QSC Audio PL224A, PL230A, PL218A, PL236A POWER LIMITER TRACKING- continued, When to use it

FEATURES & SETUP- SIDE PANEL SWITCHES: CLIP LIMITER

POWER LIMITER TRACKING- continued

The high frequency driver requires a lower power threshold and fast limiting response. Try the FAST setting and the PEAK mode. Short peaks will be limited aggressively, but signals will return to normal almost instantly. This response (fast with low threshold) would have too much “ducking” and low frequency distortion for use with full range material.

Once each driver has optimal protection, you need to make them work properly together. When only one channel is limiting, the frequency balance will be upset. This may not be a problem with some material, but testing is required. The different tracking “modes” offer different solutions. For example, if the crossover frequency is low, both drivers may have similar power capacities and protection speed requirements. For this type of bi-amping, you may find that “mode” 4 (stereo tracking, below) offers the best sound performance.

Experimentation with the actual speakers is needed.

4- Each channel tracks the other (stereo tracking)--switch section 9 of both channel’s limiter adjustment DIP switches should be set to the right (TRACKS CH 2 and TRACKS CH 1). Stereo playback usually uses matched speakers and thus if one channel limits, it will effect the image and placement of the instruments. When each channel tracks the other, any limiting on one channel causes limiting on the other, preserving the overall “balance” while protecting the speakers. The power threshold and speed settings for each channel should be matched.

CLIP LIMITER: The PL2A amplifier also has separate limiters which respond only to amplifier clipping. These may be used with or without the adjustable Power Limiters.

When the audio signal drives the amp's output circuit beyond its power capability, the amp clips and flattens the peaks of the waveform. The clip limiter detects this and quickly reduces the gain to minimize the amount of overdrive. To preserve as much of the program dynamics as possible, limiting occurs only during actual clipping.

Each channel has its own clip limiter that can be switched on or off independently, as shown at right.

When to use it-

When driving full-range speakers, clip limiting reduces high frequency distortion caused by bass overloads. It also protects high frequency drivers from excess overdrive and harsh clipping harmonics.

We recommend using the clip limiters in all applications.

Clip limiter switches are at the bottom of each LIMITER ADJUSTMENT DIP switch (1 per channel)

NOTE: After all side panel switches have been set and SIP resistor networks installed, verify your setup and reinstall the side cover plate to keep dirt, dust, and foreign objects from entering the chassis.

CAUTION: Clip limiting reduces extreme overdrive peaks, allowing a higher average signal level without audible distortion. However, increasing the gain with the clip limiter engaged, until clipping is again audible, can double the average output power. Be careful not to exceed the power rating of your speakers.

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