Doc Q7.0
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SLOPE –
This parameter allows fine adjustment of the high-frequency impedance of the virtual voice coil
(which affects the slope of the impedance curve). A speaker voice coil is “semi-inductive” due to eddy current
losses in the motor. This presents an impedance to the power amp that is neither fully inductive nor fully
resistive. The amount of resistive loss varies by brand and type. Reducing the Slope simulates a speaker that is
less inductive, increasing Slope simulates a speaker that is more inductive. Typical speakers range from 3.0 to
4.5 with the median being about 3.7. Lower values yield greater midrange while higher values are more
scooped and sizzly.
SPEAKER DRIVE
–This parameter simulates distortion caused by pushing a speaker too hard. It interacts
with the
MASTER,
which determines how hard the actual power amp is pushing.
XFRMR DRIVE
– Controls how hard the virtual output transformer is driven. Higher values simulate a
smaller, more easily saturated transformer.
Amp EQ Page
The amp block includes a built-in graphic equalizer, eliminating the need to use a separate block for tone-shaping.
You can change the number of bands to a variety of types. Press
to reset all EQ bands to flat.
TIP: You can also change the Amp EQ type with the UP and DOWN nav buttons.
block on (p.79) for additional detail on bands, Q, etc., but remember that the GEQ
in the amp block is limited to a maximum of eight bands.
Power Amp Dynamics Page (“PWR DYN”)
5.1.5
SUPPLY SAG
– This controls power amp dynamics. Higher settings simulate higher power supply impedance,
and thus greater tube plate voltage “droop,” for a more compressed feel. This control interacts with the
Master and will have little effect if the power amp is not being pushed. As the power amp is pushed and draws
more virtual current from its virtual power supply, the
SAG
control will have more effect. (Note this same
parameter appears in the ADVANCED menu as
MAINS IMPEDANCE (SAG).
IMPORTANT:
Turning
SUPPLY SAG
fully counterclockwise defeats power amp simulation for an individual
AMP block, allowing it to be used into an external (real) tube power amp without globally disabling power
amp simulation. (See section
on p.
or the “FOH + Real Amps” diagram on p.
for more.) In this mode,
MASTER
works as a simple volume,
DEPTH
is deactivated, and
PRESENCE
turns into a simple shelving filter.
B+ TIME CONSTANT
(in the Advanced menu) interacts with the Sag control because it makes the power
supply response slower or faster. When the supply is fast it will sag rapidly accentuating the pick attack and
compressing after. Most guitar players like this, but setting it too fast will cause excessive AC ripple and ghost
notes. For convenience the virtual power supply voltage (B+) is shown as a meter on this page when the
SUPPLY SAG
control is selected. The meter displays the supply voltage in dB, relative to the idle voltage.
TUBE BIAS
– (This is the same parameter as the
PWR TUBE BIAS
control on the Advanced page). This sets the
controls the quiescent operating current of the virtual power tubes. This powerful parameter allows you to
fine-tune power amp distortion characteristics to your particular style. The higher the value, the
less
crossover distortion. When bias is reduced the amp sags and bounces more, with tighter bass and edgier tone.
