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View Full Version : This box just doesn't seem right.



miccheck
09-18-2011, 05:44 AM
I've been reading and watching videos day in and day out just a month ago I didn't even know what ohms had to do with subs. But anyways here are a few pictures of what I have done, thinking I did right. But I have a feeling I'm not quite going in the right direction or missing something. The first picture is of a sketchup that I did. Sorry if it ain't that pretty I just learned about this program today.

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This next one is of bass box, the dimensions for the 1st pic is found in design 2 which are measurements of the space I can use in my trunk.

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The box seems to big for the subs and the port length seams way to small for what I have been seeing. I picked 40hz because I listen to a lot of different music and thought maybe 40 will be a good balance ( I may be totally wrong).

One thing that I don't understand is "Vent Ends" being One Flush or Two Flush. Well honestly I have no clue about those graphs but I'm just trying to duplicate what others do to try and learn but after so much learning I feel a brain aneurysm coming.

Both of these subs are being pushed by the new DX1000.1 by kicker and they go into a 98' Regal.
Thank you very much for your time and any help will be greatly appreciated.


After some sleep I remember why I really put a post of Bassbox. Designs 1,2, and 3 are all of the box size I entered just changing the tunning freq. and port width, while design 4 is of me clicking the optimize key and letting the program do everything. To me the box size that it is telling me seems to small and the FB is 25hz which seems to low as well. With one and two by changing just the port width (and length respectively) I get like double the vent air velocity, should I even care about that though?

kushy_dreams
09-18-2011, 05:16 PM
what type of subs

regardless of what they are the port opening is wayy too small. If this is your first box, put the port to 1 side, its easier to design and build.

miccheck
09-18-2011, 06:46 PM
Its two SWR-1023d. The wood working doesn't seem to hard unless the math (which is **** at to begin with) is easier. But another thing I live in an apartment so just building boxes until I get it right isn't really feasible once I have everything on paper, its off to a co-workers house I go to build this thing.

wenn_du_weinst
09-18-2011, 06:51 PM
programs like that will only tell you how the sub will sound as it is sitting in your driveway.
try more like 3ft, a slot port with 50'' of surface area, and tune lower to 35hz.
those subs will play high enough to not need higher tuning, they have a harder time going lower than they do higher.

kushy_dreams
09-18-2011, 06:56 PM
programs like that will only tell you how the sub will sound as it is sitting in your driveway.
try more like 3ft, a slot port with 50'' of surface area, and tune lower to 35hz.
those subs will play high enough to not need higher tuning, they have a harder time going lower than they do higher.

The 12s handle the lows no prob, they do well on 30-32hz tunes, Im not sure how the 10s do though. I would try tuning them to 33hz

wenn_du_weinst
09-18-2011, 07:06 PM
The 12s handle the lows no prob, they do well on 30-32hz tunes, Im not sure how the 10s do though. I would try tuning them to 33hz

I own both. They won't play as low as other drivers will as easily. They will do it but you need to know how to make them do it. With out knowing what car he is driving it's all just a guess anyway.

kushy_dreams
09-18-2011, 07:08 PM
He said the car is a 98 regal.

Z1NONLY
09-18-2011, 08:49 PM
I think you mean "flared" rather than "flush" on your vent question. Flaring your port can help reduce flutter and allow you to get away with a smaller port opening. However the flared portion(s) of the port need to be deducted from the overall length when you are calculating tuning frequencies. (That's why BB asks you the question)

Looking at your graphs, the green plot looks like it's going to give you a lot of port flutter. (Vent air velocity graph)

The gray and yellow plots are close to fluttering too. If you ever want to put more power than your are plotting them at in the graph, you will probably get flutter then too.

You can enlarge the port opening to avoid the fluttering problem, but then you will end up with a higher tuning frequency if you don't lengthen your port.

And yes you should care about vent air velocity. When the curve goes "light" like your green plot, BB is telling you that you are going to hear your port making noises you probably don't want to hear. (flutter)

miccheck
09-18-2011, 08:59 PM
Well what about my sorta first question being that the box looks to big for these subs 34.5w x 14h x 16d being roughly 3.4 cu/ft. Alpine says 1.4 for each sub and most people say to put them in a bigger box. Or should I go with what the program says is optimal and go with a 2.051 cu/ft?

Sorry I'm trying not to go in here like a complete noob and ask dumb questions but this stuff just isn't sinking in.

miccheck
09-18-2011, 09:16 PM
I think you mean "flared" rather than "flush" on your vent question. Flaring your port can help reduce flutter and allow you to get away with a smaller port opening. However the flared portion(s) of the port need to be deducted from the overall length when you are calculating tuning frequencies. (That's why BB asks you the question)

26527252

Here is where it asks, there is flush and there is flared


And yes you should care about vent air velocity. When the curve goes "light" like your green plot, BB is telling you that you are going to hear your port making noises you probably don't want to hear. (flutter)

So in actuality on that graph the lower the peak the less flutter which is better or is there a balance. In my mind I'm thinking its a good thing for the air to be traveling faster.

Z1NONLY
09-18-2011, 09:18 PM
"Too big" is relative. There are a lot of draw backs to bigger boxes, (space weight, cone excursion etc).

If it's not causing problems and better, great.

The last plot (green) *looks like it would sound better, but you may not be able to make the port big enough (wider opening, longer port) to avoid the flutter problem.

You also should look at cone displacement at the power you intend to use vs the X-max of your drivers.

Z1NONLY
09-18-2011, 09:27 PM
26527252

Here is where it asks, there is flush and there is flared



So in actuality on that graph the lower the peak the less flutter which is better or is there a balance. In my mind I'm thinking its a good thing for the air to be traveling faster.

That has more to do with the logistics of building the box. You could get a big long pipe and stick it into the box with most of the pipe outside of the box and have neither end "flush" with any part of the box. -Forgot about that in the software.

Once the air coming from your vent exceeds ~35m/sec it will flutter. Rather than reinforcing the sound you are trying to reproduce, it will start making up it's own noises that detract from the music you want to hear.

Lower is generally better on that chart, but sometimes you have to work with higher vent air velocities due to space/packaging constraints. When the line goes dark on that graph, I consider it a "deal-breaker" that I need to fix. Sometimes by going to a smaller sub, or more complex box design that allows for more internal volume.

miccheck
09-19-2011, 03:02 AM
Hows this make up?

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So this time I did everything with the12volt.com. Internal cu/ft is 3.46137 when I determined the port length I told it to be 3.3cu/ft because each sub has a .080 displacement.

Looks better but I can't duplicate port length in basebox program so I didn't use it.

Z1NONLY
09-19-2011, 02:20 PM
Rather than have two feed into one, I would move the port to one side of the box or use two ports that exit on the outside of the subs. I have never ran two into one like your latest box does. BBP should allow you to plot two ports.