Cayin m-845D User manual

VACUUM TUBE MONO BLOCK POWER AMPLIFIER
-845D
m
REV：1.1
User's Manual

Table of Contents
Thanks for choosing CAYIN M-845D vacuum tube mono block power and please read the user's
manual carefully before installation and operation.
In order to prevent damage during transportation, the amplifier is packed with protective foams surrounding
the tubes. Before installation and operation, please remove these foams to avoid any risks.
amplifier
Table of Contents
Package Contents…………………………………………………………………………………………………………2
Product Features…………………………………………………………………………………………………………3
Safety Precautions………………………………………………………………………………………………………3
Specifications………………………………………………………………………………………………………………4
Maintenance………………………………………………………………………………………………………………5
Warranty Service…………………………………………………………………………………………………………5
Precautions…………………………………………………………………………………………………………………6
Front Panel…………………………………………………………………………………………………………………7
Rear Panel…………………………………………………………………………………………………………………8
Top Panel……………………………………………………………………………………………………………………9
Installation………………………………………………………………………………………………………………10
Tube Replacement ……………………………………………………………………………………………………10
Audio Connection………………………………………………………………………………………………………11
Speaker Connection……………………………………………………………………………………………………12
Turn on……………………………………………………………………………………………………………………13
Small Tips…………………………………………………………………………………………………………………13
Troubleshooting ………………………………………………………………………………………………………14
How to Install Vacuum Tubes…………………………………………………………………………………………15
……………………………………………………………………………………………… 1…………
1

Please carefully check the package first and then open it.
Package contents include:
1. CAYIN M-845D 1 piece
2. Main Fuse 2 pieces
3. Power cord 1 piece
4. Users' Manual 1 piece
Please make sure local voltage level is matched with the input level of the amplifier, which indicates on the rear
panel. Too low or too high voltage may cause problem. Please contact our company or our local agent if you've found
improper voltage.
Recommendation:
Keep all packing materials for future use .
CAYIN M-845D vacuum tube mono block power amplifier
and reaching the best results. We are not responsible for problems and damages caused by non-original parts
replacement in the amplifier.
is designed and manufactured with our original parts
NOTE:
2
Package Contents
All other parts except above are not included.
NOTE:

1. Unplug the power cord if you are not going to use the product for an extended period of time.
2. The machine will become hot after working for a long time. Please keep the unit's ventilation open and
install the amplifier at a well-ventilated place to avoid troubles and fire hazard.
3. Forbidden to operate when the output is open or shorted.
4. Do not attempt to service this product yourself. Opening the cover may expose you to dangerous
voltage or other hazards.
5. We are not responsible for any problems caused by checking and opening without permission of our
company. For service, Please contact a qualified service technician.
6. Do not place any objects filled with liquids such as vases or some others on the top or around.
7. Clean only with dry cloth.
8. Please move the amplifier carefully not to drop the unit or be subject to other strong shocks.
3
Product Features
Safety Precautions
◆ Hand-made construction with the finest point-to-point wiring
◆ EI output transformer with wide bandwidth and push transformer are applied.
◆ Specially designed toroid transformer for power supply.
◆ One piece of 6SN7 has been used in the preamp stage for voltage regulation.
◆ Two pieces of 6SN7 has been used for voltage amplification.
◆
◆ Switchable between different negative feedbacks. NFB.-0dB, NFB.-2dB, NFB.-3dB, NFB.-4dB, NFB.-5dB
can be chose under different hearing environment.
◆ User Bias adjustment, Hum Balance adjustment are accessible on top of the amplifier with true ampere
meter.
◆ BALANCE and RCA input function.
◆
◆
◆ Time-delay power supply for both high/low voltage and preheated filament to prolong tube's life.
◆
◆
TJ Full Music 300B with Porcelain base has been used for drive amplification. 845 vacuum tube has been
used for Single-end Class A amplification.
High quality German WBT top grade Speaker terminals, USA Multicap Capacitors and Japanese Takman
Carbon Film Audio grade resistors have been used in the amplifier.
High-grade gold-plated porcelain tube socket is used to raise reliability of connection.
Thickly silver plated signal cables and connectors have been used.
Equipped with easily-installed aluminum tube cover for protection.

4
Specifications
◆ To reduce the risk of electric shock, do not remove the cover.
◆ No user serviceable parts inside. Refer servicing to qualified service
personnel.
◆ To reduce the risk of fire or electronic shock, do not expose the unit to
rain or moisture.
The lightning flash with arrowhead symbol is intended to alert user to the presence of uninsulated
“dangerous voltage” within the product's enclosure that may be of a risk shock to persons.
The exclamation point is intended to alert user to the presence of important operation and maintenance
(servicing) instructions accompanying the appliance.
Power Output
60W
Frequency Response
15Hz~28kHz (-3dB)
THD
0.3%(1W/1kHz;5% Under Rated Power)
Sensitivity
RCA:750mV
BALANCE:1500mV
S/N Ratio
89dB
Input Impedance
100kΩ
Output Impedance
0,4Ω , 8 Ω ,16Ω Ω Ω Ω
Input Terminals
BALANCE, RCA
NFB. Selection
0dB，-2dB，-3dB，-4dB，-5dB
Tube
845×2、300B×1、6SN7×3
WDH
480mm×577mm×252mm
Net Weight
50kg
Max Power Consumption
380W
Working Condition
Temperature：0℃～40℃ Moisture：20%～80%
Storage Condition
Temperature：-20℃～70℃ Moisture：20%～90%

Warranty Service
1.This product is warranted for a period of twelve months beginning from the date of purchase.
2.The defective product must be returned to your dealer or our company for repairing when your dealer or our
company accepts your requirement.
3.The warranty doesn't extend to any product that has been opened by you without permission of our company.
Maintenance
5
NOTE:
◆
◆ Do not use any chemicals for cleaning.
Use the soft dry cloth to clean up the chassis regularly.
The information in this manual is subject to change without
further notice.
NOTE:

Precautions
◆ Connect the power only after finishing other connections.
◆ It is normal that power transformer becomes hot for extended period of operation.
◆ Unplug the power cord if you're not going to use the product for an extended period of time.
◆Please make sure corresponding voltage is the same as required. We are not responsible for damage caused by misuse
of unsuitable voltage.
6
Connection of power cord:
Connect the speaker cables and signal cable first and then insert the power cord into the power socket.
NOTE:
YALIDA YN-401
Connected to AC INPUT
Connected to power socket

7
Front Panel
1.Power Indicator/Mute Indicator
Used to indicate the working state. The green
indicator will be on when it is working normally.
The red indicator will be on when it delays to
work. The indicator will keep flickering for 30
seconds when it delays to work under high
voltage.
2.Power Switch
Used to switch on/off the amplifier.
Note: Unplug the power cord if you're not going
to use the product for an extended period
of time.
3.NFB.Indicator：
The NFB. 0dB indicator will be on when it is NFB.0dB.
The NFB. -2dB indicator will be on when it isNFB. -2dB.
The NFB. -3dB indicator will be on when it is NFB.-3dB.
The NFB. -4dB indicator will be on when it is NFB.-4dB.
The NFB. -5dB indicator will be on when it is NFB.-5dB.
2
1 3

8
Rear Panel
1. BALANCE Signal Input Terminal
Used to connect balance output terminal.
2. Signal Input Selector
Used to choose BALANCE or RCA signal.
3. NON-BALANCE Signal Input Terminal
Used to connect non-balance output terminal.
4. NFB.Indicator
Used to choose different negative feedbacks.
5. BIAS Selector Knob
Used to choose the vacuum tube needs
adjustment. Put it at “off” after the adjustment.
6. Channel Output
Used to connect with the channel of speaker.
7. Power Socket with Main Fuse
Main fuse is located just below the power socket.
Replace the fuse with the same type and value.
7
1 2 3 4 56

Top Panel
9
1.Be careful of the high temperature of the tubes during operation.
2.Replace the tubes carefully and correctly.
3.Power tubes must be matched for well function.
NOTE:
1.845 Tube
2.300B Tube
3.845 Tube Hum Adjustment Knob
Used to adjust the 845 tube hum sound. You can adjust the 845 hum sound to the lowest by knobbing
deasil or widdershins.
4.845 Tube Bias Adjustment Knob
1). Choose the tube by BIAS SELECTOR knob; adjust the according BIAS ADJ. Knob; adjust the pointer of
BIAS meter to the center. Please make the adjustment once more for making the specification of tube
consistent.
2).Once finished bias adjustment please turn BIAS SELECTOR to the position of "OFF".
5.845 Tube Indicator
6.6SN7 Tube
7.NFB.Selector Knob
8.BIAS Selector Knob
9.BIAS Meter
Installation and Tear down of 845 Tube: Turn the tube deasil when installation and turn it widdershins when
tear down.
Installation and Tear down of 300 Tube: Install and tear down the 300B vertically.
1
3
4
9
2
8
5
7
6

Carefully read and follow the manual for installation:
◆
produce heat.
◆ In order to avoid being overheated please keep the unit's ventilation open.
◆ Do not expose this appliance to rain or moisture.
◆ Keep the amplifier in a certain distance so that it can be easily connected.
◆ Amplifier should install steadily and make sure all four feet are on the same level.
◆ Keep the amplifier over 15cm's distance to the surrounding walls.
Do not place the machine near heat sources such as radiators, heat registers or other products that
Installation
10
Input voltage level of the amplifier is 230V ±5% . Please
make sure that the supply voltage is proper. Too low or too
high voltage may cause problem or shorten the amplifier's life.
～
NOTE:
Tube Replacement
Tubes for the Machine
Tube Replacement
845
845
300B
300B
6SN7
6SN7GT、6H8C、ECC32、CV181、6N8P

11
Audio Connection
Connection method of CAYIN M-845D with other audio equipments Take pictures below for your reference.
Wrong connection
Right connection
To output terminal of CD player
To input terminal of pre-amplifier
To output terminal of pre-amplifier
To input terminal of right channel
To input terminal of left channel
BALANCE Socket：
1. The BALANCE socket is with XLR input. The
functions are following:
◆Music signal is transferred as balance signal without
the outside disturbance.
◆Professional XLR connectors are used to raise
reliability of connection.
2. In the following two systems, professional XLR
connectors are used for inside connection.
①European System (②=COLD,③=HOT)
② USA System (②=HOT,③=COLD)
3. This amplifier uses the USA System.
If the XLR balance connector is used by European
system, the restored signal of pre-amplifier or main
amplifier will be inverse. Therefore, please setup the
correct phase in advance.
①
②③
GND
HOT
COL D
①
②③
GNDCOL D
HOT
NOTE:
• Please refer to the manual s for connection with other
equipments during the installation.
• Do not insert the power cord in to the main socket
before all other equipments are well connected.
• R refers to right channel while L represents left
channel.
• Please take the right guidance for connection as
wrong connection may cause noise, down graded
function or damage.
• Do not fasten signal cable together with power
cable and speaker cables. It will seriously affect the
audio performance.

Speaker Connection
12
Check the impedance of your speakers:
Attach the positive from your speaker to the 4 or 8 ohm terminal and the negative to the 0 ohm terminals
separately. If your speakers are 6 ohm, 4 ohm or 8 ohm (recommended) terminal is preferential and it would not
cause damage to the amplifier.Connecting the left and right speakers according to the guidance can make sure
of the acoustic fidelity.
Connection of speaker cables:
1. Unscrew the terminal knob
2. Insert the speaker cable
3. Screw the terminal knob Banana plug Normal plug
Connect the speaker cables with the amplifier after it is
well connected with the speakers.
• Connect both of the speakers to make sure of the
acoustic fidelity.
• Please notice the signal direction indication of the cables.
• Do not mix up the positive and negative ends of speaker
cables or it will cause short circuit.
•
NOTE:
RED
BLACK
SPEAKER（L）

13
Turning On
Before turning on the amplifier please make sure all connections are right and power supply is stable.
• Turn on the amplifier, The red indicator will be on.
• The working indicator will be on after 30 seconds. It means that the amplifier is working normally. If the
working indicator is off, please turn off the power and contact with our local agent or our company.
• Select the right audio source channel, adjust the volume to a certain position and then you can enjoy themusic
you prefer.
•
•
Turn on: CD player- decoder- pre-amplifier-power amplifier
Turn off: power amplifier- pre-amplifier- decoder- CD player
Read the Manual —— Please read the user's manual carefully before installation and operation.
Keep the Manual —— Please keep the manual for future reference.
Warning Signs —— Don't tear off or rub off the serial number.
Operation —— Do the operations as you are instructed in the Manual.
Parts —— If you are going to use parts not supplied by our company like power cord, fuses etc please make
sure that parts you used are compatible with the safety requirements. Or it will cause fire or electric
shock.
Placement —— Put the amplifier on a level place. Make sure that it doesn't bring damage to the children,
adults and the amplifier itself.
Power —— Please make sure the local voltage is the same level as indicated on the rear panel.
Overload —— If the power socket is overloaded with other equipment, it will cause fire or electric shock.
Warranty Service —— Do not open the product and change the components inside yourself. Opening the
cover may expose you to dangerous voltage or other hazards. The warranty doesn't
extend to any product that has been opened by you without permission of our
company.
Troubleshooting —— If any problems when you are using the product, please check according to following
tips to look for the exact reason. Please contact with our company if you can't solve
the problem.
Small Ti p s
1. When the audio system is under working state, don't unplug the signal cable or speaker cables, or it will cause damage to
the amplifier and other equipments.
2. It should at least takes 2 minutes before you turn on the power again, or it will cause damage to the vacuum tubes.
NOTE:

14
Please follow the instruction in the manual in order to keep the amplifier work in its best state. If wrongly
operated and you thought that would be troubles please check according to following tip to look for the exact
reason.
Troubleshooting
NOTE: is the registered trademark of Zhuhai Spark Electronic Equipment Co., Ltd.
Problem
Cause
Remedy
NO OUTPUT
Power Indicator is
OFF.
Power cord is not well-connected.
Check power cable connection or
power outlet connection
Main fuse is out.
Replace with the same type
and value fuse.
Troubles of inner parts or components.
Please contact with local
agents or our company.
Power Indicator is
ON.
Volume is at ZERO.
Turn up the Volume.
NO signal input.
Check the function of the
sound source.
Check the input selection and
switch to the proper input.
Sound Distortion
High input signal level.
Turn down the volume to
suitable position.
Noise output
Ground of input signal cable is open
or bad contact of the input signal cable.
Replace the input signal
cable with a new one.
Components or circuits are in trouble.
Please contact with local
agents or our company.
Sound field Positioning
is not so good.
Signal input cables or speaker
cables are wrongly connected.
Reconnect it as suggested in
the manual.

How to Install Vacuum Tubes
Pin No. 9 Pin No.1
How to Install 9-Pin Vacuum Tubes
12AU7(ECC82)、 1 2AX7(ECC 83)
Applicable vacuum tube:
、5B K7、12 BH7、
12AT7(ECC81)、6922（ECC88), etc. 9-Pin vacuum tubes.
Instructions to Change and Install the vacuum tubes:
To install a nine-pin vacuum tube, align the pins of the vacuum
tube with the holes of the tube socket and insert the tube
vertically up and down (as shown in the figure above).
Please note that when installing the nine-pin vacuum
tube, pay attention to the alignment of the vacuum tube
pins with the holes of the tube socket. Otherwise wrong
insertion will cause damage to the vacuum tube and
prevent the amplifier from working properly, which may
lead to failure of the amplifier.
Positioning Pin
How to Install 8-Pin Vacuum Tubes
Applicable vacuum tube:
KT150、KT170、KT88、6550、EL34、6V6、6SN7、6SL7、5AR4,
etc. 8-pin vacuum tubes.
Instructions to Change and Install the vacuum tubes:
To install an eight-pin vacuum tube, align the positioning pin of
the tube with the grooves in the positioning holes of the tube
socket, and install the tube by pulling up and down vertically
(as shown in the figure above).
Please note that when installing the eight-pin vacuum tube,
pay attention to the alignment of the vacuum tube positioning
pin with the positioning hole of the tube socket. Otherwise
wrong insertion will cause damage to the vacuum tube and
prevent the amplifier from working properly, which may lead to
failure of the amplifier.
How to Install 4-Pin Vacuum Tubes
Applicable vacuum tube:
300B、2A3 etc. 4-pin vacuum tubes .
Instructions to Change and Install the vacuum tubes:
To install a four-pin vacuum tube, please pay attention to the
thickness of differnet pins of the vacuum tube and the size of
the tube socket hole. Thick pin should be aligned with the big
hole, and the thin pin should be aligned with the small hole.
Install the tube vertically up and down (as shown in the figure
above).
Please note that when installing the four-pin vacuum tube,
pay attention to the thickness of differnet pins of the vacuum
tube and the size of the tube socket holes. Otherwise wrong
insertion will cause damage to the vacuum tube and prevent
the amplifier from working properly, which may lead to failure
of the amplifier.
Thin Pin Thick Pin
Big Hole
Small Hole
How to Install Big 4-Pin Vacuum Tubes
Applicable vacuum tube:
845、805、211 etc. 4-pin vacuum tubes.
Instructions to Change and Install the vacuum tubes:
To install the big four-pin vacuum tube, align the vacuum tube
positioning pin with positioning pin slot of the tube socket and
then rotate 45° clockwise to tighten. (As shown in the picture
above). To take out the big four-pin vacuum tube, turn the tube
45° counterclockwise and take it out upward after loosening.
Please note that when installing the big four-pin vacuum
tube, pay attention to the alignment of the vacuum tube
positioning pin with positioning pin slot of the tube socket and
then rotate 45° clockwise to tighten. It is strictly forbidden to
install the vacuum tube when the positioning pin is off or
missing. Otherwise wrong insertion will cause damage to the
vacuum tube and prevent the amplifier from working properly,
which may lead to failure of the amplifier.
Positioning Pin
Positioning Pin Slot
15