How would i go about making the perfect box for a 12" adire audio shiva sub?

[WarDemon666]

I have a Kenwood KAC-7201 amp. I just bought myself an adire audio shiva, and im thinking of getting another one pretty soon, should i make myself a 2 sub box, and only put one in for now, or should i make a 1 sub box, and make another one completly for the next sub?

Ive got lots of room in my trunk so the size of the box doesnt matter basically.

I got that WinISD program, but dont entirely know how it works.

If anyone could help me make the perfect box, i would be forever greatful

Thanks guys,
Carl

 

[yakko]

I would just build a box for two and only put one in since they should each have their own chamber.

 

[Howard]

Don't make it a cube.

 

[Howard]

How are you with woodworking, anyway? What about equipment?

 

[glen]

Well, the best possible box would be of infinate size - best transients, flattest curve, most extention.
In the real world, if you can get at 4 times the drivers VAS, you are close enough.

 

[Howard]

4 x the VAS of this driver is 60 cubic feet. :Q

 

[erikiksaz]

Don't they have recommended builds at the Adire site?

 

[KingNothing]

Originally posted by: Howard
4 x the VAS of this driver is 60 cubic feet. :Q

Pfft. Only a 3x4x5 box. Just imagine the looks on your friend's faces when they come over to watch a movie and see that thing sitting there with one coil in the middle.

 

[Shockwave]

Piss me off. Had a BIG respone typed up and IE crashed. Damnit.
*starts re-typing*

 

[MarkW]

What I am planning on doing when I buy my shiva next week is getting the shiva (obviously), and a subzone box from www.thezeb.com, model h-121. its like 1.25 cubic feet (the reccomended enclosure is 1.5cf). What I will do is just stuff it with polyfill which you can get at wal-mart for like 2.50. Polyfill makes the sub think that it is in a bigger box than what it is, so it should be able to offset that .25 difference in the recommended enclosure. From what I have heard, the shiva is one of the best in the business for its price range.

As far as the type of sub box, single or dual, its your choice. Just make sure that they have seperate chambers for the subs if you are going with the dual!

 

[Shockwave]

Ok, again....
I would do either sealed or ported box. My preference.
In WinISD, start a new project. It defualts to the Transfer Function Field. This shows the response of the box OUT OF CAR. (Important point there.)
Do a sealed box at 2.5 ft^3. Below box size is a field for QTC. Optimal is .707 Anything higher is a bit more boomy, anything lower is pretty tight n dry. Thats essentially all theer is to a sealed box is setting the QTC where you would like it. So like .707, some like it high, some like it low. Just personal taste there.
Now do a ported box. You have box size and tuning frequency. I like a low tuned box with a fairly flat response. Alot of street boxes are tuned rather high, 35-40 hertz. This give a nice bump in the 35-50 hertz range to get loud.
Model a box (I'm so pissed at IE I have to re-type this....) at 4.5 ft^3 tuned to 25 hertz. Thats the kind of box I like. Nice n flat down to about tuning then a slight bump. Now go to the Vent tab. It should default to 4 inches. Length shouldnt be too bad. You can click the cirlce icon to change to a square vent. More on this later.
So, you got the box, response looks good and port is normal sized (I've had some boxes with 60+ inch ports....)
Now lets fvck it all up. Click on Signal tab. Put in your power. Probably 5 to 600 watts for a Shiva. Now, Click the Transfer Function Magnitude button. Go down to Rear Port Air Velocity. You want to keep it between 60-100 ft / sec. It depends on the type of port as to exactly what speed it can support before becoming audible, so I would try to stay under 70 is possible. Our little ported box is around 190 ft / sec. Port noise will follow.
Back to Vent Tab. Change to a Square Port. Do a 3"x15" port. Back to Air Speed. It should have dropped to around 55 ft / sec. Thats good right there. Port length is 37 inches which is do-able as well.
Keep in mind, box size does NOT account for port / driver displacement. So, you'll have 4.5 ft^3 THEN the port.
Vent Port example
Theres an example of how to make a vent port, you can fold it back on itself over and over to get the right length.
Now, play around with it. You can see changing tuning frequency changes port length. Changing port size also changes port length. Changing port size ALSO changes Air Speed, and changing both Tuning Freq and Box Size affects Transfer Function.
Its really a bit of a juggling act to get everything to work together. Now, to the out of car thing. A car has the great ability to cause a upward slope. Its the transfer function of the vehicle. Model a sealed box, then invert it, and thats kinda what I mean. So, your sealed box that looks like it rolls off mroe and more the lower you go....Your vehicle will offset that downward slope. The one great thing about cars.

 

[glen]

And of course I disagree and would only go with an IB, so you get good respone all the way down to 5hz.

 

[Shockwave]

Originally posted by: glen
And of course I disagree and would only go with an IB, so you get good respone all the way down to 5hz.

Yeah, but at 18 hertz and up my ported box PWNS J00!!

IMO response that low is of little value.

But again, personal preference. The beauty of the hobby.

 

[glen]

5hz to 20hz is the same amouont of music as from 5,000hz to 20,000.
It is huge IMHO.

 

[Viperoni]

Originally posted by: glen
5hz to 20hz is the same amouont of music as from 5,000hz to 20,000.
It is huge IMHO.

glen, I know you want the best for SQ and such glen, but for the average car audio enthusiast, it's not even wanted.
I just stick to recommendingthe popular 1.5cf sealed per sub.
It'll give enough midbass bump to keep most people happy, without sounding overly sluggish/muddy.

I'll probably be tossing my own 12inch Dayton Titanic MK2 in either a 1.5cf sealed box, or a ~2cf box with pluggable ports (sealed, SQ and SPL all in one box).


WarDemon, that amp only does 4ohms bridged, not 2 ohms as a pair of Shiva's would present.
Stick to just 1 Shiva, unless you change the amp.
1.5cf sealed will handle the power fine.

 

[Shockwave]

Glen, I should say I understand the validity of being able to reproduce these low frequencies. But, the bigger question...Would a Shiva even be capable of doing it? Capable of doing it in ANY notciable fashion? Yes, the cone will move, but whether the effects of the movement would be detectable by a human....... Thats the question. Some would say yes, some would say no. But, at low frequencies (REALLY low) it becomes much more dependent on the listeners sensitivity. And most (I dont think) would notice them. So, the ability to reproduce them really comes down the the individual listeners ability to detect them.

 

[glen]

Originally posted by: Shockwave
Glen, I should say I understand the validity of being able to reproduce these low frequencies. But, the bigger question...Would a Shiva even be capable of doing it? Capable of doing it in ANY notciable fashion? Yes, the cone will move, but whether the effects of the movement would be detectable by a human....... Thats the question. Some would say yes, some would say no. But, at low frequencies (REALLY low) it becomes much more dependent on the listeners sensitivity. And most (I dont think) would notice them. So, the ability to reproduce them really comes down the the individual listeners ability to detect them.

No way. That is a total myth about us hearing from 20 to 20khz. No one hears over 15khz very well over the age of 12, but ALL of us hear down pretty low. And, it make a huge difference. HUGE HUGE HUGE.

 

[Shockwave]

Originally posted by: glen

Originally posted by: Shockwave
Glen, I should say I understand the validity of being able to reproduce these low frequencies. But, the bigger question...Would a Shiva even be capable of doing it? Capable of doing it in ANY notciable fashion? Yes, the cone will move, but whether the effects of the movement would be detectable by a human....... Thats the question. Some would say yes, some would say no. But, at low frequencies (REALLY low) it becomes much more dependent on the listeners sensitivity. And most (I dont think) would notice them. So, the ability to reproduce them really comes down the the individual listeners ability to detect them.

No way. That is a total myth about us hearing from 20 to 20khz. No one hears over 15khz very well over the age of 12, but ALL of us hear down pretty low. And, it make a huge difference. HUGE HUGE HUGE.

Oh wow.
I can break into 18khz before i start to lose it. Not superhearing by any means, but fairly high.. Below about 30 just doesnt get me though. Guess I'm fvcked up somehow...
Too many ported boxes in high school probably shorted out my low end detector.

 

[glen]

Everyone can hear over 15hz, but your perception rapidly falls off.
In other words, 18khz sounds only half as loud as other frequencies played at the same volume.
Also, I am sure you can hear well below 30hz. Go get the Telarc 1812 with the digital canons.
They have a 5hz sound recored at almost the CD max.

 

[glen]

Also, if you can't hear below 30hz, look for an amplifier or crossover or some other piece of equiptment filtering sounds below it.

 

[Shockwave]

Originally posted by: glen
Also, if you can't hear below 30hz, look for an amplifier or crossover or some other piece of equiptment filtering sounds below it.

Thats a good point actually. My amp is right at RMS power for the sub, and graphing it out shows over exuction around 28 hertz. Thus, my filter is set to around 30.....

May explain it.

 

[WarDemon666]

WarDemon, that amp only does 4ohms bridged, not 2 ohms as a pair of Shiva's would present.

Arent the shivas 4 ohms?

If i connect them in parallell they shouldnt be 4?

Im not clear on the ohms and frequencies and stuff... Anyone mind explaining this a bit?

Viperoni says sealed, Shockwave says ported.

Technically, i dont know what to do. haha.... Sealed is gonna be a hell of alot easier to make, but supposedly ported will sound better?

I dont know what to do help!

Thanks,
Carl

 

[glen]

Originally posted by: WarDemon666

WarDemon, that amp only does 4ohms bridged, not 2 ohms as a pair of Shiva's would present.

Viperoni says sealed, Shockwave says ported.


Thanks,
Carl

And I say IB, which is a sealed with a volume equal to or larger than 4 times the VAS.
Then again, I won't give up trunk space and I want it flat to between 5 and 10hz.

5hz to 40hz may not seem like a lot, but it is a full 3 octaves.
That is the same as going from 2,500hz to 20,000hz, also 3 octaves.

5 to 10 one octave
5 to 20 two octaves
5 to 40 three octaves
5 to 80 four octaves
5 to 160 five octaves
5 to 320 six octaves
5 to 640 seven octaves
5 to 1280 eight octaves
5 to 2560 nine octaves
5 to 5120 ten octaves
5 to 10, 240 eleven octaves
5 to 20,480 twelve octaves

 

[Lithium381]

Originally posted by: WarDemon666

WarDemon, that amp only does 4ohms bridged, not 2 ohms as a pair of Shiva's would present.

Arent the shivas 4 ohms?

If i connect them in parallell they shouldnt be 4?

Im not clear on the ohms and frequencies and stuff... Anyone mind explaining this a bit?

Viperoni says sealed, Shockwave says ported.

Technically, i dont know what to do. haha.... Sealed is gonna be a hell of alot easier to make, but supposedly ported will sound better?

I dont know what to do help!

Thanks,
Carl

if this is your first project evar, go sealed, you will still experience so much bass you'll have bass comming out of your @$$......personally i would go sealed, i respect viperonis opinion, he seems to know a thing or two....if you want to change it later you can.



basic info on car audio good luck!

 

[WarDemon666]

Alright so i decided to make a sealed box. On the adire site, i found 3 different sizes. One is Q=0.95 another Q=0.707 and Q=0.6, 25.5 liter, 54 liter, and 88.5 liter.

Which one should be the best?

Also, how should i connect 2 subs? Right now ive got 2 old kicker 4 ohm subs. How should i connect them?

Thanks.
Sorry for asking so many questions
Carl