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iK81 / iK42
USER GUIDE
Output
Gain and Polarity
The gain page of the output channel allows users to increase or decrease the relative signal gain for the selected output. The
Gain value may be adjusted in 0.2dB steps from -40dB to +20dB. This page will also allow users to change the polarity of the
selected output from normal to reverse.
Delay
The delay page controls the amount of delay associated with the output channel selected and is adjustable from 0 to 998ms. The
delay parameter is adjustable in fine steps at low values; the adjustment becomes progressively coarser as the value increases.
High and Low pass Filters
High pass and low pass crossover filtering is provided for the output signal. Filter type is selectable from 1st order, Butterworth,
Bessel, Linkwitz-Riley, Hardman and LIR Linear Phase. Filter slopes of up to 8th order or 48dB / octave are provided. Not all filter
types are available in all slopes. For example 18dB / octave Linkwitz-Riley filters cannot be selected because they do not exist.
The Hardman type filter is always described by its order as the filter becomes progressively steeper rather than following a linear
slope so a dB/octave description is not accurate.
LIR Crossover Filtering
Unique to Martin Audio, "Linear Impulse Response" (LIR) crossover filtering gives a Linear Phase crossover which has a constant
delay regardless of frequency (unlike other types of crossover which delay different frequencies to a different extent, thus
smearing the arrival time). The LIR crossover can thus be described as having a flat Group Delay response, and thus entirely free
of Group Delay Distortion, this is exactly the same as can be provided by common FIR filtering but without the complications and
disadvantages inherent with the FIR technique.
The shape of the LIR crossover filter is similar to a 4th order Linkwitz-Riley filter, and maintains zero phase difference between
the adjacent bands across the crossover region to keep the polar response rock steady.
Note that very narrow bandwidths are not possible with this crossover type. If the Low Pass frequency is too close to the High
Pass frequency, then the filter will 'mute'.
Linear Phase filtering necessarily introduces delay; the laws of physics demand it. To keep this delay to a minimum, it is
recommended that more conventional crossover shapes (such as Linkwitz-Riley) are used for the very lowest frequency high-
pass edge, particularly if this is less than perhaps 100Hz, which is well below the frequency thought to cause audible 'Group
Delay Distortion'.
This constant delay will depend on the lowest high-pass frequency used in the crossover filters in a given Drive Module.
See also the section on Latency Delays.
Parametric Equalisation
There are ten different EQ filters; two shelving filters and eight parametric filters. Parametric filters are defined by frequency,
bandwidth and gain. The frequency is controlled over the range from 10Hz to 25.6 kHz. The bandwidth, shown as Width on the
screen, ranges from 0.10 octaves to 5.2 octaves. Bandwidth can be shown and adjusted as Quality Factor or (Q), or Octaves (Oct).
Gain is adjustable in 0.2dB increments.
See also Bandwidth Units in Utilities.
Limiters
The iK42/iK81 Series includes three limiters in the output signal path. Please note that whilst the Limiters in this product offer
protection for amplifiers and drivers, they can never protect from all possible scenarios, therefore Martin Audio is not responsible
for any damage which might occur.
VX Limiter
This is a peak-detecting signal limiter. The VX Mode parameter determines the style of limiter. When Virtual Crossover (VX) mode
is off, the limiter is controlled in a conventional manner; the only controls being Threshold and Overshoot.
iK81 / iK42 User Guide V2.3
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