level in all of the SA-3055's thirty display bands. This display may be stored in any memory location, averaged, etc.

1. Press and hold the RTA/RECALL button for one second. The red RTA LED is now

flashing, indicating the peak-hold mode is active. The display now holds the overall peak level for each of the thirty bands.

3-2

2. Pressing the RTA/RECALL button again exits the peak-hold mode.

Peak-Hold Digital SPL

The digital SPL display may also be operated in peak-hold mode.

1. Press and hold the SPL button until the instrument enters digital SPL mode.

2. Press and hold the RECALL/RTA button until the SPL LED starts flashing.

3. The SA-3055 is now in digital SPL peak-hold mode.

Clearing the Internal Memories

1. Press and hold the STORE/FREEZE button while turning on the SA-3055.

SA-3055 Owner’s Manual

Chapter 3 - Operation

Printer Operation

A standard printer interface allows making hard-copy printouts of the SA-3055's display . The printer output is a form with space provided for logging the time and date of the job, as well as any other data. A sample is shown in figure 3.1. The SA-3055 prints special output formats when in IASCA or USAC scoring modes.

Printers Supported

The SA-3055 printer interface is designed to connect to any Centronics-type parallel interface compatible printer (dot matrix, ink jet, laser, etc.). No special printer control codes or emulations are required.

Note

The parallel PC printer interface standard does not require any baud rate, parity or stop bit settings. You should not have to make any special settings in your parallel printer to use the SA-3055.

CAUTION: Do not connect the SA-3055 to a serial interface printer (Apple, Point of Sale, etc.). It will not print, and damage may be done to the analyzer and/or printer.

Printing the display is easy.

1. Connect a parallel printer to the Printer Port on the rear of the SA-3050A.

2. Recall the response curve memory that you wish to print...or...freeze the display.

3. Make sure that the printer is loaded with paper, connected to a power source,

turned on, and on-line.

4. Press the rear-panel PRINT button.

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Chapter 3 - Operation

PERFORMANCE MATCH

SYSTEM ANALYSIS

By:

Client _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ Date _ _ _ _ _ _ _ _

Address _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ Telephone _ _ _ _ _

City _ _ _ _ _ _ _ _ _ _ _ State _ _ _ _ ZipCode _ _ _ _ _ _

Description of Vehicle _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

System Components: Head Unit _ _ _ _ _ _ _ Speakers: Tweeters _ _ _ _ _ _ _ _ Performance Match Midranges _ _ _ _ _ _ _ Units _ _ _ _ _ _ _ _ _ Bass _ _ _ _ _ _ _ _ _ _ Crossover _ _ _ _ _ _ _ Subwoofer _ _ _ _ _ _ _ _ Amplifiers _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

Suggested System Improvements _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

Figure 3.1.

Printout Example.

Performance Match Technician _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

AUDIOCONTROL SA-3055 SPECTRUM ANALYSIS

System Frequency Response--One Third Octave

***

25 50 100 200 400 800 1.6k 3.15k 6.3k 12.5k 2 0k

Bass Midrange Treble

****

+12

+9 +6 +3

-3

-6

-9

-12

92 89 86 83

80 77 74 71 68

3-4

Note

An abbreviated printout showing only the R TA curve may also be printed by double-

clicking (pressing twice quickly) the Print button.

SA-3055 Owner’s Manual

Chapter 3 - Operation

Connector Pin Designations

The printer interface connector uses a DB25F connector. The connector wiring is the same as that used by PC-type computers so you can use any standard PC printer cable to connect the SA-3055 to your printer.

The connector pin designations are shown in Figure 3.2.

Figure 3.2. Parallel Interface Signals and Pin Assignments.

Battery Operation

A standard battery package allows the SA-3055 to be operated without connection to the AC mains supply . The battery supply has sufficient capacity to operate the SA-3055 continuously for 3 to 4 hours. The battery package uses a sealed gel-cel, leadacid battery pack.

An integral battery charger operates when the SA-3055 is plugged into the AC mains supply. The instrument must be turned off to charge the battery.

Charging the Internal Battery Pack

1. Plug the SA-3055 into a suitable source of AC power .

2. Set the front panel POWER switch to OFF.

3. Leave the SA-3055 for a period of 8 to 10 hours (twice the discharge time).

4. The battery charger automatically adjusts the rate of charge as the battery reaches

full charge. The POWER/CHARGE LED will glow red then flash slowly when a full charge is reached. Once this occurs, the battery charger switches to trickle-charge mode to maintain the battery at full charge. Operating the SA-3055 on AC power will eventually discharge the battery.

Getting the Most From Your Battery Pack.

The SA-3055 uses a sealed, lead-acid storage battery. These batteries are not of the Nickel-Cadmium type commonly used for rechargeable applications. Lead-acid batteries

SA-3055 Owner’s Manual

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Chapter 3 - Operation

offer some significant advantages over NiCad batteries.

• Given proper charging and discharge depth, the batteries should deliver 1000 to 2000 charge/discharge cycles (4-5 years of normal operation).

• Lead-Acid cells do not have memory effects from partial discharging or charging.

• Higher energy density . The lead-acid design delivers more ener gy per unit volume than NiCad battery systems.

• Lead-acid batteries can be charged in less time than NiCads.

• Wider temperature range: -65 degrees Celsius to +65 degrees Celsius.

Getting maximum performance from your battery pack is simple.

Follow these simple suggestions:

• Lead-acid batteries do not operate well when deeply discharged. Operate the SA- 3055 until the green LOW-BATTERY indicator begins flashing. When the indica- tor begins flashing, you have approximately 30 minutes of operation left. Cease operation and recharge the battery or switch over to AC power.

• A low-voltage cutout prevents operation of the SA-3055 once the battery voltage reaches this point. The low-voltage cutout could make the instrument appear to be totally dead. If the SA-3055 appears dead, plug the instrument into a source of AC power. Ensure that the POWER switch is set to the OFF position. Leave the instrument plugged in for at least two hours and look for the red battery charging LED to glow continously .

If this "revives" the instrument, simply continue charging the batteries for another six

to eight hours. If not, consult the factory for additional information.

NOTE:

The low-voltage cutout could make the instrument appear to be totally dead. If the SA-3055 appears dead, plug it into a source of AC power. Ensure that the analyzer is turned off. Leave it plugged in for at least two hours to charge. If the CHARGE LED by the power switch does not light, then you may not have AC power and the battery cells are not charging.

If this “revives” the SA-3055, you can resume normal operation using AC mains power. Be sure to charge the batteries for another six to eight hours before using the portable battery mode.

Plugging the SA-3055 into AC mains while using the battery power may cause the microprocessor to “hang”. If this occurs, turn the power off, then back on again.

CAUTION: Always store the SA-3055 with the batteries fully charged. Leaving the analyzer stored with a partial charge for extended periods (more than two weeks) can damage the battery cells irreparably . The battery charging circuitry cannot overcharge the cells, so it is best to always leave the analyzer plugged into AC power for charging whenever it is not in use.

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SA-3055 Owner’s Manual

+ 44 hidden pages