2nd ported box build

[shake this 10+ year member]

Sorry guys, I'm sure you get tired of answering the same "will this box sound good" question but I've done about as much research as I can do. I've played around with the different box programs that are free (can't download on the company computer) and seem to be getting slightly different scenario.

The first box I built sounded good but I'm always willing to tweak things just to see. I also felt the original box was a little on the small side. Do any of you mind looking over my numbers and telling me what you think.

Both boxes are set up for a single Alpine 12" type R (not my choice, the owners)

First box dimensions were:

22x14.75x16.75

total internal volume of 1.9ft3 after speaker and port displacement.

slot port was 2x13.14x28.5

tuned at approximately 32hz

Second box I'm thinking about building will be the same basic dimensions but a little larger

25x14.75x16.75

total internal volume of 2.5 after speaker and port displacement

slot port 2.5x13.25x28

tuned at approximately 33hz

Will the two boxes in up sounding very similar or will the 2nd one be a little smoother?

btw...Alpine shows putting this speaker in a 1.5ft3 ported box. That just seems crazy small to me.

Click to read more...

 

[Moble Enclosurs 10+ year member]

Unless someone else can beat me to the punch, I will look over them and give you some basic info about them soon if I can. Gotta play catch up, but I would love to help. Ill re-post soon if I get the chance, ok?

 

[shake this 10+ year member]

I really appreciate it. If you need the specs for the driver let me know and I can provide them to save you from searching for them yourself.

This box will be going into the greyhound bus so the owner isn’t looking for sound nirvana but I like to try and better myself from what I’ve done previously. I just felt the first box was lacking that “something”. It just seemed at certain frequencies it would get a little “snare-y” for lack of a better word. Best way to describe it is a change (for a split second) from a base drum/guitar to a snare drum. Maybe the driver was being over extended? I was able to remove most by adjusting the amp gains/x-over but like I said before, controlling it with box design would be better.

 

[VisceralSound 10+ year member]

I have a box at 2.5cft and I feel even thats just a little too small but I do enjoy it, being someone who currently (soon to change to a 15"VVX) owns a Type R I'd go with the bigger box to be honest.

 

[Buck 5,000+ posts]

2-2.5 at 31-33 hz, depending on vehicle. I'd do about 14 in^2 per cube. I did one in a colorado at work that was 2 @ 31 hz, side firing port and up firing sub. Sounded great. What vehicle is this going in?

 

[shake this 10+ year member]

Oh just your typicle greyhound bus //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

 

[VisceralSound 10+ year member]

Is this that party bus build?

 

[Buck 5,000+ posts]

Is this setup for music?

 

[shake this 10+ year member]

Yes, this is the 2nd one or as we refer to it "the big brother". We are doing 4 12's and 8 6x9's with about 3.5k watts

 

[Buck 5,000+ posts]

So is the type r going in the smaller bus?

 

[shake this 10+ year member]

We did two type r's in the small bus and putting 4 in the above bus

 

[shake this 10+ year member]

Winisd is showing 3.5ft3 at 23hz but the Fs of the speaker is 31hz

 

[Moble Enclosurs 10+ year member]

Im calculating 2.28ft3@41.35Hz. Keep in mind that Fs is not directly related to cutoff or tuning frequencies. The reason being, when loaded, this Fs changes based on the acoustical restrictions and abilities of the box at that point. You can make a speaker with an Fs of 60Hz, play a 30Hz tune in the right box with authority.

But, now the question is, what tuning do YOU want to use? Most on here will say, "41Hz is too high" because that is what they are used to, and depending on their preferences, that is correct. but this is what the sub likes the best is what I am showing you. This is the dual 4 ohm driver with the Fs of 31Hz.

But say you want to tune it to the low 30s, then I come up with 3.37ft3@33Hz, as an average of 30-35Hz for sake of argument. Port characteristics change with each change in tuning as well, but most do not account for that so I will leave that part alone for now.

//content.invisioncic.com/y282845/emoticons/biggrin.gif.d71a5d36fcbab170f2364c9f2e3946cb.gif

 

[Moble Enclosurs 10+ year member]

Now, to keep the efficiency the same as the recommended box characteristics, tuning as 23hz can make it quite large. But I just wanted to note that even this can be ok for this particular driver. The response of this sub actually goes pretty low based on what I figured for. I am calculating that it can go all the way down to 28.69Hz in a full response LF range. So, tuning to 23Hz is not that far off from what it can really do in a box with efficiency. But again, my recommendations are shown above. Take em or leave em.

 

[shake this 10+ year member]

I'm glad to know that I wasn't that far off on the size of box but wouldn't have thought about tuning in the low 40's. It difently should give me the SPL needed to fill the bus. Thank you for taking the time to crunch the numbers.

One question, how low below the tuned frequincie do you think we can go before audible distortion will be a factor? Most music will be dance/ hip hop with some rap thrown in I'm sure. Just don't want to tune to high and have the speaker drop out in the lower range.