My Audio thread

[deansbimmer]

Why is it a pet peeve? Merriam Webster Defines:

To Dampen:
1: To check or diminish the activity or vigor of : deaden
2: To make damp
3: To become deadened or depressed. :p

I did spray in the first layer of Spektrum yesterday morning and am working on the second this morning. I'm not doing this for reduction of sub induced rattle, but rather for reducing the amount of exhaust drone and road noise entering the cabin. When I got home last night to see how it looked dry, I rapped on the tire well and was amazed at the dull thud that resulted. I think it will really do wonders when all of it is in the car.

[dude8383]

wow looks good! so you bought 3 gallons right? how much have you used up already?

[deansbimmer]

I've used about 3/4 gallons so far to get through the second coat in the areas shown. One more coat to finish off the gallon and the trunk will be ok. The other two gallons will be used in the front doors, the cavity behind the rear doorcards, the interior of the seatback panel, and under the rear seats.

[StereoInstaller1]

Why is it a pet peeve? Merriam Webster Defines:

To Dampen:
1: To check or diminish the activity or vigor of : deaden
2: To make damp
3: To become deadened or depressed. :p

To finish what I left unsaid, you are damping spurious vibrations, not getting them wet. However, apparently definition 1 seems to support the use of "dampen" as well as "damping", as it basically is the same principle.

So now back to the story: the reason I say damping unnecessary is the way the box bolts in clamps MDF and foam securely to the rear firewall, so it already reduces road noise significantly, both through mechanical clamping and mass.

I really do wish you had driven the car with the box in, before the spray, measured it with an RTA (or even SPL meter) and then sprayed it.

That would be some marvellous info right there! I have EXTENSIVE time in my car reducing noise, but my technique is a serious pain in the butt.

Fine job on that spray stuff so far, though...it looks great!

[deansbimmer]

Yes, I wish I would have been able to do some db testing. Unfortunately this audio stage is just one of many stages I need to complete before the car can be fired up or driven. Testing would have increased my "time 'till completion". Something I can't afford right now. Plus, Where does one acquire an SPL meter?

I finished the Spectrum spray in yesterday, and got the sub box wired and installed this morning.

It IS a tight fit! Well done Luke! Just thumping by hand on the sub makes a big boom in the cabin. LOL :D I got pics and will post tonight.

[StereoInstaller1]

Pressure FTW!

What else is there to do on the drivetrain?

[e30slut]

this is great... be sure to share templates of the amp holder thing....

[Mless5]

but my technique is a serious pain in the butt.

Do share nonetheless.

[CorvallisBMW]

do share nonetheless.

+1

[StereoInstaller1]

Do share nonetheless.

Oh shit, here we go...

What I did was more to strengthen the panels in question rather than reduce noise/vibration. The noise issue was only a secondary gain.

A rigid box has better sound. A rigid environment is just as important.

What I did was grab some scrap 1.25" MDF and grind/shape (angle Die grinder w/60 grit 3M pads) to fit as precisely as I could into all of the corrugated shapes under the rear deck and behind seat, in the trunk.

Then, I covered the metal in Extreme Dynamat, mushed the MDF panels in place and shot drywall screws through the wood into the metal, creating a dense metal/rubber/MDF sandwich.

When you rap on the metal with your knuckles, it goes "THUD", but sounds more like concrete.

When I built the box, it absolutely squeezed in place, making even more of a solid wall to help focus and "rigidify" the bass energy.

Unfortunately, I removed the trunk tar AFTER I did all this, like 3 years later.

What that means is that now I get to build a new box...which will be even more solid, with better port aerodynamics.

I don't explain much about how or why I did this...but if you wanna see just exactly what I am talking about, go pop your trunk and look at the bottom of the rear deck. Mine is basically flat MDF with just about no exposed metal, except for the port holes.

I am still not 100% happy with the bass. Certainly enough BOOM, but I want that level of bass with better clarity. It already smokes any car I have ever heard, easily better than Richard Clarks Grand National in detail, but not anywhere near as accurate, or as loud.

Now I want that level (better, actually) of clarity and detail, but I want a woofer with under 100 grams of moving mass. The woofer I use now is 254 grams, which is OK compared to the "force" of the motor.

Of course that means a $1200ish woofer, which I just cannot justify spending.

So /lukesbullshit, what about Deans car?

Luke

[deansbimmer]

A few progress shots from today.

I made a couple plates to put the front crossovers where the old speakers used to be.


Mounted up the rear speakers and tweets. Their crossovers are small enough to go underneath the parcel shelf.


Put in the three coats of Spectrum. This junk is a pain in the ass. I hope the results are worth it.




I also fixed another two rust holes in the seat panel above the tank. God I hope thats the last of the rust. I feel like my progress is really slow. Like I'm getting "in-over-my-head-itis", LOL. There's just so much more to do before the car is done. I'm not one to be scared of projects, but consider that this whole thing originally started with me needing to change out the tail lamps. :|

Another day comes tomorrow!

[Alpine003]

easily better than Richard Clarks Grand National in detail, but not anywhere near as accurate, or as loud.

Ah, the good ol days. Wasn't he the one responsible for bringing the horn loaded mids/tweets under the dash to the car audio scene back in the day?

[StereoInstaller1]

Ah, the good ol days. Wasn't he the one responsible for bringing the horn loaded mids/tweets under the dash to the car audio scene back in the day?

No, not quite.Speakerworks, a shop owned by 2 brothers, in Orange County IIRC, were hired to do a car for a studio engineer.

That studio engineer (Bill Schnee, IIRC) asked that they use BIG mids (like 10" TADs) and BIG horns (like Altecs, or pro Klipsch, I cannot remember) in basically the same configuration that has been copied so many times.

They built the car, and were astounded at the sound. The engineer taught them all about things like time smear,wave path differences, and how to eliminate them through proper placement, using very few pieces of top quality.

Basically, they got a serious education in sound reproduction from this engineer guy.

Then, they built that Grand National and absolutely destroyed the IASCA scene. Later, the car was sold to Richard Clark, who rebuilt the thing, then took credit for the whole damn idea, which is typical for that douche.

I last heard that car in late '88. It had the aperiodic woofers, the 6 mono amps, the 10's in the floor and the horns. Mighty impressive, let me tell you!

Luke

[deansbimmer]

Well, good and bad news. I finished up the deadening, the sub box and trunk, and the speaker installation. I got to fire it up for the first time last weekend, and was seriously wowed by the sound. I have no idea how to set up all the EQ, line out, or crossover settings yet, but for how it sounded "out of the box", I am quite impressed with the results, and especially the box. I had a Suburban with a respectable system and a single 10" in a box, and it produced nowhere near the quality and amount of bass that Luke's box makes. The efficiency is incredible as well. With his box design and my sound deadening, I can be inside the cabin listening at volumes high enough to feel it in your chest and make your ears hurt, yet step outside and close the doors and you can barely hear a thing! I'd been listening to it every night as I work on the rest of my interior.

Then, bad news sets me back. I left last Thursday to Michigan on business and got back this afternoon. I was looking forward to getting some listening time as I wrench, but as I turned on my stereo, I got nothing from the speakers and my line out converter was blinking trouble. I look at the amp which had a red light and then nothing. It powered out....Permanently....

Its fried I suppose. I read 12v at the disconnected Amp power block, but as soon as I connect it, it drops to 2.6v as if something is shorting out. No fuses ever blew. Disconnected all RCA's and speakers wondering it something shorted, but still is dead.

I suppose I'll be on the phone with Infinity support. I hope they'll take care of it. Didn't get to enjoy the amp for very long. :(

[StereoInstaller1]

BUMMER!

Dammit, that NEEDS to be a good amp, it is the best looking option out there.

LMK if they don't do really good on support. I will wring necks!

Luke