Page 23
Limiters
The limiters in the KS26 are peak limiters and can be used to help minimize amplifier clipping or to help keep
the peak voltage driving a loudspeaker under control. The loudspeaker presets in the KS26 have the limiter
thresholds set to provide one of these functions based on which needs to occur first, minimize amplifier clip-
ping or limiting the peak voltage to a loudspeaker. These both assume the use of the recommended amplifi-
er(s) for a particular Bag End loudspeaker system. In all cases the amplifier should be set for a voltage gain
of 26 dB.
Amplifiers run in bridged mode and set to 26 dB gain will have a gain of 32 dB. This is accounted for in the
limiter thresholds. Do not set the gain for amplifiers run in bridged mode to 32 dB. This will result in 38 dB
of gain for the amplifier and the amplifier will clip sooner (at a lower input voltage) and drive the loudspeaker
hard than anticipated.
If different limiter threshold settings are desired for a particular application they should be set at approxi-
mately 7.7 dBu (or 5.5 dBV) below the maximum peak level desired.
As an example, let’s say we want to keep a Bag End PT4-1000 amplifier from clipping. At a gain setting
of 26 dB its rms input voltage sensitivity is 5.0 V. This means its peak input voltage sensitivity is 7.07 V.
This is the peak input voltage that will drive the amplifier to its maximum level (assuming no current limiting
or other protection mechanisms are encountered). We need to limit the output of the KS26 channel driving
the PT4-1000 to a peak voltage of no more than 7.07 V, which is 17 dBV or 19.2 dBu. Setting the limiter
threshold to about 11.5 dB should keep the amplifier out of clipping.
Limiter Threshold Setting (dBV) based on input voltage to amplifier
Limiter Threshold Setting (dBu) based on input voltage to amplifier
As a different example let’s say we want to keep the maximum peak voltage to the high frequency section
of a loudspeaker from exceeding 63 V. This is equivalent to a peak level of 36 dBV or 38.2 dBu. The am-
plifier has 26 dB of gain so the peak input to the amplifier should not exceed 10 dBV or 12.2 dBu. A limiter
setting of about 4.5 dB should accomplish this.
Limiter Threshold Setting (dBV) based on output voltage from amplifier.
Limiter Threshold Setting (dBu) based on output voltage from amplifier
Limiter Threshold
=
20
∗
log
(
Max Voltage
peak
0.775
)
−
7.7
Limiter Threshold
=
20
∗
log
(
Max Voltage
peak
)
−
5.5
Limiter Threshold
=
20
∗
log
(
Max Voltage
peak
)
−
Amplifier Gain
−
5.5
Limiter Threshold
=
20
∗
log
(
Max Voltage
peak
0.775
)
−
Amplifier Gain
−
7.7
