allowing the
heaters
to remain energized. The STAND-BY mode is used during short breaks
and is usually preferred to turning the amplifier off. This allows the amplifier to cool and
greatly enhances the useful life of the output tubes.
NOTE: MATCHLESS amplifiers are biased
hot
and should not be allowed to idle with no
Input signal for long periods of time.
3. Tube type amplifiers are inherently sensitive to speaker impedance matching.
This is due to the relationship of the internal res
istance’s of the output transformer, the
output tubes, and the load they are required to drive. A load imbalance can cause loss of
power, self-oscillation, or excessive current to flow in the output stage. In severe cases this
condition can cause the output transformer to run hot and may damage and destroy the
output tubes. This kind of damage is not covered by the warranty. The impedance switch,
located at the rear of the chassis, is used to match the amplifier to the speaker load. This
rotary switch has three positions and can match the amplifier to four, eight, or sixteen ohm
loads. This switch should be set before the amplifier is turned on. MATCHLESS single and
four-ten cabinets are normally eight ohms. Dual speaker models are normally four ohms.
When it is desired to use additional speakers with the amplifier, or multiple speakers with an
amp head or combo in conjunction with an additional 112 speaker cabinet, it is necessary to
calculate the proper impedance setting. This is easily accomplished using a
simple “Ohm’s
Law” formula:
FORMULA: Load 1 x Load 2 EXAMPLE: 8 Ohms x 8 Ohms
_______________ ________________ = 4 ohms
Load 1 + Load 2 8 Ohms + 8 Ohms
The correct setting for two 8 ohm cabinets connected in
parallel
should be the four ohm
setting at the amplifier. It is also possible to connect speaker systems of unequal
impedance values using the same formula, simply set the impedance switch to the value
closest to the result. Remember that volume output may be also be unequal, as the lower
impedance speaker is likely to be slightly louder because it demands most of the power
from the amplifier. Also, be sure that the power handling capacity is adequate.
POWER SOAK DEVICES
The use of “power-soak” devices is not recommended on your amplifier. These devices can
severely shorten the life of the output tubes which
should be replaced as a matched
quartet
.
Replacing vacuum tubes can be quite expensive. If however one of these devices is an
integral part of
your
sound, choose one that is well designed and built by a reputable
company. When the amplifier starts to sound
dull
, it’s time to replace the output tubes.
Always replace tubes with premium quality tubes only!
Cheap tubes will not sound good and
will not last. MATCHLESS sell replacement tubes for all models. Please contact your dealer
or call the factory at (310)-444-1922.
SWITCHES AND INDICATORS
POWER: OFF/ON
This switch supplies power from the A.C. mains and is used to turn the amplifier
off
and
on.
The amplifier
on
status is indicated by the illumination of the
“MATCHLESS”
logo on
the front of the amplifier.
