Moonriver Audio 404 User manual

M O D E L 4 0 4
S T E R E O I N T E G R A T E D A M P L I F I E R
M O O N R I V E R A U D I O
O P E R A T I N G I N S T R U C T I O N S

We, at MOONRIVER AUDIO, would like to thank you for choosing the MOONRIVER 404 integrated amplifier.
We spend 3 years in research and development to achieve this high level of performance. The same high
performance is applied to the optional phono stage and the USB DAC.
As for the sound, we are not to say whether MODEL 404 is virtually transparent or inherently forgiving.
Voicing it to appreciate the playlist and respect the user at all times has been the sum of all our effort;
A sincere effort to achieve effortlessness.
IMPORTANT NOTE: Before installing your new MOONRIVER AUDIO component, please read this manual carefully. It will
inform you for proper installation, correct operating procedures and of the product specifications.

Contents
Important Safety Instructions 6
Unpacking And Installation 8
Box Contents 8
Introduction 10
Moonriver Audio 10
Made In Sweden 10
Moonriver Model 404 11
Design & Ergonomics 11
Modular Architecture 11
Features 12
Balance Control 12
Discovering The Layout 12
The Importance Of Tape Monitor Loop 13
Stereo/mono Switch 13
Optional Phono Stage 13
Optional Usb Dac 14
The Soft Start Function 11
MM/MC Phono Stage 15
Front Panel Description And Operation 16
Back Panel Description And Operation 17
Remote Control Operation 18
Specifications 19
Limited Waranty 20
Limits Of Warranty 20
Warning! 20
Troubleshooting 20

RISK OF ELECTRIC SHOCK
DO NOT OPEN
CAUTION
NO USER SERVICEABLE PARTS INSIDE. REFER SERVICING
TO QUALIFIED SERVICE PERSONEL.
AVIS: RISQUE DE CHOC ELECTRIQUE. NE PAS OUVRIR
IMPORTANT SAFETY INSTRUCTIONS
Before using your MOONRIVER AUDIO component, carefully read the applicable
items of these operating instructions and the safety suggestions. Please keep these
instructions in a safe place.
Before connecting a MOONRIVER AUDIO component to your audio system, turn off
all other equipment. Many audio components have automatic turn-on circuits that
may potentially cause damage to electronic components and/or speakers. This
type of damage is not covered by product warranties, and MOONRIVER AUDIO
specifically disclaims responsibility for any such damage. Connect only to AC
power outlets rated 220-240V 50Hz.
CAUTION: Do not open the chassis of the MOONRIVER 404 while the amplifier is on
or plugged into an AC wall socket. There is high voltage inside.
Do not perform any service operations. Service is required when the unit has been
damaged in any way, such as:
 mains socket is damaged
 liquid has been spilled or objects have fallen into the unit
 the unit has been exposed to rain or moisture
 the unit does not operate normally or changes in performance in a significant
way
 the unit is dropped or the enclosure is damaged
Do not place the unit on an unstable box, stand, tripod, bracket or table. If the unit
falls, it may cause injury to a person or damage to the unit. Mount the unit in a stable
and safe place.
Slots and openings in the cabinet create ventilation to protect the component from
overheating. These openings on the bottom panels must remain unobstructed.
Allow at least 10cm of clearance above the unit and an opening behind the unit for
airflow. Do not place the unit on a bed, sofa, rug, built-in bookcase, or rack without
adequate ventilation.
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Do not place near heat sources, such as radiators, heat registers, or appliances
which produce heat. Keep the rear of the unit at least 10 cm from walls or other items
that might block heat radiation. Do not use the unit near water (swimming pool, bath
tub, kitchen sink or laundry tub) or in a damp environment like a basement or outside
in the rain.
Do not step on the power cords. Do not place items on top of power cords so that
they are pinched or leaned on. Pay particular attention to the cord at the plug end
and the point where it connects to the unit. Do not defeat the safety purpose of the
grounding schuko type plug. A grounding IEC type plug has two blades and a third
grounding prong. The third prong is provided for your safety. When the provided
schuko plug does not fit into your outlet, consult an electrician to replace the broken
or obsolete outlet.
Do not push objects of any kind into the unit through openings as they could touch
dangerous voltage points and short-out parts, possibly resulting in a fire or electric
shock. Avoid spilling liquid of any kind on the unit. If water or any metal object (such
as a paper clip, coin, or staple) accidentally falls inside the unit, disconnect it from
the AC power source immediately and contact Moonriver Audio for further
instructions.
For added protection during a lightning storm or when is the component is idle for
long periods of time, unplug the unit from the wall outlet. This will help protect the
unit from lightning and power line surge damage.
Do not overload wall outlets, extension cords, or integral convenience receptacles
as this increases the risk of fire or electric shock.
7
RISK OF ELECTRIC SHOCK
DO NOT OPEN
CAUTION
NO USER SERVICEABLE PARTS INSIDE. REFER SERVICING
TO QUALIFIED SERVICE PERSONEL.
AVIS: RISQUE DE CHOC ELECTRIQUE. NE PAS OUVRIR

Unpacking and Installation
MOONRIVER AUDIO 404 integrated amplifier was shipped in a carton particularly
designed to protect the contents. Special care has been taken to prevent damage
during shipping. Carefully remove your new 404 amplifier from the packing carton
and examine it closely for signs of shipping damage. If shipping damage is
discovered, take photos of the damage, contact the transport carrier immediately
and retain the packing as evidence. We strongly recommend saving all original
packing cartons to protect your component for storage or future shipping.
Box Contents
User Manual x1
Power Cord x1
Remote Control x1
AAA batteries x2
MOONRIVER MODEL 404 amplifier x1
Packing Material
8

POWER SENSOR
OUTPUT
M O DEL 44 0
STEREO I N T E GR A T ED AM P L I F I ER
MODE
STEREO
LEFT RIGHT
MONO
NORMAL
DIMMED
MO O N R I V E R
AUDIOSOURCE
TAPE
MONITOR
VOLUME
L1/PHONO
L2/USB LINE 3
LINE 4
BALANCE
LIGHTS
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Moonriver Audio
Inspired by the famous song, MOONRIVER AUDIO is a combination of the vintage
and the contemporary in audio reproduction.
Classic, timeless, user oriented design. Organic texture acquired within an open
space, dynamic behavior unrestrained while preserving natural color, provisions
made for modular upgrades and direct access to all functions.
Moonriver loves vinyl records, analog tapes, compact discs and digital streams and
features upgradable modules for all those formats. We employ every technology
available today, without staying dogmatically exclusive to one design principle
versus another, be it solid state, integrated circuit or vacuum tube.
We are fond of hybrid designs that fuse well known and fresh tech elements, but,
most of all, that fit the application.
Made In Sweden
Our products are designed and made in Sweden. We hand-assemble each unit, a
painstaking but precise procedure. Through a global inventory that is constantly
updated, it is our sophisticated research, efficient development and extensive
listening tests -the fun part- that lead us to select the right component for a no-
compromise audiophile sound.
We also care for sustainability as well as for reliability. Moonriver products are
covered by a 3-year warranty and are designed to last for decades without any need
of maintenance.
Introduction
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Moonriver Model 404
is the outcome of a 3-year research, the aim being to achieve incredible
performance regardless of price range. The 404 amplifier will extract hidden
elements and render textures from within any audio format, with the source,
speakers and room to set the limits. Its culture will suit all music, as the Model 404 is
by design set to define the faintest nuances of which tone integrity is composed.
A hefty supply section ensures that ample healthy power is available at all times at all
stages through separate rails. A fully discrete preamp section serves for acute
dynamic awareness, while a high output stage that is custom-optimized for
bandwidth and distortion warrants for neutral predisposition and transient fidelity. A
laborious selection of components armors the design against tonal alteration,
pretentious or not, thus preserving naturalness throughout the shortest feasible
path.
Furthermore, an integrated phono stage, a USB DAC, two preamp outputs and a
tape monitor loop expand functionality to form an ideally flexible integrated
amplifier.
Design & Ergonomics
We had a very clear vision when we conceived the MOONRIVER 404 amplifier:
Classic design with a modern touch; high quality materials such as massive
aluminum knobs, solid walnut cheeks, sturdy enclosure; ergonomic user interface.
There are no “shaved” aesthetics here, no display with complicated serial menus
and hidden functions, nor a single multi-function knob for “minimalistic” purposes.
The heart of MODEL 404 is pure and minimal but the interface is user oriented and
easy to operate by anyone in seconds with no need to resort to the user manual.
Four knobs and three switches give direct access to any function.
Modular Architecture
MOONRIVER 404 amplifier is modular by nature; it can accommodate an MM or
MM/MC phono stage and a USB asynchronous DAC. Fitting these modules is quite
simple and can take place at any time, on or after purchase. The USB DAC may also
be upgraded with a newer version to meet future needs.
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Balance Control
You may find this feature to be vanishingly scarce in audiophile products as a result
of today’s “minimalist” design mentality and the various myths accompanying it.
However, balance control addresses a common problem; speakers that are
positioned in asymmetry, in a non-balanced room environment. It thus provides the
simplest tweak towards achieving a proper sound stage.
Living rooms and house furniture are meant to serve everyday life and may not be
provisioned with an ideal listening spot, evenly distanced from each speaker to form
an equilateral triangle. It is also not uncommon for one speaker to have to be placed
nearer room boundaries than the other, having various frequencies boosted in a
more or less predictable pattern. More often than not, balance control would come
in handy in that it drastically helps overcoming volume level unevenness and in
some cases even reclaiming stereo effect and the resulting focused sound stage.
As expected, the way balance control is implemented on the MOONRIVER 404
amplifier, in parallel, will not degrade or affect the signal in any way determinable.
Discovering The Layout
MODEL 404 incorporates no less than 5 separate power supplies, each featuring
overload protection. The power amplifier specifically runs on a dual mono
configuration, beginning from separate windings on the toroidal transformer.
Signal switches are implemented via relays, while volume attenuation is trusted on
the legendary blue ALPS pot.
A soft start circuit based on a 30A relay ensures that even the on/off switch is thought
out to work with virtually no burden or wear for decades.
Components are carefully selected for both suitability and reliability. We make no
use of surface-mount in analog circuits, despite the fact that through-hole costs
more and requires advanced space management & layout strategies.
Each element utilized has to be of proven stability and sustained higher
performance -proficient implementation provided- before making it into our analog
paths.
Features
12

The Importance Of Tape Monitor Loop
Probably most of today’s manufacturers reject the idea of their product featuring a
tape loop. At MOONRIVER AUDIO, we have concluded that the tape monitor loop is
essential. Not only does it add the option of monitoring the difference between
recorded and source material at a real time.
It also, and most importantly, makes possible to insert to the chain -at will- a digital
or analog room correction processor, a buffer, a noise reduction system or any
other line device available to improve the sound of connected sources.
Stereo/mono Switch
As vinyl record revamping climaxes, whether a modern rage, a fashion thing or a
real movement, countless monaural pressings emerge out there, often along with
their “digital” image. Too many of them, among others waiting to be rediscovered,
have currently become collector’s items, 78 rpm direct-cut gems being no
exception. This is not unreasonable, as what happened between say the 30s and
the 80s in terms of both musical interpretation and recording technique is by many
considered to be “most of the music” – this sentence doing perhaps no justice to
stunning actual developments in creation and reproduction. Stereo/mono switch
gives you the chance to enjoy recording art milestones with respect to how they
were initially intended to please; in genuine mono, 2-channel, doing away with
artificial phase discrepancies induced by mandatory stereo mode.
So, “less” may well be “more”, but better is to have a choice.
Optional Phono Stage
Model 404 comes with two options in the phono stage department; one is MM only
and the other is MM/MC selectable. Both follow the exact quality principles that
Model 404 is built on. Quality components and massive power supplies are also
employed here, to efficiently accommodate very low noise, high performance op-
amps.
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Optional USB DAC
What was desired for our USB DAC module was not to make an addition rather than
an omission; instead we had to be confident of substantially raising the true value
and functionality of Model 404.
Some key features; state-of-the-art XMOS USB asynchronous interface; AKM 4490
DAC chip; separate high-precision clocks for the 44,1K and the 48K sample rate
group respectively; supports PCM streams up to 384kHz. USB, D/A and analog out
section each one fed by its own dedicated power supply.
We work hard to get the best possible sound performance and we believe that this
USB DAC is a enormous added value to the Model 404 amplifier.
The USB DAC works without the need of a special driver with Windows 10 or
OSX version 10.6.4 or above. Windows 7 are supported also with a special
driver. Download the Windows 7 driver on www.moonriveraudio.com
The Soft Start Function
MOONRIVER MODEL 404 features a sophisticated soft start circuit that protects the
speakers from annoying “clicks and pops” and, at the same time, protects the
amplifier from malfunction. Each time you push the power button, a microcontroller
takes control over the relays of the amplifier: First, there is a delay of 2 seconds
followed by the input relay that lights up. 2 seconds later the preamp relay connects
the preamp output and 3 seconds later the output led lights up as well showing that
the output stage is active.
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MM/MC Phono Stage
The MM/MC phono stage can drive both Moving Magnet and Moving Coil
cartridges. The gain is 40dB for MM and 50dB for MC and the input impedance
47Kohms and 100 ohms respectively. The input capacitance is fixed at 100pF.
In order to change the setting from MM to MC or vice versa you should change the
position in 2 dual dip switches:
1. Turn off the power, disconnect the power cord, input and speaker cables.
2. Wait 1 minute while the capacitors are discharging.
3. Using a HEX screwdriver to remove the 8 screws of the cover (4 on the top and 4
on both sides).
4. Locate on the right side the nickel shield box and remove the 3 screws that hold it
in place. Remove carefully the shield box by pulling it vertically.
5. The phono stage PCB is revealed. On the right side looking from the top you can
find the dip switches. There are 2 dual switches: The left pair is for the left channel
and the right pair for the right channel.
6. Change the setting according to the instructions of your cartridge. Moving
Magnet cartridges work properly with MM setting and low output Moving Coil
cartridges with MC setting. For MC high output type the correct setting is the MM in
most of the cases.
WARNING: DO NOT change the setting of the dip switches with the amplifier turned
on! This can cause permanent damage to the op-amps. DO NOT turn on the
amplifier without the cover secured in place.
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OUTPUT
S T E R E O I N T E G R A T E D A M P L I F I E R
M O D E L 4 0 4
POWER SENSOR
MODE
STEREO
MONO
TAPE
MONITOR VOLUME
SOURCE
L1/PHONO
LINE 2 LINE 3
L4/USB
BALANCE
NORMAL
DIMMED
LIGHTS
LEFT MIN
RIGHT MAX
OFF
M O O N R I V E R
A U D I O
fågelsång
3
3
8
8
2 7
7
541 6 9
9
SOURCE SELECTOR
Turning the source selector clockwise selects the next line
source and counterclockwise the previous one. There are 4
options from line 1 to line 4. Line can be converted to mm/mc
phono stage and line 4 to asynchronous USB DAC.
POWER SWITCH
Turns the unit on or off. Off position doesn't consume any
power. CAUTION: If you just turned off the unit, please wait
at least 30 seconds before you turn it on again.
LIGHTS SWITCH
This switch changes the light’s luminosity. There are 3
options: Normal, Dimmed (50% of the normal) and off.
TAPE MONITOR
Turning the tape monitor selector clockwise activates the
tape monitor function and counterclockwise deactivates it
and return to the selected source (1-4).
OUTPUT LED
It show the status of the output stage. When the mute
function is activated by the remote the led is off.
BALANCE CONTROL
Turning the balance knob to the right, the left channel
decreases progressively, while turning it to the left the same
will happen to the right channel.
SENSOR
This mark indicates the position of the remote control sensor
MODE SWITCH
This switch swifts the signal from stereo to mono. It should
be used to old monaural analog recordings.
VOLUME CONTROL KNOB
This controls the output level. This knob is coupled to a world
class motorized Blue ALPS potentiometer.
FRONT PANEL DESCRIPTION AND OPERATION
1
2
4
5
6
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TAPE OUT (RECORD)
The record output can be used to connect a analog or a
digital recorder, a headphone amplifier or, combined with
the tape input, a tape recorder, a tube buffer, a room
correction unit etc.
PREAMPLIFIER OUTPUTS
There are 2 outputs to drive additional power amplifiers or
subwoofers. The output impedance is a few ohms.
SPEAKER OUTPUTS
These are the speaker outputs. Be sure that the left output is
connected to the left speaker and the right output to the right
one. The right polarity must be kept between the amplifier
and the speaker to avoid wrong phase.
SERIAL NUMBER
The serial number carries useful information for the unit.
MAINS INPUT
This is the mains input. It must be connected to a grounded
230VAC line.
ASYNCHRONOUS USB INPUT
When the USB DAC is installed, a Windows 10 PC or an
Apple Macintosh with OSX version 10.6.4 or above will work
flawlessly with DXD files up to 384khz/32bit without the need
of a driver.
PHONO GROUND
When a MM or a MM/MC phono stage is installed, the
turntable ground must be connected in this terminal.
ANALOG INPUTS
There are 4 line inputs to connect your line sources. Note
that line 1 can be converted to phono input. Also, when the
USB DAC is installed, the line 4 is not working.
TAPE IN (PLAY)
This is an additional line input that is useful for monitoring a 3
head tape recorder, a tube buffer, a room correction device,
etc
L
R
MAX POWER
CONSUMPTION 250W
MOONRIVER AUDIO
www.moonriveraudio.com
[email protected]
MADE IN SWEDEN
LINE 1
(PHONO) LINE 2
PHONO
GROUND LINE 3 LINE 4
(USB)
ANALOG INPUTS
AC MAINS INPUT
230VAC / 50Hz
RISK OF ELECTRIC SHOCK
DO NOT OPEN
CAUTION
NO USER SERVICEABLE PARTS INSIDE. REFER SERVICING TO
QUALIFIED SERVICE PERSONEL.
AVIS: RISQUE DE CHOC ELECTRIQUE. NE PAS OUVRIR
R
R
I
E
A
U
P
S
E
E
R
R
E
E
R
S
O
T
RIGHT SPEAKER LEFT SPEAKER
M O D E L 4 0 4
S T E R E O I N T E G R A T E D A M P L I F I E R
M O O N R I V E R A U D I O
TAPE
IN
(PLAY)
OUT
(REC)
USB
PREAMP
OUT 1 OUT 2
BACK PANEL DESCRIPTION AND OPERATION
1
1
3
3
4
4
5
5
7
7
6
6
2
2
8
8
9
9
17

CH
POWER
AV
VOL
Power indicator when a button is pressed Enables Tape Monitor ON or OFF Switches to the next line input Switches to the previous line input Increases the Volume Decreases the Volume Mutes the output
REMOTE CONTROL OPERATION
18

Specifications
Inputs: 5 (line 1 and 4 optionally occupied by phono
stage and USB DAC respectively, 1 x tape loop)
Outputs: 2 x preamp out, 1 x rec out
Power output: 50 W per channel into 8 Ω
Frequency response: 10 Hz to 50 kHz
Total harmonic distortion: 0.05%
Signal to noise ratio: 95 dB (line)
MM phono stage gain: 40dB
MC phono stage gain: 50 dB
MM input impedance: 47KΩ
MC input impedance: 100 Ω
Input capacitance: 100pF
Dimensions (mm): 430 (W) x 390 (D) x 135 (H)
Weight: 12,5 kg
19

Limited Waranty
MOONRIVER AUDIO warrants that your newly purchased hardware product shall
be free from defects in material and workmanship for three (3) years, beginning from
the date of purchase. Shipping charges are paid by the owner. Except where
prohibited by applicable law, this warranty is non transferable and is limited to the
original purchaser. This warranty gives you specific legal rights; you may also have
other rights that vary under local laws.
Limits Of Warranty
This warranty does not cover problems or damage resulting from accident, abuse,
misapplication, or any unauthorized repair, modification or disassembly; improper
operation or maintenance, usage not in accordance with product instructions or
connection to improper voltage supply.
Warning!
MOONRIVER AUDIO LABORATORY SHALL ALSO NOT BE LIABLE FOR ANY
SPECIAL, INDIRECT, INCIDENTAL, OR CONSEQUENTIAL DAMAGES
WHATSOEVER, CAUSED BY PROBLEMS IN THE MAINS ELECTRIC SUPPLY, NON
PROPER USE OR USE WITH NON COMPATIBLE APPLIANCES WITH
INCOMPATIBLE OPERATING VOLTAGE. IN ANY CASE THE LIABILITY OF
MOONRIVER AUDIO LABORATORY IS LIMITED STRICTLY TO THE INITIAL VALUE
OF THE UNIT. Some jurisdictions do not allow the exclusion or limitation of special,
indirect, incidental, or consequential damages, so the above limitation or exclusion
may not apply to you.
Troubleshooting
Incorrect operations are often mistaken for trouble and malfunctions. If you think
that there is something wrong with this component, check all the connections, the
power switch and the indicating lights. Sometimes the trouble may lie in another
component. Investigate the other components and electrical appliances being
used. If the trouble cannot be rectified even after checking everything, return your
MOONRIVER AUDIO device to your dealer to carry out repair work.
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