6
transformers well above 200,000 cycles. The combined use of these special output transformers in conjunction
with video pulse amplifier techniques and multiple feedback loops have enabled us to achieve the exceptionally
wide frequency response of two octaves above and below the normal range of human hearing.
This design employs 2-KT88/6550 beam power pentodes in each channel, driven by video power pentodes
used conventionally in pulse amplifiers and wide band industrial equipment such as computers. All low
frequency coupling networks have been inserted into internal feedback loops, thereby reducing phase distortion
to an absolute minimum in the subsonic region. At the same time the high frequency response of the amplifier,
exclusive of the output transformer, is flat to the megacycle region.
From the moment you turn this amplifier on and the stylus touches the record with an assured “thump”, you
will know you have constructed an exceptional instrument. Critical listening tests will reveal subtleties in your
records and tapes you never knew existed, and each performance will prove to be a new experience for you.
UNPACKING
Set aside ample room on your workbench to unpack the contents of this kit. Open the carton carefully and
place all of the components on your workbench, separating them into their respective categories. Handle all
parts with care, for they may become damaged through carelessness. Check the contents of the carton and folds
of the packing material before discarding it.
After all of the parts have been unpacked, check them against the master parts list in this manual to make
certain all parts are present and are correct as to type and value. Whenever possible, the values are stamped on
the outside of the parts to facilitate identification.
PLEASE NOTIFY YOUR DEALER IMMEDIATELY IF A SHORTAGE OR ERRONEOUS PART IS
DISCOVERED.
In the event of visible shipping damage, notify your dealer at once. If the kit was shipped to you, notify the
transportation company without delay. Harman-Kardon will cooperate with you in such instances, but please
note that only you can recover from the carrier for damages incurred during shipping.
To help us expedite delivery to you, it may occasionally be necessary for us to make minor part substitutions.
Before these substitutions are made, they are thoroughly checked to be certain that the replacement is equal to or
superior to the original component in every respect. For example, a 50 volt capacitor may be substituted for a 25
volt unit. In some instances, a 5% tolerance component may be substituted for a 10% unit. This would provide a
component with closer tolerances than required. In every case, these substitutions will not a ffect the per-
formance of the unit.
CONSTRUCTION INFORMATION
Tools Required
Only standard tools are required for the proper assembly of this kit. The most important and frequently used
tool will be the soldering iron. It should therefore be a good one. A pencil type iron between 50 and 80 watts or
a solder gun up to 100 watts is recommended. You will also require a long-nose pliers, diagonal cutters,
screwdriver, sharp knife, solder
(
rosin core only
)
, and an adjustable wrench. An ohmmeter could be of value but
is not essential.
Soldering Technique
Good solder connections are essential for the proper operation of this instrument. An improperly soldered
connection or a “cold” solder joint can cause considerable difficulty and is extremely hard to locate. If you have
little or no experience with soldering, it is suggested you read the following section carefully before proceeding
with the construction of the kit. Practice your soldering on an old terminal strip or tube socket u ntil you are
certain you can attain a workable degree of skill. Soldering is not difficult. Merely observe the following rules and
precautions:
