D-fend SA300 User Manual - page 18
18
D-fend™ SA300 User Manual
Please note: The software may not accept one of your entries exactly as entered, defaulting to the closest selection found
in the microprocessor firmware.
High Frequency path configuration
The first thing you will need to do is configure the HF’s high pass filter. This can be done within the Advanced
Programming section of the GUI under the panel labeled “High Frequency”, wherein you are provided via drop down boxes
the available cutoff frequencies and filter slopes that are available within the SA300. Use the HF frequency cutoff and
slope selections to enter the desired spectrum that you want to subject to the RMS and peak limiters contained within
the HF path. It is recommended to select a cutoff frequency at or below the crossover frequency utilized with the HF
driver present within your loudspeaker system. If you are not sure what this frequency is, you should contact the system’s
manufacturer. If you have to guess the crossover frequency it is recommended to just use the set-up Wizard.
Next you will need to configure the HF’s RMS limiter and peak limiter blocks, generally configured for protection of your
high frequency driver. Configuring the HF RMS limiter can be done through the HF signal panel labeled ‘RMS’. This panel
provides industry standard limiter parameters (1) threshold, (2) attack, and (3) release. As with any infinite-to-one limiter,
the threshold determines the voltage level wherein the limiter will engage operation. Attack time determines the time
required to slew the attenuator to the required level needed to hold the output voltage at the threshold. Similarly, the
release time is the time required to release the attenuator back to an unattenuated or less-attenuated state. You can
set these three parameters (threshold, attack, and release) to your desired application requirements through the use of
the HF ‘RMS’ limiter panel entry windows. The HF peak limiter can be configured in a similar fashion using the HF signal
panel labeled ‘Peak’, wherein you can set the peak wattage or voltage threshold, as well as the attack and release times
associated with the HF peak limiter. It is recommended to set the attack and release times within the HF peak limiter
somewhat fast, thereby allowing quick transient protection for your high frequency driver.
All Pass path Configuration
Next you will want to configure the All Pass path (AP). The AP path displayed within the Advanced Programming window
provides an RMS limiter block generally used as the overall RMS protective limiter for the entire loudspeaker system.
Configuring the AP RMS limiter can be done through the AP signal panel labeled ‘RMS’. This panel provides industry
standard limiter parameters (1) threshold, (2) attack, and (3) release. As with any infinite-to-one limiter, the threshold
determines the wattage or voltage level wherein the limiter will engage operation. You can set these three parameters
(threshold, attack, and release) to your desired application requirements through the use of the AP ‘RMS’ limiter panel entry
window. The SA300 GUI allows for threshold entry in watts or RMS volts, and attack & release times in milliseconds.
Low Pass path Configuration
The next step will be to configure the low frequency path (LF). The LF’s low pass filter can be configured under the panel
labeled “Low Frequency”, wherein you are provided with the available cutoff frequencies and filter slopes available within
the SA300. Use the LF frequency cutoff selection to enter the desired spectrum that you want to subject to the peak
limiter contained within the LF path. It is recommended to select a cutoff frequency at or above the region wherein
your woofer enters mechanical over-excursion (hard bottoming, topping, or suspension blapping). Determination of this
frequency may require further investigation into your particular loudspeaker, but knowledge of the box type, rated F3, and
tuning (Fb) will usually provide a starting point
The LF path provides a peak limiter block, generally configured to protect your woofer against over-excursion scenarios.
Configuring the LF peak limiter can be done through the LF signal panel labeled ‘Peak’. This panel provides industry
standard limiter parameters (1) threshold, (2) attack, and (3) release. As with any infinite-to-one limiter, the threshold
determines the wattage or voltage level wherein the limiter will engage operation. You can set these parameters to your
desired application requirements through the use of the LF ‘’Peak’ limiter panel entry windows. It is recommended to set
the attack and release times within the LF peak limiter somewhat fast, thereby allowing quick transient protection for your