I've been considering the muffler from PSI but wanted to know if anyone here had
Also, either I don't understand noise levels or their advertising is confusing:
Their DC models range from 62 to around 80 DB or so...
They say that the muffler will reduce the noise 5 to 10 db resulting in "up to"
50% noise reduction..
I counted on my fingers and toes and realized that 10 db is not half of even 60
db... maybe db is exponential or something? (vague recollection of that)
Any opinions appreciated!
On a graph the increase in noise from 5 to 10 to 20 db does not show up as a
straight line. Think of income taxes, the more you make the higher
percentage of your earnings is taxed. Decibel ratings are similar.
Thanks leon and the others...
My brain is fried from the attempt at the math, but it sounds like the muffler
would make a significant difference...
Assuming amps and speakers, it takes 2x the watts to make a 3dB change in
output volume, which is around the minimal noticable difference.
I *THINK* 10dB is percived to be twice/half as loud, but don't
quote me on that one.
Chris Richmond | I don't speak for Intel & vise versa
nope, Logarithmic (base 10, not neeperian logs)...
Db mesure the difference (actually, the Ratio) between 2 sounds using the
Db = 10 LOG(Sound A / Sound B) (or, more precisely Signal A / Signal B)
so, if Signal B is 1/2 of signal A (50% reduction), Db = 10 Log(1/2) ~= -3
(ie: reduction of 3 Db = 1/2 of the signal)
10Db reduction, ie: -10 = 10 LOG(A/B) means that A/B = 10^(-1) = 0.1 ie, the
sound power has been reduced by a factor 10!
when a sound level is given in DB, it is assume that it is a mesurement of
that sound level comared with a 'unit' sound level which has been
pre-defined (but I do not remember it's definition).
now, another problem is that the human hear does not perceive different
sound frequency in the same way, so a system which reduce the sound power by
10db in a certain frequency range might make no difference to your hears
(for example, if it does -10 db at 20Khz (ultra sounds) it will do nothing
to help you)... what is important to see is the 'frequency response' of the
muffler, ie: the curve that shows the Db reduction for the whole audible
frequency spectrum (usually from 20hz to 20Khz)... and ensure that the
response is as high as possible in the 60 to 4000 Hz range (your main
For some reason, as soon as you start talking about sound, audio etc
any truth in advertising seems to fly out the window. They use a lot
of tricks to get to the number they advertise.
There are a number of ways to measure dB. Some relate to what you
hear, some don't
It is like those monster speaker wires. If it sounds better to you it
There are already plenty of replies that address the physics... I'll let you go
through them and not repeat them. On the matter of your first question, yes, I
have that exact one. I've never run the dust collector without it so I can't
really say how much difference it makes. What I can tell you is that you can
easily carry on a conversation with the dust collector running without raising
your voice. You sure can't say the same about my shop vac. I'm highly
satisfied with both the Penn State dust collector and the muffler.
On Mon, 31 Jul 2006 18:21:22 GMT, "Mortimer Schnerd, RN"
Thank you very much...
I knew someone in the group had one but couldn't remember WHO...
I think at the time, we had a few posts back and forth and I should have bought
it back then... ordered it this morning..
On Tue, 01 Aug 2006 14:03:56 -0400, Andrew Williams
wow... I must have a mental block....
I started reading that page and just sort of glazed over...
Anyway, I ordered it and hope it makes a difference (and so do the neighbors)
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