Shuguang S300MK User manual
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Thank you very much for choosing Shuguang Audio Classic Series vacuum tube amplifier
(KT88 version).
When opening the package, please carefully remove the tube cage (vacuum tubes are
packed inside the cage) and install each tube to its marked location on the amplifier. Please
double check to ensure a safe and secure connection for each tube in its socket.
Please read this manual in its entirety before you turn on the amplifier for the first time.
About Shuguang Audio
Shuguang Electron Group (aka Shuguang Electron) currently is the world’s largest vacuum
tube producer. The group was formed in 1958 and over the past decades, Shuguang has
designed and manufactured many high quality audio vacuum tubes and they are used on
tube audio products under many brands.
Shuguang Dongsheng Electronics Co. Ltd (aka Shuguang Audio) is a subsidiary of
Shuguang Electron Group, specialized in high end vacuum tubes and tube audio design,
manufacture and distribution.
This Shuguang Classic series vacuum tube amp is one of Shuguang Audio’s many
products.
Caution!
This product should only be used with its specified power supply voltage /
frequency to ensure safety and longevity.
If the product is not in use for extended period of time, please unplug the unit
from your power supply.
When the product is powered on, do not touch the vacuum tubes with bare
hands or any materials that could melt at high temperature. Tubes operate at
extremely high temperature and could cause serious burn to exposed skin.
Children should be kept away from a tube amplifier, no matter if it is powered on
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or off for safety precautions.
Each channel has two output terminals –4 ohm and 8 ohm. Under no
circumstance should the product be connected with speakers at both 4 ohm and
8 ohm terminals at the same time. This will overload your amp and cause serious
damages.
Before turning on the product, please check if your speakers are connected to the
amplifier properly. Turning on a tube amplifier without speaker load could cause
serious damage to your amplifier and it is not covered by manufacturer’s
warranty.
The product should be kept in a dry area, without excessive moisture and has
absolutely no contact with liquid.
Tube amplifier produces heat during operation –it should always be kept well
ventilated. Do not install them inside an enclosed cabinet.
Any repairs should be carried out by certified personnel only.
When moving a tube amplifier, please be gentle in case the vacuum tubes are
damaged during handling.
Under no circumstance should a vacuum tube be removed from a tube amplifier
or speakers are disconnected while the amplifier is still powered on.
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Function:
1). Top view
1. 12AX7 2. CV181-Z 3. 300B-Z
4. 5AR4 5. AC adjustment
2). Front faceplate：
1. Power switch 2. Volume control 3. Stand-by 4. Inputs 5.remote sensor
3).
1. RCA Inputs 2. Speaker connectors 3. Power socket 4. Fuse
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Specifications:
This amplifier is a single ended triode Class A 300B integrated amp. It has auto bias
circuit so no manual bias adjustment is required.
Input impedance: 100kohm
Input Power Voltage: ≤350mV
Output Power：2×8W
Output impedance: 4、8Ω
Frequency Response: 12Hz-25KHz
THD: 1%
S/N Ratio：80dB
Power supply：AC 115V 60Hz
Net weight：23 Kg / 51 lbs
Size：410mm （W）×335mm（D）×210mm（H）
Operational Instructions:
1. Install all tubes to its corresponding sockets securely. Press down gently but ensure a
tight secure connection.
2. Select 4ohm or 8 ohm speaker connectors based on your speakers specification and
connect both channels correctly and securely.
3. Connect RCA interconnects from your source to the amplifier (red to red, black to
black)
4. Connect the provided power cord to the power socket at the rear panel. Use a proper
size 3-prone power cord only if you plan to upgrade the stock power cord.
5. Check the above steps carefully to ensure all connections are secure and correct.
6. Turn the volume knob to minimum, press down“Power” button. The Power LED light
should come on and tube filaments turn on gradually.
7. Wait for 30 seconds, adjust the volume to proper level then you can start to listen to
the music.
8. In 5-10 minutes after power on, the amplifier and the tubes will be preheated and the
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sound will be warmer and fuller than just powered on.
9. If it is found that the amplifier has AC humming noise in use, you may adjust the AC
adjustment spot on the top plate to minimize the noise.
Cautions regarding vacuum tubes:
1、Each tube has a guide pin and the tube should only be installed with the guide pin fits
into the socket appropriate position.
2、Do not pull a tube by holding the glass part only. Only pull a tube by its base. Do not
shake, tap or snap a vacuum tube. A tube is a very fragile and delicate device –any
external force could cause fatal damage to it and such damage is not covered by
manufacturer’s warranty.
3、When a tube’s internal silver coating becomes grey or white, the tube’s vacuum seal
has broken and it must be replaced.
4、When a tube’s plate becomes abnormally red hot (it can only be identified in a dark
room), it indicates that the tube is running at over its heat dissipation limit. You should
turn off the amp immediately and find out what caused the overheating, which could
be a result of voltage variation, bias setting too high or a failing component in the
circuit. It’s highly recommended to have a technician to check out the amp
thoroughly before resuming normal use.
Warranty:
Please consult your local distributor for warranty policy.
Manufacturer: Shuguang Dongsheng Electronics Co., Ltd. Phone: 0731-4177129 Fax：0731-4112838
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