Rebuilding a 4th order blow through. 09 Chevy Silverado, HDS312s, Taramps 8k (log)

[dbjunior 10+ year member]

Have you modeled it to check port velocity. If you don't plan on checking sealed resonance start large tuned high so you can shrink and lower to get it where it needs to be. I'd personally build a 1 cu box to test sealed resonance first to help determine what you want to do. If the subs resonance is 50+ in 1 cu tuning to 45 won't help the lows much. Of its in the low 40's you might be able to tune a little higher to help even it out nice. Matching the tuning to the resonance will give you a nice peak but it might not have the sound you are after.

 

[germanyt 10+ year member]

I'd love that and if I had a sub easily accessible (they're not removable without destroying the current box) and a box lying around I'd give it a shot. But I have no equipment necessary for finding a resonant frequency. Basically just my ears. I may just go with the 1/2 cone area and tune to high 40s. Then go smaller and longer if I feel like it's now where I want it.

 

[germanyt 10+ year member]

Anyone have any other ideas? I'm leaning toward making the port on the high side and tune high. Then I can always shrink and lengthen it. I am getting a ton of messed up results trying to calculate acoustic power and port velocity. Does anyone know of a reliable calculator and is there an ideal vent mach for wind?

 

[Jeffdachef 5,000+ posts]

Anyone have any other ideas? I'm leaning toward making the port on the high side and tune high. Then I can always shrink and lengthen it. I am getting a ton of messed up results trying to calculate acoustic power and port velocity. Does anyone know of a reliable calculator and is there an ideal vent mach for wind?

try bass box pro instead, TPB has it free.

 

[germanyt 10+ year member]

try bass box pro instead, TPB has it free.

I wasn't sure what you mean by tpb. I figured it out. I'm clicking get this torrent and nothing happens. Downloaded uTorrent and still nothing.

edit, got it

 

[germanyt 10+ year member]

Well to hell with that. All kinds of BS making me download winzip and who knows what app to use to actually open the file. it doesn't open with any of the programs on this computer.

downloaded an rar opener on IE. It 'unpacks' and then nothing. I don't do computers well.

 

[germanyt 10+ year member]

I've now downloaded a dozen different programs that are supposed to 'unzip' or open an rar file. Nothing works. I give up.

 

[CSCStang]

4ths aren't simply build and play at all. You build, adjust, rebuild, adjust, etc.

I haven't built a ton of them but the ones I've built and the research I've done on the subject in depth conclude that it takes a lot of work. Consensus is you start with 1/2 total cone area and adjust down from there. I've also seen quite a few builds using the 312s in a 2.5:1 ratio to keep the bass punchier as opposed to muddy. Drawback there is some loss in spl and possibly some bandwidth. You just have to build and test. As dbjunior stated it's a good idea to test resonant cabin frequency to match port tuning which will give you more output at peak.

Sent from my SCH-I605 using Tapatalk

 

[germanyt 10+ year member]

I finally got BBP downloaded. Input all the specifics and got a blank graph. I'm going get drunk.

 

[germanyt 10+ year member]

Not a lot of pics today because I was kind of on a roll making cuts. Finished every cut by 3 and cleaned uo to enjoy my only day off.

 

[CSCStang]

What specs did you end up going with?

Sent from my SCH-I605 using Tapatalk

 

[germanyt 10+ year member]

What specs did you end up going with?
Sent from my SCH-I605 using Tapatalk

4.1 sealed, 10.2 ported, 46.5 hz, 210 sq inches. I can drop to 180 sq in and 45 hz or cut 2 inches of the external section of the port and go up to about 50 hz.

Oh and we wound up with birch because it was 11 ply. The oak was 7 ply. Switched just because of that.

 

[germanyt 10+ year member]

This enclosure is going to have automotive clearcoat on it. Does anyone see any issue with loading the enclosure, sealing it up, clearing it, then baking it? We have an auto paint booth that can be heated to about 150F. The subs will be inside it and they already live in the bed of a black truck in Louisiana. We could cure at about 100F to be on the safe side but I'm curious what y'all think.

 

[germanyt 10+ year member]

So we decided we are not going to bake the box after it's all assembled. It's going to get 3 layers of clear, dry overnight, then 3 layers of clear, dry overnight, then a full auto quality polish. Here is a couple of pieces dyed slightly differently than each other with 1 round of clear. The smaller board bubbled a bit in the heat. I guess some moisture evaporated and cause the pitting in the clear. The larger had a light coat of spray lacquer done days ago so it didn't have the same problem.

 

[germanyt 10+ year member]

Got a little bit done yesterday after work. And I shrunk my port down to 190 sq inches and shortened it to 49hz.



The speaker is a UE megaboom for size reference.





The 45s and a slew of dowels will set my oorted section height for the baffles to rest on and provide strength. The subs will mount in the sealed section so the baskets hang into the ported section. Like EXOs dads blowthrough but verticle. The sealed section was planned as 4 separate sections but the port made it impossible to mount the subs in a square pattern. So its 2 sections now with dowels and 45s to take up airspace and add more strength. Im also gonna use the last foot of my 16 foot dowel to make sure the lid doesnt flex at all.