I would like to write a how to article on each type of box, sealed (how to calculate volume); Ported (how to calculate volume and tune a port); and bandpass (putting it all together).
My first question is the only one I need an answer/opinion on to complete my 'how to' article on sealed boxes.
Has anyone ever heard of the 'Golden Ratio'?
>The "Golden Ratio" should be used whenever possible unless space is restricting which is a normal occurrence when dealing with an automobile. This ratio is 1 x .7937 x 1.2599. For subwoofer cabinets, dimensions with this ratio will sound less boomy and have less panel vibration. To figure the dimensions that you need for a particular volume, without trial and error, you must have a calculator with a "cube root" function. Find the cube root for the volume that you want.
For example, the overall volume you want is 2.25 cubic feet, the cube root is 15.72, make this side one (A). Now multiply side A x .7937 to get side B, or 12.48". Now you have side A = 15.72" and side B = 12.48", to get side C multiply 15.72 x 1.2599 and you get side C which is 19.80". The closer that your cabinets are to this "Golden Ratio" the better they will sound.
(^root X 1, X .7937, X 1.2599)
simplified it states that:
side A (width) is equal to 1X the cube root of the desired volume
side B (height) is equal to A X .7937
side C (length) is equal to A X 1.2599
I did calculate this out and it does come back to 2.247 close to the origional 2.25^ft desired volume. I was wondering if anyone has ever used this or heard of this. It is very hard to find information online that is factual and not someone's opinion. I would like to verify some of this before I post it as fact.
Also I can't find much information other than einstein equations on calculating port volume to tune a box. I want to break it down to an easy to understand 'how to' article, but I can't do that if I don't understand it first. Can anyone help me with this?
Replies (3)
Swez on 12/7/2003 09:10:46
Yes, have heard of this "Golden Rule" and it definitely makes sense in HT, Pro and most non-car audio applications. But in car designs, this may be next to impossible to get these ratios to work out right, unless one has a larger vehicle to work with.
Personally, it's a good guildline tool... but not always possible to use same in car audio. Besides, the more details we throw at people... (before they can digest it well) the more lost and frustrated they will feel. (Upset stomach & a massive Headache)
"KEEP IT SIMPLE" ... is the best option when writing technical application notes for this forum. I have tried generalized and a few deep "HOW TO" articles. What good is getting too deep... if the average reader is lost and frustrated? You may get it, I may not.... so we lost the intended goal ....sharing knowledge is the intended goal here I think?
We can just open the door for those who are wanting to understand the basics... for those who need/desire to get deeper, they will ask as they need it.
Swez
PS CPL.... Nice job keeping the board current with replies. Started a new job this week and the learning/energy curve is steep. Most nights, I just crash after a shower and a cool one. Will try to be on the board on the weekends as I can.... Cheerio Mate!
cplkittle on 12/7/2003 16:45:41
Thanks, Swez.. was wondering where you had been. Just figured you were too busy soaking up the new found warm weather for us haha. I got all of my articles finished and posted. It was a good learning experience for me. There are a few great links on the overview article, I highly recommend them. Also in the overview article, I included as much on the transmission line box that I could find, and there are online calcualtors for figuring these. I don't know how exactly they are calculating them, but most ask for TS parameters, so I assume they are fairly accurate. Good luck with the new job! I start a part time job doing custom boxes right after the holidays. Hopefully I can contribute some good info on how sound is affected by different box materials. looking foreward to it.
Swez on 12/7/2003 19:53:23
Cool opportunity.... now you can test some of the theories, practicality and efficacy of some of these old and new enclosure designs.
My twin bro did this stuff for almost 10 years and has settled on a few very basic designs that work in most applications he gets involved with. Sometimes, less is better for the masses. To the "Audio Purist" (read as SNOB), nothing but the best will do. But... for the average install, ported, sealed and BP are common and effective.
Assuming all being equal... matching the box well with the driver and optimizing the box for intended needs and preferences is often the best scenario. You will find out that most subs have some generic baselines. But when you optimize for specific music taste, T/S parameters and physical limitations of the enclosure... the variables get more complex than most care to bother with.
Have fun!
Swez
PS Yep, am getting lots of sun as I work out of doors a lot this week. Getting more of a tan that I got all this summer in MI. Funny not having snow on the ground, bone chilling cold and icy roads... Not too bad.. I can get used to this with time.... LOL Not only that... prices ae cheaper here for many things... but so are the wages.
My first question is the only one I need an answer/opinion on to complete my 'how to' article on sealed boxes.
Has anyone ever heard of the 'Golden Ratio'?
>The "Golden Ratio" should be used whenever possible unless space is restricting which is a normal occurrence when dealing with an automobile. This ratio is 1 x .7937 x 1.2599. For subwoofer cabinets, dimensions with this ratio will sound less boomy and have less panel vibration. To figure the dimensions that you need for a particular volume, without trial and error, you must have a calculator with a "cube root" function. Find the cube root for the volume that you want.
For example, the overall volume you want is 2.25 cubic feet, the cube root is 15.72, make this side one (A). Now multiply side A x .7937 to get side B, or 12.48". Now you have side A = 15.72" and side B = 12.48", to get side C multiply 15.72 x 1.2599 and you get side C which is 19.80". The closer that your cabinets are to this "Golden Ratio" the better they will sound.
(^root X 1, X .7937, X 1.2599)
simplified it states that:
side A (width) is equal to 1X the cube root of the desired volume
side B (height) is equal to A X .7937
side C (length) is equal to A X 1.2599
I did calculate this out and it does come back to 2.247 close to the origional 2.25^ft desired volume. I was wondering if anyone has ever used this or heard of this. It is very hard to find information online that is factual and not someone's opinion. I would like to verify some of this before I post it as fact.
Also I can't find much information other than einstein equations on calculating port volume to tune a box. I want to break it down to an easy to understand 'how to' article, but I can't do that if I don't understand it first. Can anyone help me with this?
Replies (3)
Swez on 12/7/2003 09:10:46
Yes, have heard of this "Golden Rule" and it definitely makes sense in HT, Pro and most non-car audio applications. But in car designs, this may be next to impossible to get these ratios to work out right, unless one has a larger vehicle to work with.
Personally, it's a good guildline tool... but not always possible to use same in car audio. Besides, the more details we throw at people... (before they can digest it well) the more lost and frustrated they will feel. (Upset stomach & a massive Headache)
"KEEP IT SIMPLE" ... is the best option when writing technical application notes for this forum. I have tried generalized and a few deep "HOW TO" articles. What good is getting too deep... if the average reader is lost and frustrated? You may get it, I may not.... so we lost the intended goal ....sharing knowledge is the intended goal here I think?
We can just open the door for those who are wanting to understand the basics... for those who need/desire to get deeper, they will ask as they need it.
Swez
PS CPL.... Nice job keeping the board current with replies. Started a new job this week and the learning/energy curve is steep. Most nights, I just crash after a shower and a cool one. Will try to be on the board on the weekends as I can.... Cheerio Mate!
cplkittle on 12/7/2003 16:45:41
Thanks, Swez.. was wondering where you had been. Just figured you were too busy soaking up the new found warm weather for us haha. I got all of my articles finished and posted. It was a good learning experience for me. There are a few great links on the overview article, I highly recommend them. Also in the overview article, I included as much on the transmission line box that I could find, and there are online calcualtors for figuring these. I don't know how exactly they are calculating them, but most ask for TS parameters, so I assume they are fairly accurate. Good luck with the new job! I start a part time job doing custom boxes right after the holidays. Hopefully I can contribute some good info on how sound is affected by different box materials. looking foreward to it.
Swez on 12/7/2003 19:53:23
Cool opportunity.... now you can test some of the theories, practicality and efficacy of some of these old and new enclosure designs.
My twin bro did this stuff for almost 10 years and has settled on a few very basic designs that work in most applications he gets involved with. Sometimes, less is better for the masses. To the "Audio Purist" (read as SNOB), nothing but the best will do. But... for the average install, ported, sealed and BP are common and effective.
Assuming all being equal... matching the box well with the driver and optimizing the box for intended needs and preferences is often the best scenario. You will find out that most subs have some generic baselines. But when you optimize for specific music taste, T/S parameters and physical limitations of the enclosure... the variables get more complex than most care to bother with.
Have fun!
Swez
PS Yep, am getting lots of sun as I work out of doors a lot this week. Getting more of a tan that I got all this summer in MI. Funny not having snow on the ground, bone chilling cold and icy roads... Not too bad.. I can get used to this with time.... LOL Not only that... prices ae cheaper here for many things... but so are the wages.
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