NuPrime MCH-K38 User manual

NuPrime
MCH-K38

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FCC Notice - Declaration of Conformity Information
This equipment has been tested and found to comply with the limits for a Class B digital device, pursuant
to part 15 of the FCC Rules. These limits are designed to provide reasonable protection against harmful
interference in a residential installation. This equipment uses and can radiate radio frequency energy and,
if not installed and used in accordance with the instructions, may cause harmful interference to radio
communications.
However, there is no guarantee that interference will not occur in a particular installation. If this
equipment does cause harmful interference to radio or television reception, which can be determined by
turning the equipment off and on, the user is encouraged to try to correct the interference by one or more
of the following measures:
•Reorient or relocate the receiving antenna.
•Increase the separation between the equipment and receiver.
•Connect the equipment into an outlet on a circuit different from that to which the receiver is
connected.
•Consult the dealer or an experienced radio/TV technician for help.
WARNING: Only peripherals complying with the FCC class B limits may be attached to this equipment.
Changes or modifications made to this equipment, not expressly approved by us or parties authorized by
us could void the user’s authority to operate the equipment. This device complies with part 15 of the FCC
Rules. Operation is subject to the following two conditions: (1) This device may not cause harmful
interference, and (2) this device must accept any interference received, including interference that may
cause undesired operation.
Notice for customers: The following information is only applicable to equipment sold in countries applying EU
Directives.
EU Declaration of Conformity
Hereby, NuPrime Audio, Inc. declares that this device is in compliance with the
essential requirements and other relevant provisions of Directive 2004/108/EC.
The manufacturer of this product is NuPrime Audio, Inc., 1712 Pioneer Ave. Ste 1817, Cheyenne, Wyoming
82001, USA
The Authorized Representative for EMC and product safety is NuPrime Audio, Inc., 1712 Pioneer Ave. Ste
1817, Cheyenne, Wyoming 82001, USA.
For any service or guarantee matters please refer to the addresses given in separate service or guarantee
documents.
For customers in Europe
Disposal of Old Electrical & Electronic Equipment (Applicable in the European Union and
other European countries with separate collection systems)
This symbol on the product or on its packaging indicates that this product shall not be
treated as household waste. Instead it shall be handed over to the applicable collection
point for the recycling of electrical and electronic equipment. By ensuring this product is
disposed of correctly, you will help prevent potential negative consequences for the
environment and human health, which could otherwise be caused by inappropriate waste
handling of this product. The recycling of materials will help to conserve natural resources.
For more detailed information about recycling of this product, please contact your local Civic
Office, your household waste disposal service or the shop where you purchased the product.

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SAFETY INSTRUCTIONS
There are two categories of Safety Instructions included in this manual:
•Product Warnings, (i.e., what must never be done to assure avoiding those hazards that could
cause bodily injury or property damage); and
•User Directions (i.e., what must always be done to assure the safe use of your device).
The Safety Instructions contained in this manual have been categorized in accordance with the
seriousness of the potential hazards through the use of Signal Words. Those Signal Words, and their
intended meanings, are as follows:
DANGER: Indicates that a failure to observe the Safety Instructions could result in death or catastrophic
bodily injury.
WARNING: Indicates that a failure to observe the Safety Instructions could result in serious bodily injury.
CAUTION: Indicates that a failure to observe the Safety Instructions could result in minor bodily injury or
property damage.
NOTE: Designates important information that relates to activities and/or conditions that might result in
loss of data and/or damage to your device.
Safe Use and Operation of Your Device
This equipment emits stray RF energy and will interfere with the reception of signals by airborne
electronic navigational devices or medical devices. Do not operate this equipment near any sensitive
medical devices.
WARNING: Use only grounded AC power cords.
Always immediately disconnect the power to the equipment in the event the device emits an unusual
odor or sound or generates smoke.
WARNING: Never attempt to disassemble, repair or make any modification to your device. Disassembly,
modification or any attempt at repair could cause bodily injury or property damage, as well as damage to
the device itself.
WARNING: Your device is not a toy. Never allow children to play with your device. Misuse, rough or
improper handling of your device by children could result in serious bodily injury for any of the
enumerated safety warnings in this manual. In addition, always keep all accessories and components out
of the reach of small children as small parts might present a choking hazard. Seek immediate medical
attention if choking occurs or if any small part has been swallowed.
CAUTION: Never raise the sound volume level too high when using your device with earphones. An
excessive sound volume level could cause damage to your hearing.
WARNING: To reduce the risk of fire or electric shock, do not expose the unit to moisture or water.
Do not allow foreign objects to get into the enclosure. If the unit is exposed to moisture, or a foreign
object gets into the enclosure, immediately disconnect the power cord from the wall. Take the unit to a
qualified service person for inspection and necessary repairs.
Read all the instructions before connecting or operating the component.
Keep this manual so you can refer to these safety instructions.

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Heed all warnings and safety information in these instructions and on the product itself. Follow all
operating instructions.
Do not use this unit near water.
You must allow a minimum 10 cm or 4 inches of unobstructed clearance around the unit. Do not place
the unit on a bed, sofa, rug, or similar surface that could block the ventilation openings. If the unit is
placed in a bookcase or cabinet, there must be ventilation of the cabinet to allow proper cooling. Keep
the component away from radiators, heat registers, stoves, or any other appliance that produces heat.
The unit must be connected to a power supply only of the type and voltage specified on the rear panel.
Connect the component to the power outlet only with the supplied power supply cable or an exact
equivalent. Do not modify the supplied cable.
Do not route the power cord where it will be crushed, pinched, bent, exposed to heat, or damaged in any
way. Pay particular attention to the power cord at the plug and where the cord exits the back of the unit.
The power cord should be unplugged from the wall outlet during a lightning storm or if the unit is to be
left unused for a long period of time.
Immediately stop using the component and have it inspected and/or serviced by a qualified service
agency if:
•The power supply cord or plug has been damaged.
•Objects have fallen or liquid has been spilled into the unit.
•The unit has been exposed to rain.
•The unit shows signs of improper operation.
•The unit has been dropped or damaged in any way.

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Background
In 2005, NuForce invented an amplifier that utilizes self-oscillating switching principles in an analog-
based topology (US patent #7,221,216 ) as a significant departure from bulky Class A/AB designs using
tubes or transistors, and Class-D digital designs that convert signals into digital data. Thanks in full
measure to unique innovations, the NuForce Reference 9 amp received the Power Amp of The Year 2005
award from The Absolute Sound, a prestigious American audiophile magazine. Subsequent versions of the
Reference 9 received similar awards in Japan and France.
In 2014, NuForce, having decided to focus on mobile products, sold the high-end line along with its
technology to investors who then created NuPrime Audio. Under the leadership of NuForce co-founder
and original CEO, NuPrime has assembled a design team comprised of talented engineers who earlier
worked on NuForce’s high-end line along with newly recruited experts in switching-power circuit design.
Recent developments have made it possible to redesign NuPrime’s switching amp topology from the
ground up in order to create a new generation of amps that allow NuPrime to precisely tailor sonic
characteristics.
NuPrime is not a Switching Digital Amplifier
Switching Digital Amps, commonly known as Class-D, first appeared some decades ago. From the start,
Class-D showed enormous potential along with significant shortcomings: limited usable bandwidth, and a
fixed saw-tooth waveform for audio-signal modulation accompanied by jitter that masks low-level
signals.
Instead of the conventional saw-tooth configuration, NuPrime’s patented circuit design uses a naturally
occurring analog-modulating signal that adds neither noise nor jitter. Rather than reverting to off-the-
shelf solutions, NuPrime’s in-house advances have further unlocked the switching amp’s potential
without the difficulties pure digital-switching amplifiers simply cannot avoid – in other words, the best of
both worlds.
Goodbye, heat. Goodbye, hernias.
Once upon a time heat and bulk were badges of status. Today, they’re the bane of obsolescent technology.
NuPrime amps switch at 600,000Hz – more than 10X the CD sampling rate. At these frequencies,
transformers and capacitors work far more efficiently, thus making it possible to reduce their size.
Typically, Class-A amps rarely utilize more than 30% of the power they draw; the rest is wasted as heat.

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High operating temperatures also shorten the useful life of the electrolytic capacitors used in abundance
in these designs.
A comparison with traditional designs is mind-boggling. A NuPrime amp, small enough to sit on the palm
of one’s hand, is, typically, 85% efficient – in practical terms, cool-running and easy on the utility bill.
Advantages of NuPrime Amplifier Technology
1. High bandwidth. Truly faithful reproduction of music demands bandwidth, and plenty of it.
Inadequate bandwidth withholds important spatial information and tonal complexities. NuPrime
amps deliver high bandwidth with a ruler-flat response from 20 to 50,000Hz. Only a very few, very
expensive linear amplifiers are capable of achieving that. This bandwidth allows NuPrime to amplify
complex music with faithfulness far beyond the capability of conventional amps, with particular
regard to a vast soundstage – accurate spatial information delivered in full.
2. An extremely high damping factor. Damping factor is simply a measure of an amplifier’s ability to
drive and control a speaker. The higher the number, the better. An excellent tube amplifier might
have a damping factor between 10 and 100. A high-quality Class-A amplifier might reach 200. A
NuPrime amplifier has a damping factor of about 400. And unlike conventional amps, NuPrime’s
damping factor is totally unaffected by changes in audio frequencies. Simply stated, NuPrime delivers
lightning-fast dynamics to any speaker.
3. Ultra-low distortion and noise. In conventional amplifiers, fixed specifications for distortion and noise
simply do not exist. Manufacturers invariably choose to quote the most flattering numbers, typically
measured at 1 watt. In reality, when power demands increase, so does distortion and noise. NuPrime
employs patent-pending technologies that cancel distortion at every cycle of operation. NuPrime
amps maintain the same low distortion characteristics at every output level and audio frequency.
4. No phase shift. Many amps use output filters that create phase shift. When phase shifts, spatial
information becomes inaccurate. Most amps present phase shifts of better than 45 degrees at 20 kHz,
heading toward 90 degrees as frequency increases. NuPrime amps cancel these distortions owing to a
unique closed-loop design producing zero phase shift across all frequencies. Repeat, zero.
NuPrime provides unequalled, fully regulated output without ripple voltage or noise. Absent this
electronic smog, music emerges from a pristine background, delicate details and nuances intact. Purity
has a sound, and it’s beautiful.

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NuPrime MCH-K38, A Reference LE Class Multi-Channel Amplifier
The NuPrime MCH-K38 is a Reference LE class multi-channel amplifier designed for uncompromising
home theater and music listening. With its quality parts throughout and an advanced 550kHz switching
amplifier operation, the MCH-K38 delivers a full 210 watts into 4 and 8 Ohms per channel. Each pair of
output channels can be bridged to double the power to 400W at 4 and 8 Ohms. The NuPrime MCH-K38
comes with 8 sets of RCA and true balanced XLR inputs. A self-resonant design, the amp’s 550 kHz PWM
switching frequency constantly adjusts to the input signal, output current demands, and loudspeaker
impedance variations. Exemplary speed, accuracy and exquisite dynamics nicely describes NuPrime's
signature sound.
The MCH-K38 amplifier is derived from the ULCAM (Ultra Linear Class A Module)+Class D design first
introduced in IDA-8. By joining a powerful high impedance single-ended amplifier circuit in the preamp
stage with a well integrated Class-D power stage, the MCH-K38’s rich tube-like sound and tremendous
speed is sure to impress audio enthusiasts. By utilizing a 1000W power supply and CMA capacitor array,
the MCH-K38 fully exploits the Class A+D design’s ability to deliver massive amounts of power and speed
when needed by a single or multi channels.
The NuPrime Sound
•Vast soundstage
•Wide, lightning-fast dynamics
•Ultra-low distortion and noise
•Music emerges from a pristine background, with delicate details and nuances intact
In summary, NuPrime’s sonic character stands well apart from – and indeed above – the soft, cushy
sound we often associate with most tubed amplification or the dry, edgy sound we often associate with
solid-state and switching technology. Rarely does an amp achieve an ideal balance of richly textured
timbres and harmonics, bottom-end authority, startling dynamics, exquisite low-level detail, and a fully
revealed, fully dimensional soundstage against a backdrop of mile-deep silence.
Specifications:
•Inputs:
oRCA: Un-Balanced input x 8
oXLR: Balanced input x 8
•Outputs:
oStereo Speaker Out x 8
oor

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oMono Speaker Out x 4
•Power: 8 X 210W at 8 & 4 Ohms / 4 X 400W @ 8 & 4 Ohms
•Input Impedance: 47k Ohms
•Gain: x 22
•Signal to Noise Ratio: > 80dB at 1W, 10W, 100W
•THD+N: 0.02% (Stereo) / 0.01% (Mono)
•Frequency Response: 10Hz to 50kHz
•Worldwide AC voltage: (115 VAC / 230 VAC)
•AC Fuse: Slow-blow, 7A, 250VAC
•Dimension: 430.3 mm W x 378.7 mm D x 98.55 mm H (including feet)
•Weight: 14.5 kg
•Color: Black

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User Guide
Back Panel View
The back panel of NuPrime MCH-K38 consists 4 sets of stereo amplifier output modules. Each set can
also be bridged into a mono amplifier making NuPrime MCH-K38 versatile when comes to channel
selections. This feature enables MCH-K38 capable of supporting 8 channels (all set to stereo), 7 channels
(1 set to mono 3 set to stereo), 6 channels (2 set to mono 2 set to stereo), 5 channels (3 set to mono 1 set
to stereo), and 4 channels (all set to mono).
1. XLR & RCA switch: Selecting input signal method
of either XLR or RCA inputs.
2. Mono & Stereo switch: Selecting speaker output to
be 2 channel stereo or full bridged mono channel.
3. XLR & RCA input connector.
4. Speaker output terminals.
Stereo connection:
1. Choose either RCA or XLR input and
make sure the switch is properly selected.
2. Be sure the switch is selected to
Stereo.
3. Be sure the cables are securely
connected to the desire input connectors.
4. Connect the speaker cables to
output terminals. Note: The top row is
positive and bottom row is negative.

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Mono Connection:
1. Choose either RCA or XLR connection and
make sure the switch is properly selected.
2. Be sure the switch is selected to Mono.
3. Be sure the cables are securely connected to
the desire input connectors. Please connect to the
connectors in white color. Gray
connectors do not work in Mono mode.
4. Connect the speaker cables to output
terminals.
Note: Please connect to the speaker terminal in white color. The left is positive and right is
negative speaker. Gray terminals do not work in Mono mode.
Trigger In: When in use, front panel and remote control power buttons are disabled. Power control only
available via Preamp stage.
Front Panel View
1. Standby indicator light: Red light indicates the unit is on standby. Green light indicates the unit is
power on. Light off indicates the unit is power off.
2. IR receiver: Accepting remote control signal.
3. 4 set of Stereo channel indicator light: Red indicates the input signal is from XLR. Green indicates the
input signal is from RCA. Light off indicates the channel is turn off or in full bridged mode.
4. 4 set of Mono channel indicator light: Red indicates the input signal is from XLR. Green indicates the
input signal is from RCA