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Rear Panel Features
1. MAIN INPUT
This is a female XLR-type connector that accepts
a balanced line-level signal from a mixing console or
other signal source.
2. LOOP OUT
This is a male XLR-type connector that produces
exactly the same signal that is connected to the main in-
put jack. Use it to daisy-chain several HD1521's together
off the same signal source.
Contour EQ
This built-in 3-band EQ allows the HD1521 to be
tailored for any sound application. Use it to help com-
pensate for poor room acoustics, boost highs and lows
for low-volume applications, or for any other variety of
needs.
3. EQ ON
Press this switch in to engage the Contour EQ
circuit. The LED next to the switch will light to
indicate that the EQ is on. Use this switch to
engage or bypass the EQ, or toggle it repeatedly
while listening carefully to judge the EQ’s
effect.
4. LOW
This knob allows up to
3 dB of boost or cut at
80 Hz, with no change
in level at the unity
(U) mark. This is a
shelving EQ.
5. MID
This knob allows up to 3 dB of boost or cut at a
mid frequency set by the freq knob (6), with no
change in level at the unity (U) mark. This is a
peaking EQ.
6. FREQ
This knob allows you to adjust the center
frequency of the mid-peaking EQ, from 100 Hz
to 8 kHz, with 600 Hz at the center position.
+6dB–6dB
20
Hz
100
Hz
1k
Hz
10k
Hz
20k
Hz
–3
–2
–1
0
+1
+2
+3
20
Hz
100
Hz
1k
Hz
10k
Hz
20k
Hz
–3
–2
–1
0
+1
+2
+3
20
Hz
100
Hz
1k
Hz
10k
Hz
20k
Hz
–3
–2
–1
0
+1
+2
+3
5
Owner’s Manual
Owner’s Manual
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