# Custom built sub box in-place of the spare tire. Ideas and input needed!!!!



## Cruze SRIV (Oct 26, 2013)

i am in the progress of building a sealed box in the spare wheel well i am using a single morel supremo 12 inch sub heres a start of it a pic


----------



## NickD (Dec 10, 2011)

With two four inch speakers in the front, two 5" speakers in the rear, had to do something with my 88 Supra. Does have a full size spare, just flipped it upsidedown, made a special bracket, that gave room for a ten inch woofer. Rather than paying extra for a dual voice coil, just combined the R and L channels together in the amplifier. 

You want bass, I got bass. Since the roof goes into the hatch, no such thing as a box, remade the hatch cover with 5/16" plywood, and glued insulation under it, called an infinite baffle type of enclosurer. 12" can be an overkill, with my spectrum analyzer, measured a host of different sound sources. Only thing that came close to 30 Hz, was a 32 foot organ. That pounding everybody loves is at 150 Hz, even an 8" can handle this. The lower notes on a piano that nobody uses, is a series of 150 Hz pulse that occur at about a 16 Hz rate.

For me, 20 watts per channel is more than enough when you consider a 6" speaker will output 105db at one meter with only 1 watt. OSHA states above 85db, should wear ear protection, still have excellent hearing at 78 years old. Major problem with automotive is ambient noise, can be as high as 75db, so much for dynamic range. So have to compress my music first, yes, is an audiophile sin to do this, but either blowing your ears off or can't hear it. 

Also have an HP distortion analyzer, have yet to find a speaker spec that states maximum RMS power before it distorts. Only show the maximum power the speaker can handle before the voice coil gets toasted. For a typical 6" speaker lucky to hit 6-7 watts before distortion occurs. Woofers can handle a bit more, key parameter is excursion. 

Subwoofers are boxes you can mount under a table as to why that sub prefix was added.


----------



## ma7mgte (May 16, 2014)

NickD said:


> With two four inch speakers in the front, two 5" speakers in the rear, had to do something with my 88 Supra. Does have a full size spare, just flipped it upsidedown, made a special bracket, that gave room for a ten inch woofer. Rather than paying extra for a dual voice coil, just combined the R and L channels together in the amplifier.
> 
> You want bass, I got bass. Since the roof goes into the hatch, no such thing as a box, remade the hatch cover with 5/16" plywood, and glued insulation under it, called an infinite baffle type of enclosurer. 12" can be an overkill, with my spectrum analyzer, measured a host of different sound sources. Only thing that came close to 30 Hz, was a 32 foot organ. That pounding everybody loves is at 150 Hz, even an 8" can handle this. The lower notes on a piano that nobody uses, is a series of 150 Hz pulse that occur at about a 16 Hz rate.
> 
> ...



Cool. I have a 92 Supra...


----------



## NickD (Dec 10, 2011)

Couple of photos.















Supra has a curtain that covers the hatch, where a regular car with a trunk has seat backs, but also worked in such a car, just crank up the volume for the woofer.


----------



## ma7mgte (May 16, 2014)

NickD said:


> Couple of photos.
> 
> View attachment 228498
> View attachment 228506
> ...


I always found the door speakers to be an issue. For as big as they are, surprisingly little room. Right now I have JLAudio separates in there, but would like more mid-bass out of them. Tough when there is not much room to work with.

As far as my Cruze, I'm planning on letting a local shop design a box for me. Those days of creating my own speaker boxes are behind me.


----------



## NickD (Dec 10, 2011)

Airbags kicked the speakers out of the dash and into the doors, ha, was thinking about having me ears on my head transferred to my ankles.

But if you put a box back there, what about your groceries? And should be secured or will bang up your trunk. Could learn how to live with two 6 by 9's full range speakers mounted at the rear in your package tray. Adding extra speakers causes what is called acoustical phase distortion, every frequency wavelength is different, some will add doubling the amplitude, others completely cancel each other out where others are somewhere in between.


----------

