Golden Earring wrote: > Cancelling the noise of your refrigeration units may not be as easy as > you think - how many independent units are there?... How loud are these > things anyway? :) These are commercial refrigeration units similar to these: https://upload.wikimedia.org/wikipedia/commons/thumb/8/83/Kuehlregal_USA.jpg/1200px-Kuehlregal_USA.jpg There is an area with about 15 linear meters of them, shaped like an L. They have doors, I think we are talking of 4 or 5 devices overall. Facing the angle of the L, there is a freezer unit. It's not huge but this one is a noisy b****. But hey, even in an organic foodstore I guess you can feel entitled to a frozen TV dinner. First impression, I would say the "L" group + freezer are more or less running constantly.
Then in another area there are 2 units of similar shape, these have no doors (only a curtain drawn after hours) and are used for vegetables. I'd say they are set to a higher temperature and work less hard, although the lack of doors must have an effect. They are anyway in a noisy area, near the entry/exit doors at street level. I only measured the ambient noise level once, with an iPhone... I did not expect to have to disclose my findings here :) Anyways, there was little public in the store, and the quietest place measured at ~34 dB. In the "L" group, 1m away from the freezer I measured ~46 dB. Facing the 2 doorless units, I read a bit less noise, except when doors where opened to the street. Near the doors, I measured up to 55 dB. Anyone rolling a shopping cart in there makes ambient noise spike to well over 50dB. So it's all relative, inaccurate, and that's only one measurement I took. But a difference of more than 10dB between the constantly quiet and noisy places seemed significant to me. > You'd have to "close mike" each unit separately & insert a reversed > phase signal from each through a mixing unit into your audio signal - & > even then you'll only be able to achieve one "dead zone" in which the > sound is cancelled. You would probably end up with *-greater-* > "compressor" noise in other areas where the introduced cancellation > signal itself was actually louder than the noise there from the > refrigeration units themselves... Yes I can see the can of worms. But perhaps if the units are indeed working more or less constantly, a mild noise reduction could be achieved? 3 SB 3 Libratone Loop, Zipp Mini iPeng (iPhone + iPad) LMS 7.9 (linux) with plugins: CD Player, WaveInput, Triode's BBC iPlayer by bpa IRBlaster by Gwendesign (Felix) Server Power Control by Gordon Harris Smart Mix, Music Walk With Me, What Was That Tune? by Michael Herger PowerSave by Jason Holtzapple Song Info, Song Lyrics by Erland Isaksson AirPlay Bridge by philippe_44 WeatherTime by Martin Rehfeld Auto Dim Display, SaverSwitcher, ContextMenu by Peter Watkins. ------------------------------------------------------------------------ epoch1970's Profile: http://forums.slimdevices.com/member.php?userid=16711 View this thread: http://forums.slimdevices.com/showthread.php?t=107617
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