D-fend SA300 User Manual - page 25
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D-fend™ SA300 User Manual
if needed, and also allows for faster reaction times since the circuitry will be “powered up” all the time. It also affords the
ultimate in audio purity since no audio power will be used to power the SA300 circuitry.
In this example, our planar/ribbon driver is rated for 50 watts and it is an 8 ohm load. Since we recommend always starting
the SA300 with ¼ of the rated power of the system it is protecting, you would configure the SA300 for 12.5 watts (or 10
volts). We are using a high pass filter set to 3000 Hz before the amplifier used to drive the tweeter.
HF
Set the HF filter to 2600 Hz and 3rd order slope. Set the HF RMS wattage to 12.5 watts (or 10 volts) and the HF peak
wattage to 25 watts (14 volts). 50 watts (20 v) would be the absolute peak. There’s no need to tempt fate right off the
bat.
AP
Set the AP RMS also to 12.5 watts (10 volts). The planar/ribbon can take pretty large peaks, but continuous power is
what will cause them to fail. Be very conservative and you will greatly extend the life of your tweeter.
LF
Disable the LF section.
Listen to some music at your normal playback level and keep an eye on the SA300’s indicators (either on the unit or in
the Advanced Programming GUI if the computer is still connected to the SA300). If you think the tweeter can do more,
increase the AP RMS threshold, HF RMS threshold, and/or HF Peak threshold in the Advanced Programming GUI and
download the new settings to the SA300. Likewise, if you think the tweeter needs to be protected more, then lower
these setting.
D-fend with 25-70-100 Volt Distributed Audio Systems
Before we dive into protecting your distributed system, you need to know that the SA300 can not be used AFTER an audio
transformer. So if your amplifier has an internal output transformer (like most tube amps and some amplifiers designed
to drive distributed systems) then DO NOT connect the SA300 to your amplifier’s outputs; you will not be able to use the
SA300 to protect your system if your amplifier has an internal output transformer.
If you are not sure if your amplifier has an internal output transformer, you should contact the manufacturer of the amplifier
or you can call us and we will try to research it for you. If in doubt, do not connect the SA300. If you use the SA300 after a
transformer, system damage and damage to the SA300 can occur.