Next up was Genelec. Their segment of the presentation was entitled " Active Monitoring for Multichannel Audio " with the subtitle " Monitors, Monitor Set-up, LFE Channel and Bass Management ". Professionals that they are, Genelec started by pointing out:

Important International Recommendations (and committee networking relationships)

• AES Technical Committee is working with EBU and SMPTE
• German Surround Sound Forum (SSF)
• ITU works with IEC, SMPTE and ISO/MPEG Committee
• ITU-R BS.775-1 "Multichannel stereophonic sound system with and without accompanying picture" (Geneva, 1992-94)
• ITU-R BS.1116-1 "Methods for the subjective assessment of small impairments in audio systems including multichannel sound systems" (Geneva, 1994-97)

Subwoofer in the Control Room

• Very low frequencies provide minimal audible localization cues
• One or more subwoofer(s) can be used
• Very useful to check the LF signal that is sent with program

Placement:

• Close enough to the front wall to give efficient loading ( < 0.6m)
• Offset from the symmetry axis of the room to avoid lateral standing waves minima
• In a corner, close to both front and side walls
• Flush-mounting of subwoofer(s) possible

Subwoofer Adjustment Needed:

1. Gain, to adjust for the radiation loading
2. Frequency response
3. Phase adjustment, at the crossover point

The LFE Channel

• LFE channel comes from the movie theater productions
  L ow F requency E nhancement
  L ow F requency E ffects
• Practical use of the LFE channel is not consistent
• The multichannel mix down is done to 6 or 7 discrete tracks
• All tracks are identical on the recording media-one of these tracks is labeled 'LFE channel'
• The LFE channel before encoding is NOT band limited (full bandwidth)

How to Monitor the LFE Channel?

• The subwoofer response is acoustically aligned at the same level as the main channels
• LFE channel is only monitored at +10dB (Dolby Digital, DTS)
• Thus, LFE is given 10dB additional headroom going to tape

It is important to understand the significance of this slide. The 120Hz LFE upper cut-offs listed for all Dolby and DTS are the original recommendations from the two companies . However, to my knowledge, all Dolby and DTS chipsets installed in consumer receivers and pre/pros roll the LFE channel off at 80Hz in the software.

Therefore, if you're running a 5 or 7 satellite-with-subwoofer system wherein the satellite is not capable of going down to 80Hz, you are losing all the information (musical or otherwise) from 80Hz to your satellite's low frequency cut-off point when listening/viewing to Dolby Digital or DTS sources. The loss of these frequencies, typically from 80Hz up to 150Hz or even 200Hz for tiny cube-style satellites is definitely audible once a more capable (of lower frequency response) satellite is substituted.

Similarly, if you like to listen to two-channel sources on your two-full range left and right tower speakers, augmented by a subwoofer with a fixed-at-the-sub roll-off of, say, 40Hz… when you switch back to watch a Dolby or DTS DVD your system would have a hole in it from 40Hz to 80Hz. This hole is much harder to hear given the ears' insensitivity to missing bass frequencies.