No32 Brochure - Mark Levinson

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No32 Brochure - Mark Levinson

Nº32REFERENCE PREAMPLIFIER


Nº32REFERENCE PREAMPLIFIERThe Nº32 Preamplifier is a revolutionary MarkLevinson component. It is the first preamplifier toearn the Reference label.Separating power-supply and control circuitrymakes sense in a modern, Reference-levelpreamplifier. AC power supplies, microprocessors,LED displays — essentially, anything that generatesnoise — are housed in a separate chassis fromthe low-level audio signals (the Nº32 ReferenceController), while all of the audio-preamplifiercircuitry is housed outboard (the Nº32 ReferencePreamplifier). Thus, the audio circuits are exposedonly to quiet, regulated DC power and the audiosignal itself.Two master power supplies are located inthe center section of the Reference Controller:one is dedicated to control and communications;the other is used for the audio circuits. The powerfrom the AC line is pre-filtered, and the twomaster supplies are isolated from one another. Thepower supplies use custom-designed transformersfeaturing multiple secondary windings, whichsubstantially improve isolation between separatecircuit blocks. Separate rectification, filtering, andregulation circuits are used to supply DC to thecontrol/communications circuits, a Nº25 phonoDC supply output, and the 400Hz oscillatorcircuits used in power-supply regeneration.The Nº32 employs AC power regeneration:the DC supply feeding the voltage gain stages isderived from an AC source generated within theamplifier itself. This technique is expensive butvery effective. In the Nº32 Reference Controller, a400Hz oscillator generates the AC source for thepreamplifier’s audio power.Microprocessors are noisy devices whichcan pollute low-level audio signals if care is nottaken to keep processing noise out of the signalpath. For this reason, the microprocessors in theNº32 are not only located in the controller box,physically separated from the preamplifier chassis,but are also within their own shielded box.The microprocessors in the Nº32 controlvolume changes, signal routing, and other switchingfunctions. They make it easy to name inputs,select mono modes, set mute level, or programoffset or gain levels for individual inputs — allfrom the front panel. Like other current MarkLevinson components, the Nº32 uses a softwarebasedoperating system that can be upgradedthrough its RS-232 port.The Reference Preamplifier chassis has nobuttons or knobs. The Reference Controller isused to execute all commands through its simplefront panel. Each source can be named in thedisplay, and full control of all functions, with theaddition of mono/stereo selection and polaritycontrol, is available from the remote.The Nº32’s casework is extraordinary evenby Mark Levinson standards, and, like the otheraspects of its design, reflects an uncompromising2


approach. Its chassis is a custom aluminumcasting, machined and finished with a conductiveIrridite (clear chromate) coating. This designapproach assures a rigid, stable environment inwhich vibration and microphonic effects arecontrolled.The left and right channels are separated bya solid aluminum divider wall, formed as part ofthe casting. Each channel is thus sealed into itsown environment to prevent the electromagneticnoise of one channel from degrading the other.Because each channel is effectively isolated fromthe other electrically and physically, the Nº32’sstereo separation is equivalent to that of two separatemono preamplifiers.The Nº32 is the first Mark Levinson productto use Arlon 25N ® for its circuit boards. Thismaterial’s superb dielectric properties help theNº32 achieve remarkable performance withcomplex audio signals. Arlon 25N was chosenonly after extensive listening tests revealed that itwas audibly superior to all other materials in thisparticular application.Both balanced and single-ended inputs areprovided on the rear panel. Single-ended signalshave common-mode noise (noise present on bothsignal and ground) rejected at the input stage.Fully balanced instrumentation amplifiers areemployed as the gain stages, and each input canbe separately adjusted using the software to offer0, 6, 12 or 18dB of gain. Using this feature, theNº32 allows the volume control to work in itsoptimum range even when its sources havesubstantially different output levels.While volume control is one of the primaryfunctions of a preamplifier, it is also a source ofcompromise in many designs. The Nº32introduces a new active attenuator: a discretedesign that offers an unprecedented combinationof precision and neutral sonic performance. The3


attenuator modules are constructed on their ownfour-layer Arlon 25N circuit boards, whose localpower-supply regulation and bypass capacitorsguarantee the sensitive switches receive cleanpower and optimum isolation. An array of precisionresistors provides attenuation in 0.1dB stepsdown to –57dB, where step size is increased to1dB. With over 65,000 steps available, the Nº32’sstepped attenuator gives the required precisionwhile acting and sounding like a continuouslyvariable control.High-performance buffer amplifiers form theoutput of the Nº32. These circuits feature lownoise and distortion, low output impedance, highcurrent capability, and broad bandwidth. Singleendedand balanced outputs are independentlybuffered to allow simultaneous use of bothconnector types without sonic compromise.in mu-metal that are easily installed via the rearpanel. Setting up and customizing the Nº32’sphono stage is an analog lover’s dream. Its defeatableinfrasonic filter, resistive and capacitiveloading, and gain can all be selected independentlyfor each of its two inputs. It even has a fine-trimadjustment for balance to compensate for thesmall channel imbalance found in virtually everycartridge. What’s more, all of these variables can beadjusted from the remote control.We conducted exhaustive listening testsover several years to select topologies, componentparts, and operating parameters for the Nº32Reference Preamplifier. We encourage you tospend some time listening to it — we think you’llfind the experience its own reward.For music lovers using analog disc sources,the Nº32 offers optional phono modules shielded4


Nº32 Phono ModulesFrequency Response:RIAA response±0.1dBRIAA/IEC response +0.1, -0.3dBGain:either 40 or 60dBTotal Harmonic Distortion(THD):less than 0.008%, 2V out, 1kHz test signal, 80kHz measurement bandwidthResidual Noise:ref to output w/500µV, 1kHzat input, unweighted -69dBInput Complement: (2x) Madrigal RCA connectors per channelor(2x) XLR connectors per channelInput Impedance:(user selectable)Resistive:3.3Ω, 5Ω, 7.7Ω, 10Ω, 33Ω, 50Ω, 77Ω, 100Ω, 330Ω, 47kΩCapacitive:0pF, 50pF, 100pF, 150pF, 200pF, 250pF, 300pF, 350pF, 0.01µFGold-plated, solderlessterminals are available foruser-installed load value,inside phono module.Input Overload:1kHz, 60dB gain:1kHz, 40dB gain:16mV on XLR, 8mV on RCA160mV on XLR, 80mV on RCA7


Nº32 Reference PreamplifierPower Consumption: 150W maximumOperating voltage:100V, 120V, 220V, 230V, or 240VAC @ 50 or 60Hz (preset)Preamplifier Connectors:Controller Connectors:Input Overload:When gain is set to +18dB:When gain is set to +12dB:When gain is set to +6dB:When gain is set to +0dB:Input Impedance:Output Impedance:Maximum Main Output:THD + N:Crosstalk:Residual Noise:Frequency Response:(3) balanced stereo inputs (female XLR)(5) unbalanced stereo inputs (RCA)(2) balanced main stereo outputs (male XLR)(2) unbalanced main stereo outputs (RCA)(1) balanced record stereo output (male XLR)(2) unbalanced record stereo outputs (RCA)(1) earth-reference ground terminal(2) DC power connectors(1) IEC-standard AC mains receptacle(1) IR input (1/8-inch/3.5mm mini-jack)(1) trigger input (1/8-inch/3.5mm mini-jack)(1) trigger output (1/8-inch/3.5mm mini-jack)(3) Link communication ports (RJ-45)(1) RS-232 port (RJ-11)(2) control ports (RJ-45)(1) earth-reference ground terminal(2) DC power connectors2V on XLR, 1V on RCA4V on XLR, 2V on RCA8V on XLR, 4V on RCA16V on XLR, 8V on RCA100kΩ

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