Filter
Top Products
11
Bass management is equally suited to all formats from 2-channel stereo to 5.1 and beyond. Indeed, existing control rooms
that are doing stereo 2 channel mixes, especially with smaller nearfield monitors placed on the console, can benefit
immensely from the correct integration of Bass Management and a subwoofer; because the engineer is now able to hear low
frequency anomalies caused by room rumble, microphone stand thumping, breath pops, and other artifacts that cause
undesirable actions later in the broadcast, film chain, or DVD Mastering process.
When mixes are intended for theatrical presentation, it is sometimes necessary to use an additional channel for extra low
frequency effects or enhancement. This channel is called the LFE or Low Frequency Effects/Enhancements channel. In the
control room monitoring environment, the LFE channel, if or when it is used in the mix, is monitored by the same subwoofer
used for the regular [L,C,R,LS,RS] channels. M&K Bass Management Controllers have both a 0dB (with unity gain) and +10dB
(with 10dB gain) inputs to accommodate any mixing / monitoring situation, as per Dolby specifications.
The M&K Professional Division supplies, at no additional charge, a special CD test disc to assist in the proper setup and
calibration of our Bass Management Systems. This disk has pre-filtered and calibrated tracks of noise which allow quick, accu-
rate, and error-free setup of the monitoring environment to the Dolby standard of 85dB SPL, or any other relative reference level,
by using an SPL meter.
9. CALIBRATING YOUR M&K PROFESSIONAL SYSTEM
A. For this set-up procedure, you will need the following:
1.) An SPL meter. Radio Shack has an analog SPL meter that is very effective and not expensive.
2.) The M&K Professional test CD (supplied with the M&K LFE4 or LFE-5 or available as a download from
www.mkprofessional.com).
3.) A small, flat bladed screwdriver (or “tweeker”) to adjust the channel trim pots on the LFE-4 or LFE-5.
4.) A CD player, or DVD player that can play CD-R’s (unless you have downloaded your tones).
5.) An M&K speaker system with the LFE-4 or LFE-5 Bass Management Controller.
B. 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 or LFE-5.
C. When the slot of the channel trim pots on the LFE-4 or LFE-5 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 or LFE-5 is + 27dBu. With a nominal signal level of + 4dB with 20dB of headroom, the maxi-
mum 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 or LFE-5 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 or LFE-5 for fine tuning.
The M&K Professional test disc
A specially designed and produced test disc has been included with your LFE-4 or LFE-5.
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 calibra-
tion. By using this disc with a Radio Shack SPL meter and following the instructions in this manual, you can achieve a remark-
ably 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 microphones 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.
Track three: 1 kHz sine wave recorded at –20dB FSD. Use this to set the reference level of your source (console, etc.)
On an analog console this will be 0VU. On digital sources this will be either –20dB FSD or –18dB FSD.