Need-to-know info:
29 Noise Gate Threshold Level
A tip from the designer:
IMPORTANT note; please read and heed
As a rule, it is an electrical problem with the tube that causes a
power tube fuse to blow. Normally this power tube is defective and needs to be
swapped for a new tube. The best way to tell if the defect is permanent is to replace
the fuse before installing a new power tube.
The tube map on page xx shows the positions of the power tubes. The RetroTube 100
is equipped with four fuses for the V5, V6, V7 and V8 power tubes; the RetroTube 50
requires just two fuses for the two V5 and V6 power tubes. With a replacement fuse in
every fuse drawer, there are plenty of backups on board.
This control activates an onboard Noise Gate serving to suppress any excess noise
generated when both Channel 2 and Gain Boost are active. To this end, twist the knob
clockwise, near or just beyond the 9 or 10 o'clock position.
In addition the Noise Gate can be controlled remotely (on/off) via a footswitch
connected to jack 22 (for details refer to chapter 22) or via the ENGL Custom
Footswitch Z-9 (refer to chapter 21 for details). If you want to control the Noise Gate
remotely via footswitch, you must set the Threshold knob to 10 o'clock or beyond.
Use this knob to set a threshold value (that is, the noise level) at which the Noise Gate
activates to suppress the signal within the 9 to 5 o'clock range. The further you twist
the knob to the right, the higher the signal level at which the Noise Gate kicks in. If you
set the knob to the 5 o'clock position, the Noise Gate reacts to extremely high noise
levels, meaning that there's not much of a margin between the guitar signal and
background noise.
Noise is a definite no-no in many situations. For example, studio etiquette demands
that you keep a lid on extraneous noise during short breaks. It's in the nature of high-
gain rigs to generate undesirable peripheral noise in overdriven (high gain) channels.
This is attributable to the physical properties of an amp's constituent components, in
particular its active components. That's right; those cherished tubes are the culprits.
The Noise Gate is a tool that lets you silence this noise during breaks by way of signal
mute circuit. Note that electric guitars pick up interference signals, and these are
amplified tremendously at high gain levels (Channel 2 with Gain boosted). The most
common source of noise is 50 Hz or 60 Hz (hertz/cycle) mains hum, particularly when
the guitar is positioned near transformers and power units. Because in worst-case
scenarios this humming can attain extremely high levels, the Noise Gate can hardly
distinguish between the musical signal and noise. This makes it hard to find the right
Threshold setting. It is entirely possible for this humming and other noise to rise to a
level that deactivates the Noise Gate and therefore becomes audible. My advice is to
stay as far away from transformers and power units as space allows.
: The
may open up inadvertently
when the
is activated, a high-gain Lead channel is selected, and the volume
exceeds the Threshold knob setting. At very high volume and gain settings, this may
generate instant feedback, particularly if your guitar is facing the speakers. Rather
than musical and controlled, this is the shrill, unpleasant and potentially harmful
variety of feedback squealing that sends your audience and fellow musicians packing.
Though the amp is not more susceptible to feedback when the
is activated,
Noise Gate
Noise Gate
Noise Gate
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