10" ported sub build

rexhex

Member
2016-02-04 5:16 am
Hello,

Yesterday I purchased a driver, amp, and battery for a portable sub build. This is my first time designing a sub and I was hoping I could get some assistance. My appreciation of subs has grown after learning all the subtleties that effect the out put.

The driver is by kicker and it gives me lots of specs for building the right sized box. F3 is given but I'm not sure what it's relation is to Fb, the tuning frequency. If f3 is 25hz do I calculate for a tuning frequency of 25hz?

Another question is about the port itself. Is there much of a difference between using a slot vs. a circle port?

Once I get the interior volume (which kicker provides), and port size (which I need to understand tuning frequency for), I will start building. Are there any other things I should be considering to build a solid sub?

This is not for a car system so I'm not concerned too much about size. Most resources I have been reading tend to be concerned about fitting the sub in a car for the type of Port being used.

Thank you for your time and knowledge,

It is very much appreciated,

Rex
 

rexhex

Member
2016-02-04 5:16 am
I posted this on my phone earlier at work and a part that was copied and pasted did not register for some reason. Here is the post with that part added in.

Hello,

Yesterday I purchased a driver, amp, and battery for a portable sub build. This is my first time designing a sub and I was hoping I could get some assistance. My appreciation of subs has grown after learning all the subtleties that effect the out put.

The driver is by kicker and it gives me lots of specs for building the right sized box. F3 is given but I'm not sure what it's relation is to Fb, the tuning frequency. If f3 is 25hz do I calculate for a tuning frequency of 25hz?
<<<<<<<<<<<<<<<<<<<<<<<>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
Resonant Frequency (Fs)43.8 Hz
Mechanical Q (Qms)10.03
Electromagnetic Q (Qes)0.91
Total Q (Qts)0.84
Compliance Equivalent Volume (Vas)0.57 ft.³
Maximum Linear Excursion (Xmax)12.73 mm
Vented Volume2.47 ft.³Vented F325 Hz
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Another question is about the port itself. Is there much of a difference between using a slot vs. a circle port?

Once I get the interior volume (which kicker provides), and port size (which I need to understand tuning frequency for), I will start building. Are there any other things I should be considering to build a solid sub?

This is not for a car system so I'm not concerned too much about size. Most resources I have been reading tend to be concerned about fitting the sub in a car for the type of Port being used.

Thank you for your time and knowledge,

It is very much appreciated,

Rex
 

Dave R

Member
2006-08-09 5:30 am
To see how F3 and Fb are related, you need to look at a response curve for a specific box and port combination. A lot of folks use WINISD, a free download. It plots response curves and does a lot of other design.

As far as slot port vs. round port -- for all practical purposes, they work the same as long as the cross-section area is the same. As an example, a slot that is 1.75 in x 4 in has an area of 7 sq. in. A 3.0 in diameter port also has an area of about 7 sq. in. (This is just an example, not necessarily what would be used for any specific woofer.) There are formulas that calculate the length required for a given tuning frequency, Fb.

To back up a bit, drivers that work best in vented boxes usually have Qts in the range of 0.20 to 0.50. And the ratio Fs/Qes of around 100 is another good rule of thumb for selecting drivers that are suited for vented boxes. That being said, you may still find a good combination of box size and vent size for your driver.

Check into WINISD or some other simulation program.
 
Kicker for car

Here is a sim using WinISD.
I'm always a little concerned when companies do not give all thiel-small parameters ..... with kicker we a re missing a ot of information for a really good sim. No information on the coil Re, and therefore no sim of excurtion and SPL.

The driver is made for car audio, and with the two different suggested tunings; vented 70 liter/44Hz (green) or closed 44 liter (blue) you'll see that especially in the vented version you'll get a lot of output around 50 Hz, but not much else ..... will sound impressive, but very "one note" .....

For comparrison the new Dayton 10" RSS265HO-44 DVC (140 USD) in a 50 liter vented box ..... now this is much more subwoofer like. With 350 W input you will get impressive 107,5 db @ 25 Hz.

But in the vented 70 l box with the Kicker you'll probably get a lot more output around 50 Hz .... but nothing in the sub region.

It's all about use and taste.
 

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rexhex

Member
2016-02-04 5:16 am
Dave and Baldin,

That winISD looks like a great tool. I will look into downloading it in a little bit. Thank you for doing a simulation Baldin. That's strange the sub is only going to sound good around one frequency... Are there ways through different box building styles to change this? Because I just purchased the driver I want to use it but if it no good I guess I will need to try something else out.
 

rexhex

Member
2016-02-04 5:16 am
I was unable to download the software because I work on a Mac. Thankfully they have an online java applet. I played around a little bit and think that I have come up with a decent design.

The reason I am going with a car driver is its going to be battery operated. The car subs seem to be more efficient for low voltage applications. The sub will be used in many different spaces ranging from open space fields to small rooms.

ported sub enclosure w/ 1 driver:
Qts = 0.84
Vas = 0.57ft^3
Fs = 43.8hz
Vb = 1.5ft^3
fb = 25hz
1 vent
vent diameter = 2 Inches
vent length = 7.656 Inches
vent Mach = 0.16 (right at the cutoff recommended.. )
Qms = 10.03
Pe = 100Watts
Acoustic Power = 0.14

The numbers and graph look good as far as I can see.
20hz = -3db
30hz = -3db
40hz = 0db
50 - 100hz = curve from 0db to +3db back to 0db
100+hz = 0db

What are your thoughts?
 

rexhex

Member
2016-02-04 5:16 am
Ok I will be going with the flared port then. Why would I tune for 30hz in a 1.5ft^3 instead of 25hz? Im still not really understanding the tuning frequency.
https://www.parts-express.com/800-hz-low-pass-8-ohm-crossover--266-450

For the eq Im using a low pass crossover(800hz @ 8ohms). Because it will all be running at 4ohms it should let everything through under 400hz. I have the high pass filter counterpart that will be hooked up to the "full range" speakers.