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REAR PANEL CONTROLS
[7] Balanced XLR audio inputs - use these balanced XLR line level audio inputs to connect any line
level audio device such as a DJ Mixer, Mixing Console, CD player etc. For more information on
the advantages of using balanced audio connections visit www.kam.co.uk/tuition.
[8] Unbalanced 1/4" Jack audio inputs - use these unbalanced 1/4" Jack line level audio inputs to
connect any line level audio device such as a DJ Mixer, Mixing Console, CD player etc.
[9] Channel A&B speaker outputs - use these Speakon Type connectors to attach your speakers in
normal stereo mode. KX Pro Speakon terminals are wired in a +2/-2 configuration.
[10] Bridge Mode output - use this single (red) Speakon type connector to attach your speakers in
Bridge Mode. Please read the 'Bridge Mode' section below before attempting to use Bridge
Mode.
[11] BR/STE switch - use this switch to choose between standard stereo operation (STE) and
Bridge Mode operation. Please read the 'Bridge Mode' section below before attempting to use
Bridge Mode.
[12] Limiter switch - use this to switch the built in Limiter circuit on/off. When in the on position
the audio signal will be automatically prevented from exceeding the maximum signal level beyond
which clipping (distortion) will occur and the Peak LED will light.
[13] Low Cut Filter controls - each channel features an adjustable Low Cut Filter designed to
remove low frequency rumble etc to deliver an uncluttered low/mid sonic response.
These controls are used to adjust the Cutoff Frequency and everything below the Cutoff Frequency
is removed. The range is Off to 170Hz.
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About Crossovers
The idea of a 'two way' speaker (which is what most 'full range' speakers are) is usually that the
speaker cabinet houses two separate actual speaker drivers. It is common for one to be
dedicated to reproducing High frequencies and the other to be dedicated to reproducing Low and
Mid range frequencies. In order to make this work it is necessary to split the incoming audio
signal in such a way that only High frequencies are sent to the High Frequency tweeter and only
Low/Mid frequencies arrive at the Low/Mid driver. The device used to split the signal is called a
'Crossover'. It is common when assembling a more powerful PA system to have either a 'three
way' system consisting of 3 separate speaker cabinets (1 each for Low, Mid & High frequencies)
or a two way system where several full range speaker cabinets are augmented by an additional
Sub or Bass speaker. In such set ups it is also necessary to employ Crossovers to divide audio
signals so that the right PA system components receive only the right audio frequencies.
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[14] Crossover Mode switches - the KXPro built in Crossovers are designed to be as versatile as
possible and this Mode switch enables the selection of the correct configuration.
Once the correct Mode has been chosen the Cutoff Frequencies are adjusted via the Crossover
Frequency controls [15]. There are four Mode switch positions;
BYPASS - the Crossover is inactive.
HIGH - both Crossover Controls act as High Pass Filters so all frequencies above the selected
Cutoff Frequencies are passed onwards to your speakers. Use this Mode when you wish to
connect only a HF speaker. You may also wish to use the 'x10' switch [] to set the range of
the Low /Mid Control to 500Hz-5kHZ.
MID - The Low/Mid Control acts as a High Pass Filter. The Mid/High Control acts as a Low Pass
Filter. Use this when you wish to connect a Mid range speaker cabinet.
LOW - both Crossover Controls act as Low Pass Filters so all frequencies below the selected
Cutoff Frequencies are passed onwards to your speakers. Use this Mode when you wish to
connect only a LF speaker.
[15] Crossover Frequency Controls - each channel has two controls that enable you to adjust the
Cutoff Frequencies of the Crossover. Their function is determined by the setting of the Crossover
Mode switches.
[16] Ground Terminal - using an M4 screw to attach a ground cable from other equipment to
this terminal can sometimes help eliminate 'ground loop' problems.
About Bridge Mode
Bridge mode is a professional feature that can seem simple but is actually fairly complex.
Bridge mode devotes the entire power output capacity of the amp to the Channel A input,
That may sound simple but the way in which the amplifier achieves this is not so simple.
If you understand how a balanced audio connection works you'll know that it provides three
wires within an audio cable; one of them is simply an earth, the other two each carry half of the
audio signal - one carries the positive half of the signal and the other carries the negative half.
When you place an amplifier in bridge mode, it uses channel A to amplify the positive half of the
signal and uses channel B to amplify the negative half of the signal.
So the first thing to understand about bridge mode is that you can't use it with an Unbalanced audio
input... so you can only use Bridge Mode when using the balanced XLR input connection to
channel A.
The next really important thing to know about Bridge Mode is that it can require a very unusual
method of speaker connection with many amplifiers. Fortunately the KXPro provides a dedicated
Bridge Mode Speakon output [10] so if you wish to use Bridge Mode connect your speaker to the
red Bridge Mode output but do not connect any speakers to the stereo channel A&B outputs.
If you require additional advice on using Bridge Mode with models of amplifier which do not
feature a dedicated Bridge Mode output you will find it online at www.kam.co.uk/tuition.
You also need to be aware that bridge mode potentially delivers considerably more power to your
speakers. In much the same way that attempting to use an over powered amplifier to drive an
under sized speaker is obviously a recipe for trouble... so is trying to use bridge mode to coax
more volume from low impedance speakers. Bridge mode can be useful for using an amplifier to
drive a speaker with a higher impedance than usual (perhaps driving a single 16 Ohm speaker
with an amplifier you might use to drive a pair of 8 Ohm speakers).
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