About the
POWER AMPLIFIER SECTION
MATCHLESS amplifiers are cathode biased and operate mostly in a "class A" mode. This
means that current flows continuously through the output tubes whether a signal is
present or not. Most amplifier designs employ the more popular "AB" or "AB1" biasing
technique, which although capable of producing more power for a given tube
configuration and transformer size, produces crossover distortion and more odd order
harmonics. This is why MATCHLESS amplifiers are described as having a smooth tone
that won't fatigue the ears even at high volume.
The MATCHLESS design also does away with controlled or corrective
negative
feedback,
allowing the amplifier to run "open loop" or wide band. This is why our
amplifiers sound full and rich at low or high volume levels.
These are what we call
'features of design'
and very much a part of the distinctive
MATCHLESS tone.
There are four controls that enable the user to adjust the parameters of the power
amplifier section. They controls are the
IMPEDANCE
switch, the
HI-LO
power switch,
the
CUT
control and the
MASTER VOLUME
control. The impedance switch is used to
correctly match the speaker load to the amplifier, as mentioned earlier. This control
(located at the rear of the amplifier)
should be set and left in the proper position before
the amplifier is turned on.
"HI-LO" POWER SWITCH:
This switch is located at the rear of the amplifier and determines the overall
output power of the amplifier. In the "HI" position all four output tubes are functioning
and the amplifier is producing maximum power. C-30 amplifiers are conservatively rated
at thirty watts. In the "LO" position, two of the output tubes are
turned off
and power is
reduced approximately 50%. Cathode bias levels are adjusted for each power setting. This
function is very useful in recording studios or small clubs where less power may be
preferable. The low power setting also produces its own distinctive tone and should be
explored fully.
MASTER VOLUME:
The MASTER volume control function is activated by push-pull switch attached to
it. When the switch is activated, the master volume control circuit is active. In the bypass
mode, the master volume control is completely out of the signal path. The MASTER
volume control adjusts the overall gain of the output amplifier regardless of the HI-LO
power setting and functions with channel one and channel two. Normally this control
would be set at its maximum (fully
clockwise)
position or bypassed (switch pulled). This
allows the power amplifier to run at full gain. This would be the normal configuration for
a cleaner sound.
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