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[TowerTalk] RE: idea(l?) hamshack

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Subject: [TowerTalk] RE: idea(l?) hamshack
From: (Chris BONDE)
Date: Tue Jun 3 01:38:06 2003
The complete rsponse is very interesting.

I was doing some literature research for soundproofing awhile back.  There 
were some suggestions that might have been left behind for some 
reason.  Two I remember were:  For ordinary stud walls, non-bearing, slice 
the stud in half  to about 4 inches from each end.  Put a limp metal foil 
on the inside of the drywall, say lead.  (Lead has been used on the base of 
building support columns to dampen earth vibrations to the building, eg 

One concept was to think of the sound like water in a box or heat, it will 
flow through the holes, just find what are the 'holes'.  eg conduction and 
radiation paths.  Another is place fans outside and suck the air out.

Chris opr VE7HCB

At 02:21 PM 2003-06-02 -0700, Jim Lux wrote:

>>Regarding a ceiling fan for ventilation, if I buy a quiet whisper
>>bathroom-type ventilation fan do you think I need to worry about EMI from
>>the fan?
>Those fans are shaded pole, and should have very low noise (other than the 
>existing 60 Hz noise you've already got everywhere). Brushed motors are 
>the ones that will generate plenty of noise (i.e. vacuum cleaners, 
>blenders, etc.)
>>  If so, do you all know of an electrically quieter fan?  Also,
>>there was some mention of sound proofing, ideas on where to get this or what
>>to use?
>Sound proofing is a big topic.. What sounds are you trying to 
>suppress?  High, low, internal reflections, etc.
>High frequencies are usually reduced by attenuation with multiple 
>scattering in stuff like fiberglass or foam.
>Low frequencies are attenuated by making them move something lossy and 
>massive (lead sheet, sand, etc.)
>If all you're looking to do is kill the "liveness" of flat, plain walls, 
>then carpet works fairly well at reducing the reverberation time (it 
>doesn't attenuate much, but reverberation is a multiple reflection kind of 
>thing, so after a few tens of reflections, even a 1 dB loss is a lot)
>The real challenge in soundproofing is usually eliminating conduction 
>paths (i.e. a standard wall with wood studs is pretty bad... drywall 
>sounding board on one side, 4" rigid connection through the stud, then 
>drywall sounding board on the other side).. Offset studs (3.5" studs, but 
>wall thickness of, say 6", so each side has it's own studs, with the studs 
>offset from each other (16" o.c. on each side, but one side is set 8" from 
>the other) works fairly well at minimal cost. You could go to 24" o.c. 
>studs even.  They make "z-strips" for just this sort of thing. They are 
>vibration isolating mounts for the drywall.
>Jim, W6RMK
>See:  for "Self Supporting Towers", "Wireless 
>Weather Stations", and lot's more.  Call Toll Free, 1-800-333-9041 with 
>any questions and ask for Sherman, W2FLA.
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