PDA

View Full Version : what frequency?



accuab
10-16-2011, 01:00 AM
If a box is designed for a certain frequency, can any sub be put in it? What about the sub determines what frequency I can tune a ported box to? I looked a lot for the answer but just couldn't figure this question out. I'm looking at a sub with a Fs of 26.1 if that matters.

Kangaroux
10-16-2011, 01:04 AM
Fs is useless once you put a sub in an enclosure. The Fs is only useful if you were using the sub in a freeair/infinite baffle setup. What are the box specs and what sub are you thinking of putting in?

accuab
10-16-2011, 01:06 AM
was looking at around 2.25 cubes and a kicker cvr 12.

i've looked at re audio to determine port lengths for different frequencies but can't decide on what frequency is best for that sub and for middle ground bass.

UnderFire
10-16-2011, 01:10 AM
I've heard a few CVR's, and the ones that sounded best to me were in large boxes, like 2.25 cubes, tuned to around 30-32hz.

accuab
10-16-2011, 01:24 AM
i was thinkin precisely in that range to allow me to get lows out of it. would an amp with a subsonic filter at 30 hz have any effect on which frequency i should choose

Kangaroux
10-16-2011, 01:26 AM
Can you adjust the subsonic filter? If you tuned to 30-32 you would want the filter somewhere around 25

accuab
10-16-2011, 01:43 AM
it's set at 30hz. i could turn it off but then would risk damaging the sub. right? so with it on i should tune more around 35?

Moble Enclosurs
10-16-2011, 04:27 PM
was looking at around 2.25 cubes and a kicker cvr 12.

i've looked at re audio to determine port lengths for different frequencies but can't decide on what frequency is best for that sub and for middle ground bass.

This is one of the last times I am going to do this.but here you go...for optimal specs. This can obviously be changed to your liking but provides a basis. Recommended tuning is 35.57Hz. Recommended box volume is 2.19 cubic ft. Recommended port area is 334.19 square cm. And recommended port length is 37.53inches. Will give you something like this:

http://img542.imageshack.us/img542/7267/deletecd.png (http://imageshack.us/photo/my-images/542/deletecd.png/)
This is at 2.83V for efficiency

Hope that helps a little. :)

accuab
10-16-2011, 06:20 PM
Thank you for your help. But are those recommendations for that particular sub or just for a middle ground bass sound. I'm really trying to learn as much as possible instead of just getting the answer from someone else. I just got hung up there and my search didn't really get me anything on it.

FlexnInLa
10-16-2011, 06:36 PM
This is one of the last times I am going to do this.but here you go...for optimal specs. This can obviously be changed to your liking but provides a basis. Recommended tuning is 35.57Hz. Recommended box volume is 2.19 cubic ft. Recommended port area is 334.19 square cm. And recommended port length is 37.53inches. Will give you something like this:

http://img542.imageshack.us/img542/7267/deletecd.png (http://imageshack.us/photo/my-images/542/deletecd.png/)
This is at 2.83V for efficiency


Hope that helps a little. :)

^^ I'd listen to this guy.

Moble Enclosurs
10-16-2011, 07:18 PM
Thank you for your help. But are those recommendations for that particular sub or just for a middle ground bass sound. I'm really trying to learn as much as possible instead of just getting the answer from someone else. I just got hung up there and my search didn't really get me anything on it.

No problem. Those are for that particular driver..no other. Just that one. There is no middle ground that I calculate for, but if you want to say middle ground, then the guy that mentioned 2.25cubic ft at 30-32Hz is great for a 12. Recommended box volume is usually 2-3.5X the cubic dimensions of the driver as a very very basic middle ground, with the port tuned accordingly. For example, a 12 inch driver with a depth of 6" will yield a minimum box volume of 1 cubic ft-1.75 cubic ft.then add the port. Smaller compression areas usually yield better (averaged) SQ. But no one usually goes by that. Everyone goes with the correct option of trying to design on a driver by driver basis.
As far as learning as much as possible........well..........it has taken me over 10 years to get where I am now, effectively about 6. And most of it was based on trial and error and logging what happens when I make certain changes to a design and checking for scientific consistency of at least 3 proper responses for each change. And the rest is military and college training. SO, learning will be an adventure depending on how much you want to learn. With that said, I am excited for you! And as a recommendation for starters, any audio books, like the cookbook and such are great ways to get started in understanding certain acoustical changes that we all deal with in designing. I hope that helps.

accuab
10-16-2011, 07:53 PM
So your recommendations come from your experience? I'm not wanting a complete understanding but want enough to be able to build a simple ported box for a sub without having to ask someone. Like if one of my friends got a sub I could help him get better sound out of a sub and cheaper than prefab. Is there any way to know what will be good for a particular sub without experience with that specific sub? And I really do appreciate your help.

dontbeaprix
10-16-2011, 08:22 PM
So your recommendations come from your experience? I'm not wanting a complete understanding but want enough to be able to build a simple ported box for a sub without having to ask someone. Like if one of my friends got a sub I could help him get better sound out of a sub and cheaper than prefab. Is there any way to know what will be good for a particular sub without experience with that specific sub? And I really do appreciate your help.

every sub is different and therefore needs a different enclosre , there is no general size that works well with all of them in one size. Quit being cheap and pay a professional to at least design the box for your particular needs and then build it yourself if you have the skills and tools neccesary.

-01limited-
10-16-2011, 08:39 PM
Box design programs will be your friend for a basic understanding. Try one out and just mess around with it.

accuab
10-16-2011, 08:52 PM
every sub is different and therefore needs a different enclosre , there is no general size that works well with all of them in one size. Quit being cheap and pay a professional to at least design the box for your particular needs and then build it yourself if you have the skills and tools neccesary.

I'm not being cheap. I'm trying to learn. You are the kind of person that turns people trying to learn away from forums. If you had read my earlier posts, you'd see I don't want someone to just tell me the answer. I want to understand the answer.

And to 01limited I've been playing with a few of them already and understand the box designing just not how to design it around a particular sub.

Moble Enclosurs
10-16-2011, 09:04 PM
So your recommendations come from your experience? I'm not wanting a complete understanding but want enough to be able to build a simple ported box for a sub without having to ask someone. Like if one of my friends got a sub I could help him get better sound out of a sub and cheaper than prefab. Is there any way to know what will be good for a particular sub without experience with that specific sub? And I really do appreciate your help.

And I appreciate the support. My recommendations come from knowing about sound and the physics, psycho-acoustics, and science behind it all rather than what I know will work based on experience alone. The experience is submitting to the limitations of sound and knowing what can and cannot be done rather than saying, like most, "I think 3 cubic feet and 33Hz will be best for you". Its so much more than that. Those quotes are based on experience mainly. But more is involved. So no, my recommendations are not based on experience. My experience is based on what physics and acoustics allow me to accept as what will work. So, no recommendation I give is from mainly experience, but from advanced acoustics of sound and the reality of its limitations based on real world applications. But now, as far as what you are saying that you want to be able to do all of that......that is kewl. And commendable to jump right in there, but again, much will be needed to be able to accurately do any of that without the experience, and even if you have experience in a specific field of audio, such as those who build walls and bandpass', it still can be tuned more accurately than one would think or most of us would want to accept. its tough to talk about what actually goes into it all without having someone back me up on what I try to get across. But like mentioned before, a lot of reading and understanding can play a major role in what you want to do, and experience is a means of verifying your calculations, if not, correcting them as well. So, yes, its possible, just not in a few days. Will take some work. I would help you more about the acoustics side of it, but I do not have the availability to teach it with the time and effort involved. Other than that, I know you want to keep it simple it seems, like being able to just recommend something and it work out. But what I do is not simple. Hopefully someone on here can help you more with the simple side of it-I hope. Again, good luck to you!

Moble Enclosurs
10-16-2011, 10:07 PM
Orangecavi, I appreciate you lookin out for us, that's kewl man. And to the OP, I like that you are trying to learn. Let me say this.......there are many of many people in the world that love what we do as designers and want to do it the same. A lot of people can. Just have to find them. But most of the audio world does rely on these programs and believe that it is the best way to go. And a lot of them believe themselves to be great designers for that reason. You do not become an engineer by pluggin numbers in and seeing the results, and you understand that, which is good. But what you do need to know, that may be disturbing, is that it will take you quite a bit of not only training, but hands on experience, as a balance of accuracy with repeatable results to become what you are talking about becoming. Understanding how these programs work is one thing. Understanding audio in general is a whole new world. it doesnt take a math genius to figure out the speed of sound and work it into an acoustical equation, but there is much more than quarterwave theory(for example) to be understood, along with knowing not only what the environment will do, but what each factor of the source will do to the sound to get you what you are looking for. Look, I think the programs are great. They, like me, give you a good starting point. But we go much further than that to provide a sense of accuracy that was not available in the mid 20th century....at least that they knew what it meant or how to utilize it yet. So, it has taken some people a lifetime to come up with formulas that work for most designs out there. And for that, we now have hornresp. Another great program, but not the end of designers as we know it (yet, lol). Anyone can use hornresp-and that is no joke. They even have tutorials out there. But that doesn't make you a designer or audio genius. Nor does it give you the right to sell what the program comes up with. Because most who use it, know how to control it and by making a throat size smaller or S2 changes the tuning so much, etc only says that you understand "how" to change it, but doesnt tell you why or when. This program actually kills me because it is fairly accurate. But it does not account for environmental factors, in which those who have been around long enough know how tough that is to get right. Some of us have it figured out though, and they have for many years. But it takes people like me, and other designers (who are real) to present it to you without fear of you stealing the ideas. That is why patents exist.because everyone is afraid. The knowledge is out there. But to be able to use it here, to those that matter most to me (not those who think a $50,000 system is the best thing ever made and actually has the money to spend on it-Im referring to HT as well), is more important than taking it to a patent company and trying to make a mill of it. you guys make up the audio world, not the people in the mansions with glass horns and revamped tube style amps (which have their flaws as well). Those who want to learn more, should be able to. But it will take more than a forum to get the ability to do so. You gotta put yourself in the position. And I hate to say it, but the forum is not the place to learn about real acoustics. This is the place for generalization, which makes it tough more me as well to manage selling myself. I hope that opens your mind up a little about what needs to be done if you want to get serious with it, because to "understand" it as you mention, takes more than you might want to think.

accuab
10-16-2011, 10:18 PM
i have a great deal of understanding of electronics as I'm working on a degree in electrical engineering but not so much acoustics except where it pertains to physics. I will definitely be taking your recommendations on the box az you definitely know what you are doing. I've seen the audio cook book mentioned. Is that a good boom to help me understand more? Obviously I'm not learning this for a profession, but I like to know why I am doing something a certain way than just doing it and having no idea why. I've seen way too many people I know with decent subs that sound bad because of the box and would like to be able to help.

CHEMMINS
10-16-2011, 10:20 PM
Now that post should be stickied!!!

Moble Enclosurs
10-16-2011, 10:24 PM
That is awesome. You will learn some acoustics in electrical engineering I imagine. I did through electronics engineering, and that deals more with building cell phones and such, lol. You can always elect for it to have acoustics in it, as considering loudspeakers, they are in a circuit used a the load. So, Im sure it will have something. The cookbook I think is updated to the 7th edition so far (maybe further idk) and it has a good basic of acoustics. But to understand things such as efficiency and coupling,etc, yea, you can learn a lot more other places. i don't have any available book I could send you as a pdf, but I will check. other than that, maybe google some ebooks or go to the local library and search for something with the word acoustic in it. Thank you again for the support and I hope you get where you want to be! Good luck to you man!:D