2019 GMC Terrain 4th order "wall"

[Buck 5,000+ posts]

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

In general, my experience says there’s very little effect on the front chamber tuning by changing the rear port, if any. I mean, it’ll make the front chamber pressurize differently when changing rear tuning, but if you think of the series 6th as a box within a box, you can take the whole rear section out, and the front will still be tuned to 50 hz; you can’t do that reverse and have the same results.

The biggest mistakes I see in series 6th’s, IMO, is too little rear port area or box volume. There’s not really a magical reason to make the rear chamber ports excessively small or rear airspace too small. I see that a lot. Idk what the airspeed on your rear port is. I’ve done upwards of about 14 in^2/cube rear before, and would’ve done higher, in some cases, if I could’ve. I’ve also done as low as 5-6 in^2/cube, and the port area is largely power and overall chamber air-space-dependent. Different sized woofers have different relative wattage/cubic foot inputs, so the relative energy density of the air charge can increase greatly with smaller woofers and high power, requiring huge ports. Tuning low, especially once you start getting into the mid 20’s, the port speeds can really fall off. So, you have to know how to balance all of that together, lol.

 

[Dafaseles]

In general, my experience says there’s very little effect on the front chamber tuning by changing the rear port, if any. I mean, it’ll make the front chamber pressurize differently when changing rear tuning, but if you think of the series 6th as a box within a box, you can take the whole rear section out, and the front will still be tuned to 50 hz; you can’t do that reverse and have the same results.

The biggest mistakes I see in series 6th’s, IMO, is too little rear port area or box volume. There’s not really a magical reason to make the rear chamber ports excessively small or rear airspace too small. I see that a lot. Idk what the airspeed on your rear port is. I’ve done upwards of about 14 in^2/cube rear before, and would’ve done higher, in some cases, if I could’ve. I’ve also done as low as 5-6 in^2/cube, and the port area is largely power and overall chamber air-space-dependent. Different sized woofers have different relative wattage/cubic foot inputs, so the relative energy density of the air charge can increase greatly with smaller woofers and high power, requiring huge ports. Tuning low, especially once you start getting into the mid 20’s, the port speeds can really fall off. So, you have to know how to balance all of that together, lol.

That's a good read right there. Thank you!
Actually being able to hear this box, is far out there. I'm super excited, and can't wait, but have to keep telling myself to take my time and don't rush. My goal is to be done with my truck by December, though I doubt that will happen. I've got a lot of work to do lol.
I'm going to install a mini DSP 6×8 and buy an MK-2 (if I remember the name correctly) to really tune the system in and get the crossover points where I want them, so it'll be interesting to be able to see the enclosure truly on a graph to check out the response.

 

[hispls 5,000+ posts]

I'll go up against anybody with 200 square inches of cone area and 3.5K watts.

In our region the 2500W class meters sealed at the dash and most people are above 150, the leaderboard last year was a couple 152 and change.

You are not going to ever catch up with the field in that cone area and power metering dB drag style in a pickup truck. What does the top 3 look like in the USAC leaderboard in that class right now?

 

[mrj858 10+ year member]

In our region the 2500W class meters sealed at the dash and most people are above 150, the leaderboard last year was a couple 152 and change.

You are not going to ever catch up with the field in that cone area and power metering dB drag style in a pickup truck. What does the top 3 look like in the USAC leaderboard in that class right now?

https://img1.wsimg.com/blobby/go/62230b39-efaf-4847-b12a-679f1c3e1f64/downloads/WorldRecords4.5.22.pdf?ver=1657573175400

 

[Bobbytwonames 5,000+ posts]

In our region the 2500W class meters sealed at the dash and most people are above 150, the leaderboard last year was a couple 152 and change.

You are not going to ever catch up with the field in that cone area and power metering dB drag style in a pickup truck. What does the top 3 look like in the USAC leaderboard in that class right now?

I'm in the Stock 3K class. Post what people are metering in the stock 3K class. I've competed in USACi three times with two firsts and one second. Nobody will touch me cone area for cone area that I do know.

 

[Bobbytwonames 5,000+ posts]

https://img1.wsimg.com/blobby/go/62230b39-efaf-4847-b12a-679f1c3e1f64/downloads/WorldRecords4.5.22.pdf?ver=1657573175400

There aren't any scores in the Stock 3K class. That is the class that I compete in.

 

[hispls 5,000+ posts]

There aren't any scores in the Stock 3K class. That is the class that I compete in.

Well go put up a world record then and see how long it stands.

 

[Bobbytwonames 5,000+ posts]

Well go put up a world record then and see how long it stands.

I could probably come close but I don't want to give up being comfortable while I'm driving.

 

[Bobbytwonames 5,000+ posts]

The advantage that those vehicles have is if you are allowed to open a door or window during metering and this is true with behind the seat box, blowthrough or wall (in extended cab varieties). Hopefully you have tested and verified this for yourself.

On topic, I would think that acrylic window is not going to be thick enough to stay rigid and will be a weak link.

I metered Friday night and metered .6db less from the windshield compared to the kick with the driver's door open. I'm sure with the driver's door closed it would be at least 2db less if not more.

 

[Bobbytwonames 5,000+ posts]

.

 

[Dafaseles]

Quick little update.
We weren't able to both work on the vehicle this last weekend because my buddy got covid and it's been kicking his butt. But he has been doing a little work himself when he can.
You can see in this picture, he put a little makeshift wooden dowel brace in. Once I talk to my welder, we'll get that replaced with a steel cross. To top bottom, back to front.
He also did some vinyl work. I like the crome buttons, and the pillow look, I just wish they where a bit more uniform in spacing... again though, that's my taste and this is his build. As long as he likes it, I'm happy.
He also installed the black light LED's. It actually looks pretty dope! That Skar logo on the back is actually invisible without the black light. It came out pretty damn sweet if you ask me

 

[audiobaun 5,000+ posts]

Quick little update.
We weren't able to both work on the vehicle this last weekend because my buddy got covid and it's been kicking his butt. But he has been doing a little work himself when he can.
You can see in this picture, he put a little makeshift wooden dowel brace in. Once I talk to my welder, we'll get that replaced with a steel cross. To top bottom, back to front.
He also did some vinyl work. I like the crome buttons, and the pillow look, I just wish they where a bit more uniform in spacing... again though, that's my taste and this is his build. As long as he likes it, I'm happy.
He also installed the black light LED's. It actually looks pretty dope! That Skar logo on the back is actually invisible without the black light. It came out pretty damn sweet if you ask meView attachment 40384

Looks Bad AZZ!!! Nice work man!! Looks like everyone involved has done a bit of customizing to the Install and it looks really good man. I hope your friend gets over that nasty virus and gets to feeling better for sure

 

[Buck 5,000+ posts]

That purple and green is wild with that black! There’s definitely another round of covid going around, so definitely take care of yourselves. Do you like those tweeters?

 

[Dafaseles]

Looks Bad AZZ!!! Nice work man!! Looks like everyone involved has done a bit of customizing to the Install and it looks really good man. I hope your friend gets over that nasty virus and gets to feeling better for sure

Thanks man! It's coming along and looking pretty decent in the process

 

[Dafaseles]

That purple and green is wild with that black! There’s definitely another round of covid going around, so definitely take care of yourselves. Do you like those tweeters?

Thanks man! Yeah, it seems like everyone around me is getting it. I haven't gotten it yet. I accredit that to the fact I work outside, in the streets of nasty *ss San Francisco lol. I think at this point, I've been exposed to everything and am immune. No, in all seriousness, I'm sure sooner or later I'll get it. Hopefully it doesn't kick my *ss too bad.
Do I like those tweeters? No. I haven't liked any bullet tweeters I've heard so far. They all seem too harsh for my taste. They're loud though! They are responsive, and aren't too muddy and they are crisp. Just... too crisp for my taste....i guess you could say. I don't know. Once I heard silk dome tweeters, I fell in love. The 4 tweeters that are going in each door in my build are all silk dome. I'd like to hear a ribbon tweeter.