Getting Started
About Your Amplifier: JD 502B
Jolida’s JD 502B integrated vacuum-tube stereo amplifier is an example of state-of-the-art in vacuum-tube
technology as it exists today. This product was designed to provide: 1) an amplifier that would deliver musical
accuracy 2) a significant value based on a high performance to price ratio and 3) an all-vacuum tube
amplifier that would approach the reliability of good solid state amplifiers.
The JD 502B is housed in a heli-arc welded chassis and uses 2 sets of matched pairs (4 pieces) of 6550
power output tubes, two pieces of 12AT7 power drive tubes and 2 pieces of 12AX7 tubes for the preamplifier.
Please note that the tube types KT88 through KT100 can be used in place of the 6550s. The JD 502B is
rated at 60 watts per channel RMS. Parts quality is the best currently available, and the overall circuit layout
is maximized for sonic purity. Since the JD 502B already has a built in pre- amplifier, all that is required to
create a sound system is the addition two speakers of 4 or 8 ohms and a CD player.
Construction and Testing
Like every Jolida product, your JD 502B power amplifier has been carefully hand-crafted, using precision
mechanical parts. Electronic components and assembly procedures are similar to those used in the
manufacture of scientific equipment and musical instruments. To assure consistent performance, each JD
302B is visually inspected at several assembly points, test run, electronically tested and sonically evaluated
prior to shipment.
This time-consuming perfectionist approach in the design and manufacture of audio equipment is intended to
provide the best in musical satisfaction with lasting value.
Handling Vacuum Tubes
Many may not have had experience handling vacuum tubes. However, most people have handled
incandescent light bulbs which is very similar to dealing with vacuum tubes. As with light bulbs, you should
not touch a vacuum tube when it is on since you can burn yourself. Similarly, if a tube is dropped on a hard
surface the tube will break. When you replace a tube you should make certain the unit is disconnected from
the AC outlet and that the tube has cooled down. Never force a tube into a socket. You should treat the tube
gently when holding or replacing it. The precautions needed when handling a light bulb will give you a good
guide on how to handle a vacuum tube.
Packaging
Save all the packaging in a dry place. Your Jolida, Inc. amplifier is a precision electronic instrument and
should be properly packaged any time shipment is made. Because of its weight (45 pounds), it is highly
probable that the unit will be damaged during shipment if repackaged in a box and packing other than that
designed for the unit.
You may have occasion to return the unit to the factory for service or shipment of the unit may be required for
some other situation. Should shipment prove necessary, the original packaging may save your investment
from unnecessary damage, delay and expense.
Unpacking
The JD 502B is packed within a custom made impact absorbing foam wrap that holds the amplifier in the
carton. Because of the unit weight and because it is a precision electronic instrument, reasonable care
should be taken when unpacking the unit and preparing it for use.
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