book

Small- Signal Audio Design

by Douglas Self

July 2013

Intermediate to advanced

486 pages

17h 2m

English

Focal Press

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SignalsAmplifiersVoltage AmplifiersTransconductance AmplifiersCurrent AmplifiersTransimpedance AmplifiersNegative FeedbackNominal Signal LevelsGain StructuresAmplification Then AttenuationAttenuation Then AmplificationRaising the Input Signal to the Nominal LevelActive Gain ControlsNoiseJohnson NoiseShot Noise1/f Noise (Flicker Noise)Popcorn NoiseSumming Noise SourcesNoise in AmplifiersNoise in Bipolar TransistorsBipolar Transistor Voltage NoiseBipolar Transistor Current NoiseNoise in JFETsNoise in Op-AmpsLow-Noise Op-Amp CircuitryNoise MeasurementsHow to Attenuate QuietlyHow to Amplify QuietlyHow to Invert QuietlyHow to Balance QuietlyUltra-Low-Noise Design with Multipath AmplifiersUltra-Low-Noise Voltage BuffersUltra-Low-Noise AmplifiersReferences
ConductorsCopper and Other Conductive ElementsThe Metallurgy of CopperGold and Its UsesCable and Wiring ResistancePCB Track ResistancePCB Track-to-Track CrosstalkImpedances and Crosstalk: A Case HistoryResistorsThrough-Hole ResistorsSurface-Mount ResistorsResistor ImperfectionsResistor NoiseResistor Non-LinearityCapacitorsCapacitor Non-Linearity ExaminedNon-Electrolytic Capacitor Non-LinearityElectrolytic Capacitor Non-LinearityInductorsReferences

Why Use Discrete Transistor Circuitry?Bipolars and FETsBipolar Junction TransistorsThe Transistor EquationBetaUnity-Gain Buffer StagesThe Simple Emitter-FollowerThe Constant-Current Emitter-FollowerThe Push-Pull Emitter-FollowerEmitter-Follower StabilityCFP Emitter-FollowersImproved Unity-Gain BuffersGain StagesOne-Transistor Shunt-Feedback Gain StagesOne-Transistor Series-Feedback Gain StagesTwo-Transistor Shunt-Feedback Gain StagesTwo-Transistor Series-Feedback Gain StagesDiscrete Op-Amp DesignHigh-Input-Impedance Bipolar StagesReferences
A Very Brief History of Op-AmpsOp-Amp Properties: NoiseOp-Amp Properties: Slew RateOp-Amp Properties: Common-Mode RangeOp-Amp Properties: Input Offset VoltageOp-Amp Properties: Bias CurrentOp-Amp Properties: CostOp-Amp Properties: DistortionOp-Amp Internal DistortionSlew-Rate-Limiting DistortionDistortion Due to LoadingThermal DistortionCommon-Mode DistortionBipolar input op-ampsFET op-ampsRail bootstrapping to reduce CM distortionSimpler rail bootstrappingBootstrapping series-feedback JFET op-amp stagesSelecting the Right Op-AmpOp-Amps Surveyed: BJT Input TypesThe LM741 Op-AmpThe NE5532/5534 Op-AmpDeconstructing the 5532The LM4562 Op-AmpThe AD797 Op-AmpThe OP27 Op-AmpThe OP270 Op-AmpThe OP275 Op-AmpOp-Amps Surveyed: JFET Input TypesThe TL072 Op-AmpThe TL052 Op-AmpThe OPA2134 Op-AmpThe OPA604 Op-AmpThe OPA627 Op-AmpReferences
Passive FiltersActive FiltersLow-Pass FiltersHigh-Pass FiltersCombined Low-Pass and High-Pass FiltersBandpass FiltersNotch FiltersAll-Pass FiltersFilter CharacteristicsSallen-and-Key FiltersDistortion in Sallen-and-Key FiltersMultiple-Feedback Bandpass FiltersMaking Notch FiltersDifferential FiltersReferences
Passive PreamplifiersActive PreamplifiersAmplification and the gain-distribution problemActive Gain ControlsRecording FacilitiesTone ControlsReferences
The Vinyl MediumSpurious SignalsMaximum Signal Levels on VinylEqualization and Its DiscontentsThe ‘Neumann Pole’Implementing RIAA EqualizationPassive and Semi-Passive RIAA EqualizationCalculating the RIAA Equalization ComponentsRIAA Equalization Component TolerancesSimulating Inverse RIAA EqualizationPhysical Inverse RIAA EqualizationOverload MarginsCartridge ImpedancesCartridge LoadingCartridge–Preamplifier InteractionCartridge DC and AC CouplingDiscrete MM Disc Input StagesOp-Amp MM Disc Input StagesNoise in RIAA PreamplifiersNoise Results with A-WeightingRIAA Noise MeasurementsElectronic Cartridge Loading for Lower NoiseSubsonic FiltersCombining Subsonic and Ultrasonic FiltersReferences
Moving-Coil Cartridge CharacteristicsAmplification StrategiesMoving-Coil TransformersMoving-Coil Input AmplifiersA New Moving-Coil Amplifier ConfigurationThe Complete CircuitPerformanceReferences
Volume ControlsVolume Control LawsLoaded Linear PotsDual-Action Volume ControlsTapped Volume ControlsSlide FadersActive Volume ControlsThe Baxandall Active Volume ControlA Practical Baxandall Active Gain StagePotentiometers and DCMotorized PotentiometersStepped Volume ControlsSwitched Attenuator Volume ControlsRelay-Switched Volume ControlsTransformer-Tap Volume ControlsIntegrated Circuit Volume ControlsBalance Controls: PassiveActive Balance ControlsMono/Stereo SwitchesWidth ControlsReferences
Passive Tone ControlsBaxandall Tone ControlsThe Baxandall Two-Capacitor LF ControlThe Baxandall Two-Capacitor Tone ControlThe Baxandall Two-Capacitor HF ControlSwitched-Frequency Baxandall ControlsVariable-Frequency LF and HF EQsTone-Balance ControlsMiddle ControlsFixed-Frequency Baxandall Middle ControlsThree-Band Baxandall EQ in One StageWien Fixed Middle EQSweep MiddlesThe Single-Gang Sweep MiddleSwitched-Q Variable-Frequency Wien Middle EQsSwitchable Peak/Shelving LF/HF EQsParametric Middle EQsGraphic EqualizersReferences
Architecture and PhilosophyThe Line InputsThe High-Impedance Input BufferThe Tone-Control StageThe Active Gain StagePerformanceReferences
Performance FactorsMixer Internal LevelsMixer ArchitectureThe Split Mixing ArchitectureThe In-Line Mixing ArchitectureA Closer Look at Split-Format ModulesThe Channel Module (Split Format)Effects Return ModulesThe Group ModuleThe Master ModuleTalkback and Oscillator SystemsThe In-Line Channel Module
Microphone Preamplifier RequirementsTransformer Microphone InputsThe Simple Hybrid Microphone PreampilifierThe Balanced-Feedback Hybrid Microphone PreampilifierMicrophone and Line-Input PadsThe Padless Microphone PreampilifierCapacitor Microphone Head Amplifiers
External Signal LevelsInternal Signal LevelsInput Amplifier FunctionsUnbalanced InputsBalanced InterconnectionsThe Advantages of Balanced InterconnectionsThe Disadvantages of Balanced InterconnectionsBalanced Cables and InterferenceElectrostatic CouplingMagnetic CouplingGround VoltagesBalanced ConnectorsBalanced Signal LevelsElectronic vs. Transformer Balanced InputsCommon-Mode RejectionThe Basic Electronic Balanced InputCommon-Mode Rejection: The Basic Balanced Input and Op-Amp EffectsOp-Amp Frequency Response EffectsOp-Amp CMRR EffectsAmplifier Component Mismatch EffectsA Practical Balanced InputVariations on the Balanced Input StageCombined Unbalanced and Balanced InputsThe Superbal InputSwitched-Gain Balanced InputsVariable-Gain Balanced InputsHigh-Input-Impedance Balanced InputsThe Inverting Two-Op-Amp InputThe Instrumentation AmplifierTransformer Balanced InputsInput Overvoltage ProtectionLow-Noise Balanced InputsLow-Noise Balanced Inputs in Real LifeUltra-Low-Noise Balanced InputsReferences
Unbalanced OutputsZero-Impedance OutputsGround-Canceling OutputsBalanced OutputsQuasi-Floating OutputsTransformer Balanced OutputsDriving Heavy LoadsReference
Mechanical SwitchesInput-Select SwitchingThe Virtual ContactRelay SwitchingElectronic SwitchingSwitching with CMOS Analog GatesCMOS Gates in Voltage ModeCMOS Gates in Current ModeSeries-Shunt Current ModeControl Voltage Feedthrough in CMOS GatesDiscrete JFET SwitchingJFETs in Voltage Mode: The Series JFET SwitchThe Shunt JFET Switch in Voltage ModeJFETs in Current ModeReducing Distortion by BiasingJFET Drive CircuitryPhysical Layout and OffnessDealing with the DC ConditionsA Soft Changeover CircuitControl-voltage feedthrough in JFETsReference
Mixer Bus SystemsInput ArrangementsEqualizationInsert PointsHow to Move a Circuit BlockFadersPostfade AmplifiersDirect OutputsPanpotsPassive PanpotsThe Active PanpotLCR PanpotsRouting SystemsAuxiliary SendsGroup Module Circuit BlocksSumming SystemsVoltage SummingVirtual-Earth SummingBalanced Summing SystemsGround-Canceling Summing SystemsDistributed Summing SystemsSumming AmplifiersHybrid Summing AmplifiersBalanced Hybrid Summing AmplifiersPFL SystemsPFL SummingPFL SwitchingPFL DetectionVirtual-Earth PFL DetectionAFL SystemsSolo-in-Place SystemsTalkback Microphone AmplifiersLine-Up OscillatorsConsole Cooling and Component Lifetimes
Signal-Present IndicationPeak IndicationDistributed Peak DetectionCombined LED IndicatorsVU MetersPPM MetersLED Bar-Graph MeteringA More Efficient LED Bar-Graph ArchitectureVacuum Fluorescent DisplaysLCD Meter Displays
Gain-Control ElementsA Brief HistoryJFETsOperational Transconductance AmplifiersVoltage-Controlled AmplifiersCompressors and LimitersAttack ArtefactsDecay ArtefactsSubtractive VCA ControlNoise GatesClippingDiode ClippingActive Clipping with TransistorsActive Clipping with Op-AmpsNoise GeneratorsPinkening FiltersReferences
Op-Amp Supply-Rail VoltagesDesigning a ±15 V SupplyDesigning a ±17 V SupplyUsing Variable-Voltage RegulatorsImproving Ripple PerformanceDual Supplies From a Single WindingPower Supplies for Discrete CircuitryLarger Power SuppliesMutual Shutdown CircuitryVery Large Power SuppliesMicrocontroller and Relay Supplies+48 V Phantom Power SuppliesReference
PCB Layout ConsiderationsNominal Levels and ADCsSome Typical ADCsInterfacing with ADC InputsSome Typical DACsInterfacing with DAC Outputs

Content preview from Small- Signal Audio Design

Chapter 15

Line Outputs

Unbalanced Outputs

There are only two electrical output terminals for an unbalanced output – signal and ground. However, the unbalanced output stage in Figure 15.1(a) is fitted with a three-pin XLR connector, to emphasize that it is always possible to connect the cold wire in a balanced cable to the ground at the output end and still get all the benefits of common-mode rejection if you have a balanced input. If a two-terminal connector is fitted, the link between the cold wire and ground has to be made inside the connector, as shown in Figure 14.2 in the chapter on line inputs.