GoodSoundClub - Romy the Cat's Audio Site

In the Forum: Horn-Loaded Speakers
In the Thread: Macondo’s lowest channel.

Post Subject: ULFPosted by Bill on: 3/10/2011

What I heard in your room on Saturday was superb reproduction of what was recorded from 40 Hz. up. This is ideal probably for a recording of a chamber group in a small hall without anybody present. One could hear the hall surroundings which replaced your room acoustic, but not the ULF that fills the hall and gives one the feeling of true concert hall space.
When i walk into a large hall filled with people, AC noise, background noise from the street, etc. is a pressurization effect of primarily low frequency information which can be recorded onto both analog and digital media. For instance on my DAT recordings of second generation RCA tape of a recording from London, when the tape starts the room pressurizes with the tape hiss, but as soon as the mikes get turned on one can feel the room pressure from the surroundings, and then one can actually hear several different subways running under the hall and tell that there are more than one and even which direction they are coming from. In several done in Symphony Hall, one can hear the road traffic on the right side from Mass. Ave., an d can distinguish the rumble of truck vs. auto engine noise. Thus the deep bass is recorded onto the original tapes and records and can be transcribed even onto 16/48 DAT's. Whether the system can reproduce it properly is the problem.
Thus recording media can pick up that low frequency information, and without that ULF information the room never pressurizes and one feels that one is in an anechoic chamber.

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