Mondial Sound System Upgrade: Sub-woofer

While not my usual upgrade thread, I thought there might be some interest.

In addition to the exhaust upgrade, I am upgrading my sound system a bit. I am using an Alpine head and two channel amp under the passenger seat, but the quality of the sound was never in line with the kind of car. I did not have luck with my Polk speakers, and have switched to a kevlar Pioneer 6.5" for the two doors, and have added a Dynomat door kit for resonance suppression in addition to a rubber acoustimat behind the original fiberglass speaker enclosure behind the doors.

This gave a fairly good sound that can be heard over the engine, but not a full sound. So after discussing this with a local high end shop, we have decided to add another driver amp under the driver seat and place a 6" - 6.5" subwoofer in the area of the rear seat storage compartment replacing the compartment door and being completely reversible. It will be timmed in black speaker material with matching tan or black vinyl upholstery over the small tasteful (hopefully) enclosure that will be built for it.

Will post pictures and results.

Again, this is by design a simple, effective bolt in/out deal that can be replaced, and will hopefully be very subtle, and add a lower end fullness to the sound that quite frankly is missing from the current set up.

If it works, will make plans or kit available if interest.
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If its of any use Russ, I have one of the compartments if you didn't want to remove your door etc.., only slight problem is mine is in the tan finish
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yes, I think I may be interested. I will pm for details.
thanks

 

Again, this is by design a simple, effective bolt in/out deal that can be replaced, and will hopefully be very subtle, and add a lower end fullness to the sound that quite frankly is missing from the current set up.

Great idea, I thought it was my set up that lacked bass, would be good to see how you fare. AS I have a QV the rear pocket is just a piese of leather with an elasticated band at the top, I guess the space is the same though?

 

My Qv has the box as shown above.

 

Here are some photos of the subwoofer box construction. It is made of fiberglass and composites, and will be covered on the sides by a color matched vinyl to the seats, and the middle will be a removable black speaker cloth piece to access the woofer from the front. A challenge was what to do with the trunk pull lever - I think we are going to notch the box and have it come out on the top or something nice like a small recess for it.

In addition to the woofer box having dynomat, it was noticed that while the firewall had a pretty good insular rubber mat, the seat pans were un muffled and quite resonant (see photo) so we'll place some dynomat to deaden the seat pan resonance and hopefully lower road nise. The doors were also treated with a dynomat door kit and the fiberglass speaker enclosures in the door dynomatted as noted before. you can knock on the body and notice a big difference in the sound when you get to the door - much less resonant.

OBTW - decided to tint the side windows with a light metallic (better UV reflective) to help out my buddy the A/C - it does try so hard but Texas summers are rough! Hopefully will cut down the temps and the glare of an often hot Texas sun.

Sorry for the picture quality - just had the phonecam; will hopefully have finished photos tomorrow with installation of the woofer driver under the driver's seat. The blue tape in the picture is to protect the sound deadening mat as the box was built and fitted - it will be removed.

More later
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Will have better photos this evening, but here is a phone photo as a preview.
Details later
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Russ,

You should obtail all the Thiele-Small parameters on that driver and you should calculate the box volume prior to the driver being installed.

That box might be too small for the driver which will prevent it from developing full low frequency waves.

Remember that the box will shrink by the volume of the driver itself!

Give me all that info and I'll run the parameters to tell you what you'll get. It could be that you may need to vent the box.

Great work, however.

 

Will look around for the parameters. We may need to put a vent.
Other equally important factors are location availability and impact on aesthetics; an optimum performance will be negated by the extremely high noise environment, so it becomes a value added judgement call. It's all a balance, of course.

I can tell you on a prototype run today, the increase in the sound quality over simply having the two door speakers is amazing. There was NO appreciable lower end before the sub and now there is a full range. I still need to fiddle with the output balances, but it's darn close and looks better than I thought it would - and WAY WAY better than the original equipment.

I'll try to get those parameters tomorrow and calculate the box volume.

The total system consists of an Alpine head and 60W per side nom. Alpine Amp (under passenger seat) powering a pair of Pioneer TS-D601P 6.5" kevlar 260W max coaxial 2 way speakers in the doors. The doors were dynomatted. The JL 6W04 6" sub is powered by a Pioneer GM-3200T dual 120W amp (under driver seat) bridged to 300W max. One of the prime selection criteria for the selection was size, particularly height, as under the seats afforded the best amp mounting available and the area between the rear seats for the sub. And remember, it's already very loud from the engine/exhaust.


Will have more install photos tomorrow - here's a better picture of the prototype installed.
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Nice enclosure...

These are going into the 328 (Subs and Comp. set), Saves a ton of room, and sounds awesome. In fact if memory serves me correctly we placed 3rd or 4th in the world a few years ago in our sound quality vehicle with these speakers.

http://www.illusionaudio.com/docs/carbon.htm

Wow just checked the website again under testimonials, our comment is still there after all these years, the last one.

 

Here are some more install photos, showing the dynamat to address the resonant metal pieces, amplifier and one of the light metallic tint put on the windows.
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russ,

wow!
I am in the process of doing the exact same thing to upgrade the OEM sound system in my T , however, I have a cabriolet that does not have teh rear compartment for the subwoofer you are making. You move so damn fast with these mondial project , I wish I could convince you to put the subwoofer in the front foward of the setroe head in the console ( a huge empty space there) so that all mondial T owners ( cab and coupes) could buy and benefit from the enclosure you fabricate.

I will also do dynamat in teh doors -- I am doing a Boston Acoustics pro system (please show pics of you door installation ( with panels off if you took those pics)) also where did you mount mid and tweets...
Do you know how the OEM tweets are wired? can we use any of teh stock OEM wiring?

How much power you pushing and how are you wiring it so not to overload teh weak OEM alt output

 

Another couple of photos from the fab shop and install. Will still try to find the numbers to eval for the box vents. It would be easy to do as the speaker cloth pops out. Will try to get some door pics., but basically the fiberglass speaker enclosure was lined with dynomat and extra put on the inside of the door skin to dampen the resonance. You can hear a big difference as you tap along the body - when you get to the door it goes thunk instead of dink.

Now back to designing the perfect exhaust - the headers will be here next week. Thead is in the tech section.
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One of the first things done to my vehicle when I purchased it was to change out the period cassette player and replace it with a cd player.

However, I love to just listen to the music made by my engine!
I listen to music maybe only about half the time I'm in the car.

Don't get me wrong, I give you lots of credit for a great looking project.
Maybe its just that I haven't owned my Fcar as long as most of you.

 

Russ, that is simply awesome man! Now, some questions.

1. Did you build that box from scratch using the OEM compartment as a guide, or did you modify the original compartment?

2. Are you taking orders? ;-)

That box does look too small to be a sealed enclosure for that woofer. If that is indeed the case, it will be overdamped. The output will not be very efficient (dBs per watt) nor will it hit the bottom end of the spectrum well. Adding the appropriately sized and tuned resonator vent will make it sound a lot better and more efficient.

Birdman

 

Thanks.

1. The box was totally built from scratch (see photos), so the original piece can just pop back in if needed.

2. I guess I could - it would not be cheap as a lot of labor was involved to build , round odd the sides, fit, etc. That said, yes it can be duplicated or even modified to be bigger (more $).

I'm just an Alabama Public High School Graduate and a rank amateur at all this audio stuff - I just wanted a more full sound. When designing this, a factor was the interior is such a loud noise environment and the door speakers do a poor job with the low tones anyway that anything would be an improvement, and there would be a point past which a lot of $$ would not help that much.. I also wanted the installation to be very simple, subtle and keep the factory lines and appearance. To vent the box would require a lot more to the construction

The results? The new sound with the new speakers and sub is amazingly improved as you can imagine - even with the open exhaust the sound is much fuller. Perhaps not perfect, but now the sound is 'full' and the goal achieved. I don't hear well anyway after years of flying F4s anyway.

And, yes, it looks absolutely great in person like the factory put it in.

Thanks to everyone for all the comments and advice!
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Hi Russ,
I in no way meant to put down the installation! Even if its overdamped it still will sound a heck of a lot better than no subwoofer! Venting is not as hard as you might think. You can add a helmholtz resonator which is just a tube of the appropriate length and diameter. It can even hand a bend in it so it's the right length inside. The whole resonator is inside the enclosure and all you see from the outside is a "bass port" (hole) which can be hidden behind the grille. I can help with the calculations on that if you give me the specs on the woofer you used and the approximate volume of the box.

So for a guy that has never built anything out of fiberglass before, how did you form it? I would like to see some pics of it being made a little earlier in the process!

Birdman

 

gorfeous black mondial, russ, you are a mondials best freind! Am I right that T cabs do not have that compartmetn, at least mine doesn't

 

I upgraded my 3.2 Cab with an Alpine 400W system last year. Replaced the speakers in the doors and the tweeters in the dash. The installer fabricated a subwoofer box below the dash in the footwell between the driver and passenger spaces. I think it's 8 inches. It sounds really good. Then I took it to an upholstery shop, and they matched (as well as they could) the french stitch pattern, vinyl, and carpet. I ended up with a sunglasses cubby above the radio, too. The whole thing cost me about $2000. I can also plug in my ipod. The bass and high range is fine, but I need more mid range, and the AM radio is still full of static. I figure its something in the spark wires, and I don't know how to fix that.

 

Hey Guys, not trying to hijack your thread....and I had this item posted in the ads on the site. Just seemed logical to give notice on what I have since the discussion is on subs for the Mondial.

I have a Z Box sub-enclosure for the Mondial that I'd like to get rid of and would like to see it go to a good home where it will be installed and enjoyed

It fits coupe or cabrio in the area between the top of the console & bottom of dash, and is basically Plug & Play with no modification to the interior needed. It has an Alpine EQ mounted in the center of it that ads to the finite adjustability of your music. To those who really don't know the Mondial, it looks factory

Its a fiberglass unit which has been professionally padded & covered in black leather with stitching to match that of the Mondial. Unfortunately these are very rare, as aftermarket parts go, as you can't buy theses anymore. I have actually been trying to get one for both my 308 and my 930 but cant seem to locate.

See the attached pics, pic 1 shows the box covered in tan without the EQ when mounted in my 1st Cabrio. The other 2 pics show the unit as it is currently..uninstalled, EQ mounted and trimmed in Blk leather.

The box itself retailed for about $500, plus the speaker and Alpine EQ, and the cost of having it covered in leather.

Somebody make me a reasonable offer and its yours.

[email protected]

Thanks

Paul
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This tasty little tidbit has been sold to a fellow F-Chatter for use in his Mondial Cabrio. He was as surprised as me that the item was still available and his "shot in the dark" inquiry paid off.

Me, I finally found a Z-box unit for my 930.. just need to cover to match the interior.. would still love to find the same for the 308.. oh well.

"Enjoy The Music!"

 

OH MAN!!

I saw this a couple years ago but thought "it had to be sold!"!!

Oh well, my interior is not black anyway..

Best,

H