Thank you very much for choosing Shuguang Audio Classic Series vacuum tube amplifier (845 version). When opening the package, please carefully unpack all tubes 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 or off for safety precautions. 1
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. Function: Top View: 2
1. CV181-Z 2. 300B-Z 3. 845B 2. Front: Power on/off 3. Rear: Please note the fuse is located below the power socket. Fuse value is as indicated on the back panel. Specifications: This product is of a high fidelity single ended Class A design. As mono power amp, you must use a matching preamplifier in order to replay music. Input impedance: 100kohm Input Power Voltage: 4.0V Output Power:28W Output impedance: 4 8Ω Frequency Response: 10Hz-30KHz THD: less than 1.5% S/N Ratio:85dB Power supply:ac 115V 60Hz Power consumption: 170w per channel Net weight:25 Kg / 55 lbs per channel Size: 245mm (W) 420mm(D) 255mm(H) 3
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. Connect the two S845MK power amps to the matching S200MK preamplifier. 6. Check the above steps carefully to ensure all connections are secure and correct. 7. Turn the volume knob on the preamplifier to minimum, turn on the source (such as CD player) first, then preamplifier, turn on the power amplifier last. 7. Wait for 30 seconds until the preheat indicator light turns green, adjust the preamp 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 sound will be warmer and fuller than just powered on. Bias Adjustment: This is a manual biased tube amplifier please strictly follow the below instructions to adjust the bias. If you are not sure how to do so, please consult a technician. 1. When a new tube amp is turned on for the first time, although the bias has been pre-set at factory, you still need to re-check and re-bias the unit since your power supply might vary from factory testing voltage. 2. Before adjust bias, please turn off your source signal and turn volume to minimum. 4
3. Use a multi-meter and set it to V(DC) position. Connect the two probes from the multi-meter to the + and of the bias test point (1). Red probe for +, black probe for. Use a small screw driver to adjust the bias adjustment spot (2) until the multi-meter reading is at 80-90mV. After adjusting one channel, repeat the same process at the other channel. Make sure the readings at the two channels are no more than 1mV apart. When tubes are new, the bias readings could drift a bit in the first few hours. Check the bias in 2-3 hours after power on and reset it to above suggested 80-90mV. After the first day, check bias every 2-3 days for about a week then check bias monthly. A properly biased amplifier will run flawlessly for much longer time than an amp that is not regularly maintained. (3) in the above picture is for adjusting AC noise for the 845 tube. (4) in the above picture is for adjusting 300B AC noise. Adjust both of them until the AC noise is at minimum. The correct sequence for biasing adjustment is to adjust 845 tube bias setting first, then adjust the AC balance of 845 tube and 300B. Repeat this process for several rounds until all settings are optimized. Please note that any damage to a tube amp if such damage is caused by lack of maintenance and bias adjustment is NOT covered by warranty. 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 5
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 6