Application Notes

10.APPLICATION NOTES

10.1. The Advantage of DN9848 Look-Ahead Limiters

The limiter in a loudspeaker processor is the last line of defence in protecting the speaker drivers from damage, and as such it has a very specific and critical job to do. One of the chief modes of loudspeaker failure is driver over-excursion, and unless the limiter is designed to act instantly in response to sudden increases in level, it will allow through brief transients that can cause damage through over-excursion. All dynamics processors take a finite amount of time to respond to a change in input level, and unless additional steps are taken the result is that the input signal is initially let through at anything up to its full level, until the gain element in the limiter can act in response to the increase in signal level.

The DN9848 exploits the fact that digital signal processing works on a sample-by-sample basis (the signal data samples are clocked through the unit at the sample rate of 48 kHz) and that there is a small delay through each processing block, and literally ‘looks-ahead’ further back in the signal chain to sample the data for the limiter side chain, so that the limiter can apply the required gain reduction on an instantaneous sample-by-sample basis, so that the limiter never lets through any dangerous transients.

In the example below a 10 kHz tone burst of 10 ms duration has been used as the input signal and the output of both a DN9848 and a leading competitor are shown. Note the very large transient of the competitor unit which does not have a look-ahead limiter.

Signal source: Audio Precision System One

Settings: Waveform: Burst – Normal. Frequency: 10.0 kHz. Burst: 10 ms. Interval: 100 ms. High Level: +10.0 dBu Low level: - 40.0 dBu

DN9848 settings: HPF: 1.25kHz Lnk-Ril 24dB/Oct. LPF: 20kHz Lnk-Ril 24dB/Oct. Limiter Threshold: 0.0dBu Release: 50ms

Response: Hard Knee

Competitor settings: HPF: 1.26kHz Lnk-Ril 24dB/Oct. LPF: 22kHz Lnk-Ril 24dB/Oct. Limiter Threshold: 0.0dBu Attack &

Release: Automatic

All other settings are default on both units.

As with all units that use sigma-delta ADC and DAC converters, there is a propagation delay from input to output, 3.2 ms for the DN9848 and 2.1 ms for the competitor unit, the additional delay in

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Telex DN9848 Loudspeaker Processor, DOC02-DN9848 specifications Application Notes, Advantage of DN9848 Look-Ahead Limiters
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DOC02-DN9848, DN9848 Loudspeaker Processor specifications

The Telex DOC02-DN9848, commonly referred to as the DN9848 Loudspeaker Processor, is an advanced audio processing device designed to enhance sound quality in both live and recorded environments. With a sleek and modern design, the DN9848 is engineered to meet the demanding needs of professional audio applications, be it in concert venues, theaters, or broadcast studios.

One of the key features of the DN9848 is its comprehensive processing capabilities. Equipped with a powerful DSP (digital signal processing) engine, it offers extensive equalization options, dynamic range control, and advanced crossover functionality. The device utilizes up to 48 input and output channels, allowing for unparalleled flexibility in routing audio signals. This makes it ideal for installations that require precise control over multiple loudspeakers.

The DN9848 also boasts an intuitive user interface, which facilitates straightforward navigation through its various functions. The front panel features a large LCD display that provides clear visibility of parameters, and a selection of knobs and buttons enables easy adjustments. For remote operation, the device can be controlled via Ethernet, allowing technicians to make changes from virtually any location.

Another standout aspect of the DN9848 is its customizable algorithms that accommodate different speaker systems and acoustical environments. Users can fine-tune the processor to optimize performance for specific venues or loudspeakers. The device supports both FIR (finite impulse response) and IIR (infinite impulse response) filters, providing users with the flexibility to deploy advanced filtering techniques according to their needs.

The DN9848’s robust connectivity options further enhance its utility. It features standard analog XLR connectors, as well as digital interfaces that include AES/EBU and Dante. This multi-format compatibility ensures seamless integration into existing audio setups, making it a versatile choice for audio professionals.

In terms of reliability and durability, the DN9848 is built to withstand the rigors of the professional audio world. Its rugged chassis and high-quality components ensure that it can perform consistently in various conditions, making it a trusted partner for sound engineers.

In summary, the Telex DOC02-DN9848 Loudspeaker Processor combines sophisticated audio processing capabilities with user-friendly features and robust connectivity. Its advanced technology and flexible options make it an indispensable tool for achieving optimal sound in a variety of professional audio environments.
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