MK Sound LFE-4 - Manual (Page 11)

5. If you are using passive speakers with external amplifiers, connect your speaker system to the
power amplifiers.
6. Locate the external power supply for the LFE-4 and plug it into the 4 pin power connector on the back of
the LFE-4. Secure it in place by turning the outer ring clockwise. Plug the external power supply into a
power outlet. The front panel LED will glow red when power is applied.
9. CALIBRATING YOUR M&K PROFESSIONAL SYSTEM
1. For this set-up procedure, you will need the following:
a.) An SPL meter. Radio Shack has an analog SPL meter that is very effective and not expensive.
b.) The M&K Professional test CD.
c.) A small, flat bladed screwdriver (or “tweeker”) to adjust the channel trim pots on the LFE-4.
d.) A CD player, or DVD player that can play CD-R’s.
e.) An M&K speaker system with the LFE-4 Bass Management Controller.
2. It may be helpful to have one person sit at the listening position and read the meter while another person
adjusts the trim pots on the LFE-4.
3. When the slot of the channel trim pots on the LFE-4 are pointing straight up and down, the gain of each
of the channels is approximately 0dB or unity. The trim pots have a plus or minus 12dB gain range.
Rotating the pot counter-clockwise will attenuate the channel a maximum of –12dB and rotating the pot
clockwise will boost the channel gain a maximum of +12dB. The maximum output of the LFE-4 is + 27dBu.
With a nominal signal level of + 4dB with 20dB of headroom, the maximum signal level from the source
(console, etc.) can be + 24dB. Therefore, at very high signal levels you can only add around + 3dB of gain
with the trim pots before the signal chain of the LFE-4 overloads. If you need more than 3dB of gain at
high signal levels, it is better to increase the output of power amplifiers and use the trim pots on the
LFE-4 to reduce the gain.
The M&K Professional test disc
A specially designed and produced test disc has been included with your LFE-4.
Ken Kreisel has designed this test disc expressly for use with M&K satelite/subwoofer loudspeaker systems.
The tones on this disc are all bandwidth-limited Pink noise. This is to avoid room anomalies and therefore provide
a more accurate calibration. By using this disc with a Radio Shack SPL meter and following the instructions in this
manual, you can achieve a remarkably accurate system calibration.
The goal here is not to find an absolute SPL level, but to balance the SPL level of all channels relative to each
other. For this application, the Radio Shack SPL meter will work very well.
If a more accurate calibration is desired, we recommend using a real time analyzer with calibrated micro-
phones and appropriate room analyzing software.
Following are the tones found on the M&K test disc:
Track one: Band limited Pink Noise from 500Hz to 3kHz recorded at –20dB FSD. Use this tone to
calibrate your main and surround (satellite) speakers.
Track two: Band limited Pink noise from 40Hz to 80Hz recorded at -20dB FSD. Use this tone to
adjust your subwoofer level.
Bass Management Controller
11