Index
Note: Page numbers in italic indicate a figure and page numbers in bold indicate a table on the corresponding page.
1/f noise (flicker noise) 20–21, 25–26
2N4403 transistor 288
2N5457 transistor 686
2N5459 transistor 686
2SB737 transistor 28, 28; moving-magnet inputs 258–260, 258, 266–267, 266; tape replay 303–304, 303
3.3 V single-rail operation 176–178
+5 V supply rail 167–176, 176, 178
±17 V power supply 723
+48 V phantom power supplies 731–732
4000 series analogue gates 580, 580
4016 analogue gates 579–583, 581–582, 590–593, 591–593, 653, 685
4066 analogue gates 581–585, 583, 585, 587, 587, 591–593, 593
7824/7924 integrated circuits 272
AC 81–83, 284–287, 292–293, 721–723; MM cartridge DC and AC coupling 255
active balance controls 386–387; and Baxandall stage 409
active clipping: feedforward 711–713; with opamps 706; transistors 703–705
active gain controls 196–197; plus passive attenuators 197
active panpot 625–627, 626–627, 630, 633
active preamplifiers 194, 386, 483
active volume controls 339–343
AD797 opamp 128–130, 129–130, 151, 152, 531, 531–532
AD1854 DAC 738
AD1871 ADC 735
AD8022 168; in +5 V operation 171–172, 171, 178
AD8397 177–178, 177–178: in +5 V operation 172–176, 176
AFL systems 658
all-pass filters 182
Ambler concept 424
amplification: moving-coil head amplifiers 281, 283; and the gain-distribution problem 195; quiet 34; strategies 281; see also amplifiers
amplifiers 2; amplifying stages 199–204, 206–210; CA3080E 688–689; component mismatch effects 497–500; current 2; dual-gain pot 203–204, 209–210; an effective MC amplifier configuration 285–286; guitar 322; hybrid MM amplifiers 262; hybrid summing 646–650; instrumentation 514–521, 514, 516, 518, 520–521; Johnson noise 17–18; limitations 224; line inputs 482; LM13600 689; MM amplifier configurations 227–228; moving-coil input amplifiers 283–284; multiple 40; Neumann SAL 74B; noise 22–23, 280, 572; post-fade 617–618; a practical MM amplifier 273–278; Radford HD250 196; single-gain pot 199–202, 206–208; stereo power 52; summing 115–116, 643–651; switched-gain 211–214; tape replay 300–301; transconductance 2; transimpedance 3; voltage 2; see also headphone amplifiers; opamps; summing amplifiers
analogue-to-digital converters (ADCs) 733–737
attack artefacts 695
attenuation: then amplification 15, 15; quiet 32–33
attenuator volume controls 362–371
Audio Note cartridge 279
Audio Precision (AP) SYS-2702 measuring system 32, 93, 102, 120–121, 138, 149, 351
Augustadt, Herbert 189
auxiliary sends: mixer sub-systems 634
bainter filters 190–191, 190, 272
balance controls: active 386–387; combining balance controls with other stages 388; ideal balance law 381–383; mono/stereo switches 391; passive 383–385; switched 388–390; width controls 392–394
balanced connectors 489
balanced-feedback hybrid microphone preamplifier (BFMA) 469
balanced headphone amplifiers 572–574
balanced hybrid summing amplifiers 649
balanced inputs: cables and interference 487–488; combined line input and balance control stage with low noise 509; combined unbalanced/balanced 504; connectors 489; ground-cancelling outputs 547; high input-impedance balanced inputs 511–512; instrumentation amplifier 514–522; interconnections 485–490; inverting two-opamp 513; MM 263–264; practical 501–503; self variable-gain line input 510; signal levels 489; superbal input 505; switched-gain 506; variable-gain 507–508
balanced interconnections 485; advantages of 486; disadvantages of 487
balanced signal levels 489
balanced summing systems 637
band-pass filters 181; multiple-feedback 188
Baxandall, Peter 246, 251–253, 253, 344
Baxandall active volume control 344; improved volume stage with lower noise 352–353; loading effects 350–351; low-noise Baxandall active volume stages 347–349; passive control 354–355; a practical Baxandall active volume stage 345–346; volume control law 344
Baxandall tone controls: combining a Baxandall stage with an active balance control 409; fixed frequency middle controls 425–427; impedance and noise 406–408; one-LF-capacitor tone control 397–402; switched-HF-frequency 410–411; three-banded EQ in one stage 428–429; two-HF-capacitor tone control 404–405; two-LF-capacitor tone control 403
BBC 292, 362, 392, 505, 678, 696
belt-ganged volume controls 359
Benet, Stephen Vincent 719
Bessel filters 179, 182–185, 183–184, 184, 739
beta (hfe) ratio 88
bias current 131–132, 132, 484–485
bipolar junction transistors (BJTs) 86, 144; +48 V phantom power supplies 731–732
bipolar transistors: current noise 25–28; and FETs 86; noise 24; voltage noise 25
Blackmer, David 690
blue noise 17
Boctor filter 191
bootstrapping: collector 106–107, 107, 112–114, 124–125, 124; junction field-effect transistors 476, 593–598, 594; supply rail 113
bridged-differentiator notch filter 190–191, 190
bridging impedance 455
broadcast consoles 450–451, 652, 698
bus: residual 115–116, 115, 636, 645–646, 645; trim control 453, 462, 464
cables: balanced 487–488; braided screen 487–488; mercury 45–46; overlapping foil screen 487; ribbon 611–613, 635, 649, 658; wiring resistance 46
Cambridge Audio 388; 840A integrated amplifier 371; 840E preamplifier 363, 371; 840W power amplifier 530; P50 integrated amplifier 255, 343
cancellation 272
capacitance: impedance and crosstalk 52–53; Johnson noise 17–18; PCB track-to-track crosstalk 49–52, 49–50; resistors 52–53, 73–75, 499–501, 633–634
capacitors 73–82; blocking 74–75, 229–230, 502–504; capacitor microphone head amplifiers 476–477; ceramic 74, 734; decoupling 74, 157, 647, 667, 680, 720–724; electrolytic capacitor non-linearity 80–82; input sampling 736; leakage 73; non-electrolytic capacitor non-linearity 75–79; non-linearity 75; polyester 76–79, 76, 77, 187–188, 188; polyethylene terephthalate (PET) 75; polypropylene 74–75, 270–272; polystyrene 74–75; properties 73–74; reservoir 721–727; series 74; tan-δδ (tan-delta) 73
carbon composition resistors 53, 65
carbon-film resistors 53, 67–70, 69
cartridges: cartridge–preamplifier interaction 254; cartridge types 215; DC/AC coupling 255; frequency response 253; impedances 226–229, 254–260, 279–282, 285–287, 316–318; loading 253; load synthesis for lower noise 266–267; moving-coil cartridge characteristics 279; sensitivities 223
CAST see Current Audio Signal Transmission
CBS (broadcaster) 676
channel modules: group module circuit blocks 634–635; in-line 462–464; routing 462, 653; split-format 455–461
Chebyshev (elliptical) filter 179, 182
circuit block 15–16, 614, 634, 674–675, 675
clipping: active clipping with opamps 706; active clipping with transistors 703–705; biased diode 702; by clamping 706–707; diode 700–702, 702; feedforward 711–713; negative-feedback 708–711; opamps 481–482, 518–519, 669–670, 700–701, 706–713; soft 322, 662; transistors 90–91, 714–715
CMOS analogue gates 580; control voltage feedthrough 590; costs 592; current mode 588; at higher voltages 591; at low voltages 591; series-shunt current mode 589; voltage mode 581–587
collector bootstrapping 125
Columbia (record label) 215
combined LED indicators 676
combined low-pass/high pass filters 181
combined unbalanced/balanced inputs 504
common-mode (CM) distortion 136–142; bipolar input opamps 137–140; JFET opamps 141–142
common mode (CM) range for opamps 130
common-mode rejection 490–492; basic balanced input and opamp effects 495; basic electronic balanced input 493–494; line inputs 490–495; opamps 495
complementary feedback pair (CFP): configuration 88, 95–96, 98, 117; constant-current 88, 96–97, 99; emitter-followers 96–98, 96–97; parametric middle EQs 441; two-transistor series feedback gain 117
component lifetimes in mixer subsystems 666–668
components see specific components
compressors/limiters 691–694; attack artefacts 695; combination; decay artefacts 696; subtractive VCA control 697
conductors 43–48; cables 46; copper 43–45; gold 46; PCB track resistance 47–48; properties 44, 44; silver 44, 44; wire resistance 46
consoles: broadcast 450–451, 652, 698; cooling in mixer subsystems 666–668
constantan 44
control interaction 397, 410, 413, 428, 433
control law: balance controls 389; gain 196–197, 201, 209; level control and special circuits 686, 691; microphone preamplifiers 467, 475; mixer sub-systems 617; tone controls and equalisers 409; volume controls 325–331, 334–339, 341–345, 352, 354, 357, 379
control-room monitor (CRM) 452–453, 460
cooling: electronic 666; fan 729
copper: balanced cables and interference 488; conductors 45; metallurgy 45–46; mixing bus systems 51, 612; moving-coil transformers 44; PCB track resistance 47–48; properties 44, 44
correlated noise 531
cost of opamps 132
crosstalk 52; balancing tracks 650–651; impedances 52; inductors 83, 488; input-select switching 575–577; inter-bus 116, 636
Current Audio Signal Transmission (CAST) 1
current-carrying capacity 46
current feedback amplifiers (CFAs) 2
current-mode connections 1
current source: Johnson noise 17–18; transconductance amplifiers 117, 689
DC: discrete JFET switching 607; drain resistors 230, 484–485, 503, 510; MM cartridge DC and AC coupling 255; potentiometers 359; see also DC blocking capacitors
DC blocking capacitors 74; line inputs 504, 510; line outputs 535; microphone preamplifiers 469, 471, 475; mixer sub-systems 617, 646; moving-magnet inputs 255–256, 275; opamps for low voltages 168; signal switching 607; tone controls and equalisers 422; variable gain stages 206
decay artefacts 696
decoupling capacitors 74, 157, 647, 667, 680, 720–724
“destructive solo” 660
differential amplifier array 528, 530, 532
differential filters 191
digital domain interface: analogue-to-digital converters 733; interfacing with ADC inputs 735–737; interfacing with DAC outputs 738–739; interfacing with microcontrollers 740–743; nominal levels and ADCs 734; PCB layout considerations 733; typical ADCs 735; typical DACs 738
digital-to-analogue converters (DACs) 2–3, 180, 191, 733–734, 738–740
DIN interconnection standard 1, 485, 489–490, 494, 547
direct outputs in mixer subsystems 619
discrete circuitry and power supplies 727
discrete class-A headphone amplifiers 570
discrete class-AB headphone amplifiers 566–569
discrete JFET switching: advantages 593; control voltage feedthrough in 609–610; current mode 600–602; DC conditions 607; drive circuitry 605; physical layout and offness 606; reducing distortion by biasing 603–604; series JFET switch in voltage mode 593–598; shunt JFET switch in voltage mode 599; soft changeover circuit 608; voltage mode 593–599
discrete transistor circuitry 85; beta 88; bipolars/FETs 86; bipolar junction transistors 86; discrete opamp design 117–121; high-input-impedance bipolar stages 122–125; reasons for use 123; transistor equation 87; see also discrete transistor circuitry (gain stages); discrete transistor circuitry (unity-gain buffer stages)
discrete transistor circuitry (gain stages) 103; one-transistor series-feedback gain stages 103–104; one-transistor shunt-feedback gain stages 103; two-transistor series-feedback gain stages 117; two-transistor shunt-feedback gain stages 105–116
discrete transistor circuitry (unity-gain buffer stages) 88; CFP emitter-followers 96–97; constant-current emitter-follower 92; emitter-follower stability 95; improved unity-gain buffers 98–102; push-pull emitter-follower 93–94; simple emitter-follower 88–91
distortion 555–560; biasing 603–604; bipolar input opamps 137–140; common-mode distortion 136–142; JFET opamps 141–142; loading 136; opamp internal distortion 135; opamps 133–142; operational transconductance amplifiers 688–689; Sallen-and-Key filters 187; slew-rate limiting distortion 135; thermal distortion 136
distributed gain control 196, 331
distributed peak detection 674–675
distributed summing systems 640–642
dominant-pole compensation 254, 263
dual-action volume controls 331–333
dual-gain pot 203–204, 209–210
dual supplies from a single winding (power) 726
E3 capacitor 745
E12 resistor 745
Early, Jim 87
Early Effect 87, 118, 125, 141
Ebers-Moll transistor equation 87
effects return (split-format) 464
efficient LED bar-graph architecture 680–682
Einstein, Albert 19
electric guitar see guitar preamplifiers
electrolytic capacitors 9–10, 75–76, 76, 80–83, 80–82
electrolytic tough pitch (ETP) copper 45
electronic balanced line inputs 490
electronic cooling 666
electronic switching 579
electronic versus transformer balanced inputs 490
electrostatic coupling 488, 670, 730
emitter-follower (EF) circuits 89; CFP 95–101; constant-current 88, 92, 94, 96–97, 99, 102; push-pull 88, 93–97, 100, 122, 224; simple 88–91; stability 95
endstop resistor see under resistors
equalisation 225; mixer sub-systems 612; tape replay 297–299
equalisers (EQs): graphic 443–448; new type of switched-frequency LF EQ 415; parametric middle EQ 440–442; single-gang variable-frequency middle EQ 435–438; switchable peak/shelving LF/HF EQ 439; switched-Q variable-frequency Wien middle EQ 438; three-band Baxandall EQ in one stage 428–429; variable-frequency HF EQ 412–413; variable-frequency HF and LF EQ in one stage 416–421; variable-frequency LF EQ 414; variable-frequency middle EQ 433–434; Wien fixed middle EQ 430–432
equivalent input noise (EIN) 24; discrete transistor circuitry 109, 112; guitar preamplifiers 317–321; headphone amplifiers 566, 572; line inputs 515, 522; microphone preamplifiers 468, 475; moving-coil head amplifiers 288; moving-magnet inputs 256–261, 265–266; tape replay 303; variable gain stages 200
equivalent series resistance (ESR) 73, 283, 667
evaluation boards 734
excess resistor noise 68–69, 69
external signal levels 481
fader flip 455
faders 615–617; mixer sub-systems 616; linear 361, 457–458, 690; short 454, 464; slide 336–338, 615, 672
fader-start switches 338
Fairchild μA709 opamp 127
fan cooling 729
feedforward 307, 616, 616, 694–696, 696; clipping 711–713
field-effect transistors (FETs): balanced summing systems 638; CMOS analogue gates 580, 586, 591, 600; control voltage feedthrough 591; noise gates 698–700, 699; see also junction field-effect transistors (JFETs)
filters 179; active 180; all-pass 182; Bainter 190, 190, 272; band-pass 181; Bessel 179, 182–195, 739; Boctor 191; Butterworth 182–186, 268–272; characteristics 182; Chebyshev (elliptical) 179, 182; combined low-pass/high pass 181; differential 191; high-pass 180, 185–186; low-pass 180, 182–184; multiple-feedback 188; notch 181, 189–190; passive 179; pinkening 715–717; radio frequency 273; roofing 179–180, 482; Sallen-and-Key 182–187; state variable 442; subsonic 233–234, 268–275; subsonic/ultrasonic combination 181, 273; third order 186–187, 269–270, 374, 455
First Law of Thermodynamics 19
fixed frequency Baxandall middle controls 425–427
flicker noise see 1/f noise
foldback 451–452, 457, 459, 461
four-layer summing 643
frequency response 6–10, 554; all-pass filters 182, 395; Bessel filters 182–184, 184, 184; Butterworth filters 182–184, 183–184, 184, 227, 269, 271, 271; cascaded stages 6–10; electrolytic capacitors 74, 81, 81, 187, 422; equalisation 225–227, 303–304; high-pass filters 182, 187, 187; MM cartridge 253; moving-coil transformers 281; negative feedback 409–410; non-electrolytic capacitors 10, 187; notch filters 189; opamps 182–183, 312–313, 443–445, 496; output transformer 554; RIAA amplifiers 74; Sallen-and-Key filters 182–183, 187, 189; ultrasonic filters 184; vinyl 219; violet noise 17
front-of-house (FOH) mixer 451
gain-control elements: history 685; junction field-effect transistors (JFETs) 685–687; operational transconductance amplifiers (OTAs) 688; voltage controlled amplifiers (VCAs) 689–691
gain-distribution problem 195
gain law: variable gain stages 199–203, 201, 203, 206–207, 207, 210, 212; volume controls 346, 356
gain stages 199–214; one-transistor series-feedback gain stages 103–104; one-transistor shunt-feedback 103; opamps 103, 147–148, 199–200; two-transistor series-feedback gain stages 117; two-transistor shunt-feedback 105–116
gain structures 14–16; active gain controls 16; amplification then attenuation 14; attenuation then amplification 15; raising the input signal to the nominal level 15
galvanic isolation 84, 487, 489–490, 553, 579
Gaumont, Leon 620
Gershwin’s Law (“it ain’t necessarily so”) 43, 91
Gilbert, Barrie 88
gold plating 46
graphic equalisers 443–448; constant-Q 445; LCR filters 83; proportional-Q 445
grey noise 17
green noise 17
ground-canceling outputs 543–549
ground-canceling summing systems 638–639
ground plane 50–51, 611, 634, 734
ground voltages 494, 543–544, 548, 638, 642
group modules: circuit blocks 634; split-format 458
guitar preamplifiers: electric guitar technology 311; guitar amplifiers 322; guitar direct injection 323–324; guitar effects 322; guitar leads 314; guitar pickups 311; guitar preamplifiers 315–321; guitar wiring 313; pickup characteristics 312
headphone amplifiers: balanced 572–574; discrete class-A 570–572; discrete class-AB 566–569; driving headphones 561; driving heavy loads 561; multiple opamps 562–563; opamp-transistor hybrid 564–565; special opamps 562
heat sinks 25, 54, 566, 570, 722, 729–730
heavy loads 40, 155, 283, 407, 520, 554, 561
hi-fi preamplifiers xxv, 325, 395, 599, 621–623
high frequency (HF) correction pole 224–225, 228, 231–233, 232, 236–238, 237–238, 246–248, 273–275, 274
high-input impedance amplifiers 122
high-input-impedance bipolar stages 122–125
high-impedance inputs 1, 124, 156
high-pass filters 180; Sallen and Key 185–186
Hitachi Cable company 45
Holman, Tomlinson 218, 221, 225–226, 254, 373–374, 379
hybrid microphone preamplifier 468–469
hybrid MM amplifiers 262
hybrid summing amplifiers 646–648
hysteresis 669
IEC 98 standard 226
IEC 60098 standard 226
IEC Amendment 226; implementing 233
impedances 52; bridging 455, 512; crosstalk 484–485, 536–537, 575–579, 635–639, 650–651
in-line channel module (mixer architectures) 462–464
in-line mixing architectures 453–454
inductance 65–67; guitar preamplifiers 311–314, 317–321; line outputs 554–556; moving-coil head amplifiers 279–281; moving-magnet inputs 228–229, 253–257; tape replay 292–297, 303–305
inductors 83–84, 179–180, 444–445
input: amplifier functions 482; bias current 131; and ground-cancelling outputs 548; high-input-impedance bipolar stages 122–125; input-select switching 575–576; interfacing with ADC inputs 735–737; microphone and line input pads 470; mixer sub-systems 612; moving-coil input amplifiers 383–384; offset voltage 131; opamps 118–119, 131, 137–140, 144, 156–165, 229, 495, 513; overvoltage protection 524; sampling capacitors 736–738; selector switch 193–194, 325, 483; signal and nominal level 15; transformer microphone inputs 466–467; see also line inputs; moving-magnet (MM) inputs
input-select switching: mechanical 575–576
insert: points 612–614, 457, 464; return 458; send 458–459, 613–614, 619, 643–644, 644
integrated circuit volume controls 372
internal signal levels 481
instrumentation amplifier 514–522
insulation-displacement connectors (IDCs) 611, 636, 665, 720
integrated circuits (ICs) 21, 32, 360–362, 372; volume controls 372
interfacing with digital domain: interfacing with ADC inputs 735–737; interfacing with DAC outputs 738–739; interfacing with microcontrollers 740–744; nominal levels and ADCs 734; PCB layout considerations 733; typical ADCs 735; typical DACs 738
internal signal levels 5, 450, 481, 490
intrinsic emitter resistance 24–25, 89
inversion, quiet 35
inverting two-opamp input 513
JFETs see junction field-effect transistors (JFETs)
Johnson, John B. 17
Johnson noise 16–20, 67–68; guitar preamplifiers 316–317; how to amplify quietly 34; how to attenuate quietly 32–33, 33; how to invert quietly 35; line inputs 484–485, 505–506, 511–514; microphone preamplifiers 473–475; mixer sub-systems 636–37, 639–640; moving-coil head amplifiers 282–283; moving-magnet inputs 227–230, 232–233, 256–259, 266–267; noise in amplifiers 24; noise in bipolar transistors 25–28, 27; noise gain 31; noise in JFETs 29–30; noise measurements 32; opamps and their properties 131–132, 141–143; preamplifier architectures 194–195; tape replay 300–303; ultra-low-noise design with multi-path amplifiers 36, 38, 40
junction field-effect transistors (JFETs) 28, 258; common-mode distortion 141–142; control voltage feedthrough in 609–610; in current mode 600–602; drive circuitry 605; gain-control elements 685–687; input types 156–165; mixer sub-systems 663–664; noise in 29–31; opamps and their properties 127–129, 129, 143–144, 147–148; series JFET switch in voltage mode 593–598; shunt JFET switch in voltage mode 599; signal switching 603–604, 606–608; tape replay 305–306
larger power supplies 728
Late Effect 87
laws: ideal balance law 381–382; sine/sine squared 620–621, 620; thermodynamics 19; volume controls 325–327
leads 314
leakage from capacitors 18, 73, 168
Left-Center-Right (LCR): filters 83, 179–180; graphic equalizers 83, 443–444; panpots 628–629
level control and gain-control elements 685–691, 694–695
level control and special circuits: active clipping with opamps 706; active clipping with transistors 703–705; clipping by clamping 706–707; compressors and limiters 692–697; diode clipping 700–702; feedforward clipping 711–713; gain-control elements 685–691; negative-feedback clipping 708–710; noise gates 698–699; noise generators 714; pinkening filters 715–717
level indication: combined LED indicators 676; distributed peak detection 674–675; LED bar-graph metering 678–679; liquid crystal displays 684; Log Law Level LED (LLLL) 213, 672–673; a more efficient LED bar-graph architecture 680–682; peak indication 670–671; plasma displays 683; PPMs 678; signal-present indication 669; vacuum fluorescent displays 683; VU meters 676–677
light emitting diodes (LEDs) 653–656, 664–666, 669–671; bar-graph metering 678–679; combined LED indicators 676; Log Law Level LED (LLLL) 672–673; more efficient bar-graph architecture 680–682
linear faders 361, 457–458, 690
linearity 53–54; discrete transistor circuitry 85–86, 88–91, 93–98, 101–103, 111–112, 121–122; level control and special circuits 685, 688–690, 709–710; line outputs 554–555, 564–565; opamps and their properties 146–147; signal switching 587–591; two-transistor shunt-feedback stages 109–111
line inputs: amplifier component mismatch effects 497–500; balanced cables and interference 487–488; balanced connectors 489; balanced interconnections 485–487; balanced signal levels 489; combined line input and balance control stage with low noise 509; combined unbalanced and balanced inputs 504; common mode rejection 490–495; electronic balanced 493–494; electronic v. transformer balanced inputs 490; external signal levels 481; high input-impedance balanced inputs 511–512; input amplifier functions 482; input overvoltage protection 524; instrumentation amplifier 514–522; internal signal levels 481; inverting two-opamp input 513; low-noise balanced 525–530; microphone and line input pads 470; opamp CMRR effects 497; opamp frequency response effects 496; a practical balanced input 501–503; self variable-gain line input 510; superbal input 505; switched-gain balanced inputs 506; transformer balanced 523; ultra-low-noise balanced 530–534; unbalanced 482–484; variable-gain balanced inputs 507–508
line outputs: balanced 549–551; ground-canceling 543–549; heavy loads 523; output transformer distortion 555–560; output transformer frequency response 554; quasi-floating 552; transformer balanced 553; unbalanced 535; zero-impedance 536–542
Linkwitz-Riley electronic crossover 182
Lipshitz, Stanley 13, 230–231, 234–237
liquid crystal displays 683–684
“Listen” facility 461
LM317/337 variable-voltage IC regulators 724
LM338K variable-voltage regulator 728
LM741 opamp 144
LM3914 integrated circuit 680
LM7815 fixed IC regulator 720, 723
LM7815/7915 fixed IC regulator 720, 723
LM7824 fixed IC regulator 727
LM7924 fixed IC regulator 727
LM13600 amplifier 689
LM13700 amplifier 689
loaded linear pots (volume controls) 328–330
loading 136
load synthesis 305
Log Law Level LED (LLLL) 672–673
low-impedance design xxvi, 37, 40, 80; filters 182; line inputs 509; line outputs 547; tone controls and equalisers 406, 416, 419; volume controls 325, 356, 379
low-noise: balanced line inputs 525–530; Baxandall active volume stages 347–349; operational amplifier circuitry 31
low-pass filters 180; Sallen and Key 182–184
low voltages: AD8022 in +5 V operation 171; AD8397 in +5 V operation 172–175; high fidelity from 167; LM4562 in +5 V operation 170; NE5532 in +5 V operation 169; opamps for 3.3 V single-rail operation 176–178; opamps for 5 V operation 169; running opamps from a single +5 V supply rail 167–168
LT1028 opamp 31, 128–130, 129–130, 133, 498, 531–532, 531
LT1083CK variable-voltage regulator 728
magnetic conductors 43
magnetic coupling 263, 486, 488–489
MAGNOISE model 317; MAGNOISE2 256, 258, 266
manganin 44
master module (split-format) 459–461
master section 451, 453, 455, 653–654, 658
Math CAD software 256
mechanical switches 575
mercury: cables 45–46; properties 44, 44
Metal Electrode Face-Bonded (MELF) resistors 54
metal oxide semiconductor field-effect gates (MOSFETs) 685
metal-film resistors 53–54, 57, 65, 70
metering: combined LED indicators 676; distributed peak detection 674–675; LED bar-graph metering 678–679; LCD meter displays 683–6843; Log Law Level LED (LLLL) 672–673; a more efficient LED bar-graph architecture 680–682; peak indication 670–671; plasma displays 683; PPMs 678; signal-present indication 669; vacuum fluorescent displays 683; VU meters 676–677
microcontroller and relay supplies (power) 730
microgroove technology 215–216, 255
microphone capsules 24, 466, 476
microphone preamplifiers: balanced-feedback hybrid microphone preamplifier (BFMA) 469; capacitor head 476–477; microphone and line input pads 470; microphone types 465; padless 471–475; requirements 465; ribbon 478–480; simple hybrid 468; transformer microphone inputs 466–467
microphone transformer 468
middle controls (tone) 424; fixed frequency Baxandall middle controls 425–427; single-gang variable-frequency middle EQ 435–437; switched-Q variable-frequency Wien middle EQ 438; three-band Baxandall EQ in one stage 428–429; variable-frequency middle EQ 433–434; Wien fixed middle EQ 430–432
mixer architecture 449–451; in-line 453–454; in-line channel 462–464; internal levels 450; performance factors 449; split mixing 452; split-format modules 455–461
mixer bus systems 611
mixer sub-systems: active panpot 625–627; AFL systems 658; auxiliary sends 634; balancing tracks to reduce crosstalk 650; circuit block 614; component lifetimes 666–668; console cooling 666–668; direct outputs 619; equalisation 612; faders 615–616; flash bus 664–665; group module circuit blocks 634; inputs 612; insert points 612–613; LCR panpots 628–629; line-up oscillators 661–663; mixer bus 611; panpots 619–629; passive panpots 621–624; PFL systems 652–657; post-fade amplifiers 617–618; power supply protection 666; routing systems 630–633; solo-in-place systems 658–659; summing amplifiers 643–649, 651; summing systems 635–642; talkback microphone amplifiers 660
Molly guard 660
monitor mix 451–452, 454, 458–459, 464
monitor mixer 451
mono/stereo switches 391
motorised potentiometers 360–361
moving-coil (MC) head amplifiers: amplification strategies 281; cartridges 279; complete circuit 287; effective MC amplifier configuration 285–286; input amplifiers 283–284; limits MC noise performance 280; performance 288–290; transformers 281–282
moving-magnet (MM) inputs: amplifier configurations 227–228; balanced MM inputs 263; calculating the RIAA equalisation components 230; cartridge load synthesis for lower noise 266–267; cartridge sensitivities 223; cartridge types 215; equalisation 225; hybrid MM amplifiers 262; IEC Amendment 226; implementing the IEC Amendment 233; implementing RIAA equalisation 230–232; maximum signal levels from vinyl 219–222; MM cartridge DC and AC coupling 255; MM cartridge-preamplifier interaction 254; “Neumann Pole” 227; noise in balanced MM inputs 263–264; noise measurements 265; noise in MM RIAA preamplifiers 255–261; noise weighting 265; opamp input stages 229; open-loop gain and RIAA accuracy 249; overload margins and amplifier limitations 224; passive and semi-passive RIAA equalisation 249–252; a practical MM amplifier 273–278; RIAA optimisation 237–245; RIAA series-feedback network configurations 234–236; spurious signals 216–217; subsonic filters 268–272; switched-gain MM/MC RIAA amplifiers 248; switched-gain MM RIAA amplifiers 246–247; ultrasonic filters 273; vinyl medium 215; vinyl problems 218
Mr Spock (Star Trek) 50
multi-function summing amplifier 651
multi-path amplifiers and ultra-low-noise 36–39
multiple amplifiers 40
multiple-feedback band-pass filters 188–189, 189, 662, 665
multiple-feedback filters 190–191, 739–740
multiple voltage controlled amplifiers (VCAs) 691–692, 692
multi-track recording 294
mutual shutdown circuitry and power supplies 729
NBC (broadcaster) 676
NE5532/5334 opamp 144–155, 169; AD797 151; LM4562 148–150; OP27 151–152; OP270 153–154; OP275 155
negative feedback (NFB) 2–4; clipping 708–710; discrete transistor circuitry 117–121; level control and special circuits 710–711; line inputs 494–495; line outputs 536–537, 541–542, 558–559; microphone preamplifiers 469; mixer sub-systems 656–657; opamps and their properties 141–142
negative-impedance-converter 625
“Neumann pole” 227
Neumann SAL 74B amplifier 227
Newcomb and Young loudness control 377–380
NJM4556A opamp 562
noise: a-weighting 17, 217, 256, 265; active gain control 196–198, 339, 347, 353–356; amplifiers 22–23, 36–39; in balanced MM inputs 263–624; bipolar transistors 24; blue 17; cartridge load synthesis for lower noise 266–267; correlated 531; description 16; discrete class-AB headphone amplifiers 572; excess resistor 68–69; flicker 20; gates 698–699; generators 714; green 17; grey 17; improved Baxandall active volume stage with lower noise 352–353; junction field-effect transistors 29–30; limits on MC noise performance 280; measurements 265; in MM RIAA preamplifiers 255–261; opamps 29–30; pink 17, 714–716, 716; red 16–17, 714, 717; replay noise 302–304; resistor excess noise 67–69; routing systems 631–633, 631, 633; send amplifier 547; summing systems 619, 637–638, 640, 642; violet 17; weighting 265; white 16–19, 714–717, 715–716; see also Johnson noise; noise (gain)
noise (gain) 16, 31; in amplifiers 22–23; balanced output 551; bipolar transistor current noise 25–28; in bipolar transistors 24; bipolar transistor voltage noise 25; in JFETs 29; noise reductions systems 305–306; opamps 29, 128
noise figure (NF) 24, 27–28, 28, 74–80; filters 187–188; moving-coil head amplifiers 287–288; moving-magnet inputs 237–246, 238, 242, 242, 243, 244–245, 261–262; tape replay 303–304
noise measurements 32
nominal levels and ADCs 734
non-conductors 44
non-electrolytic capacitor non-linearity 75–79
non-linearity: capacitor 75; electrolytic capacitor 80–82; non-electrolytic capacitor 75–79; resistor 70–72
offness: discrete JFET switching 606; faders 616–617; level control and special circuits 698–699; mixer sub-systems 624–627, 630–634, 638–639; signal switching 575–577, 583–588, 590–591, 599–602, 604–605; volume controls 327–328, 338–339
Ohm, George Simon 43
one-capacitor LF control (Baxandall tone controls) 397–402
one-ounce copper 47
one-transistor: hybrid summing amplifiers 646; series-feedback gain stages 103–104; shunt-feedback gain stages 103
OP275 155
OPA604 162
opamps (operational amplifiers) 127; for 3.3 V single-rail operation 176–178; for 5 V operation 169–175; active clipping 706; AD797 151; AD8022 171; AD8397 172–175; bias current 131; BJT input 144; CMRR effects 497; common mode range 130; common mode rejection 495; cost 132; discrete 117–121; distortion 133–142; frequency response effects 496; high fidelity from low voltages 167; history 127; input 118–119; input offset voltage 131; JFET input 156–166; Johnson noise 17–18; line inputs 495–497; LM741 144; LM4562 148–150, 170; MM input stages 229; multiple 562–563; NE5532/5534 144–155, 169; noise 128; OP27 151–152; OP270 153–154; OP275 155; OPA2134 160–161; OPA604 162; OPA627 163–166; opamp-transistor hybrid amplifiers 564–565; running opamps from a single +5 V supply rail 167–168; Sallen-and-Key filters 187; selection 143; slew rate 129; special 562; supply rail voltages 719; TL052 158–159; TL072 156–157; see also opamps (distortion); specific opamps by name
opamps (distortion) 133–134; bipolar input 137–140; common-mode 136–142; internal 135; JFET 141–142; loading 136; slew-rate limiting 135; thermal 136
OP27 opamp 129–130, 133, 151–152, 152–153, 497, 498
OP270 opamp 129–130, 133, 153–154, 154
OPA604 opamp 129–130, 133, 162–163, 258, 261
OPA627 opamp 129–130, 132, 133, 163–164, 498
OPA2134 opamp 128, 129–130, 133, 143–144, 160–162, 164; guitar preamplifiers 317–319, 318–319, 321–322; line inputs 496, 498; moving-magnet inputs 258, 261, 266; signal switching 586, 607; tape replay 303, 304, 305
open-loop gain: and RIAA accuracy 249
Operational transconductance amplifiers (OTAs) 2; gain-control elements 688–689
OTAs see Operational transconductance amplifiers (OTAs)
overlapping foil screen cables 487–488
overload margins 224
padless microphone preamplifiers 471–475
palladium/silver (PdAg) 55
panpots (panoramic potentiometers) 619–620; active 625–627; full-width LCR 628–629, 628; half-width LCR 628–629, 629; law bending 623, 625; laws 620–628; Left-Center-Right (LCR) 628–629; mixer sub-systems 619–629; negative-impedance-converter 625–626; passive 621–624; sine/sine squared laws 620–621, 620
passive attenuators 197
passive balance controls 383–385
passive control: Baxandall active volume stage 354–355
passive filters 179
passive preamplifiers 193
passive/semi passive RIAA equalization 249–252
passive tone controls 396
PCB track-to-track crosstalk 49–50
PCM1802 stereo ADC 735
PCM1794A stereo audio DAC 738
peak detection, distributed 674–675
peak program meters (PPMs) 678
performance: discrete class-AB headphone amplifiers 572; MC head amplifiers 280, 288–290; mixer architecture 449; ripple 725
Perpetual Motion Machine of the Second kind 19
PGA2310 integrated circuit 372
pickups 311; characteristics 312
plasma displays 683
polyester capacitors 78, 187–188, 188
polyethylene terephthalate (PET) capacitors 75
polypropylene capacitors 79, 79, 188, 270–272, 422
polystyrene capacitors 78, 78, 241, 275
popcorn noise 20
post-fade amplifiers 457–458, 674; mixer sub-systems 616–618
post-fade sends 452, 457, 617, 619
potentiometers: DC 359; motorised 360; see also panpots
power consumption: discrete class-AB headphone amplifiers 572
power supplies: ±15 V 720–722; ±17 V 723;+48 V phantom 731–732; discrete circuitry 727; dual supplies from a single winding 726; larger 728; microcontroller and relays 730; mutual shutdown circuitry 729; opamp supply rail voltages 719; protection 666; ripple performance 725; variable-voltage regulators 724; very large 729; “wall-wart” 726
power supply rejection ratio (PSRR) 719–720, 720
PPMs see peak program meters (PPMs)
practical balanced inputs 501–503
practical MM amplifier 273–278
preamplifiers 193–198; active 194; active gain control 196–197; amplification 195; architecture 193–198; evolution 194, 195; gain-distribution 195; hybrid microphone 468–469; LM7824 727; microphone 465, 468–469, 471–475; MM cartridge–preamplifier interaction 254; noise in MM RIAA preamplifiers 255–261; padless microphone 471–475; passive 193; passive attenuators 197; recording 197; tone controls 197–198; tone-control stage 180; see also guitar preamplifiers; microphone preamplifiers
Precision Preamplifier 225, 236, 246, 346–347, 346, 409, 416
pre-fade listen (PFL): AFL 658–660; channel module (split format) 653–654, 658, 666; detection 654, 656–657; master module 452, 457, 459, 461, 660; peak indication 670–672; simple 656; split mixing 452; summing 654; switching 654; systems 652–657; virtual-earth detection 656–657
prefade sends 457
printed-circuit boards (PCBs): digital domain interface 733; layout 733; mixer bus systems 611; Signal Transfer Company 275; three-layer 51; track current capacity 48; track resistance 47–48; track-to-track crosstalk 49–50
Progressive Electronics 440
protection diodes 584, 722–723, 722
psychoacoustic weighting 265
public address (PA) 180, 451–452, 468, 552, 660, 667, 729
push-pull: CFP emitter-follower 96–97, 100; CFP follower 100; emitter-follower 93–94
Radford HD250 amplifier 196
radio frequency (RF): field strengths 554; filters 179–180, 193, 227, 483
rail bootstrapping 106–109, 107–109, 113–116, 123–125, 584
RCA Victor (record label) 215
recording facilities 197
Recording Industry Association of America/RIAA: accuracy 249; amplifiers 246–248; differential amplifiers 527; moving-magnet input stages 229; noise in preamplifiers 255–261; overload margins 224–225; preamplifiers 255–261; series-feedback network configurations 234–236; signal levels from vinyl 216–217, 219–222; see also Recording Industry Association of America/RIAA (equalisation)
Recording Industry Association of America/RIAA (equalisation): amplification 15, 224, 250, 281; Audio Note cartridge 279–280; cartridge–preamplifier interaction 254; components 230; curve 219, 226–227, 231, 250; implementing 230–232; input signals 15, 229; inverse 221, 250, 270; noise in preamplifiers 255–261; non-electrolytic capacitors 74–75, 233, 270; optimisation 237–245; passive/semi passive 249–252; subsonic filters 270
relay supplies 730
relay-switched volume controls 371
relay switching 579
reservoir capacitors 696, 721–724, 726
resistances and Johnson noise 16–19, 24–34, 67–68; guitar preamplifiers 316–317; line inputs 505–506, 511–512; moving-coil head amplifiers 282–283; moving-magnet inputs 256–257; preamplifier architectures 194–195
resistors 53–72; accuracy 57–62; carbon composition 53, 53, 65, 69–70; carbon-film resistors 53–54, 53, 65, 67–70, 337; combinations 57–63; common-mode rejection ratio 485, 492, 495, 497, 535, 650; end stop 399–400, 418, 433, 508–509; excess noise 67–69; imperfections 67; MELF 54; metal-film 53–55, 53, 57, 65, 68, 70–71, 634; metal oxide 53–54, 53, 68; noise 67–69; non-linearity 70–72; series 56; surface-mount 54–55; switched attenuators 362; temperature coefficient 53, 53, 55; thick-film 54–55, 68–72, 499; thin-film 53–55, 65, 68, 72–73; three-resistor combinations 62; through-hole 54; tolerances 59–66, 73–74, 238–244, 342–343, 362–364, 491–492, 498–500, 507–508; two-resistor combinations 57–61; uniform distribution 66; value distributions 64–65; voltage coefficients 53–55, 65, 70–71, 73; wirewound 53–54, 56, 68, 70
return-to-flat (RTF) tone-control 416, 418, 440
RF filtering 180, 482–483, 487, 502, 517
ribbon cable 611, 613, 635, 639, 658
ribbon microphone amplifiers 478–480
ripple performance (power supplies) 725
routing systems: back grounding 630–631; matrix 633; mixer sub-systems 630–633; offness 630–633; panpots 630
ruthenium oxide 55
safe-operating-area (SOA) 731
Sallen and Key filters: capacitor microphones 476; distortion 187–188; high-pass 185–186; low-pass 182–184; subsonic filters 268, 273
Schlotzaur configuration 88, 98, 101
‘sea of micro-diodes’ 43
Second Law of Thermodynamics 19
series-feedback: one-transistor 103–104; two-transistor 117; RIAA 234–236; see also individual circuits
shot noise 19
shunt-feedback: one-transistor 103; two-transistor 105–116; see also individual circuits
Shure M75ED 2 cartridge 256, 265, 267
signal-present indication 669
signals 1; balanced signal levels 489; external signal levels 481; internal signal levels 481; maximum signal levels from vinyl 219–222; nominal signal levels and dynamic range 4–5; raising the input signal level to the nominal level 15; signal-present indication 669; spurious 216–217; warping 216–217; see also signal switching
signal switching: electronic switching 579; input-select switching 575–576; mechanical switches 575; offness 606; relay switching 579; virtual contact 577–578; see also CMOS analogue gates; discrete JFET switching
Signal Transfer Company 273, 275, 277, 288, 530
simple emitter-follower (EF) discrete circuit-block 88–93, 96–98, 123–124
simple hybrid microphone preamplifier 468
sine-squared laws 620
sine/cosine characteristic 381–382, 385, 620–621
single-gain pot 199–202, 206–208
single-gang sweep middle tone controls 435
single-gang variable-frequency middle EQ 435–437
single-jack insert 612–613, 613
“slate” facility 461
slew limiting 130, 135, 144–145, 179, 217, 250
slew rate 129; slew-rate limiting distortion 135
solo-in-place systems (SIP) 658–659
Soundcraft 3200 recording console 458, 650
SPICE simulation 91, 97–98, 248–249
split-format modules: channel 455–457; effect return 458; group 458; master 459–460; oscillators 461; talkback 461
split mixing (mixer architecture) 452
Star Trek 50
state-variable filters 181, 191
stepped volume controls 361
stereo image 325, 327, 381, 392, 452
stereo power amplifiers 52
subsonic filters/filtering 268–272
subsonic/ultrasonic filters combination 181, 273
subtractive VCA control 697
summing amplifiers 643–645; balanced hybrid 649; hybrid 646–648; multi-function 651; two-transistor shunt-feedback stages as 115–116
summing noise sources 21
summing systems: balanced 637; bus residual 636, 645; distributed 640–642; four-layer 643; ground-canceling 638–639; noise; three-layer 611, 642–643, 643; two-layer 640–643; virtual-earth summing 635–636; voltage summing 635, 636; see also summing amplifiers
superbal input 505
supply-rail voltages and opamps 85–86, 167–169, 591–593
surface-mount (SM) resistors 54–56, 70–72, 132, 682
sweep middles tone controls 425
switchable peak/shelving LF/HF EQ 439
switched attenuator: resistors 362–371; volume controls 362–370
switched balance controls 388–390
switched-frequency LF EQ 415
switched-HF-frequency Baxandall controls 410–411
switched-gain balanced inputs 506
switched-Q variable-frequency Wien middle EQ 438
symmetrical clipping 662
switched-gain amplifiers 211–214; MM/MC RIAA 248; MM RIAA 246–247
Szilaki configuration 96
talkback: microphone amplifiers 660; split-format modules 461
tan-δ δ (tan-delta in capacitors) 73
tape replay: basics of tape recording 292–293; Dolby HX-Pro 307; history of tape recording 292; load synthesis 305; multi-track recording 294; noise reduction systems 305–306; the return of tape 291; tape heads 294–295; tape replay 296–304
tapped volume controls 334–336
temperature coefficient 44, 53, 55
thermal distortion 136
thermodynamics laws 19
Thevenin-Norton transformation 19
thick-film resistors 54–55, 68–72, 499
thin-film 53–55, 65, 68, 72–73
third-order filters 181, 183, 186, 268–275, 321, 739
three-band Baxandall EQ 428–429
three-layer PCB 51
three-layer summing 611, 642–643, 643
through-hole (TH) resistors 54, 56, 70–71, 634
TID 194; see also slew limiting
time-constants 74–75, 230–231, 250–251, 695–696
TL072 opamp 127–131, 129–130, 133, 135–136, 141–145, 156–162; guitar preamplifiers 317–318; headphone amplifiers 565–566, 566; line inputs 495–496, 498; line outputs 538–539; moving-magnet inputs 258, 261, 265–266, 266; power supplies 719–720, 720; signal switching 586, 607–608; tape replay 303–305, 303, 305
TL783C high-voltage regulator 731, 731
tolerances of resistors see under resistors
tone controls 395; Ambler concept 423; graphic equalisers 443–448; parametric middle EQs 440–442; passive 396; preamplifier architectures 197–198; return-to-flat (RTF) 416, 418; single-gang sweep middle 435–437; sweep middles 425, 433, 435; switchable peak/shelving LF/HF EQ 439; switched-frequency LF EQ 415; tilt 422–423; tone-balance 422–423; variable frequency LF/HF EQs 412–414, 416–421; Wien fixed middle EQ 430; see also Baxandall tone controls; middle controls
total harmonic distortion (THD) 70, 70, 72–81, 72, 78–79; discrete transistor circuitry 102, 110–114, 110, 112, 114, 116, 123; headphone amplifiers 563–564, 566; level control and special circuits 689–690; opamps for low voltages 169–177, 173–178; opamps and their properties 134, 144–146, 145, 149, 149, 152–156, 152–155; signal switching 582–584, 591–592, 591, 601, 603; volume controls 351–352
track current capacity 48
track resistance in printed-circuit boards 47–49
track-return/group switch 452–455, 457–458, 462, 464
track-to-track crosstalk 49–40
transformer balanced line inputs 490, 523
transformer balanced line outputs 553
transformer microphone inputs 466–467
transformers, moving-coil 281–282
transformer-tap volume controls 371
transistor equation 87
transmission gates 580
Twin-T notch filter 189–190, 190
two-ounce copper 47
two-transistor hybrid summing amplifier 647–648, 647–648
two-transistor series-feedback gain stages 117
two-transistor shunt-feedback gain stages 105–108; bootstrapping 112–114; improving linearity 109–111; noise 112; as summing amplifiers 115–116
ultra-low-noise: amplifiers 38–39; balanced line inputs 530–534; multipath amplifiers 36–39; voltage buffers 37
ultrasonic filters 273
unbalanced line inputs 482–484, 535
uncorrelated noise 21–22, 21, 283
unipolar peak detector 671
unity gain 520
unity-gain buffer stages 88; CFP emitter-followers 96–97; constant-current emitter-follower 92; emitter-follower stability 95; improved unity-gain buffers 98–102; push-pull emitter-follower 93–94; simple emitter-follower 88–91
vacuum fluorescent displays 683
variable-frequency LF/HF EQs 412–414, 416–421
variable-frequency middle EQ 433–434
variable-gain balanced inputs 507–508
variable gain stages 199–214; and active filters 205; dual-gain pot 203–204, 209–210; single-gain pot 199–202, 206–208; switched-gain amplifiers 211–214
variable-voltage regulators 724
VCAs see voltage controlled amplifiers (VCAs)
very large power supplies 729
vinyl 215–216, 297, 449; maximum signal levels from 219–222, 220; problems 218
violet noise 17
virtual contact (signal switching): mechanical 577–578
virtual-earth PFL detection 656–657
voltage coefficient 53–55, 53, 70–71, 70, 71, 73
voltage controlled amplifiers (VCAs): gain-control elements 689–691; subtractive control 697
voltage-followers 175, 526, 537, 564, 578
voltage noise 20, 23–31, 128–129; guitar preamplifiers 316–317; line inputs 530–531; moving-magnet inputs 255–256; tape replay 303–304; volume controls 352–355
volume controls 325; active 339–343; attenuator volume controls 362–370; Baxandall active 344–355; belt-ganged 359; DC 359; dual-action 331–333; integrated circuit 372; laws 325–327, 344; loaded linear pots 328–330; loudness controls 373–376; motorised 360; Newcomb and Young loudness control 377–380; overlap penalty 356–358; potentiometers 359; relay-switched 371; slide faders 337–338; stepped 361; switched attenuator 362–370; tapped 334–336; transformer-tap 371
Walker, HP 229
“wall-art” power supplies 726
wet monitoring 464
White, Eric 94
white noise 16–17, 714–717, 715–716
Whitlock bootstrap 522–523, 522
Widlar, Bob 127
width controls (balance) 392–394
Wien bridge configuration 663
wirewound resistors 54
wiring 313
wiring resistance and cables 46–47
WM8726 stereo DAC 740
WM8740 stereo audio DAC 738
