Sebago Sound DT50 50-Watt Two-Channel Head & 1x12 Cabinet
The first Volume control in the preamp section sets the level of the clean channel. The Bright switch adds a nice high end sparkle to the sound. The Mid switch fattens up the midrange significantly, it adds a nice mid boost to the clean channel, and lot of harmonics and drive to the overdrive channel. The Rock/Jazz switch adds a bit of extra midrange gain when set in Rock mode. The Preamp tone controls can be used to set the balance of the sound based on volume level, room configuration, and guitar type. They are not quite as active as some other guitar amps due to the fact that the preamp does not filter or "scoop" the mids. This causes the Treble and Bass controls to have a slightly more subtle effect on the tone. Set the Middle control at 2 or 3 to scoop the mids a bit, and the Treble and Bass controls will have more of an effect.
The Overdrive section has two controls. The Drive control sets the amount of overdrive or distortion that will be introduced, and the Volume sets the level of the Overdrive channel. Use the Overdrive Volume to match the volume level to the clean channel volume for a nice transition when switching between the two channels.
The Power Amp section has two controls. The Master volume sets the overall level of the amp, and the Presence control can be used to add some high end sparkle or bite to the tone. Settings between 7 and 10 add an audible amount of highs to the sound. Below 7, the Presence control has a more subtle effect on the "feel" of the amp that might not be audible.
The power input connector is on the left. The amplifier should always be plugged in to a three-pronged outlet running at 120V and 60Hz unless otherwise stated on the amplifier itself. There is a replaceable 3 amp Slo-Blo fuse to protect the amp should something cause a short. Before replacing the fuse and restarting the amplifier, always make sure to understand what caused the fuse to blow. Many times it is due to a faulty or failing tube, but may be due to something more serious. Always have a qualified amp technician diagnose any problems, or send your amp back to Sebago Sound for Warranty repairs.
The Mains switch turns the amplifier on and off, and the Standby switch turns the high voltage to the tubes on and off. It is best to turn the amp on with the standby switch in the off position, let the amp warm up a little and then turn the standby switch on. This is especially important if you are using vintage tubes, to prevent damage to the cathode of the tube that may be caused by applying a high voltage before the cathode has had time to warm up. Modern or recently manufactured tubes do not have as much of a tendency to suffer cathode damage on a cold startup.
There are two speaker outputs that are wired in parallel. The Impedance selector switch can be used to match your speaker confiruration to the amplifier output section. There is an unbuffered effects loop labeled Signal Access. The Output takes the signal after the Master Volume control, and the Input returns the signal directly to the Power Amp input. Be careful not to plug and unplug the Effects loop without first turning off the standby switch, you may hear a loud pop otherwise as the return is coupled directly into the power amp. This amp has a 12" Legend GB128 speaker.
There are two switches that select the Preamp Boost and Overdrive channel. If you are using the external footpedal, leave the switches in the Manual position and the footswitch will control the selection of the Boost and Overdrive functions.