Aiken Amplification Invader MKII User Manual page 6

Dwell:
The dwell control adjusts the drive to the reverb tank. Higher dwell levels result in an
apparently "longer" decay time of the reverb. The dwell control also allows adjustment of
the proper drive level when playing clean or distorted. Distorted settings typically require
a much lower dwell level than clean settings, as there is more drive to the reverb tank
when the volume control is increased. A good "rule of thumb" is to back off on the dwell
as the volume is turned up, unless you want a very deep "surf" reverb.
Reverb:
The reverb control adjusts the amount of reverb added to the main signal. The reverb
circuit is a parallel mix circuit, so the dry path is not affected by the signal, and the reverb
is completely out of the circuit when the control is turned fully off.
Presence:
The presence control adjusts the high frequency equalization in the output stage. It is a
"shelving" control that operates by cutting the amount of high frequencies in the global
negative feedback loop, which results in a boost in the output high frequency range and a
subjectively "brighter" and more "open" tone in the highs due to the lower negative
feedback at those frequencies. Note that a small amount of noise during rotation of the
presence control is normal, and is due to a small DC voltage present on the control. This
was deliberately done, in keeping with the "old-style" presence control circuitry.
Attenuator:
The attenuator controls the overall output level, and allows turning the amplifier up to get
full-volume overdrive tones at lower volumes, without sacrificing tone quality.
approach avoids the "buzzy" sound characteristic of master volume amplifiers. The
attenuator features 0dB, -3dB, -6dB, -9dB, and -12dB positions, as well as a VAR
position which enables a second, continuously-variable control that goes from –15dB
down to "bedroom" levels for low volume recording or bedroom/apartment practicing. It
is okay to switch the attenuator to different settings with the amplifier on, but it is
recommended to not be playing while changing positions, because a rotary switch, such
as that used in the attenuator, will have a small fractional amount of time where there is
no connection at all during the switching process. While we have never seen an output
transformer or tube damaged by this, it is remotely possible that the transient may cause
a problem, so it is not recommended. Before changing positions, just stop playing for a
second, change to the different attenuation level, and continue playing.
Variable:
This control is only enabled when the attenuator is set to the "VAR" position. It allows
adjustment from –15dB down to very low "bedroom" levels to allow quiet practicing or
recording.
Pilot lamp:
The pilot lamp lights when power is applied to the amplifier and the power switch is on.
The pilot lamp features a screw-on "jewel" that can be removed from the front panel to
replace the bulb without having to remove the chassis.
"bayonet" style bulb, available at most electronics supply stores.
InvaderMKIIManual.doc 12/08/11
Copyright 2003-2011, Aiken Amplification, Inc.
The bulb is a standard #47
Page 6 of 17
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