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Re: Spit speakers

To: triumphs@Autox.Team.Net
Subject: Re: Spit speakers
From: hobrien@webos1.com (Will O'Brien)
Date: Thu, 22 Jan 1998 23:41:48 -0600
>Will O'Brien wrote:
>>
>> >Joe Curry wrote:
>> >>
>> >> Julian,
>> >> I have two oval 8" dual coaxial speakers mounted on that removable panel
>> >>behind the
>> >> seats on my '63 Spit.  The aftermarket panel is strong enough to support
>> >>the weight
>> >> of the panels with no noticable effect.  The sound is adequate,
>> >>considering that
>> >> the Spit is noisy on its own and the speakers have to compete with
>>the Monza
>> >> Exhaust system.  However, It seems to be the only logical space to
>>mount the
>> >> speakers and get proper separation.
>> >>
>> >> If it is a problem with sound bleeding out the back and around the
>> >>edges, you can
>> >> install covers behind the speakers to trap the sound.  I would fabricate
>> >>them out
>> >> of some kind of heavy cardboard and line with foam rubber.
>> >>
>> >> BTW, I don't have the details of your Spit for the International
>> >>Spitfire database
>> >> I am compiling.  Please provide the following.
>> >>
>> >> Year
>> >> Model
>> >> Color
>> >> Commission Number
>> >> Owner
>> >> Location (City, County, Country)
>> >>
>> >> Regards,
>> >> Joe Curry
>> >>
>> >> J.Daley wrote:
>> >>
>> >> > I've just got a new radio/cassette for my Spit 1500 and am trying to
>> >> > optimise the position of the speakers.  At the moment I have 2 speakers
>> >> > in the rear panel behind the seats.  This is not ideal, as far as I can
>> >> > see, for at least two reasons
>> >> >
>> >> > 1.  The panel is very flimsy.
>> >> > 2.  The panel is not well sealed so that sound from the rear of the
>> >> > speaker can leak round the edges.
>> >> >
>> >> > So from a theoretical point of view this setup should sound pretty bad,
>> >> > although it may be that if the leaks are small compared to the volume of
>> >> > the boot (of course the petrol tank is in the way) this problem is a
>> >> > small one.  Has anyone got any practical experience ?  Would reinforcing
>> >> > the panel with some plywood or something make much difference ?
>> >> >
>> >> > I'd also like to put a pair of speakers in the doors, but looking at
>> >> > it, it looks like there is very little room.  Again, has anyone played
>> >> > around with door speakers ?
>> >> >
>> >> > I'm not looking for the ultimate in high fidelity, just something that
>> >> > doesn't sound too offensive.
>> >> >
>> >> > Julian.
>> >> >
>> >> > [Third attempt - Does majordomo reject mail if the From: field doesn't
>> >> > match a subscriber to the list ?  I usually send mail from a different
>> >> > account to the place I read mail, so that may be the problem.]
>> >> >
>>
>>>__________________________________________________________________________
>> >>_____
>> >> >                 Julian Daley, Dept Phonetics, University College London
>> >> > _______________________________ j.daley@ucl.ac.uk
>> >>_____________________________
>> >>
>> >> --
>> >> "Thanks to the Interstate Highway System, it is now possible
>> >>  to travel across the country coast to coast without seeing
>> >>  anything." -- Charles Kuralt
>> >
>> >
>> >Depending on the size of the speakers (i.e., around 6 inches in diameter),
>> >mounting them
>> >on the rear side panels is not really a problem.  Those cardboard pieces
>> >don't have a
>> >lot of strength, but enough for this purpose.
>> >
>> >As for fitting covers to the backs of the speakers, Joe, I believe this
>> >would only
>> >reduce their effiency.  Speaker cones vibrate on two sides -- the front
>> >and the back.
>> >Enclosing the back is fine, as long as your create a port on the front
>> >mounting surface
>> >so as to relieve the back pressure -- i.e., "sound" -- coming from the
>> >backside of the
>> >speaker cone.
>> >
>> >More to the point -- it don't hardly make no damn difference when you
>> >driving with the
>> >top down, the tailpipe blaring, and the rattles rattlin'.
>> >
>> >--
>> >Martin Secrest
>> >74 Spitty
>> >73 GT6
>> Martin,
>>         I hate to burst your bubble.  There are actually two kinds of
>> enclosures.  One is a sealed enclosure.  This type performs better through
>> the entire range of sound, while a ported or vented enclosure allows a
>> speaker to perform better in the lower ranges.  Did you ever notice on
>> decent speakers at the store, the three way speakers that have a tweeter,
>> midrange, and woofer will usually have a port, while the smaller two way
>> enclosures are usually sealed.(On the decent ones)  The two way boxes have
>> a full range speaker as well as a tweeter to create the sounds in the
>> higher ranges.
>>
>> Will
>>
>> ___________________________________________________________
>> Will O'Brien
>> OS Design & Consulting
>> email: hobrien@webos1.com
>> alt email: will@students.missouri.edu
>> ___________________________________________________________
>
>Aw hell, burst away.  Now that you mention it, of course I've seen
>enclosed speakers, but you've left me hanging, Will ... why does porting
>improve a three-way speaker, but degrade a two-way box of lower frequency
>capability?  Inquiring minds want to .. you know ... know.
>
>--
>secrest

Martin,
        When you get into deep bass the speaker has to move back and forth
very fast or the sound may be distorted.  In a sealed enclosure the air
acts as a spring force against the speaker.  Therefore it cannot move as
fast.  This decrease in speed cn distort hard hitting bass.  The opposite
is also true in the full rage boxes.  The hard hitting bass can take over
the speaker if the it is moving so much that it's momentum causes the
midrage sound to be distorted.
Once again it is a trade off.  Seems like it always is eh?


Will

___________________________________________________________
Will O'Brien
OS Design & Consulting
email: hobrien@webos1.com
alt email: will@students.missouri.edu
___________________________________________________________



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