Audionet DAC User manual

Audionet
User’smanual
Digital toAnalogue Converter
DAC

2
TheAudionetDAC-Digitalto AnalogueConverter -is ahigh-
performance systemforconvertingdigitalaudio signals, which improves
thequalityofsound reproduction ofyourwholemusicequipmentto a
much higher level. Further you can individuallychoosebetween different
oversampling-filters.
Centralelements oftheDACare thedigitalsignal-processingsystem
(DSP), thetemperature-regulation circuit, decouplingtheconverter from
theclock ofthesignalsource, a20-bit D/A-converter as well as the
completelydiscretebuilt up analoguesection.
Before thefirstusepleaseread this manualcarefully. So you will get
optimized results fromyourDAC. Nevertheless, in caseofanyproblem,
pleaserefer to yourlocaldealer orourselves.

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Connectingthe system
Pleaseconnectthepower jack attherear with yourwall outlet. Usethe
provided powercord oranother oneallowed foryourhomecountry
specifications.
Note:
Thepower specifications ontherearmustmeet to yourhomecountry
specifications.
IftheDACis connected with adigitalsignal-source (input), e.g. DAT,
CD-Player, and a(pre-) amplifier (output), theconverted digitaldatawill
beoffered to theoutputs as analoguedata.
CD-Player Pre-Amp
DAC
L
R
analoguedigital
TheDACoffers inputs forup to sixdigitalsignal-sources (CD-Player,
DAT …)
- 2 * RCA(gold-plated)
- 2 * BNC
- 1 * XLRAES/EBU(symmetric)
- 1 * TOSLINK oroptional1 * AT&T
Pleaseconnectatleastonedigitalinputwith thedigitaloutputofyour
signalsource.
TheDACoffers Coaxial-/RCA-outputs fortheconnection to a(pre-)
amplifier. Pleaseconnectleftand rightoutputto thecorrespondinginputs
ofyouramplifier.
Power supply
Integration
Inputs
Outputs

4
Further amonitorcircuit is available, which enables e.g. theuseofdigital
effectequipment. Thefollowingin-and outputs are available:
- 1 * RCAout
- 1 * Toslink out
- 1 * RCAin
PleaseconnecttheanalogueoutputoftheDAChas to a(pre-) amplifier
bytwo RCAwires (leftand rightchannel). Themonitorinputdetects by
itself, ifasignalis comingin and switches it into theprocessingcircuit.
TheDACcan beswitched on and off automatically, ifconnected to other
Audionetcomponents byan opticalfibre cableto theAudionetlink.
digitalmonitor
digitalinput
preamp
CD
DAT
DSR
DAT (in)
Netzanschluß
right left
analogoutput MAINS
Sicherung1A/T
in out
link
6 4 3 2 1 in out1out2
AUDIONET
Monitor
Audionet-link

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Operatingthe system
Pleasepush the power button on thefrontpanel. TheDACis operational
after aboutfiveseconds. In order to switch off, pleasepush again the
power button.
Pleaseturn the input switch (leftknob)on thefrontpanelto choosethe
wanted input. Thenumbers oneto sixbelongto theinputnumber on the
rear panel.
TheDACuses asmooth inputselection. In caseofswitchingover the
input, firsttheoutputs are turned off (muting), then thenewinputis
switched on and finallytheoutputs are activated.
Pleaseturn the filter switch (rightknob)on thefrontpanelto choosethe
wanted filter. Thenumbers oneto sixbelongto thesixdifferentfilters.
Fordetails pleaserefer to thenextchapter.
TheDACuses asmooth filter selection. In caseofswitchingover the
filter, firsttheoutputs are turned off (muting), then thenewfilter
programis loaded and finallytheoutputs are activated.
Pleasepush the phaseinvert button on thefrontpanelto invertthephase
oftheoutputsignal. This maybenecessaryforsomecompactdiscs. The
activated phaseinversion is indicated bythegreen LEDnextto the
button.
TheLEDs (Lightemittingdiodes)in themiddleofthefrontpanelshow
thesamplingfrequencyofthechosen signal-source and, ifnecessary, the
activated de-emphasis. TheDACautomaticallydetects thesampling
frequencyand necessaryde-emphasis.
. .
32 44.1 48
sampling frequencyinkHz
input filter
inputselector
filter selector
front panel
DAC
power phaseinvert
.
..
emphasis
Switching onand
off
Inputselection
Choosing a filter
phaseinversion
Sampling fre-
quency /Emphasis

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Features
Conception
Theblock diagramon thefollowingpageshows theDACin principle.
Main features are thesignalprocessingsystemDSP56004 forsoftware-
controlled digital-filtering, the20 bit noise-shaping/converting-
combination SAA7350 and TDA1547, thedecouplingoftheconverter
clock fromthesignalsource clock byatemperature regulation circuit, the
complete(electricallyand galvanic) separation ofdigitaland analogue
section, thediscretebuilt up Audionetoperationalamplifiers and the
lavish power supplywith awealth ofpre- and main regulators.
TheAudionetDACeliminates clock-jitter perfectlywith an unique
temperature regulated clock-generation. Theclock oftheconverter is
completelyseparated fromthesource clock. Theincomingdataare
loaded into abuffer, which can store up to 0.7 seconds ofmusic.
Thestored dataare read with an internallygenerated clock and converted.
Theinternalclock is generated with highestprecision bytwo
temperature-regulated quartzes. Theclock generatoris located nextto the
converter partin order to preventelectricalinterference.
Thetemperature regulation circuit ensures, thattheinternalclock is
adjusted with highestaccuracyto theoriginalclock frequencyofthe
signalsource. Forthis thesignalprocessorpermanentlychecks thestate
ofthebuffer memoryand calculates fromthis thevaluefortheheatingof
theinternalclock generator.
All dataare transmitted on opto-electricallypaths to eliminateany
interference.
Becauseofthenecessarysluggishness ofthetemperature regulation
circuit, theDACneeds abouttwo hours warming-up time, before you can
enjoythehighestfidelity.
clock decoupling

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TheAudionetDAChas asoftware-controlled digital-filteringunit. The
calculatingis donebyasignalprocessingsystem. Thetonaldifferences
between thefilters allowyou to adaptthesound to yourindividual
requests. Further thefilters can beexchanged.
Followingyou havealistoftheavailabledigitalfilters.
Thediagrams (appendix)showyou theattenuation characteristics as well
as theimpulseresponseofeach filter.
Alongstandard filter accordingto Kaiser with high stop-band
attenuation (>20 kHz)and linear frequencyresponse, therefore long
transientand ringingtime.
Ashortfilter accordingto Kaiser with lower stop band attenuation and
lightattenuation forhigh frequency(aboveabout17 kHz), therefore
shorter transientand ringingtime.
Combined Audionetfilter with adequatestop band attenuation and linear
amplituderesponse(<22 kHz). Shorttransienttimeabove20 kHz
becauseofrenunciation oflinear phaseresponse.
Shortfilter accordingto theprincipleoftheLagrangepolynoms,
therefore other weightingofthestop band attenuation. Has averydirect
impulseresponse.
Equiripplefilter ofmediumlength accordingto Remezwith constantstop
band attenuation and linear amplituderesponseup to 20 kHz.
Standard filter accordingto Blackman with usefulstop band attenuation
(high attenuation forsignalfrequencies with statisticallyhigh amplitude).
Samelength as filter 5, butminordifferenttransientand ringingtime.
Digitalfiltering
Filter 1
Filter 2
Filter 3
Filter 4
Filter 5
Filter 6

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Technicalinformation
All circuits are constructed with theshortestpossiblesignalpaths to
ensure besthigh frequencycharacteristics. BecauseofusingSMD
techniques and both sidecomponentequipping, all circuits haveahigh
functionaldensity.
In order to preventelectricalinterference, digitaland analoguesection are
completelyseparated and work together bylightingwire. Thevoltages
foreach unit are prepared and regulated separate.
Altogether fiveintegrated, 14 discretebuilt up main regulators and
further eightpre regulators are in use.
Thefilteringofthedigitaldatais performed byaprogram-controlled
signalprocessingsystem. Itis equipped with sixfilter types. Thesix
filters representthelateststateoffilter technology. Theasymmetricfilter
developed byAudionetcombines themerits ofall filter types without
acceptingtheirdisadvantages forthefirsttime.
TheDACis completelydecoupled fromtheclock ofthesignalsource.
Theinternalclock is generated bytwo temperature regulated quartz
oscillators. Thedigitaldatais read outofadynamic2 megabit buffer
memory. Afastsignalprocessingsystemchecks and controls buffer and
temperature regulation circuit.
A1 bit D/A-chip converts thedatawith 20 bit accuracyand 196 times
oversampling.
Thereproduction oftheanaloguedatais effected separateforeach
channelbysixespeciallydeveloped and optimized discreteSMD
operationalamplifiers. Tonaldistortions are reduced to alevel, thatcan
hardlybemeasured and quiteeven nothear.
Fundamentals
digitalfiltering
clockdecoupling
analoguesection