TubeDepot JTM45+, Инструкция по сборке

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Final Assembly
Step 1 – Install the knobs on all controls and the impedance selector.
Step 2 – Install the completed chassis into the cabinet (head or combo).
Step 3 – Connect the speakers and now … really test the amp.
Step 4 – Your amp is done and ready for play.
Final notes (important stuff to mention):
- To determine which direction of the solid state / tube rectifier switch is which, remove the
tube rectifier and turn the amp on as if you were going to play. Which ever position of this
rectifier select switch provides sound is the solid state rectifier position.
- The feedback selector has three settings: 1) bassman position; 2) 1987 model (middle)
position; 3) JTM45 position. The setting of this switch that gives the least overall midrange
gain is the bassman position (most negative feedback). The middle position is the high gain
“plexi” position (least negative feedback), and the final position is the JTM45 position.
- You can run the amp perfectly well with the rectifier tube removed and the rectifier select
switch in the “solid state” position. The power transformer runs cooler without the rectifier
tube since it is not having to provide the 5V filament supply for the rectifier tube.
- If the amp squeals (becomes unstable) when played at high volumes, I recommend using a
wooden stick (old chop stick works great) and move the hookup wires around. These are the
wires between the turret board, the tube sockets, and the controls. Because the amp has so
much gain, proper wire routing becomes important. Often a signal will “bleed” into an
adjacent wire and cause troubles. This is easily corrected by moving the physical location of
the wires around. Turn the amp on as if you are going to play (the amp must be connected to
a cabinet), turn the controls fully up, and with your wooden probe, move the wires in the amp
around. Find the locations for these wires that are the quietest (for hum and for potential
feedback). You can use a dab of silicone sealant to hold the wires in place if you like.
- When turned, the presence control will give a little audible “swish” in the sound. This is a
result of the very small level of DC voltage present on this control.
- I recommend "jumpering" the inputs and using the two volume controls independently to
provide more bass gain or more treble gain as needed. This is the classic set-up and
operation with these 4 input / no master volume style amps.
- The effectiveness of the tone controls will change at different volume levels. Because of this
interaction between the tone controls and the volume, it will take some experimentation to
really dial in the sound of the amp.
photo 9.1b
THE END
9
Final Assembly
8.1
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