11
GAIN Control
The GAIN control is marked in dB of attenuation. There are 
21 detents for repeatable adjustments. Turn the GAIN con-
trol clockwise to increase gain and counter clockwise to 
decrease gain. 
The upper 14 steps are about 1 dB each and settings 
should normally be made within this range. When operat-
ing with the GAIN set below -15 dB, it may be possible to 
exceed input headroom. If this is the case, reduce the input 
signal strength and increase the gain of the loudspeaker 
amplifier.
Subwoofer Gain Notes
Scenario: One input signal only to the subwoofer, 
one full-range loudspeaker for each subwoofer- The 
HPR loudspeakers are designed to be used as a system, 
typically using one subwoofer for each full-range loud-
speaker. If the subwoofer and the full-range loudspeaker 
have their Gain controls set identically, the tonal balance 
will be correct (or very close to correct).
Scenario: Two input (L+R) signals to the subwoofer, 
and two full-range loudspeakers per subwoofer- 
When two inputs (L+R) are applied to the subwoofer, an 
additional gain of 6dB is automatically applied to the sub-
woofer. The additional gain is added to the subwoofer to 
keep the tonal balance correct for use with two full-range 
loudspeakers.
100 Hertz Low-Cut Filter Switch: 
HPR122i, HPR152i, and HPR153i
Below the LED indicators is a small recessed slide-switch 
that enables or disables a 100 Hertz low-cut filter. 
Filter OFF (Full Range)
Turn the filter OFF when using without subwoofers or dedi-
cated low-frequency enclosures.
Filter ON (100 Hz Low-Cut)
Turn the filter ON when using with optional subwoofers or 
low-frequency systems. This results in proper subwoofer 
operation and allows the top box to provide improved clar-
ity in the middle and high frequencies. HPR122i: If using 
as a floor monitor, turn the filter ON for improved vocal 
range clarity and to reduce low frequency build-up on 
stage.
Gain control.
HPR152i and HPR153i 100 Hertz low-cut filter switch.
HPR122i 100 Hertz low-cut filter switch.