Small Signal Audio Design is a highly practical handbook providing an extensive repertoire of circuits that can be assembled to make almost any type of audio system. This fully revised third edition offers new chapters on tape machines, guitar electronics, and variable-gain amplifiers, plus much more new material.

Chapter 1: The BasicsSignalsAmplifiersVoltage amplifiersTransconductance amplifiersCurrent amplifiersTransimpedance amplifiersNegative feedbackNominal signal levels and dynamic range Frequency responseFrequency response: cascaded stagesPhase perceptionGain 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 voltageNoise in JFETsNoise in opampsNoise gainLow-noise opamp 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 amplifiersMultiple amplifiers for greater drive capabilityChapter 2: ComponentsConductorsCopper and other conductive elementsThe metallurgy of copperGold and its usesCable and wiring resistancePCB track resistancePCB track-to-track crosstalkThe 3-layer PCBImpedances and crosstalk: a case historyResistorsThrough-hole resistorsSurface-mount resistorsResistor seriesResistor accuracy: two resistor combinationsResistor accuracy: three resistor combinationsOther resistor combinationsResistor value distributionsThe uniform distributionResistor imperfectionsResistor excess noiseResistor non-linearityCapacitorsCapacitor seriesCapacitor non-linearity examinedNon-electrolytic capacitor non-linearityElectrolytic capacitor non-linearityInductorsChapter 3: Discrete transistor circuitryWhy 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 shunt-feedback stages: improving linearityTwo-transistor shunt-feedback stages: noiseTwo-transistor shunt-feedback stages: bootstrappingTwo-transistor shunt-feedback stages as summing amplifiersTwo-transistor series-feedback gain stagesDiscrete opamp designDiscrete opamp design: the input stageDiscrete opamp design: the second stageDiscrete opamp design: the output stageHigh input impedance bipolar stagesChapter 4: Opamps and their propertiesIntroductionA Very Brief History of Opamps. Opamp properties: noiseOpamp properties: slew rateOpamp properties: common mode rangeOpamp properties: input offset voltageOpamp properties: bias currentOpamp properties: costOpamp properties: distortionOpamp internal distortionSlew-rate limiting distortionDistortion due to loadingThermal distortionCommon-mode distortionCommon-mode distortion: Bipolar input opampsCommon-mode distortion: JFET opampsSelecting The Right OpampOpamps surveyed: BJT input typesThe LM741 opampThe NE5532/5534 opampDeconstructing the 5532The LM4562 opampThe AD797 opamp The OP27 opamp The OP270 opamp The OP275 opampOpamps surveyed: JFET input typesThe TL072 opampThe TL052 opampThe OPA2134 opamp The OPA604 opamp The OPA627 opampChapter 5: Opamps for low voltagesHigh Fidelity from Low VoltagesRunning opamps from a single +5V supply railOpamps for 5V operationThe NE5532 in +5V operationThe LM4562 in +5V operationThe AD8022 in +5V operationThe AD8397 in +5V operationOpamps for 3.3 V operationChapter 6: FiltersIntroductionPassive filtersActive filtersLow pass filtersHigh pass filtersCombined low pass & high pass filtersBandpass filtersNotch filtersAll-pass filtersFilter characteristics Sallen & Key lowpass filtersSallen & Key highpass filtersDistortion in Sallen & Key filtersMultiple-feedback bandpass filtersNotch filtersDifferential FiltersChapter 7: Preamplifier architecturesPassive preamplifiersActive preamplifiersAmplification and the gain-distribution problemActive gain controls plus passive attenuatorsRecording facilitiesTone controlsChapter 8: Variable gain stagesAmplifier stages with gain from unity upwards: single gain potAmplifier stages with gain from unity upwards: dual gain potCombining gain stages with active filtersAmplifier stages with gain from zero upwards: single gain potAmplifier stages with gain from zero upwards: dual gain potSwitched-gain amplifiersChapter 9: Moving-magnet inputs: levels & RIAA equalisationCartridge typesThe vinyl mediumSpurious signalsOther vinyl problems Maximum signal levels from vinylMoving-Magnet cartridge sensitivitiesOverload margins and amplifier limitationsEqualisation and its discontentsThe unloved IEC AmendmentThe ‘Neumann pole’MM amplifier configurationsOpamp MM input stagesCalculating the RIAA equalisation componentsImplementing RIAA equalisationImplementing the IEC amendment RIAA series-feedback network configurationsRIAA optimisation: C1 as a single E6 capacitor, 2xE24RIAA optimisation: C1 as 3x10nF capacitors, 2xE24RIAA optimisation: C1 as 4x10nF capacitors, 2xE24RIAA optimisation: the Willmann TablesRIAA optimisation: C1 as 3x10nF capacitors, 3xE24RIAA optimisation: C1 as 4x10nF capacitors, 3xE24Switched-gain MM RIAA amplifiers Switched-gain MM/MC RIAA amplifiers Open-loop gain and RIAA accuracyPassive and semi- passive RIAA equalisationMM cartridge loading & frequency responseMM cartridge-preamplifier interactionMM cartridge DC and AC couplingNoise in MM RIAA preamplifiersHybrid MM amplifiersBalanced MM inputsNoise in balanced MM inputsNoise weightingNoise measurementsCartridge load synthesis for lower noiseSubsonic filtersSubsonic filtering: Butterworth filtersSubsonic filtering: elliptical filtersSubsonic filtering by cancellationUltrasonic filtersA practical MM amplifier: #3Chapter 10: Moving-coil head amplifiersMoving-coil cartridge characteristicsThe limits on MC noise performanceAmplification strategiesMoving-coil transformersMoving-coil input amplifiersAn effective MC amplifier configurationThe complete circuitPerformanceChapter 11: Tape replayThe Return of TapeA brief history of tape recordingThe basics of tape recordingMultitrack recordingTape headsTape replayTape replay equalisationTape replay amplifiersReplay noise: calculationReplay noise: measurementsLoad synthesisNoise reduction systemsDolby HX-ProChapter 12: Guitar preamplifiersElectric guitar technologyGuitar pickupsPickup characteristicsGuitar wiringGuitar leadsGuitar preamplifiersGuitar preamplifier noise: calculationsGuitar preamplifier noise: measurementsGuitar amplifiers and guitar effectsGuitar direct injectionChapter 13: Volume controlsVolume controlsVolume control lawsLoaded linear potsDual-action volume controls Tapped volume controlsSlide fadersActive Volume controlsThe Baxandall active volume controlThe Baxandall volume control lawA practical Baxandall active volume stageLow-noise Baxandall active volume stagesThe Baxandall volume control: loading effectsAn improved Baxandall active volume stage with lower noiseBaxandall active volume stage plus passive controlThe Overlap PenaltyPotentiometers and DCBelt-ganged volume controlsMotorised potentiometersStepped volume controlsSwitched attenuator volume controlsRelay-switched volume controlsTransformer-tap volume controlsIntegrated circuit volume controlsLoudness controlsThe Newcomb and Young loudness controlChapter 14: Balance controlsThe ideal balance lawBalance controls: passiveBalance controls: activeCombining balance controls with other stagesSwitched balance controlsMono-stereo switchesWidth controlsChapter 15: Tone controls & equalisersIntroductionPassive tone controls Baxandall Tone ControlsThe Baxandall one-LF-capacitor Tone ControlThe Baxandall two-LF-capacitor Tone ControlThe Baxandall two-HF-capacitor tone controlThe Baxandall tone control: impedance and noiseCombining a Baxandall stage with an active balance controlSwitched-HF-frequency Baxandall controlsVariable-frequency HF EQVariable-frequency LF EQA new type of switched-frequency LF EQVariable-frequency HF and LF EQ in one stageTilt or tone-balance controlsMiddle controlsFixed frequency Baxandall middle controlsThree-band Baxandall EQ in one stageWien fixed middle EQWien fixed middle EQ: altering the QVariable-frequency middle EQSingle-gang variable-frequency middle EQSwitched-Q variable-frequency Wien middle EQSwitchable peak/shelving LF/HF EQParametric middle EQGraphic equalisersChapter 16: Mixer architectureIntroductionPerformance factorsMixer internal levelsMixer architectureThe split mixing architectureThe in-line mixing architectureA closer look at split format modulesThe channel module (split format)Effect return modulesThe group moduleThe master moduleTalkback and oscillator systemsThe in-line channel moduleChapter 17: Microphone preamplifiersMicrophone typesMicrophone preamplifier requirementsTransformer microphone inputsThe simple hybrid microphone preamplifierThe balanced-feedback hybrid microphone preamplifierMicrophone and line input padsThe padless microphone preamplifierCapacitor microphone head amplifiersRibbon microphone amplifiersChapter 18: Line inputsExternal signal levelsInternal signal levelsInput amplifier functionsUnbalanced inputsBalanced interconnectionsThe advantages of balanced interconnectionsThe disadvantages of balanced interconnectionsBalanced cables and interferenceBalanced connectorsBalanced signal levelsElectronic vs transformer balanced inputsCommon mode rejectionThe basic electronic balanced inputCommon-mode rejectionThe basic electronic balanced inputThe basic balanced input and opamp effectsOpamp frequency response effectsOpamp CMRR effectsAmplifier component mismatch effectsA practical balanced inputVariations on the balanced input stageCombined unbalanced and balanced inputsThe Superbal inputSwitched-gain balanced inputsVariable-gain balanced inputsCombined line input and balance control stage with low noiseThe Self variable-gain line inputHigh input-impedance balanced inputsThe inverting two-opamp inputThe instrumentation amplifierInstrumentation amplifier applicationsThe instrumentation amplifier with 4x gainThe instrumentation amplifier at unity gainThe instrumentation amplifier and gain controlsThe instrumentation amplifier and the Whitlock bootstrapTransformer balanced inputsInput overvoltage protectionLow-noise balanced inputsLow-noise balanced inputs in actionUltra-low-noise balanced inputsChapter 19: Line outputsUnbalanced outputsZero-impedance outputsGround-cancelling outputs: basicsGround-cancelling outputs: zero-impedance outputGround-cancelling outputs: CMRRGround-cancelling outputs: send amplifier noiseGround-cancelling outputs: into a balanced inputGround-cancelling outputs: historyBalanced outputs: basicsBalanced outputs: output impedanceBalanced outputs: noiseQuasi-floating outputsTransformer balanced outputsOutput transformer frequency responseOutput transformer distortionReducing output transformer distortionChapter 20: Headphone amplifiersDriving heavy loads Driving headphonesSpecial opamps Multiple opampsOpamp-transistor hybrid amplifiersDiscrete Class-AB headphone amplifiersDiscrete Class-A headphone amplifiersBalanced headphone amplifiersChapter 21: Signal switchingMechanical switchesInput-select switching: mechanicalThe Virtual Contact: mechanicalRelay switchingElectronic switchingSwitching with CMOS analogue gatesCMOS gates in voltage modeCMOS gates in current modeCMOS series-shunt current modeControl voltage feedthrough in CMOS gatesCMOS gates at higher voltagesCMOS gates at low voltagesCMOS gate costsDiscrete JFET switchingThe series JFET switch in voltage modeThe 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 JFETSChapter 22: Mixer subsystemsMixer bus systemsInput arrangementsEqualisationInsert pointsHow to move a circuit blockFadersImproving fader offnessPost-fade amplifiersDirect outputsPanpotsPassive panpotsThe active panpotLCR panpotsRouting systemsAuxiliary sendsGroup module circuit blocksSumming systems: voltage summingSumming systems: Virtual-earth summing Balanced summing systemsGround-cancelling summing systemsDistributed summing systemsSumming amplifiersHybrid summing amplifiersBalanced hybrid summing amplifiers Balancing tracks to reduce crosstalkThe multi-function summing amplifier PFL systemsPFL summingPFL switchingPFL detectionVirtual-earth PFL detectionAFL systems Solo-In-Place systemsTalkback microphone amplifiersLine-up oscillatorsThe flash busPower supply protectionConsole cooling and component lifetimesChapter 23: Level indication & meteringSignal-present indicationPeak indicationThe Log Law Level LED (LLLL)Distributed peak detectionCombined LED indicatorsVU metersPPM metersLED bargraph meteringA more efficient LED bargraph architectureVacuum fluorescent displaysPlasma displaysLiquid crystal displaysChapter 24: Level control & special circuits Gain-control elementsA brief history of gain-control elementsJFETsOperational transconductance amplifiers (OTAs)Voltage-Controlled Amplifiers (VCAs)Compressors and limitersAttack artefactsDecay artefactsSubtractive VCA controlNoise gatesClippingDiode clippingActive clipping with transistorsActive clipping with opampsNoise generatorsPinkening filtersChapter 25: Power supplies Opamp supply rail voltagesDesigning a ±15V supplyDesigning a ±17V supplyUsing variable-voltage regulatorsImproving ripple performanceDual supplies from a single windingPower supplies for discrete circuitryLarge power suppliesMutual shutdown circuitryVery Large power suppliesMicrocontroller and relay supplies+48V phantom power suppliesChapter 26: Interfacing with the digital domainPCB layout considerationsNominal levels and ADCsSome typical ADCsInterfacing with ADC inputsSome typical DACsInterfacing with DAC outputsInterfacing with microcontrollers

"Self provides solid, well-explained technical information throughout the book, all gained from years of experience and a thorough understanding of the entire topic (...) His book exudes skilful engineering on every page, and I found it a very refreshing, enjoyable, and inspirational read (...) if you have the slightest interest in audio circuit design this book has to be considered an essential reference. Very highly recommended." - Hugh Robjohns, Sound on Sound Magazine"This book presents a large body of knowledge and countless insider-tips from an award-winning commercial audio designer (...) Douglas Self dumps a lifetime's worth of thoroughly-tested audio circuit knowledge into one biblical tome." - Joseph Lemmer, Tape Op