911 audio the way it was meant

[Eric Coffey]

Originally posted by bell
basically it sounds fantastic, i'm still playing with the internal volume of the box.....it's not quite where i want it yet.

Looking good dood! If you are trying to get a little more "cubes" out of that tiny space, you may want to play with acoustic fill levels. The best stuff I have found, hands-down is Dow "Mirra-Flex" insulation (aside from high-dollar virgin wool). It has a cotton candy like texture, and is non-itchy (I still wear gloves). It's ideal (at 3/4 to full-fill) for making most cramped drivers "think" they are in a little bit bigger enclosure (usually resulting in lower f3's). It also provides the best damping IMO. Of course, you probably already knew all of that!




-Eric
(self-taught acoustical engineer )

[bell]

ok here's some photoshop explanation.....
the red "board" is one side of the box...
the blue board is another side.........
the yellow lines indicate the top pieces where the sub mounts and the cover for access to the sterring mechanicals....
the other walls to the box are the chassis of the car in the smugglers box. total airspace is around 1.3 cu.ft.
the sub i'm using needs around .7 cu.ft ............so i'm removing airspace from the current chamber by adding solid pieces of mdf.
i siliconed over the metal than liquid nailed over that (this makes it easier to remove should the day come), the liquid nail really dampens/stiffens up everything when applied in layers.
here's the pic i made

[Randy Webb]

Since the topic has emerged again, I may as well bump this thread up -- Bell, what's the red vs blue parts in your diagram? And does the yellow mean anything (glueing?).

Also, did you do calculation based on the size of the pipe into the passenger compartment as port?

[bell]

Originally posted by bell

i'll run through it again.......
the top (in yellow) is 2 pieces, 1 piece is simply a cosmetic cover over the steering mechanicals, the other is what the woofer mounts too and is sealed to the chamber.
the red board is side 2 of the box......
the blue board is side 3.....the hose is a drain i didn't want to reengineer so i simply let it run through the box
the other 3 sides of the box are the smugglers box walls.

the box is a sealed enclosure and the woofer fires up into the hood.

[lateapex911]

I did this myself, but was using stuff I had in stock. My results were great when it was parked, but not so good moving. That whole bass cancelation affect and all. Essentially I needed more bottom end, which meant more power and more piston size.

Am I correct in understanding that you have no pass through from the trunk to the pass compartment? So you are essentially reverberating the bass to you? I know that works well in pass car trunks with nothing but a thin peice of cardboard seperating the two, but I didn't know it could work well in a 911!

In the other thread on this, the owner is using the trunk as his volume and has a pass through into the pass. compartment in the smugglers box. Is there a sub that will perform well for him in such a large enclosure?? (Essentially a free air space?)

[bell]

"free-air" subs will lack the punch you need to produce to be able to hear it at highway speeds. i have no problem hearing mine with the targa off rolling at 80mph.....and i have loud exhaust too.

you don't get as much cancelation when you are only using 1 sub, also if you look behind your dash from under the hood you'll see that there isn't really that much restriction for sub bass......the dash of the 911 is much less resistant than the rear seat/deck on a honda, so there is no real benifit to having the sub fire dirrectly into the cabin in a 911 IMO.

[RoninLB]

[Shaun @ Tru6]

this thread couln't be more timely as I've had a busy weekend. New ultrasuede interior is going in nicely and I just installed an Eclipse 3422 and JL 300/4 today. I made the Al brace myself, but could have really benefitted from a proper brake rather than shop vice. Still, it's as rigid as you could ever want.



I WAS going to put 2 sets of MB Quart QM 218.61 Q 6.5" components in the front and back.

Then I read a few posts here and have no idea what to do.

Two things: the top is off almost all the time and with a "tester" set of 6.5" Boston Acoustics Rally series, they are just not loud enough at speed.

Second, very different car, but the Saab has a high-end Clarion component system w/ JL components in the front and back. I went out and tested front speakers only, and it sounds terrible compared to fading -1 to the back.

Should I really not put speakers in my rear deck?

Thanks for your input.

Shaun

[RoninLB]

6.5 front door speakers only being powdered by 75w each should be 115db with no distortion, IMO. which is in the ear damage range.. but I'm not not an SC doctor...........Ron

[Shaun @ Tru6]

Head unit volume was at 60 out of 80 (does that 75% rule apply?)

I installed the amp out of the box, did not even think about touching the various adjustments on the interface panel. Sound was clean and clear.

[bell]

you could probably dial it in better with the gains and crossover.......tuning is a vital part of audio performance

[ricwon]

What type of an alarm are you going to install in your car? And are the door lock l.e.d.'s from a later model or are you going to custom install? Great set-up for the audio! The sub in the smuggler's box is a cool idea! ric

[Yargk]

I was expecting a picture of an exhaust

I'm not trying to be harsh though, I put a nice stereo in my 930 before I became the hardcore track wannabe I am now. An 8 inch JL sub and two 5 1/2 inch MB Quarts run off a Kenwood Excelleron 75X4 amp (two channels going to the MBs, the other two bridged to the sub). Though I want to save weight and I'm probably going to ditch AC, I can't bring myself to axe the audio.

You have a nice system.

[9XI]

Bell,

Stupid question.

When you mount the sub in the front, does it resonate outside the car more than one mounted inside the cabin would? It really bugs me when the kid next to you in the light is going thump thump thump with some yuck music. I wouldn't want to join the crowd.

[wesayso]

About a year ago I played with the idea of putting better speakers in my SC and the thought had crossed my mind using the space available in the smugglers box for some bass extention. It wasn't until a thread surface with a front sub solution: 1971 911 ultimate stereo to put me back on that path and persuing the idea.
So I figured it could be done with reasonable results and I decided to search the forums. That's when this thread came up. I immediatly bookmarked it for future reference. You could concider this post a "thank you" for the info and it might help others with similar ideas or needs.

My aproach is a bit different from the one in this thread. I figured I could build a box to fit inside the smugglers box to use with an 8" sub. My choise of sub is the JBL GTO 804. It only needs a small box (0.3 ft 3) and with the help of the posted info here in this thread I knew it would be possible to get that size. (Documentation JBL GTO 804)

My trunk with the nice empty smugglers box:


After cutting some cardboard shapes I came up with this:

The result was a 9 liter box so a bit more than the 0.3ft 3

It fit pretty well and after some paint it looked better too:


The completed install looks like this:


For mounting the speakers Pelican forums came trough with the info in this thread:
Mounting door speakers That was very helpfull and complete info to properly mount some door speakers. I used 6 3/4" drivers without a problem. Trow in a good head unit with time alignment and EQ and an amp and you might be surpriced what it can give you. I know I was!

More details including dimensions and the rest of the install can be found here:
DIYMA Porsche 911 SC audio install

I know many say you don't need tunes exept the one comming from the exhaust but I sure am glad I tried. It sounds so good that I need to replace my home system to bring it up to the same level!

[rattlsnak]

Wait, people actually 'listen' to radios in a 911?? Seriously??

[wesayso]

Originally Posted by rattlsnak

Wait, people actually 'listen' to radios in a 911?? Seriously??

I just knew this was comming, but to answer: yeah, I do

[bell]

wow old thread LOL
before i sold my 911 almost 2 years ago i had made a few major changes to the sub setup, i changed to a jl 10w6 and ported the enclosure, placing the port through the passenger footwell.....i was surely amazed at the increase of volume in the car, took a bit of math to get it right as my box wasn't anywhere near square.......
but right now i'm simply rocking my 924s with 2 12" in the spare tire well.......LOL

[WolfeMacleod]

Originally Posted by bell

but right now i'm simply rocking my 924s with 2 12" in the spare tire well.......LOL

Many years ago I had a '77 924. It had a pair of 6x9's in the carpet covering the "storage" area behind the wheel wells. Sounded damn good, really, and this was 20 years ago. I've been tempted to do it again, but don't want to cut holes in the existing carpet.

[slow&rusty]

While I have never cared for Blaupunkt equipment..I love the rest of your componentry and very nice install!