Re: rear speakers(very long)

From: Glenn S. Wiltse (iggy@merit.edu)
Date: Fri Dec 06 1996 - 07:23:55 EST


   In my Dakota, I got 6.5 inch round speakers in front and rear
factory locations, with only a little inginuity, and no sheet metal damage.
    Well since everyone else has been telling you all about what they have
done with there Dakota's sound system, I'll tell you about mine...(the
long part)

   I have a 96 SLE club cab 4x4 with V8.(you dind't say what year yours
was or nothing by the way, it may make a differance). First I yanked the
stock radio and front speakers. Eveyone I talked to told me that the
front stage is the most important, I found this contrary to every car
stero I had did before, but I figured these guys sounded like they
knew what they were talking about and I had several differnt places tell
me that. So I purchased a Clarion AM/FM Cassette(head unit), and a pair
of JBL 6.5" speakers. I had the store install the head unit, and they
used one of those wiring addapters and used the stock wiring without cutting
any of the wires. I installed the speakers myself, and this was simple
just removed the door pannels, the old front speakers and mounted the
new ones...(well since I have the JBL seperates I had to mount the tweaters
somewhere else) I mounted the tweaters near the door handles, where your
hand would be if you put your elbow and forearm on the door handle/rests.
The head unit puts out about 15 watts RMS into each of the four channels.
This set up improved the sound tremendously, I was impressed, and I no
longer doubted that the front stage is the most important(or should be).

   Well the rears still sounded kind of muddy to me, and I also had my
eye on this gadget that was able to connect directly to my head unit and
give me a 7 band graphic equalizer, two(fron and rear) 4 band parametric
equalizers, 12 preset Digital Sound Processing images as well as 6 user
programable ones.... (it was/is expensive, like $500 min.) I had been
reading about car stereos and such alot, trying to figure out what I could
best do next... I had been bitten...

   Against most peoples recomendations I went ahead and forked out the
big bucks for the DSP/EQ/PEQ module... It give me something to play with
and improved the sound slightly(if I set some of the settings right).

    I still had this muddy sounding bass... I was contimplating purchaseing
some rear speakers but didn't know how to aproach it... I had been reading
lots about modern compitition level car audio, and they all were saying
that all you want the rear speakers for is for "rear fill". That is
you just want something to add some ambiance so to speak. I also wanted
some lower bass wich was only going to be had by a sub woofer... So I
figured I'd buy buy a sub, and of course a amp.

    My goal was to find a sub woofer that I could install in the small
tool box area in the back area of the club cab. I figured out that the
space available(volume) was about .47 cubic feet(I did this by yanking
out the whole box, pluging the wholes in the box, pouring watter in it
up to the top where I would be putting the top on then figureing out
how much water was in there, ect...) Well I found that many people make
8" subs that will fit in less then .47 cubic feet of space, and you can
find some 10"ers that will. I choose a 8" kicker solobaric 4 ohm
speaker. That speaker will handle about 200 watts of power, and a
Rockford Fosgate 40x2 amp will put out about 180 watts when both channels
are bridged and conencted to a single 4 ohm load, so that's the amp I
purchased.
     I had to make my enclosure smaller some how, as the speaker only
needed(and was recomended to have) .33 cubic feet of volume. I had the
rear box out still and I figured out where to put a little barrier and
get the volume I needed. I had a little barrier wall cut out to closely
match the curves of the bottom of the tool box area, I placed it in the
box and had .33 cubic feet of bird seed measured out... I moved the
barrier wall over untill the bird seed filled the box to the top, and
then I knew exactly where to place the barrier... I cut another peice of
wood that matched the first one, I glued them together so I would have a
wider barrier to allow for ample surface area to put glue/sealant on
because I knew this box had to end up air tight... I placed ample
amounts of liquid nails on the surfaces where the barrier would meet
I had pre drilled holes (about 50 of them) in the exact spots I needed
them to be to mount the barrier wall... The wall was installed at the
correct location with excelant seal and stability... I had also cut
out a peice of the partical board to replace the stock top to the tool
compartment, along with a whole the correct size for the speaker I was
going to install. (the whole was situated in a spot where the speaker
would fit, and it allowed me accsess to the hole where the bolt/screw
fassend the box to the cab on that side) I cut this so the area on
the oposit side of the barrier was still accessable, mainly because
the accessory box had another attachment point in that area of it.
I installed the top board in a simmilar fashion to the barrier board.
When I was done I had a completely air tight box that was also remarkable
solid(you don't want a sub enclosure that flexes).
    When it came time to installing the amp, and running the wires I
decided not to do it half assed, so I yanked the rear pannels out,
then bottom door moldings, and the front kick pannel peices. Well
I wanted to keep the power wire(8 guage) seperated from the audio
wiring, and the amp was going under the drivers seat, so I yanked the
seats, and the center console. I could then runn the audio wires down the
passanger side of truck along where the door sills would cover it...
I ran the power wire direcly from the positive terminal of the
battery(fused near the battery of course), throught the fire wall, along
the transmission hump(I had the carpet all peeled back by this time) to a
distibution block I made and mounted under where the center console would
be going back in place. I added a large ground wire near that center
console area, with another distribution block. I connected the amp
power and ground to the power distribution blocks I had installed.
The audio wires cam in from accross the back floor too the amp totaly
isolated from the power wires... the speaker wires ran directly back
from the amp to the area where the accessory box/sub encloser would
get re-installed....
      After putting every thing back in place, the stereo system worked
like a charm, I had more low bass but still had some kind of mudy mid
bass. Well don't let me under rate what I had at that point, it did sound
pretty dam good... I still wasn't sure if I wanted to spend over $100
on some 5x7 speakers for the rear factory locations, when it was just
going to be used for rear fill sound... weeks went by...
    I started looking into options for the rear factory speakers because
I had a system that was extreemly close to being absolutely great...
I remembered that there was/is about a inch of room between the factory
mounting holes in the back and the back interior door pannels... I thought
I could probably figure out a way to take some 6.5" round mid bass speakers
and get theme installed in that area, using some sort of a adapter plate.
I bought some Radio Shack 6.5 inch dual voice coil "sub"s, and convinced
myself that I could get them mounted without cutting any of the sheet
metal in my truck... I used the 5/8ths partical board I still had from
the sub enclosure project, and cut out a 5x7 oval with a hole just big
enough to mount the 6.5" subs(that sounds impossible, but the 5x7" thing
is actually bigger then 5x7, and the hole for the 6.5" is smaller then that)
I got hem mounted and connected them to the head unit still using the
stock wires(with differnt ends).
     So by this time I had 6.5" seperates in front, a 8" sub mounted
in the tool box area of my club cab, and a pair of 6.5" subs in the
back factory locations... My muddy bass got less muddy. I was
pretty happy, but knew something could be better...
      By this time I had read alot, and purchased some CDs that could
be used in evaluating sound systems along with a Radio Shack Sound
Pressure Level meter i had from before. I had done some critical
listening and evaluation using 30 1/3 octive bands of pink noise. I was
still trying to put to use this $500 gadget I had with it's Parmetric
equalizers... I mucked around and mucked around, and mostly convinced
myself that while I had a pretty good system, it still had some pretty
serious flaws in it.... I moved the tweaters from the doors to the
front kick pannel area, and this improved the imaging, as well as
lowered a high point i had in the highs, of my frequency response curve.
Things were sounding good, but since I had gotten rid of some of the
bad vibes from my stock speakers and such, I decided I needed MORE
POWER(arhhh arhhh arrh).

       Well I added another Rocford Fosgate amp, this time a four channel
one a 160x4(rated 20 watts per channel RMS, but puts out about 50). It
seemed like it would match up with the power I had to the sub, and if
I was ever to compete I would still be only at 120 watts total. I yanked
all the interior out of my truck again, ran two more sets of RCA cables
to the new amp, re-wired the speaker wires with 14 gauge wire, ect...
I got more power now...(not so much that you blow your head off though)
At high volumes I had some fuzzy mid bass still it seemed, but only at
more or less max volume(just below clipping of my amps).

      Well I started reading about sound deading, and alterintives to
expensive product on the market for that purpose... I added sound deadening
to reduce road noise mainly, and it did that a little. However what
I knotice the most was a noticeable improvement in the frequency response
of my stereo system(measured using 1/3rd octive bands of pink noise and
a SPL meter). I atribute this to reduction in sound canceling vibrations
of my door pannels. I have yet to deaden the rear pannels, because it
will require me to tear out my interior pannels wich is not a simple
task. It is also winter now, and that makes this task even more
uncomfortable because it's COLD out in the garage...
     I am still working on covering my sub enclosure with carpet and
a fancy speaker grill(custom), but it's there and the rear seats still
fold down. The amps only stick out bellow the seats when the seats
are fully pushed forward and the RF amps have covers on the ends, so
no wires are exposed. At a quick glance from the outside of my truck
you would never know I had a serious aftermarket sound system installed
it's pretty stealth...

    I have not made any changes to my system in seveal weeks now... My
pocket book is still recovering, since the $2000 I spent over the
last several months did some damage... My sound system is about 95%
of what I would consider perfect, and that's about 500% better then
stock. The more I know about car audio, the more I know it's a difficult
thing to do extreemly well. I also feel that one of the biggest
improvemants I made, was one of the least expensive, and that's the
sound deadening material. I also figure there are alot of stereos around
that have had loads of money thrown at them, and I'd be very surprized
if they are half as good as their owners think they are. If you've not
had some sort of frequency response measurments taken, or added any
sound deadening, then I bet you've got some pretty serious flaws in
your system...

On Wed, 4 Dec 1996, Michael Clark wrote:

> Has anyone tried putting 6X9's in the regular cab Dakota, instead of the
> 5X7's? What would be involved in doing this. Would there be a lot of
> fabricating to get things to fit. I would like 6X9's because they are
> more abundant than the 5X7's.
>
> Same with the front ones, how about 6in. instead of 5 1/4in.? Would
> that be worth the trouble?
>
 



This archive was generated by hypermail 2b29 : Fri Jun 20 2003 - 12:07:28 EDT