Date: Fri, 14 Aug 2009 11:20:56 -0700
Reply-To: Rocket J Squirrel <camping.elliott@GMAIL.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Rocket J Squirrel <camping.elliott@GMAIL.COM>
Subject: Re: Speaker/Amp Recommendation
In-Reply-To: <4A84D8DE.8040803@westyventures.com>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
dBa scale? The majority of the road/tires/suspension-borne noise is bass.
The dBa filter attenuates bass and treble, it's down 20dB at 100Hz where
80% of the transmitted noise is. A-weighting is only useful for low-level
sound measurements.
"...A-weighting, though originally intended only for the measurement of
low-level sounds (around 40 phon), is now commonly used for the
measurement of environmental noise and industrial noise ... although it is
badly suited for these purposes, being only applicable to low levels so
that it tends to devalue the effects of low frequency noise in particular."
(http://en.wikipedia.org/wiki/A-weighting)
Set yer meter to unfiltered and you'll see a huge increase in measured
sound level. It's the high sound pressure levels of the low-frequency road
noise that batters the ear and muddies the sound.
One would need to turn up the bass of the music system sufficiently loud
to overcome the rumble and grumble down there. As a bass player I can tell
you that even with a 500W bridged power amp driving a 12'' subwoofer
mounted in the bench seat, bass stuff -- which I like to listen to -- is
pretty much inaudible at freeway speed unless you turn the music up real
loud, louder than I like it because I also want to be able to hear the
engine.
This because one time I forgot to shift out of 2nd (automatic) after
getting onto the freeway after a long descent. Too oblivious to look at
the tach, too.
On the other hand, your higher frequencies -- I have some 5'' door
speakers and speakers in the cabinet above the lower bunk -- are always
pretty much audible. Clavichord music, anyone?
--
Mike "Rocket J Squirrel" Elliott
84 Westfalia: Mellow Yellow ("The Electrical Banana")
74 Utility Trailer. Ladybug Trailer, Inc., San Juan Capistrano
Bend, OR
KG6RCR
On 8/13/2009 8:24 PM Karl wrote:
> I measured my 'noisy', rusty TDI Syncro Westy a few months ago - using
> the dBa scale of a fairly accurate meter, it was only in the high 70's
> and low 80's.
>
> Karl
> www.westyventures.com
>
>
> Rocket J Squirrel wrote:
>> Drown out road noise? Have you measured the noise in the van when driving
>> at freeway speeds? It's gotta be at least 90 to 95dB. You'd need a 1,000
>> watts and a whole lotta Metallica to drown out a Vanagon's road noise.
>
