Infinitely Baffled The Do-Over. :P

[onebadmonte 235]

First Impressions:

I don't use any tools to setup the system. This is what I do. I pop in something I'm familiar with with bass. This time around I popped in Kylie Minogue, Fever. I turn up the radio 3/4 of the way up and start off with the fronts. I guestimate the crossover. Since the fronts are 3-1/2 co-ax I shot for 500Hz. There are markings on the amps crossover. I turn the gain up till I hear a hint of distortion then back off a 1/16th of a turn. Then I disconnect the fronts and repeat the process for the rears. For the rears I shot for a crossover point of 120Hz. To set the subs I have all the speakers going. I shot for a 80Hz crossover point then just turn the gains up till it sounds right with the inside speakers. From here I'll fiddle with the EQ in the head unit to get the sound right. That will happen over time over a wide range of music. I'll also have friends listen and get their take. This is what I have always done, and for the most part it has worked.

As for the sound so far, it's good. There is more bass output. At low and moderate levels you now it's there. When I go for full tilt, it's a bit much. There is a bunch of air moving through the large rectangular openings in the rear deck. It's almost like a speaker port. I'm definitely going to work on that. I'll get some measurements first with my SPL-Labs Meter. Shameless plug there for my friends.

[Kanaworm$ 292]

Very nice craftsmenship! I like how this turned out. I love the old school US Acoustics amplifiers.

[onebadmonte 235]

Very nice craftsmenship! I like how this turned out. I love the old school US Acoustics amplifiers.

Thanks. I've got a bit mote work to do to pretty up the install. Heck, I've still got some work to do to improve the sound.

[onebadmonte 235]

I conducted my first system test. This test was raw, I hope to improve on this. This first test is was

conducted windows and doors shut.

This is the meter location.

This is the setup. No rear seat, no rear deck cover.

Here are the results from my second test. The drivers side door was open for this one.

My thoughts. Meh.

[ssh 924]

If you run your hand along the edges of the rear wall and top can you feel any breeze of air escaping? Perhaps there's a couple spots that are leaking and can be sealed?

[Julian 641]

Try popping your trunk when you're playing.

[altoncustomtech 773]

The rear deck looks like it has a couple of gaping holes in it to me. Also the tweeter cups will leak some air as well.

[cheese20323 13]

use expanding foam for sealing everything off or sound deadner.

[CadillacMatt 31]

You make it look so easy Hugo!!

As the guys said I bet a full sound deadening job would do the trick, especially since the trunk is your enclosure.

Oh and would you mind shooting me a PM with your number again man? New phone FTL

Here's to the best installer in the U.C. area! :drink40:

Edited July 21, 2010 by CadillacMatt

[onebadmonte 235]

Thanks for the tips guys. There is some air moving through the rear deck openings. Actually, at full tilt, there's probably enough air to float a tee-shirt. I'm currently working on the rear deck. A bit slower than I like, but I'll have some more pics soon.

[kryptonitewhite 1]

very impressive!

just curious, with the car audio croud, is there an "Infinite Baffle Vas:enclosure volume ratio"? Home theater is usually 20X Vas, sometimes 10X Vas. Josh, Ricci, says 4X Vas is close enough to diminishing returns.

[altoncustomtech 773]

Thanks for the tips guys. There is some air moving through the rear deck openings. Actually, at full tilt, there's probably enough air to float a tee-shirt. I'm currently working on the rear deck. A bit slower than I like, but I'll have some more pics soon.

That much air leaking is killing the score, and the sound. IB's only work when the back wave is COMPLETELY sealed off from the front wave, which in a car is nothing short of nearly impossible. I have great confidence though, that once you seal those holes and apply sound deadener to the rear deck you'll notice a tremendous difference in the sound and score. It may not be a bad idea to go around the back there where the subs are mounted and test for more possible leaks. The better you seal that from the cabin, the better off you'll be.

[inkfx 3]

i wanna hear it

I'll let you know when it's done. We'll have a little mini meet.

Mini meet!!!!

[onebadmonte 235]

very impressive!

just curious, with the car audio croud, is there an "Infinite Baffle Vas:enclosure volume ratio"? Home theater is usually 20X Vas, sometimes 10X Vas. Josh, Ricci, says 4X Vas is close enough to diminishing returns.

From what I understand. In car audio, IB is all about displacement. The more the better. For SQ purposes there might be a limit. I dont know.

That much air leaking is killing the score, and the sound. IB's only work when the back wave is COMPLETELY sealed off from the front wave, which in a car is nothing short of nearly impossible. I have great confidence though, that once you seal those holes and apply sound deadener to the rear deck you'll notice a tremendous difference in the sound and score. It may not be a bad idea to go around the back there where the subs are mounted and test for more possible leaks. The better you seal that from the cabin, the better off you'll be.

I'm working on it.

Mini meet!!!!

[kryptonitewhite 1]

well either way, I dig your build, and it's what I have been doing locally with "the wrong" drivers, with excellent rsults and happy owners.

I get flamed a lot for using my IB3's. For one thing, all the self proclaimed know-it-alls should know full well that a vented enclosure acts as a sealed enclosure above port usage. So my 23Hz tuning is basically sealed, therefor I am running mine "IB" with 13 cubes per sub, which is what I guestimate both of yours are sharing.

As others have been saying, and I see that you intend on working on, yours is a lossy/leaky sealed enclosure, as each driver has a Vas of 14 cubic feet, so each driver alone should have more than 140 cubic feet each using the smaller "10X" Vas rule of thumb. mI am not hating by any means, I want these things to be more common... as the subs are cheaper, lighter, the ampscan be much smaller as power REQUIREMENT is less ( not better power handling) and no need for heavy enclosures that take up your whole trunk.

Keep it up!

[onebadmonte 235]

Hey everybody, I'm back. After so many days in a row on this project I had to get back and tend to my

fatherly duties. No I'm not a priest, just a family man. I left this project with the rear deck in

question. This is where I'll pick up. I started off by tracing the original rear deck cover on to a

piece of 1/2" thick piece of MDF.

Here is my outline

I use a square to complete incomplete lines. These always come in handy and can be found on the cheap

at Walmart.

Just square up to the two lines

Viola. Lines completed.

Here is the new cover ready to cut

The finished product. Well, not yet. I still need the speaker cut outs.

[onebadmonte 235]

I made some paper templates using a fancy 3-D modeling software. I printed them to scale and cut them

out. I put them in place and drew some reference marks. You can see my reference marks at the bottom

of the paper template.

I used the factory insulation as a template, and transferred it's shape on to some cardboard. Here is

the card board in place.

I transferred my reference marks on to the cardboard. These will help me get the paper templates in the

right location on the cardboard template.

Here are the paper templates in place lined up with my reference marks.

Here is the cardboard template back in the car for a test fit. The speaker cutouts lined up nicely.

[onebadmonte 235]

I transferred the cardboard template to the MDF cover.

Here is the MDF cut. I looks a little funny.

I couldn't resist.

I put the factory insulation back in place.

Finally the rear cover is back in place. I put some threaded inserts in the MDF and bolted it in place

from the underside of the rear deck.

[jcarter1885 995]

Nice way to tackle the rear deck, what do you plan on covering it with?

[onebadmonte 235]

Nice way to tackle the rear deck, what do you plan on covering it with?

I'm not sure. I'm thinking about trimming the factory piece and fitting it in on top of the MDF. For now I'll throw the factory carpeting over it from attracting wondering eyes. I have a bunch of squeaks and rattles I'm chasing down. Till I get those chased down, nothing is permanent.

[j-roadtatts 1,129]

The trunk looks SWEEEEEET!!!! I bet the MDF really stiffins up that rear deck. Keep up the clean work.

[altoncustomtech 773]

It's looking good, some sound deadener will finish off the deck nicely with that new cover. Good luck chasing down the squeaks and rattles.

[onebadmonte 235]

I'm down to what I hope is my last major mods, bolting down the center brace. This is usually a simple

nut and bolt affair, but in my situation it's never that simple. I'll be bolting the center brace to

the section of the rear floor pan that rolls up supporting the lower seat back. Complicating things is

the gas tank blocks the holes from the underside of the car. Luckily there is a solution to simplify

the ordeal. I'll be using some rivet nuts and a special hand riveter like tool to install them. Rivet nuts

are like rivets in that they compress onto the sheet metal, but they have threads on the inside to

provide mounting location for bolts. Snazzy, huh?

Here is the installation tool. I picked this up at Harbor Freight. Came with different size mandrels

for popular machine screw sizes.

The rivet nuts that came with it are made of aluminum and they suck. I picked up these zinc plated steel

ones from Mc Master Carr.

It's pretty straight forward. Here is the insert next to the mandrel

Thread the insert onto the mandrel. Insert the rivet nut into the hole and squeeze the handle to

compress the rivet nut onto the sheet metal.

Here are the holes I drilled to mount the center brace. It's important to get the hole size right.

Here is the rivet nuts installed. A threaded mounting provision in sheet metal, or what I'd like to call

heaven on earth.

The center brace is finally in place.

[kryptonitewhite 1]

beautiful! I love your work! I hope youre gonna use PL PRO subfloor adheisive, and a lot of it. That would be stronger and more spread out than the bolts, but also will make it more air tight. Plus fill in with foam.

Lookin good!

[onebadmonte 235]

I have a seemingly solid install now, but my score has stayed the same. I decided to test the output

of one of my sub amps. I tested with tones from 25hz to 65hz. I checked the AC voltage output of the

amp. Simultaneously I checked the output amperage to the sub at the positive wire to the sub. With

these numbers I calculated the wattage by multiplying the volts times the amps. I also calculated the

impedance by dividing the voltage by amperage. I followed the instructions on the Digital Designs

website on amp output testing.

This is what I got

25Hz 53.0Volts 3.4Amps 180.2Watts 15.58Ohms

30Hz 48.7Volts 4.0Amps 194.8Watts 12.17Ohms

35Hz 47.3Volts 4.8Amps 227.0Watts 9.85Ohms

40Hz 46.6Volts 5.2Amps 242.3Watts 8.96Ohms

45Hz 46.7Volts 5.1Amps 238.1Watts 9.15Ohms

50Hz 47.2Volts 5.1Amps 240.7Watts 9.25Ohms

55Hz 47.9Volts 5.0Amps 239.5Watts 9.58Ohms

60Hz 48.5Volts 5.0Amps 242.5Watts 9.70Ohms

65Hz 49.1Volts 4.9Amps 240.5Watts 10.02Ohms

My subs are 4 ohm. Looking at the impedance curve I'd be inclined to say that these are 8 ohms subs. I

haven't checked yet. Is this normal for the impedance curve of a 4 ohm sub to be so high? Are there

other factors contributing to this? Do you think the seat back and small volume of air in front of the

sub affecting the impedance curve much? What else should I be looking at?