I appreciate all the kind words guys. I'm planning on staying up on Thursday till it's done...even if that means no sleep. So you guys should get an update by the weekend!
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Originally Posted by quietfly
I'd love to see a true wide angle photo of the entire dash in one shot, the blend of the side pods looks better every time i look at it.... Damn it... now i'm going to have these UN-realistic expectations of my attempt at them....
We don't have a wide angle lens for our Canon SLR, but my father does on his Nikon. I'll make sure I get a picture before the weekend is over. Wide angle, better quality, in the daylight.
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Originally Posted by BowDown
Coming along nicely. Curious how wide the stage is..
I'm hoping it's the widest I've heard (who doesn't hope for that). I did everything I could to limit boundary reflections, everything within MECA Modex rules and my wife's "rules", so I'm hopeful that the front stage doesn't set width or depth at all. I'm hopeful that width and depth will be set by the rear and side speakers in the MS8 and it's L7 processing.
*Lot's of hope going on here...tis the season.
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Do you know the difference between education and experience? Education is when you read the fine print; experience is what you get when you don't.
1.) There are basically no acoustic treatments done to the vehicle at the moment. It isn't because I don't see value in them, but because I want to be able to go back and fix problem areas if/when/where they arise (another reason I made things easy to remove and access). The only things done are: foam filled a-pillars and metal crossmember, foam between baffle and pods and mounting surfaces, pod faces covered in 1/8" foam, and dash stuffed with foam (which brings me to the next item).
B.) The midbass are too far forward to externally vent. I also don't have enough room for true enclosures. I originally planned to put them in aperiodic enclosures, but have decided to hold off. The reasons came down to time (not enough to do it right now) and because I didn't like how it killed the modeled response on the low end. I stuffed the dash to help slow the rear wave down, but if it doesn't work I'll go back and add enclosures and membranes later. The "open baffle" should still keep the impedance peak outside of the passband (I've modeled everything to avoid this and I'll get into it more when I start with the sub enclosure design).
3.) If the baffle rattles the dash from the midbass, I plan to decouple it and mount it to the metal crossmember and the firewall instead. This would not be easy, so I went with the easier option first, but it can be done if needed. The plan is to make a truss that will bridge between the two (seen below--forgot to label the round part as the crossmember but I'm hoping this note was needed either). As you can see, options 1, B, and 3 show that accessability was important here and that's why I worked hard to achieve it.
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Do you know the difference between education and experience? Education is when you read the fine print; experience is what you get when you don't.
exelent job thus far. todd and aaron are great guys for sure.
as far as the center pod, id like to have seen the left and right sides get the same plug treatme t that the corner pods got. i dont like the asthetics of its square shape that much - but your craftsmanship has been awesome. im interested to see how the stage reacts to the setuo, thats for sure. i have some ideas for directivity controlled lens syoe things that id like to try as well though. most of the ideas out there have already been tried just not applied to car audio, or had DIYs yet =)
i think you are going to run into vibrations in the dash plastics though sir. from my expeirence, its hard to isolate but its possible to tame. im interested to see how strong it will be though.
overall its a very unique and interesting build with a well described writeup. exelent job sir, i enjoied your explinatiins for why you are doing it thusly!
Thank you for the comments, I've included my thoughts below. I don't take any of your comments as attacking, so please don't take my responses as defensive either (even if they are pointed).
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Originally Posted by req
exelent job thus far. todd and aaron are great guys for sure.
as far as the center pod, id like to have seen the left and right sides get the same plug treatme t that the corner pods got. i dont like the asthetics of its square shape that much - but your craftsmanship has been awesome.
Asthetics were an important part of the build for sure, but they came behind accessability and functionality. The center pod is designed to allow access to the drivers for service (if needed) and to reduce/delay baffle-step and diffraction issues as much as possible. If I had reduced the center pods to zero like the insides of the left and right pods, the enclosure would have needed to be around two inches taller (which won't fit because of the glass), around 6 inches deeper (which means I couldn't fit the midbass in front of it), or a combination of the two just to install or remove the whispers.
im interested to see how the stage reacts to the setuo, thats for sure. i have some ideas for directivity controlled lens syoe things that id like to try as well though. most of the ideas out there have already been tried just not applied to car audio, or had DIYs yet =)
Though some of the things I'm trying aren't common, I'm certainly not claiming to have done anything groundbreaking or have "re-invented the wheel" here. My initial idea for all of this came from Patrick Bateman's 'One Tweeter' thread (and the pod I pictured from it) and grew from there. I pulled from people who use horns in the car. I pulled from people who mimize reflections as much as possible in the car. I like to think of it as "standing on the shoulders of giants"...that is, of course, assuming it even works as planned.
i think you are going to run into vibrations in the dash plastics though sir. from my expeirence, its hard to isolate but its possible to tame. im interested to see how strong it will be though.
You may be right, but I don't plan to just let it be if it occurs. This is the main reason I went ahead and foam-filled the pillars and crossmember. I didn't use your basic "Great Stuff" from the local hardware store that needs air to cure, but professional two-part expanding foam. ( Handi-Foam Spray Foam ) It begins to cure and expand upon mixing, will not leave uncured portions trapped in the panels, will not dent panels, will structurally bond to the panels, and will reduce flex and resonance. This allows me to have as solid of a structure as possible to brace from if needed. I also have CCF, OCF, and butyl rope to put between surfaces if needed as well. I don't generally stop until my options are exhausted, and you can see the extents I went to in my Maxima below to reduce door mounted midbass rattles/resonances as much as possible. I ended up with a fiberglass panel that sandwiched CCF and 2lb/sf lead between it and the door skin. It was mechanically fastened to the door in around 20-30 places with rivnuts.
overall its a very unique and interesting build with a well described writeup. exelent job sir, i enjoied your explinatiins for why you are doing it thusly!
keep up the pro work!
Thank you.
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Do you know the difference between education and experience? Education is when you read the fine print; experience is what you get when you don't.
I want to go ahead and discuss my plan for the subs even though I haven't started building the enclosures yet. I'm doing this for two reasons: because we have ANOTHER rain day so I have time at work to do it, and because maybe somebody will chime in with a reason it's a bad idea.
I mentioned about about trying to keep the impedance spike outside of the passband in all parts of this install. For the midbass that means crossing above 60hz and for the wideband above 200hz. The solutions for the first two are pretty simple, have a large enclosure, measure with WT3 in enclosure, and cross above that. The sub is a bit more tricky since Fs/Fc is usually right in the middle of the passband. I haven't seen anybody do what I'm trying (not claiming it's a first--just that I didn't "pull" this idea from anybody) and I'll admit I kind of lucked into it.
In my install, I'm limited to having subs in the hatch that don't restrict any of the storage area. This forced me to put the subs to the left and the right of the spare tire (I did get this idea from the Murano forum and JL's Stealthbox for the vehicle). I'm limited to 10's and they need to be around 6" deep or less. I wanted to run JBL subs, and I managed to find a pair of 1000GTi's to use. For those not familiar with them, they are VERY efficient, but also have a high Fs and lowish Xmax. I started modeling them in WinISD to figure the best box...
As box size decreases, Fc (Fs+enclosure) goes up and so does F3 (-3db point). I figured if I got the box size down to 0.85cu/ft, the Fc would actually move UP outside the passband (around 90hz). The problem was that I kept pushing the driver past maximum excursion with the power I had, and if I reduced power to not push the driver pasts it's limits, output suffered. So I decided to play around with ported alignments...
As box size decreases, port length goes up but excursion goes down. I decided to try my 0.85cu/ft, and while the port length is long (4"dia. x 21" length), excursion is below Xmax (and that of the sealed box), group delay is better, output is better (modeled 2db increase over sealed), it rolls off nearly the same (after filters), and Fc stays above the intended crossover point!
I have room for the port length so I'm going to try this design first. I've included some screen caps below of how everything models. It compares 2.0cu/ft sealed (yellow), 0.85cu/ft sealed (blue) and 0.85cu/ft ported (orange). I'm sorry the blue lines are a bit hard to see...just squint real hard.
Roll-off without a highpass filter:
Roll-off with a highpass filter:
Excursion (with filters):
Group delay (with filters):
Port velocity (obviously of ported sub only--with filters):
And Fc (impedance spike):
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Do you know the difference between education and experience? Education is when you read the fine print; experience is what you get when you don't.
just be acareful with the diameter of that port and the velocity, you might run into some nasty chuffing. sounds like it could work though!! =)
The rule of thumb I've heard (and try and go by) is:
-if port diameter is 4"+, keep length to less than 30" and vent mach under 25m/s (to avoid "chuffing")
-if port diameter is 4"-, keep length to less than 20" and vent mach under 15m/s (to avoid "whistling")
That may not be completely accurate, but it's worked pretty well for me in the past. I also used unibox to model the sub since it will account for polyfil/stuffing and it shows vent length shortening to 18.5". It also helps reduce both the Fc peaks modeled above to around half.
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Do you know the difference between education and experience? Education is when you read the fine print; experience is what you get when you don't.
The rule of thumb I've heard (and try and go by) is:
-if port diameter is 4"+, keep length to less than 30" and vent mach under 25m/s (to avoid "chuffing")
-if port diameter is 4"-, keep length to less than 20" and vent mach under 15m/s (to avoid "whistling")
That may not be completely accurate, but it's worked pretty well for me in the past. I also used unibox to model the sub since it will account for polyfil/stuffing and it shows vent length shortening to 18.5". It also helps reduce both the Fc peaks modeled above to around half.
PM sent....
TEAM BOTTLEHEAD - US Distributor for AUDIBLE PHYSICS - TEAM MUSEE - TEAM PHD
Bit of bummer news fellas...car didn't get wired up last night. My wife was sick, and being pregnant and having six houses to visit over the weekend, caring for her took an obvious priority.
Things are looking positive for getting off on Monday and I'm hoping to get it done then.
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Do you know the difference between education and experience? Education is when you read the fine print; experience is what you get when you don't.
For the record, "getting off" meant work and I'll admit it's kind of sad that I still don't know if I'll have tomorrow or Monday off yet...but..."it is what it is".
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Do you know the difference between education and experience? Education is when you read the fine print; experience is what you get when you don't.
2012 MECA World Finals Street National Runner Up!!!
2012 MECA Street National Points Champion!!!
2012 MECA Street Georgia State Champion!!!
2011 MECA Street Georgia State Champion!!!
First, I hope everybody who has been checking-in had a good holiday weekend. Progress has slowed a bit, but I have a minor update anyways.
Progress has slowed for two reasons:
--I got the car back together to drive around for Christmas and forgot to "accidently" cut the line on the factory amp. That means my wife still has factory audio (minus the tweeters that were where the left and right midbass are now) AND knows she doesn't have to drive my 6-speed Maxima anymore. Needless to say...she isn't giving me the Murano back to work on. So I'm working on it in my spare time after she and I both get home from work.
--I got CoD:MW3 for Christmas and have been "selfish" in playing it a bit instead of working in the dark and cold on the Murano after my real work is done for the day.
BUT, I'm hoping to get everything done before the weekend still. I'm dying to hear it and want to get it going. I have everything back together up front except for the glove box, all the wires are run to the back of the vehicle, and I removed the crap DVD player install done for the previous owner (more on this below). I plan to build the amp rack tonight and get everything wired up that I can. This means all I'll have left to do is connect power and ground to the distribution block and splice the factory signal harness to the MS8 after that is done.
So back to the DVD player install. The Murano had two strange problems I promised to solve while working on the build. The first was an odd buzz that came from below the driver seat and occured any time any door was opened, closed, locked, unlocked and occassionaly randomly while driving. The second was that no air came out of drive side vents (located in the B-pillar) for the rear passengers. In removing the DVD player and it's wiring, I uncovered both issues. The "buzz" was coming from one of two relays that had been very carefully crammed below the driver seat. The lack of air flow came from a lack of ductwork. See, in cramming every bit of wiring below the seat and in the pillar, the installer(s) must have run out of room, and decided something like a vent for the rear passengers was not needed and therefore removed/trashed it. Now I'm on a quest to replace the vent that is MIA.
For all the picture hungry...here is what I pulled from below the seat and B-pillar:
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Do you know the difference between education and experience? Education is when you read the fine print; experience is what you get when you don't.
I gave the DVD player to my friend Oscar the Grouch. Trust me, you didn't want a cheap DVD player from 2003 that was missing a remote and had some sort of soda spilled on it (from inside the center console ).
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Glad to see you back at it. Go ahead and get all that selfishness out of your system ASAP.
You obviously have no idea how awesome it is to drive your wife insane by playing a game that repeats "we've taken the lead" and "UAV airborne" around 30+ times a game. I'll get to it though.
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Do you know the difference between education and experience? Education is when you read the fine print; experience is what you get when you don't.
Well, I didn't get as much done as I hoped last night...and I didn't even play the game at all. I swear.
I ran into a small issue when cutting out the board for the false floor. I'm using 1/2" MDF here and the thickness was putting the MS8 within 1/4" of the spare tire cover panel (which I don't care for because of potential heat issues). I can't go any lower since the MDF is sitting on the spare tire. The solution was to "thin" the panel where the MS8 goes.
First, I had to figure out where I wanted everything to go (sorry, no picture, but it looks just like "Third").
Second, I made an outline of the MS8 in pencil, went over that with a chisel-tip marker (to make the outline thicker for clearance), and carefully routed the area out 1/4" deep (for a total of around 1/2" clearance):
Third, I put everything back to make sure it all lined up again (the empty space to the left of the disto blocks is where the iPod will reside):
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Do you know the difference between education and experience? Education is when you read the fine print; experience is what you get when you don't.
Re: pionkej's 06 Nissan Murano--MECA MODEX/SQ2+ Bound
Touche' sir. Game, set, match. 
So I'm working on it in my spare time after she and I both get home from work.
Now I'm on a quest to replace the vent that is MIA.
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Linear Mode
