Application Notes

10.2. Phase-adjustment with the DN9848

To meet the demands of a wide range of situations, the Klark Teknik DN9848 provides two all-pass filters with complementary control parameters for fine-tuning the phase response on each output. Although some cross-over filter designs, e.g. Linkwitz-Riley types, are inherently phase-aligned at cross-over, others such as Butterworth or Bessel responses may require manual phase alignment. Even Linkwitz-Riley filters may not produce accurate phase coherence when HPF and LPF are combined to produce a band-pass output. In addition, the phase response of the drive units and cabinets (especially horn-loaded types) may require compensation to achieve correct acoustic phase, even if the electrical phase is correct. The DN9848 filters provide straightforward tuning control in all cases.

The first filter of the DN9848 is presented as a “phase shifter” for which you can specify a particular phase shift at a reference frequency, namely a HPF or LPF (typically the cross-over point) or one of the 6 PEQs. The plots in the graph below show the effect of these controls on the filter response when set to a 90 phase shift at references points equivalent to 20Hz, 300Hz, 1kHz and 20kHz. Referring to the figure, the overall response always remains the same shape i.e. tending from +180 at low frequencies to 0 at high frequencies, but is shifted along the frequency axis to achieve the required phase shift at the specified reference point.

Audio Precision

 

90 deg phase shift @ 20, 300, 1K, 20K

 

01/19/01 15:52:45

 

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phas e.at1

Response of the phase shifter filter for a phase shift of 90 at reference points equivalent to 20Hz, 300Hz, 1kHz and 20kHz

The second filter, presented to the user as an “all-pass filter”, enables the user to set the Order and Q of the phase shift, at a particular Frequency. The Order can be switched to Off (no filter), 1st order (90 shift) or 2nd Order (180 shift).

The graph over the page shows the response of the filter for a 1st order shift. In this mode, the Q control is disabled. As can be seen, the filter behaves in an identical manner to the phase shifter, i.e. the response tends from +180 at low frequencies to 0 at high frequencies, shifted along the frequency axis according to the chosen frequency. In effect, this is a phase shifter for which the frequency is entered directly, rather than being referred to a HPF/LPF or PEQ section.

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Telex DN9848 Loudspeaker Processor, DOC02-DN9848 specifications Phase-adjustment with the DN9848

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.