Miata Mailing List: November 1995, Message #89
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   From: doc.wynne@rodent.isdn.net (Doc Wynne)
Subject: Re: Clearwater subs
   Date: Thu, 2 Nov 1995 00:30:38 -0500

HN>My local installer offered to install an 8" subwoofer behind the
  >passenger seat in the manner described above.  I held off because
  >I can't get a chance to hear it beforehand, so it's a lot of $ to
  >blow on speculation ($900 including amp before any discount).
  >He said he did it to another miata and it sounded good.  Also, I
  >worried about the passenger being blown away by the noise.

 I'd prefer the 8" to the two 6.5" subs. As for the passenger being 
blown away, I wouldn't worry about it too much. At the frequencies you 
should be sending to the sub in a well-designed system, the sound is 
more "omnidirectional" in that you cannot really pinpoint the source as 
well as the higher frequencies.

HN>How do two 5 to 6.5" woofers would compare to one 8" woofer? I
  >think I prefer the balance of two speakers (on paper at least).

 You won't really get much more out of 5" "subs" than from the door 
speakers, in that their low frequency cut off point will be much the 
same as the door speakers. (Typically around 60Hz) With 6.5" subs, you 
may extend that down to 45-50 Hz. An 8" sub should get you down to 
35-40Hz. My installer says he can get 8" drivers into the doors on my 
Miata...although I haven't had the spare funds lately to attempt this 
project.

 As for the "balance", since you should be cutting the high end 
frequencies off at 200-250Hz, you probably won't miss the other 
speaker...however, make sure the amp you choose can run in a "mixed 
mono" mode to drive a single sub. (Mixed mono is taking the left and 
right channel inputs and electrically "summing" them for the single 
channel output. It won't sound "right" if you use an amp that will only 
do mono or "bridged" mode and only can hook the output from one channel 
to the input on the amp. I know most of this probably belongs on 
rec.car.audio but we owners of Miatae have real space problems when it 
comes to installing "ultimate" sound systems for driving enhancement. 
:)

 If anyone else on the list has had a "high end" install done on their 
Miata, I'd like to hear about it. E-mail me if you feel it somehow
inappropriate for this list.

 
HN>Also, does the Clearwater amp have to be mounted in the trunk? I
  >thought I saw something about mounting it in a fender well.  But
  >my installer said amps must be in interior compartments.

 Your installer is correct.

HN>Is there any chance of putting it under one of the seats?

 If you choose a "low profile" amp, but be careful to leave enough room 
for cooling air to flow...a minimum 1" air space anyway.

HN> Perhaps by raising them to make more room?

 If you can afford to give up the head room to do so, but have your 
local machine shop make the blocks to raise the seats so they mount 
solidly....do not attempt to "space" the bolts/studs, as they cannot 
withstand the shear loads you might put on them in sudden stops or 
(forbid) and accident.

  When I get my funds back together, I'll post to the list what I had 
installed (and where) in mine. For now, I know I'll be transplanting 
from my last car a Sony Cassette/Changer controller, Sony 6-disc 
changer, Fosgate 30Wx4 (in 60Wx2 channel bridged mode) for the door 
speakers, and a Soundstream Reference 300 (75Wx2 or 300Wx1 into 2ohm) 
for my subwoofer. Speakers have yet to be chosen, although I am leaning 
toward either Boston Acoustics Pro 6.5s or Polk MM3065s in the doors 
and a single Image Dynamics IDQ-8 for the sub.

  Hope this helps!

 Doc
 Red 92B
 Team No MSUs

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