Two For One—A Go Fast TJ and J10 Build

I forgot to take a picture, but the speaker pod should come out right around 1.26 liters after I mount the wood baffle. My speakers take up about .33 liters of volume, so the functional volume with the speaker installed will be about .93 liters.

The modeled frequency response I did last night had it peaking around 250hz, with it being 3db down at 180hz. I think once I measure it in the car the low end extension should be a bit better, maybe half an octave lower due to cabin gain and I can always stuff the enclosure with my fibre mats or some polyfill as well to help it a bit.

Pretty happy with it so far, but I'll have to do some actual measurements this week.
 
Speaking of measurements, I did a little testing on my sub the other day.

This is a 5hz to 250hz sine sweep of my sub.

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The blue line is with everything normal, just how I'd drive down the road. There's a gigantic dip around 15 hz, about 25db down from 20hz. Then a smaller dip around 28hz, another at 45 and again at 60. Pretty shitty...

The red line is the exact same measurements, the only difference is there is 200lbs of sandbags on the top of the hard top. Nearly completely got rid of the dip, and smoothed out the peaks, much much better.

So, this seems to tell me the hardtop is seriously fucking up the bass response, which makes sense if you've ever seen how much it flaps up and down on the highway.

I've been brainstorming ways to address this. I'll start with full CLD coverage on the hardtop like I was planning anyways for the headliner build. Putting something between the b pillar roll bar and the top to preload the top upwards would probably help a lot as well, at least cut the unsupported panel size in half roughly. And if all of that isn't enough I'll probably try to lay some metal strips into the grooves formed in the top of the hardtop on the outside, and encapsulate those in the hard top with fiberglass to add some more rigidity.

That's all a little ways away since my neighborhood isn't conducive to having the top off the jeep, but I thought the measurements were interesting. I'd imagine pretty much every TJ with a factory hard top and a sub would have a measurement similar to this
 
Speaking of measurements, I did a little testing on my sub the other day.

This is a 5hz to 250hz sine sweep of my sub.

View attachment 376523

The blue line is with everything normal, just how I'd drive down the road. There's a gigantic dip around 15 hz, about 25db down from 20hz. Then a smaller dip around 28hz, another at 45 and again at 60. Pretty shitty...

The red line is the exact same measurements, the only difference is there is 200lbs of sandbags on the top of the hard top. Nearly completely got rid of the dip, and smoothed out the peaks, much much better.

So, this seems to tell me the hardtop is seriously fucking up the bass response, which makes sense if you've ever seen how much it flaps up and down on the highway.

I've been brainstorming ways to address this. I'll start with full CLD coverage on the hardtop like I was planning anyways for the headliner build. Putting something between the b pillar roll bar and the top to preload the top upwards would probably help a lot as well, at least cut the unsupported panel size in half roughly. And if all of that isn't enough I'll probably try to lay some metal strips into the grooves formed in the top of the hardtop on the outside, and encapsulate those in the hard top with fiberglass to add some more rigidity.

That's all a little ways away since my neighborhood isn't conducive to having the top off the jeep, but I thought the measurements were interesting. I'd imagine pretty much every TJ with a factory hard top and a sub would have a measurement similar to this

To stiffen the top, making ribs with foam and fiberglass can be a lot lighter than metal attachments. And you avoid issues of hard spots.
 
To stiffen the top, making ribs with foam and fiberglass can be a lot lighter than metal attachments. And you avoid issues of hard spots.

Interesting, what kind of foam are you thinking.

Not exactly sure what you mean by hard spots, but I was talking about the grooves on the outside of the hardtop, maybe only 1/8"-1/4" deep, so probably just a few pounds of metal.

Hoping it doesn't come to that though and the CLD will cure most of it along with loading it upwards at the roll bar.

I'm probably going to try and avoid attaching anything more on the inside since my headliner idea is already going to be ~1.5" thick. Definitely not putting any holes in the top, I have enough water leaks already lol
 
Interesting, what kind of foam are you thinking.

Not exactly sure what you mean by hard spots, but I was talking about the grooves on the outside of the hardtop, maybe only 1/8"-1/4" deep, so probably just a few pounds of metal.

Hoping it doesn't come to that though and the CLD will cure most of it along with loading it upwards at the roll bar.

I'm probably going to try and avoid attaching anything more on the inside since my headliner idea is already going to be ~1.5" thick. Definitely not putting any holes in the top, I have enough water leaks already lol

There's a variety of structural foams for this, or it can be non-structural and just used as a mold, basically forming fiberglass hat channel for stiffening ribs. Just need to be sure the foam is compatible with the resin you're using. But as I think for a second there's a lot to be said for using wood. A little heavier but much stronger than foam, and cheaper too.

Flat steel doesn't have the depth to really help. On edge it would, but then there's the question of attaching it. Bolting it on creates a localized point much stiffer than then surrounding areas. A hard point prone to cracking.

What are you doing for a headliner? 1.5" is a lot to work with!
 
There's a variety of structural foams for this, or it can be non-structural and just used as a mold, basically forming fiberglass hat channel for stiffening ribs. Just need to be sure the foam is compatible with the resin you're using. But as I think for a second there's a lot to be said for using wood. A little heavier but much stronger than foam, and cheaper too.

Flat steel doesn't have the depth to really help. On edge it would, but then there's the question of attaching it. Bolting it on creates a localized point much stiffer than then surrounding areas. A hard point prone to cracking.

What are you doing for a headliner? 1.5" is a lot to work with!

Interesting, I'll have to look into the foams and stuff when I get there. I hadn't thought about wood either, but that's a good idea too.

Post #144 in here outlines the current audio setup and #145 is most of the details for the headliner.

But the basic idea is 100% CLD coverage on the hard top and over the top of that is 100% coverage with Resonix fibre mat 45. 45mm thick uncompressed, but it can compress to about .25" thick.

In that old post I talked about incorporating a mass barrier, either MLV or lead sheet, in-between two layers of the fibre mats to eventually complement the rest of the tub being lined with a mass barrier.

I might be ditching that part of the headliner idea though. My audio friend was explaining to me that I probably wouldn't gain a whole lot from lining the hardtop with a mass barrier, except for maybe eliminating a lot of the noise from rain hitting the top, which I can't say has bothered me a whole lot to this point. Plus, the headliner gets a lot simpler if it doesn't weigh 50lbs.

All my fibre mats actually showed up the other day and they're pretty sweet. I had a remnant of 3M thinsulate laying around and the Resonix fibre mat definitely seems to be more dense I think, kind of seems like smaller fibers with a lot more of them packed in.

All of the testing Nick at Resonix has done seems to show that these fibre mats should make a great headliner material, and they're also supposed to be a pretty good thermal insulator too which is a nice plus.
 
Had enough spare time at work today, I brought all my stuff with me.

Got a second pod poured and currently curing.

Got the baffle made for the first pod. 1/2" MDF, soft wood threaded inserts for 10-32 screws to mount to the dash and to mount the speaker. 1/4" round over around the edge and all glued together with loctite pl premium.

I set the baffle down on our sanding bench at work to DA sand the backside. That's why it's gray now...

Just 22.5 hours until the glue is cured and I can test it out...
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Pretty sure my transmission hates me by now...

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Only lost 3 quarts this time, but had to limp it back 20 miles at 40mph in second. A stupid branch cut the return line open right where it clamps to the radiator. Probably should keep a look out for a spare 32rh lol

Couple pics from the hike I went on
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Cool trip, Trev - leak not withstanding...

Big Lake, maybe? And is that 'Hood in the background?
 
Cool trip, Trev - leak not withstanding...

Big Lake, maybe? And is that 'Hood in the background?

Almost, that's a very empty Detroit lake and mount Jefferson in the last pic. We had a good time, got to do a little snow wheeling and a 4 miles hike through the snow to get the view of mount Jefferson
 
Almost, that's a very empty Detroit lake and mount Jefferson in the last pic. We had a good time, got to do a little snow wheeling and a 4 miles hike through the snow to get the view of mount Jefferson

Cool pics. I was going to guess reservoir next to 58 on the way to Oakridge but couldn't ID the mountain.
 
Well I got one of the pods in at 4:30am before I went up in the snow. Honestly not as much of a difference as I was hoping for, but it did sound a bit cleaner and the gains were still set for the stock mounts with the speakers in open air. I think I should be able to crank it up a bit once both pods are in due to the increase in power handling from the sealed enclosure.

I got some measurements the other day, they aren't the best as the near field measurements of the stock speaker mount was done a while ago, but I'm pretty sure I had all my settings the same. I'll get some better comparisons when I get the second pod made and can measure both setups in the same day.

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This is a near field measurement with the mic 6" away from the speaker to try and just measure the speaker, not all of the reflections in the vehicle. Purple is the new pod and green is the stock mount. I had the LP filter set differently, so ignore everything above 3k hz.

This is an average of 8 measurements of each setup in my normal listening position.

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Blue is the pod and red is the stock mount. This had a 63hz HP filter. The pod is definitely different lol. I'm still a pretty big noob with this stuff, but it seems to have helped out my low end a bit, I'm going to do some more testing with varying amounts of polyfill in the pods to see what I like best.

I think it's an improvement though, I was trying to improve the low end of the 5.25s so I can cross to the sub a bit lower since I'm only running 2 way active plus the sub right now, the sound bar is completely disconnected.

The response is still pretty rough though, not sure what's going on around 1200hz.

We'll see what the polyfill does. I'm just trying to see how good I can make a 2 way sound for now, then I'll switch to a 3 or 4 way plus sub. This guy showed up the other day though, should be a huge step up for processing power vs the 80PRS head unit.
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holy Xmax Batman

Makes one hell of a paperweight,

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Found two tiny pinholes in the surround on the 12". Used some of the leftover glue from repairing the JL 12" to try and seal both sides of the holes. Hopefully they won't spread anymore

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Side by side with the JL 12w6v2. Interesting how different they look and how much bigger the spider on the JL is.

I did test out the 12 today, swapped it into the JL's box. I think it sounds every bit as good as the JL after 30 minutes of listening, but my left ear is real fucked up right now, even more than it usually is.

I also got the helix DSP hooked up in the dark last night. Did a quick and dirty setup this morning so I could drive around again and listen. Listened for like 40 minutes along with the new sub and couldn't figured out why everything sounded like it was coming from the left front corner. Then I realized my crossovers for the 5.25s were applied to the tweeters and vise versa. Good thing I left a failsafe HP filter at 1250hz on the head unit for the tweets, or else they surely would've blown. I really need to put some capacitors on them...

Long story short, don't listen to anything I say. Took me 40 minutes to realize I was missing 100hz-3000hz on my 5.25s.

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Way too many things for me to play with on the helix...
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This DSP is like a magic box, an expensive magic box, but worth every penny lol.

I've only got one round of EQ done based around half whitledge curve, but it's by far the best the jeep has ever sounded. A pretty decent stage and an actual semblance of center image and left and right sound cues from music.

I need to play around with my time alignment more and keep EQ'ing, but I'm sold.

Here's each speaker measured individually after all my tuning. Pretty decent level matched and the response of pairs of drivers are starting to become more symmetrical.

It's surprising what songs are supposed to sound like compared to what I thought they should sound like. I've done quite a bit of cutting on the sub to get it to match a half whitledge curve. I might try a full whitledge next as it's a bit heavier in the bass/midbass and rolls off towards the highs more than what I have now, which will be a bit easier to match on my mids and easier on my ears.

Definitely lacking output around 100hz where the sub passes off to the mids, could be a phase issue, but I think my 5.25s are just pretty anemic in their little pods. I might make a quick test box that's ideal volume for them just to see what I'm missing.

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The sub looks high, but it actually matches the curve pretty well. I just measured the sub with both channels hooked up, so theoretically once I measure both left and right mids together, their combined curve will be 6db higher.
 
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That orange line in the previous graph is the current experiment. A single mono dipole midbass in the form of the 12" Aurasound subwoofer mounted on a small baffle playing 60hz-150hz.

I was trying to get the gains set on it and found it makes an odd chirping noise when I get to a certain gain level.

I ruled out excursion as the issue, the baffle, and I'm pretty sure I'm not clipping. I disassembled the sub today and the voice coil and magnets looked great. These subs are known for the nickel plating on the magnets flaking off due to high temperatures when run at rated power. So it was nice to see they all still look brand new.

I'm going to try a different amp tomorrow, but I'm pretty stumped at this point.

Wondering if I'm just at the natural limit of the driver in this configuration, but I can't figure out what it is and nobody seems to be able to identify this noise. It's possible though, this dipole should start rolling off around 2k hz at 6db/oct, so I'd be about 24db down by 125hz which is quite a bit

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