2019 GMC Terrain 4th order "wall"

It's ¾" thick. But you're right. It's holding up so far ok. It vibrates a little. I think I'm going to try and mock up a brace for it as well. I'll have to come up with something
Any vibration in the box loses a shitload of output. It is unlikely to break the plexi/acrylic but if you can put your hand on it and feel it flexing your gains might be audible from securing a good windowpane brace onto it.
In every competition that I've competed in people can leave the doors open or closed.
And opening a door or window in a pickup truck will consistently gain over 3dB. I don't think this even implies that you have a huge advantage, just that you'd be at a wild disadvantage if you were competing in a class where you had to meter sealed. You do not see pickup trucks in competitive DB Drag leaderboards because almost any other vehicle shits all over them with comparable power and cone area.
You should be able to verify this yourself by just sitting in there playing music with everything closed up and then opening the opposite side door or window. It usually will make a dramatic difference.
Again, this doesn't really matter, and at the end of the day, if you're happy with it driving around playing your favorite tunes you did it right, but sealed or door/window open and sensor placement are very important details to include if we're trying to compare apples to apples sound intensity from 2000 miles away, and also important things to consider if someone is doing a new build for the sake of trying to compete. Buying a pickup truck to DB Drag is a recipe for disappointment, in USACi it can be competitive and they seem to do well enough in music classes in dB Drag where you must leave a door or window open.
I'm think of metering on 31 hz. music next time. I think it's louder on music.
The meter will tell you the truth here.
 
Quick question, how much do you think it would change the internal volume and maybe the tuning or whatever if I had a custom brace made to go from the plexy to the back of the box like we've talked about, but also go from the baffle to the roof? To make a cross. I can have my welder at work fab something up. We're getting some pretty decent flex from the top of the enclosure is like to figure out a way to deal with. Ideally without having to dismantle the box of possible.

Just depends on size of the braces. Usually it’s not going matter; your front chamber looks plenty large. I couldn’t imagine you’d lose more than a few tenths of a cube.

If you’ve ever looked at my boxes, I brace a ton, and this is why. Double layers aren’t as effective as bracing, especially when the panels are individually so wide (depends on power). Bracing is usually wayyy better than double/tripling up, whatever, for strength.
 
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Any vibration in the box loses a shitload of output. It is unlikely to break the plexi/acrylic but if you can put your hand on it and feel it flexing your gains might be audible from securing a good windowpane brace onto it.

And opening a door or window in a pickup truck will consistently gain over 3dB. I don't think this even implies that you have a huge advantage, just that you'd be at a wild disadvantage if you were competing in a class where you had to meter sealed. You do not see pickup trucks in competitive DB Drag leaderboards because almost any other vehicle shits all over them with comparable power and cone area.
You should be able to verify this yourself by just sitting in there playing music with everything closed up and then opening the opposite side door or window. It usually will make a dramatic difference.
Again, this doesn't really matter, and at the end of the day, if you're happy with it driving around playing your favorite tunes you did it right, but sealed or door/window open and sensor placement are very important details to include if we're trying to compare apples to apples sound intensity from 2000 miles away, and also important things to consider if someone is doing a new build for the sake of trying to compete. Buying a pickup truck to DB Drag is a recipe for disappointment, in USACi it can be competitive and they seem to do well enough in music classes in dB Drag where you must leave a door or window open.

The meter will tell you the truth here.

I'll go up against anybody with 200 square inches of cone area and 3.5K watts.
 
Just depends on size of the braces. Usually it’s not going matter; your front chamber looks plenty large. I couldn’t imagine you’d lose more than a few tenths of a cube.

If you’ve ever looked at my boxes, I brace a ton, and this is why. Double layers aren’t as effective as bracing, especially when the panels are individually so wide (depends on power). Bracing is usually wayyy better than double/tripling up, whatever, for strength.
I agree. It's the old ignorance is blis thing. Dude that designed it, didn't put bracing in the design, so I didn't think anything of it. Live and learn. When I build my box on my truck, I'm going to add bracing as well. I've learned lol.
My welder is in Disneyland right now, so one he gets back, I'm going to get him started on a brace. Probably, maybe made out of some 1" pipe or 1¼" I'm thinking.
 
I agree. It's the old ignorance is blis thing. Dude that designed it, didn't put bracing in the design, so I didn't think anything of it. Live and learn. When I build my box on my truck, I'm going to add bracing as well. I've learned lol.
My welder is in Disneyland right now, so one he gets back, I'm going to get him started on a brace. Probably, maybe made out of some 1" pipe or 1¼" I'm thinking.

Bracing can add up, if you do a lot of it, and can be a detriment inside for airflow (with wood bracing usually). If you can, like with a new box, you can request or add the displacement for bracing. But that’s another great thing about walls; they’re usually so big that adding bracing after usually doesn’t change too much, airspace-wise.

I’ve done some wooden windows brace and 45’s that take away like a cube of airspace altogether, in some boxes, or more. Not accounting for that level of bracing can really add up.
 
Bracing can add up, if you do a lot of it, and can be a detriment inside for airflow (with wood bracing usually). If you can, like with a new box, you can request or add the displacement for bracing. But that’s another great thing about walls; they’re usually so big that adding bracing after usually doesn’t change too much, airspace-wise.

I’ve done some wooden windows brace and 45’s that take away like a cube of airspace altogether, in some boxes, or more. Not accounting for that level of bracing can really add up.
I agree. I hope to not make this same mistake in the future.
This box, the ported section, is 9.3 ft³ net. So decently big. Regardless if/ how much the bracing effects the enclosure, it needs to happen. It's just something I'm going to have to calculate beforehand in the future.
When I get to installing my box in my truck, it's a sh*t ton bigger. 16.22 ft³ in the front section (series 6th order blow through) so I'm thinking at least 2 braces in there (even that might be insufficient). It is what it is. Both builds are just daily, music builds. So the effects would be minimal to the musically listening I would assume. Though I don't really know a huge amount about enclosure design. That's why I outsourced that aspect lol.
 
I agree. I hope to not make this same mistake in the future.
This box, the ported section, is 9.3 ft³ net. So decently big. Regardless if/ how much the bracing effects the enclosure, it needs to happen. It's just something I'm going to have to calculate beforehand in the future.
When I get to installing my box in my truck, it's a sh*t ton bigger. 16.22 ft³ in the front section (series 6th order blow through) so I'm thinking at least 2 braces in there (even that might be insufficient). It is what it is. Both builds are just daily, music builds. So the effects would be minimal to the musically listening I would assume. Though I don't really know a huge amount about enclosure design. That's why I outsourced that aspect lol.

Series 6ths can be difficult, if you’ve never done one before. It’s really just a ported box inside of a ported box, where the ports are what’s in series. I can give you some pointers on that; it’s really situation dependent.
 
Series 6ths can be difficult, if you’ve never done one before. It’s really just a ported box inside of a ported box, where the ports are what’s in series. I can give you some pointers on that; it’s really situation dependent.
I had the same dude design my box that designed this one. I've had the plan for about 2 years now. I just got done cutting the pieces out for it. Hopefully I can start building it soon. If you'd like to see it, I'd be more than happy to post the aspects and pictures of the design for you. I can't deviate too much from the plan though, as I've said, the pieces are already cut, and if I had to spend almost $1000 in wood again, I don't think my wife would be too happy 🤣. But any input and/ or tips are always appreciated! I don't have anyone to really learn from other than youtube and forums lol.
 
I had the same dude design my box that designed this one. I've had the plan for about 2 years now. I just got done cutting the pieces out for it. Hopefully I can start building it soon. If you'd like to see it, I'd be more than happy to post the aspects and pictures of the design for you. I can't deviate too much from the plan though, as I've said, the pieces are already cut, and if I had to spend almost $1000 in wood again, I don't think my wife would be too happy 🤣. But any input and/ or tips are always appreciated! I don't have anyone to really learn from other than youtube and forums lol.

No worries, it’ll be cool to see it 🤓
 
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It's kind of a funky design, I know. My original plan was to mount the amps under the box. That's why that back section is raised. I have since thought better of that idea. Though I'm afraid of changing the design because series 6th orders are so temperamental.
It's also designed to have a huge plexiglass top. I'm not putting that in. I put a camper shell on my truck, instead of a tonneau cover, so I can still use some of the bed. So the top of the box will also be reinforced by lumber raising the top, so I can secure a "false floor" to sit kind of flush with the top of the bed.
I'm also going to cut vents in the false floor to accommodate 5 4" fans to keep air circulating for the amps
 
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It's kind of a funky design, I know. My original plan was to mount the amps under the box. That's why that back section is raised. I have since thought better of that idea. Though I'm afraid of changing the design because series 6th orders are so temperamental.
It's also designed to have a huge plexiglass top. I'm not putting that in. I put a camper shell on my truck, instead of a tonneau cover, so I can still use some of the bed. So the top of the box will also be reinforced by lumber raising the top, so I can secure a "false floor" to sit kind of flush with the top of the bed.
I'm also going to cut vents in the false floor to accommodate 5 4" fans to keep air circulating for the amps

I mean if you change it, you would just try keep the specs the same. I don’t think series 6th’s are quite temperamental, I just think the specs have to be correct for woofer, power, and what you’re doing with it. Series 6th’s just have to have proper energy movement through them, and the volumes are relative to the response you want. You can make a series 6th whatever you want, just as long as you do it correctly. That’s a pretty low tuning for daily, IMO, but idk what was discussed. Some people’s daily music is way different that others. A lot of people seem to tune around there with bigger series 6th’s now, for super lows.
 
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I mean if you change it, you would just try keep the specs the same. I don’t think series 6th’s are quite temperamental, I just think the specs have to be correct for woofer, power, and what you’re doing with it. Series 6th’s just have to have proper energy movement through them, and the volumes a relative to the response you want. You can make a series 6th whatever you want, just as long as you do it correctly. That’s a pretty low tuning for daily, IMO, but idk what was discussed. Some people’s daily music is way different that others. A lot of people seem to tune around there with bigger series 6th’s now, for super lows.
Honestly, I just told him it's going to be a predominately musical build. I was willing to give up some "sq" for volume, and even a little volume for "sq". I now know that doesn't make much sense 🤣.
I'm going to be running the 4 Q's off 2 SALT 4s. So I think I'll be overpowering them a little at times. Not too often though and definitely not for any extended duration of time. I don't know if that might have been a factor in the tuning being low. Or maybe he just assumed I was one of those guys that buys an 8" sub saying "I just want it to hit the lows! I want to do hairtricks!" 🤣 who knows. I didn't know enough back then to ask many questions. I've been sitting on this system for over 2 years. So I've learned a lot since then. Still learning. Show me a man that knows everything and I'll show you a man that knows nothing.
I really listen to everything, from bass mechanic, to dire straights, to slayer, back to aesop rock, over the bridge to NWA, then back around to string quartets and big symphony orchestras. So a WIDE variety of music.
I'll start a build thread for that when I get some work done, and have something to show.
I'll tell you what though, I think those 2 15's in that 4th right behind your head is going to be louder than my 6th blow through lol. That setup is pretty fun to listen to, even with not being done yet
 
Honestly, I just told him it's going to be a predominately musical build. I was willing to give up some "sq" for volume, and even a little volume for "sq". I now know that doesn't make much sense 🤣.
I'm going to be running the 4 Q's off 2 SALT 4s. So I think I'll be overpowering them a little at times. Not too often though and definitely not for any extended duration of time. I don't know if that might have been a factor in the tuning being low. Or maybe he just assumed I was one of those guys that buys an 8" sub saying "I just want it to hit the lows! I want to do hairtricks!" 🤣 who knows. I didn't know enough back then to ask many questions. I've been sitting on this system for over 2 years. So I've learned a lot since then. Still learning. Show me a man that knows everything and I'll show you a man that knows nothing.
I really listen to everything, from bass mechanic, to dire straights, to slayer, back to aesop rock, over the bridge to NWA, then back around to string quartets and big symphony orchestras. So a WIDE variety of music.
I'll start a build thread for that when I get some work done, and have something to show.
I'll tell you what though, I think those 2 15's in that 4th right behind your head is going to be louder than my 6th blow through lol. That setup is pretty fun to listen to, even with not being done yet

Idk, your series 6th should be very loud. 4 12’s on that much power should slam. All you gotta do to change tuning is shorten the rear port, or even the front port. But changing the front port also changes the effective length of the rear port, so be careful there.
 
Idk, your series 6th should be very loud. 4 12’s on that much power should slam. All you gotta do to change tuning is shorten the rear port, or even the front port. But changing the front port also changes the effective length of the rear port, so be careful there.
I was led to believe changing either port in a 6th would effect the other. Front or back.
So if I want to change the back port, shorten it for any reason, it wouldn't effect the front port? Also, would shortening to raise the tuning effect the port area for the rear chamber? I have no idea what the port velocity modeled to, but it's already small at a little over 6 in² per. Just being curious
 
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