Fwd: rear speaker option for e30

[Pearson-Franks Family <pearsonf@xxxxxxxxxxxxxxx>]

Raymond:

There are many approaches to your question; I will present
my favorites, to weigh against the others you will undoubtedly
receive!  I can send you a handful of past threads on the
subject (if provoked! ;~)

1)  Presuming your goal is quality sound, disconnect the rear
     speakers altogether.  Concentrate on the front.  How many
     concerts have you attended facing the rear of the
     auditorium?!?  I mean, while still conscious?  None, I bet.
2)  If you don't want to get too ambitious, put high quality
     two ways in the kicks.  You can get acoustic enclosures
     that fit the area as well; but then you would be into
     a couple hundred bucks for just the enclosures.  Go with
     quality "plates" if you can afford them; combos of small
     round "mid-woofers" and a dome tweeter.
3)  If you are willing to cut sheet metal, a very inexpensive
     way to go is to mount 6.5" two ways in your doors.  Yeah,
     yeah, yeah:  once you start down *that* trail, there is
     no going back.  Much better sound; the door acts as an
     enclosure; just need to get drivers that can tolerate the
     moisture in your doors.  High and towards the front, which
     gives you a straight "line-of-hearing" from your head to
     each speaker - another big improvement over the kicks.
4)  Now that you have built a reasonable sound stage up front,
     I will highly, highly recommend a sub-woofer.  Not to get
     the rap "thump", but to keep the small drivers in the front
     from attempting to reproduce bass notes.  Simple physics:
     the lower the frequency, the more air that has to be moved
     to produce the same sound pressure level, which means a
     larger cone, moving greater distances.  Give that job to
     a driver designed to *do* that:  a woofer.
5)  Oops.  Now I have escalated you into a bi-amped system;
     an electronic crossover and decent stereo amp up front and
     a single-ended amp (or bridged for a single sub-woofer).
6)  Where is the sub gonna go?  Lots of choices:  the least
     labor is a stand-alone enclosure that will fit under the
     rear deck, firing the woofer forward.  I prefer sealed
     enclosures for the transient response; many designs go
     for the ported, more efficient approach.  Many off-the-
     shelf designs, or build your own.  I have also had very
     good results with cutting a hole (blasphemy to many!) in
     the sheet metal behind the rear seat; mounting the woofer
     (known as a 'free-air driver) on that surface, firing
     through the back seat.  Works great.  Lots of religion
     here about not removing metal from a unibody; whatever.
7)  Other random opinions:  oval speakers are horrible design
     compromises, introducing all sorts of non-linear travel
     (read:  "distortion") in the name of securing a greater
     piston area in a dimension-limited space.  Gak!
8)  If you *must* put something in the rear deck, and have
     made it this far in the note, you can get 6.5" round
     two or three ways in there with a bit of cutting.  Sigh.
9)  And then there is the power diatribe - 10mm pure copper . . .

There!  More than you ever wanted to hear, but have fun!  Larry F.

>Date: Sat, 22 Apr 2000 20:13:27 -0700 (PDT)
>From: "Raymond M. Wong" <rmw325@domain.elided>
>Subject: rear speaker option for e30
>
>Car: 86' 325es
>Currently rear speakers are factory premium split
>speakers(tweeter + 5 1/4 woofer).
>
>What are my options?
>6x9 too big?
>4x6 ?
>
>Jig saw sheet metal, drop in 8"? jk =P
>
>=====
>Raymond M.Wong

- -- 
Larry Franks
Issaquah, Washington
'95 540i/6
'95 M3

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