Apple Desktop Computer manual Sound Speciﬁcations, External Sound Output, Headphone Jacks

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C H A P T E R 3

Devices and Ports

■during power cycling

External Sound Output

The external sound output jack is a 3.5-mm mini phone jack located in the I/O bay on the right side of the computer. It accepts a stereo miniplug-to-RCA cable adapter for connecting stereo equipment to the computer.

The sound output jack has the following electrical characteristics:

■output impedance: nominal 180 ohms

■maximum level: nominal 1 V rms (2.8 V peak-to-peak)

Headphone Jacks

Two headphone jacks are located on the front of the computer next to the right speaker. Each sound output jack provides enough current to drive a pair of low-impedance headphones.

The headphone jacks have the following electrical characteristics:

■output impedance: nominal 13 ohms

■maximum level: 1.4 V rms (4.0 V peak-to-peak)

Headphones should have an impedance not lower than the recommended minimum impedance of 32 ohms. Headphones with lower impedance can be used, but with some degradation in performance.

Sound Speciﬁcations

The frequency response of the sound circuits, not including the microphone and speakers, is within plus or minus 1 dB from 4 Hz to 20 kHz.

Sound System

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Contents Apple iMac Computer Page Contents RAM Expansion Devices and PortsRtas SoftwareRtas NV-RAM Appendix Abbreviations IndexFigures and Tables Page About This Developer Note Contents of This NoteSupplemental Reference Documents PowerPC G3 MicroprocessorMac OS ATA DevicesOpen Firmware USB DevicesE F a C E Introduction Features Shows a front view of the computer Case and External FeaturesFront view 2Side view showing I/O bay System Software Compatibility IssuesVideo RAM Expansion Modules Main RAM Expansion ModulesUSB Ports and Devices Page Architecture Architecture G3 Microprocessor Processor moduleBackside Cache Memory Controller and PCI Bridge Main Logic BoardController IC Video Display Subsystem USB ControllerBuilt-in Modem Infrared Link Module Devices and Ports USB Ports USB ConnectorsGND Transfer Types SupportedADB Compatibility USB Compatibility IssuesMacintosh-To-Macintosh Connections Serial Port CompatibilityUSB Storage Devices USB ControllerKeyboard Layout KeyboardKeyboard and USB MouseVideo Display Hard Disk DriveSound System Infrared Communication LinkSound Outputs Sound InputsBuilt-in Microphone External Sound InputExternal Sound Output Sound SpeciﬁcationsHeadphone Jacks Total harmonic distortion Internal Modem Ethernet PortPage RAM Expansion Expansion Slots Removing the Logic Board AssemblyPlacing the Computer Face Down Unfastening the Cables Removing the bottom coverRAM Expansion Removing the Retaining Screws 3Logic board assembly handle and retaining screwsRemoving the EMI Shield Removing the Logic Board AssemblyLocations of the Expansion Slots 6Locations of the RAM expansion slots Main RAM ExpansionElectrical Design of RAM SO-DIMMs Mechanical Design of RAM SO-DIMMsSdram Devices Conﬁguration of RAM SO-DIMMs Address Multiplexing RAM SO-DIMM Electrical LimitsVideo RAM Expansion Page Software Why Make This Change? What Has Changed Features of the New Approach RAM Footprint PerformanceUser Experience Data Structures and FilesBoot ROM Contents Rtas Mac OS ndrv DriversToolbox Image File Contents Trampoline Code NewWorld Boot ProcessToolBox ROM Image Interrupt Handling What Is DifferentRAM Footprint Outmoded ResourcesStartup Disk Control Panel NanoKernelInterrupt Layout Open Firmware and the Device TreeMachine Identiﬁcation Software Abbreviations Chrp NMI Page Index Nvram X, Y, Z Allen Watson