Yorkville PowerMAX22-2 - Manuel (Page 6)

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7. HPF Button
Situated at the top of the mono channel strips, this switch activates a High-Pass Filter
(a bass roll-off of 18 dB per octave below 80 Hz). The stereo channels do not have this
feature, as they are normally used for pre-recorded material.
The HPF (High-Pass Filter) is useful for controlling unwanted low-frequency spillover
picked up by microphones located too close to the bass drum, bass amp or the key-
board amp. It is also effective in regulating acoustic guitar pickups that are sounding
too boomy (the lowest note on a concert-tuned guitar is 81.2 Hz, so you aren’t losing
anything by rolling off the input response below 80 Hz). Additionally, the HPF works
to reduce pops and thumps from vocal microphones. Any microphone, or pickup, which
reflects a source that does not go below 80 Hz should have the HPF activated. This
includes most wind instruments, most male voices, nearly all female voices and all drum
microphones except for the kick-drum.
Why roll off the bass on these channels? …because you will obtain better clarity and
improve the system’s gain before feedback.
8. Gain Control
PowerMAX features active input circuitry with exceptionally high headroom. The Gain
control regulates the channel gain level to match it with the input signal strength. There
are two gradation circles, the outer one (-20 dB to +56 dB) for the Mic input, the inner
one (-36 dB to +40 dB) for the Bal Line input. Since this control has a range of 70 dB, it
presents the user with considerable variability given the slightest amount of movement.
A quick way to ensure that the Gain is adjusted correctly is to turn it up during a
sound check until the Clip LED begins to flash (keep the channel fader at a safe, low set-
ting during this process), then turn the Gain down slightly. PowerMAX’s Clip LED drive cir-
cuits are preset to fire at 6 dB below the onset of actual clipping so you need not worry
about seeing some activity on the lights. You will find that this or any system performs
more cleanly and quietly with the Gain controls all set properly. Also, you may use PFL
(Pre-Fade Listen) and the VU meter to set 0 dB.
9. Channel EQ
The mono channels feature 3-band Equalization with control of +/-15dB. Mids are swept
from 80 Hz to 8 kHz (2.5 kHz highlighted in the graphics as (our) standard mid frequen-
cy). The High EQ is shelving at 12 kHz and Low EQ shelves at 80 Hz. The stereo channel
EQ is 4-band (+/-15dB) with fixed mids at 250 Hz and 2.5 kHz. The Low EQ control (+/-
15dB) are the same as the mono channels.
Setting the channel EQ, like setting the Gain, is best done during a sound check. In
this case however, the less you vary things above or below “0,” the better. +/-15dB rep-
resents considerable level change. If you need to turn down the High EQ on a channel,
perhaps due to a persistent feedback problem with that microphone, you may need to re-
adjust the level fader. In any case, big boosts are probably best avoided.
One cure for a bad feedback problem is to Insert (see Insert Jack) a graphic or
parametric EQ into the problem channel and adjust it to attenuate only the feedback
frequency. That way, fewer innocent frequencies will be affected. However, the chan-
nel EQ’s Mid Sweep control can often be used quite effectively to perform a similar
function. Simply set the Mid at about -6 dB then rotate the Sweep control until the
feedback stops. Now turn the Mid up slightly to normalize the frequency response as
much as possible without feedback.
10. Mon 1 and Mon 2 Sends
These are pre-fade, post-EQ sends. Internal routing is…
1. to the Mon masters and Solo buttons
2. to the Mon 1 and 2 EQs
3. to the Mon 1 and 2 Line Level Outputs
4. through the cutoff switches in the Amp C and D Amplifier Inputs
5. to the built-in, 800-Watt amplifiers C&D and finally
6. to the Mon 1 and 2 Power Amplifier Outputs.
Post-F
ader
Ch
an
ne
l
EQ
Pr
e-F
ader
EF
X
Au
x
EF
X
1
2
Mon
1
Mon
2
Pan
EF
X
Au
x
EF
X
1
2
Mon
1
Mon
2
Pan
HPF 80Hz HPF 80Hz
Act
Clip
Act
Clip
Low 80Hz
High 12KHz
Mid
Sweep
Gain
Low 80Hz
High 12KHz
Mid
Sweep
Gain
Solo Solo
1 2
Mute Mute
1 2
-15 +15
0
dB
-15 +15
0
dB
-15 +15
0
dB
-15 +15
0
dB
-15 +15
0
dB
-15 +15
0
dB
dB
mic
+20
+30
-20 +56
0
+10
-10
+50 -36 +40 line
+20 -20
0
-6 +10
dB
mic
+20
+30
-20 +56
0
+10
-10
+50 -36 +40 line
+20 -20
0
-6 +10
0
5
2 8
7
6 4
3
9 1
10
0
5
2 8
7
6 4
3
9 1
10
0
5
2 8
7
6 4
3
9 1
10
0 10
0 10
0
5
2 8
7
6 4
3
9 1
10
0
5
2 8
7
6 4
3
9 1
10
0
5
2 8
7
6 4
3
9 1
10
0 10
0 10
80 8K
5K
2.5K
1.5K
200
100
Hz
1K
80 8K
5K
2.5K
1.5K
200
100
Hz
1K
24
12
6
0 0
3
24
dB
12
6
6
-
+
0
3
0 0
3
24
12
6
0 0
3
24
dB
12
6
6
-
+
0
3
0 0
3