Lowest-noise RIAA Phono Amps

348 Pages·2008·17.42 MB·English

by  Burkhard Vogel

The Sound of Silence
Burkhard Vogel
The Sound of Silence
Lowest-Noise RIAA Phono-Amps:
Designer’s Guide
123
Dipl.-Ing.BurkhardVogel
BUVOCON-BurkhardVogelConsultGmbH
70180Stuttgart,Germany
ISBN 978-3-540-76883-8 e-ISBN 978-3-540-76884-5
DOI 10.1007/978-3-540-76884-5
LibraryofCongressControlNumber:2007943155
©2008Springer-VerlagBerlinHeidelberg
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ToBeate
“Noiseanalysiscanbeadauntingtaskatfirstandisanunfamiliar
territoryformanydesignengineers.”
GlenBrisebois
Designnote355
LinearTechnology
“Noise–it’stheamplifier’stinnitus!Nochancetofightit!”
AvalveenthusiasticENTdocin
adiscussionwiththeauthor2006
“Akingdomforapieceofwirewithgain!”
Frustrateddesignengineer
Preface
Itisstillachallengetodevelopalow-noiseamplifier–despitethefactthatnowa-
days(2007)nearlyeverysolutionofanelectronicquestionoftheconsumerworld
canbesolvedbydigitalmeans.Thereisa widefieldoftasksleftthatcanonlybe
satisfyingly attacked with the help of old-fashionedanalogue technology:sensors
that are coupledto the existing and living world around us are always confronted
with analogue signals. Those – in most cases – tiny signals have to be amplified
and treatedwith unbelievablyhighelectroniccare. Therefore,frustrationonnoisy
devices should always be turned around into motivation for the search of nearly
noiselesssolutions!
As a producer of such tiny analogue signals the vinyl record (33 1/3 LP and
45 Single/Maxi) is a typical representative of our yesterday – 20th century – life.
Despite the nearly 100%digitization of the consumerworld it is still alive – with
growingsalesrevenuesaroundtheworld.Oneshouldexpectthatallsecretsofthe
amplifierchainthattransfersthesignalsoutoftherecord’sgroovestoourearsare
wellknown.Yesandno!Muchiswrittenaboutdistortion,overloadmatters,noise,
phase angles, frequency response, etc1. Most technical aspects of amplifiers and
sensorswerewelldescribed.
Butsimplequestionslikee.g.:“mymoving-magnetcartridge–howmuchnoise
doesitproduce?”or“what’sthesignal-to-noise-ratio(SN)ofmyphono-ampafter
A-weighting?”arestillnotthateasytoanswertoday.
World-wide,mathematicsistheonlylanguagethatcanbeunderstoodbynearly
everybody,assumed that there exists a certain talent for it, and, not to forget, the
right software for calculations. In this book calculations were all carried out with
MathCad2. An easy to get for free simulation software would help as well, e.g.
MicroSimv8.03 but,nottoincreasethenecessityfortheuseofvarioussoftwares,
thissimulationsoftwareisnotessentialtounderstandandfollowthemathematical
courses.
1Interalia:“SelfonAudio”,DouglasSelf2000,Newnes,UK,ISBN0-750647655
2MathSoftInc.,USA
3MicroSimCorp.,USA(seealsofootnote3onpage17)
ix
x Preface
Therefore,formathematics-refusal-freeandambitiousamateursand/orstudents
who want to design their own amplifier for specific cartridges this book will find
answerstosuchsimplequestionsandmanyothersconcerningRIAAphono-amps!
It’salsoacollectionofarticleswhichwerepublishedinamorecondensedformin
theBritishmagazineELECTRONICSWORLD(EW,formerlycalled“Electronics
WorldandWirelessWorld(EW+WW)”or“WirelessWorld(WW)”).
Asaconsequence,thecontentofthisbookwillleadtoaffordableamplifierde-
signapproacheswhichwillendupinlowest-noisesolutionsnotfarawayfromthe
edge of physicalboundariesset by room temperatureand given cartridges– thus,
fullycompatiblewithveryexpensivesocalled“high-end”or“state-of-the-art”of-
fersontodaymarkets–and,fromanoisepointofviewinmostcasesoutperforming
them!
Witheasytofollowmathematicaltreatmentitwillbedemonstratedaswellthat
theory is not far away from reality. Measured SNs will be found within 1dB off
the calculated ones and deviations from the exact amplifier transfer won’t cross
the±0.1dBtolerancelines.Additionally,measurementset-upsandresultswillbe
presented and comparisons with measurement results of test magazine will soon
becomeeasiertoperform.
Last remark:the presentedelectronic circuits do not contain extra made or ex-
tremelyexpensivecomponents.Theyallcanbefoundatcomponentdealersworld-
wide.
Very last remark: I guess that creativity does not mean to reinvent the wheel
again nor to find out absolutely new things. In many cases it’s nothing else but
simplyrearrangingwellknownparts.Therefore,whenIstarteddevelopingthemany
circuitschemespresentedinthisbookOkham’sRazor4 andonemaingoalranked
very high: to combine and to re-arrange well known different circuit designs to
promisingnewsolutions.
4“Ifyouhavetochoosefromsomenumberofcompetingtheories,choosethesimplestonebecause
it’smostlikelytobetrue”,
SharonKay,www.royalinstitutephilosophy.org/think/
Contents
PartI Theory
1 Amps,Pre-Amps,Pre-Pre-Amps................................. 3
2 RIAATransfer/Anti-RIAATransfer ............................. 9
3 NoiseBasics ................................................... 17
3.1 NoiseinComponentsandOtherGeneralNoiseEffects ........... 17
3.2 NoiseinBipolarJunctionTransistors(BJTs).................... 36
3.3 NoiseinFieldEffectTransistors(FETs) ....................... 55
3.4 NoiseinValves(US:Tubes) ................................. 71
3.5 NoiseinOperationalAmplifiers(Op-Amps) .................... 86
3.6 NoiseinInstrumentationAmps(In-Amps) ..................... 93
3.7 NoiseinTransformers(Trafos) ...............................106
3.8 NoiseofVinylRecords(VRs)–OnhowmuchPhono-AmpSNis
Needed? ..................................................125
PartII BestPractice
4 NoiseinMMCartridges ........................................149
5 NoiseinMMCartridges–MathematicalCalculationCourse........171
6 NoiseinMCPhono-Amps.......................................181
7 NoiseinMCPhono-Amps–MathematicalCalculationCourse ......205
8 RIAANetworks................................................227
9 RIAANetworks–MathematicalCalculationCourse ...............255
xi
xii Contents
PartIII NoiseMeasurementSystem
10 SystemOverview...............................................279
11 MeasurementAmps ............................................285
12 MeasurementFiltersandNetworks ..............................291
PartIV TheRIAAPhono-AmpEngine
13 Overview......................................................303
14 Module1......................................................309
15 Module2......................................................311
16 Module3......................................................313
17 EnginePerformance............................................319
PartV Book-EndingSections
ListofFigures .....................................................329
ListofTables ......................................................339
Constants,Abbreviations,Symbols ...................................341
Index .............................................................345
Epilogue ..........................................................351