Kick Panels Adire Extremis 93 RX7 w/ construction pics

[squalor 10+ year member]

Hi CarAudio fans. I'm hoping you can look at some of these pics and give any comments or advice to make my results better.

I'll use this sticky list to get the particulars out of the way.

Vehicle : 93 Mazda RX7 with '01 Z28 LS1 engine and 6 speed *****.

Location in the vehicle: Kick panels

Space available (Length x Width x Height): almost 4" depth

Subwoofer make and model: Adire Extremis 6.4

Subwoofer Size: 7"

Number of Subwoofers: one per side

Type of Port (Kerfed, Slot, Aero, etc.): Free Air

What type of music do you like?: news talk

Is your goal SPL or Everyday Music?: Louder than a 110 LSA cam and headers

Tuning Freq (Hz): 45Hz natural roll-off plus cabin gain

Volume : Exceed VaS

Questions: Bracing and adhesives

Around 5 years ago I got some Adire Extremis from CSS, NoS after Dan Wiggins closed Adire, the rare 4ohm version. They sat on a shelf while I got the engine swap sorted out and made other upgrades. They are too deep to go in the doors without hitting the glass or "podding out" and my foot already hits the door grill when exiting the car.

Kick panel mounting seemed to be the answer so I worker on "Pruning" the wiring behind my kick panels. This does not apply to most FD (93 thru 01 RX7 body style) but my PCM is under the passenger carpet in front of the seat with a extended harness, Much of what was behind the passenger kick panel was not in use. Pruning the driver side was much harder. The attached pics tell the story. I have attached one pic showing the opening to the A pillar and the area in the rocker panel. I hope this gives enough air space to exceed Vas and let the woofer go free air.

My enclosure takes in this opening into the A pillar. There is a large hole above this opening to allow the door harness to pass thru so I made 20ga plates from a old computer case to seal the hole but allow the harness to pass thru to the door. I hope this eliminates back wave cancelation but I have not sealed the plates yet.

I used 3/8" MDF to make the top, front and baffle. The cars sheet metal forms the rest of the enclosure. The top (roof) of the enclosure is in place. I used bondo/glass to fill gaps between the MDF and body and give a bit of support. I then attached a aluminum L-bracket to a slice of 3/4" MDF to catch the body stud and glued to the top of the enclosure with wood glue. It's solid !

Since I snapped these pics I have made steel straps to attach the baffle to a 10mm threaded hole under the baffle closer to the floor. I would like to rely on wood glue and bondo/glass to attach and seal the baffle to the car and enclosure.

The Extremis will receive 200 wpc from a Avionixx 800.2 and I wonder how much I should strengthen the baffle ? Will the baffle stay sealed and leak-free with how I plan to attach it ? Will it flex ? Will that hurt me ? Should I back it with wood to give the screws something to bite into or is MDF enough ? Do I need holofil ? Should I caulk or Peel&Seal over the bondo/glass ?

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[squalor 10+ year member]

View attachment 26544603Hmm, 125 views but no replies. I thought there would be more interest.

They're in there. I listened to the 6.5" with a 65W amp cuz I don't have the second amp hooked up yet. No tweeter yet. The passenger side was clean, female voice was well produced. Bass was nicely balanced with the rest of the range.

Driver side had cone breakup, a lot of excursion. Bass much louder than the rest. Distortion. Does this mean I have a air leak ?

 

[squalor 10+ year member]

View attachment 26544736

I made a quick & dirty spare tire amp rack. Avionixx 800.2 (200x2 wpc) for the woofers and Coustic Power Logic (65x2 wpc) for the Max Fidelity MFDT neo 30mm tweeters.

I have a old Alpine HU with Bass Engine Pro (no Imprint) set to 3-way operation. I set the hi pass and upper mid to 3.2mhz 12dB since that is close to my passive Xover. It sounded a little better at 2.5mhz 18dB but that's not the problem. I set the low mid to 50hz 24dB and the sub to OFF.

I re-seated the driver side woofer with new rope caulk and it behaved better, less distortion. Both speakers now sound equally bad. Too much cone travel for the amount of output. No Impact or hit from the 80 to 120 hz range . Kick drum don't kick. Low, "thuddy" sound even with the level down 2 notches.

The Adire seems like it needs some air suspension. See the second pic in my first post ? I'm thinking about sealing the holes to my A pillar and rocker panel to shrink the enclosure and get rid of the "leaky box" sound. This should help me locate any air leaks. I just hope I don't create a extended bass shelf.

200 views and no replies. I'm starting to think I'm in the wrong forum.

 

[trumpet 5,000+ posts]

Are you sure the woofers are in phase acoustically and mechanically?

 

[squalor 10+ year member]

Mechanically yes. I used 16ga Scosche wire. The Adire were marked, wide spade +, narrow spade - so the stripe wire went to + on the 6.5" and + on the amp.

Acoustically ? I don't know. Both sides are firing toward the transmission tunnel; not aimed. Maybe I'm getting some bass reinforcement or horn effect because of this.

 

[squalor 10+ year member]

Maybe I should build a "home audio style" test box to get a base line of how they should sound. Everything I've read suggests a 28 liter sealed box, or .99 CuFt. Here are the woofers specs:

Fs: 37 Hz,

Qms: 3.3,

Qes: 0.36,

Qts: 0.31,

Vas: 27 liters,

Re: 3.5 Ohms,

Le: 0.11 mH;

BL: 6.7 N/A,

Sd: 140 cm^2,

Cms: 1 mm/N,

Mms: 19 grams,

Xmax 13mm one way.

To shrink my kick panel enclosure to around 1 CuFt , I think blocking off air access to the A pillar by covering the right chamber in pic 2 should get me close.

 

[hispls 5,000+ posts]

"Pruning" factory wires sounds rather brave.

You know the answer already. Test and tweak.

 

[squalor 10+ year member]

"Pruning" factory wires sounds rather brave.

Not quite as bad as it sounds. It's a swapped car so much of the rotary wiring going to the PCM was gone anyway, the GM PCM is under the carpet. The driver side WAS a issue and I still have some routing to do there. NoRotors is a site dedicated to converted RX7s and I made a post there about it. http://www.norotors.com/index.php?topic=17055.0Test & tweak is the answer hispls. I could prolly EQ it out or cut the legs off with a 100hZ 24dB Xover point but then I would need a sub. I want to stay light weight, sub-less. I also want a lighter amp set-up.

How much do you think making a new baffle and aiming the woofers would help ?

 

[squalor 10+ year member]

I just lost my passenger side tweeter, it's dead.

I hooked the tweeter line up to my door speakers, Boston coax. This meant I could turn down the hi pass xover to 1kHZ 6dB, as low as the Alpine can play tweeters. It sounds really nice.