8
Tuning Your Subwoofer
A subwoofer is designed to handle the low frequency signals that nearfield monitors cannot handle. Since most nearfield monitors
cannot handle frequencies below about 60Hz, you’ll want the PS12 to handle any frequencies below that. In fact, depending on
how your satellites perform at low frequencies, you might want your subwoofer to be responsible for frequencies as high as 80 -
100Hz.
The Crossover
The point at which your nearfield monitors stop handling the audio signal, and the PS12 takes over is called the crossover
frequency. The idea when setting up a crossover is to create a seamless, inaudible transition between your subwoofer and
attached satellite speakers. You should set up your subwoofer in the following order:
1. Position and tune your satellite speakers
2. Position and set the subwoofer level.
3. Set up the crossover frequency
4. Check the phase relationship between the subwoofer and the satellite speakers.
A good audio source for setting up the PS12 is a sine wave that sweeps slowly accross the crossover point. E-MU has sine wave
sweeps available for download at the “software and manuals" page at www.emu.com/support. Adjust the output of your audio
source to a comfortable volume, and begin adjusting the level of the PS12.
Level
The level knob controls the level of the subwoofer’s amplifier, thus only affecting the volume of the subwoofer itself. Turn the
knob clockwise until the PS12’s sound is present, the low frequencies begin to seem filled out. This should be enough to hear the
subwoofer low frequencies, but not so much that the PS12 stands out above the satellite speakers— the idea is to match the
PS12’s volume with that of your satellite speakers. Don’t turn up the PS12 so much that it’s easily audible as an individual speaker.
Remember, you’re trying to blend the subwoofer and your satellites to create a full-range monitoring system.
Subwoofer Low-Pass Filter (LPF) and Satellite Output High-Pass Filter (HPF)
Now, use the Low-Pass Frequency Knob to adjust the low-pass filter for the sound coming out of your subwoofer. This filter
constitutes the lower half of the crossover, and ranges in frequencies from 55Hz to Flat (no filter). The crossover frequency you
choose for the LPF will depend on the performance of your satellite speakers.
The literature for you satellite speakers should contain information about the speakers’ low-frequency cutoff. Use that
information to determine where you want your crossover frequency to occur, and set your LPF knob accordingly. Your satellite
speakers may have an adjustable roll-off, which can potentially add to the overall acoustic slope of the high-pass filter. Set the
roll-off on your satellite speakers to its lowest frequency. It's best to have the satellites set for full-range operation whenever using
the PS12.
At the same time, use the High-Pass Frequency Knob to adjust the HPF for the sound passing through the subwoofer to the
satellite speakers. This filter ranges in frequencies from 40Hz to 135Hz. You’re probably best off starting with the same frequency
as the LPF.
Let’s say you’ve set your LPF and HPF each to 80Hz (a common crossover frequency, and a good place to start). You’ll have both
speakers playing the crossover 80Hz at the same time— one fading in while the other fades out. Your crossover would look
something like this:
What you’re aiming for is a smooth transition between frequencies handled by your satellite speakers and those by the PS12. If
you’re listening to a sweeping wave sound, try to eliminate any boosts or cuts that occur when the sweep reaches the crossover
frequencies. You can do this by increasing or decreasing the amount of crossfade you have between the two filters.
This section assumes you’ve already adjusted the positioning and levels of your satellite speakers.
For advice on setting up your satellite speakers, refer to the documentation that came with them,
and/or the information on the previous page.
-3
0
Amplitude (dB)
-6
-10
Frequency (Hz)
80
LOWPASS
FREQ (Hz)
55
60
100
120
80
flat
HIGHPASS
FREQ (Hz)
40
135
55
100
120
60
80
The settings on the knobs represent
where the filter has attenuated the
volume to -6dB.
A setting of 80Hz for both LP and HP
filters means that the subwoofer and
satellites are both at -6dB at 80Hz.
