reaudio.com enclosure calculations- How accurate are they?
- Thread starter mannyahles
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- Thread Starter
- #2
anyone???
- Thread Starter
- #3
So many enclosure gurus and no help/suggestions! Cmon people!
Also, i just got done reviewing the RE calculator, and to my surprise, it's WRONG!
WAY OFF. Well, not WAY off but not pleasing.
I did a test-
24" high
24" wide
24" deep
INTERNAL GROSS so far - 6.59 cuft.
Port height - 22.5"
Port width - 4"
Tuning 34.711 hz
OK, this is where everything starts to be wrong!
Total port length - 34" (that's wrong, it's suppose to be 32" because it's a slot but for Mike P.'s sake, we'll let it slide)
Port length 1 - 19.25" (that is correct)
Port length 2 - 8" (this is oh so wrong, not because it's suppose to be 32" total, oh no, it's wrong on it's OWN PART!) See for yourself-
Port length 1 - 19.25"
The width of the port is 4" so the internal corner is a 4" square.
When measuring a port's length, you measure down the center only.
So, when the port bends, you measure down the center, but how do you know the length?
Simple, Pythagorean Theorem.
What is half of a 4" square? 2" square.
a^2 + b^2 = c^2
So, 2^2 + 2^2 = c^2
So, 4 + 4 = c^2
c^2 = 2.83"
So we add that to 19.25" and get - 22.08"
Now remember, Even RE said we need 34" total length, i say we need 32" because it's true.
We only have 22.08" now and the L bend has already started, so according to RE, we need 12 more inches...
So why does RE say we only need 8" more? That's only 30.83"???
I do not know why but it is wrong. That would increase tuning.
Ok, you may think being off 2" raising tuning 1.5-2hz isn't that big of a deal... Well, that isn't the only thing that is wrong.
RE's calculated port displacement - 3060 cu inches internal...
WRONG!!!!!! wrong wrong wrong wrong wrong...
Do you know what it did? It did not calculate the total internal port displacement like it said it did...
It calculated internal port displacement as if the port NEVER bent.... that is 100% wrong.
And of course we are going by the picture, there is no 45 degree brace in the corner of that port so the whole 4" square is there.
The following is if the port never bent to prove how the calculator is wrong( again, in a minute)
Total INTERNAL port displacement of 22.5" x 4" x 32" = 2880 cu in (this is what it should be, but only if port never bent)
Total INTERNAL port displacement of 22.5" x 4" x 34" = 3060 cu in (this is what it says but it never even reach 34" long... pathetic.
Total INTERNAL port displacement of 22.5" x 4" x 30" = 2700 cu in (this is what it told you to make port but what ti calculated and what it told you length needs to be is different so it confused itself!)
Now, it then calculated that Port displacement, which is after wood thickness... is only 19 cu in more than internal displacement?? WHAT?!?!? this calculator is full of ignorance!
Now you will see what total displacement is after wood thickness-
22.5" x 4.75" x 32" = 3420 cu in (this is what displacement would be if port never bent)
22.5" x 4.75" x 34" = 3633 cu in (RE calculated 3079.8 but it never even achieved this length to begin with...)
22.5" x 4.75" x 30" = 3206 cu in (this is what it told you to make it but still didnt equal it's calculated 3079.8, wrong again....)
Now, you WILL SEE TRUE DISPLACEMENT-
When a port bends, it's displacement compared to a straight port changes obviously.
Compare the total displacements i just showed you above to see how wrong this program is once again.
22.5" x 4.75" x 32" with L bend as shown in pic - 3393.27 cu in
22.5" x 4.75" x 34" with L bend as shown in pic - 3607 cu in
22.5" x 4.75" x 30" with L bend as shown in pic - 3179.5 cu in
Numbers are in fact just slightly different then a straight port, less displacement even..
But small miscalculations consistently can and will eventually change something.
Oh and also, it doesn't account for sub displacement because hey, why would it? they obviously forgot to put that in there too.
So RE's calc is what Mythbusters would say BUSTED!
Since it can't do sub displacement... how are you gonna get a precise calculation? simple the reason way how you are gonna get a precise calculation on every other thing it's off on.
IT likes to use numbers in the .xxxxxxxxxxx value and still can't get simple math right.
I'm ranting but i'm glad i finally tested their calc.
WAY OFF. Well, not WAY off but not pleasing.
I did a test-
24" high
24" wide
24" deep
INTERNAL GROSS so far - 6.59 cuft.
Port height - 22.5"
Port width - 4"
Tuning 34.711 hz
OK, this is where everything starts to be wrong!
Total port length - 34" (that's wrong, it's suppose to be 32" because it's a slot but for Mike P.'s sake, we'll let it slide)
Port length 1 - 19.25" (that is correct)
Port length 2 - 8" (this is oh so wrong, not because it's suppose to be 32" total, oh no, it's wrong on it's OWN PART!) See for yourself-
Port length 1 - 19.25"
The width of the port is 4" so the internal corner is a 4" square.
When measuring a port's length, you measure down the center only.
So, when the port bends, you measure down the center, but how do you know the length?
Simple, Pythagorean Theorem.
What is half of a 4" square? 2" square.
a^2 + b^2 = c^2
So, 2^2 + 2^2 = c^2
So, 4 + 4 = c^2
c^2 = 2.83"
So we add that to 19.25" and get - 22.08"
Now remember, Even RE said we need 34" total length, i say we need 32" because it's true.
We only have 22.08" now and the L bend has already started, so according to RE, we need 12 more inches...
So why does RE say we only need 8" more? That's only 30.83"???
I do not know why but it is wrong. That would increase tuning.
Ok, you may think being off 2" raising tuning 1.5-2hz isn't that big of a deal... Well, that isn't the only thing that is wrong.
RE's calculated port displacement - 3060 cu inches internal...
WRONG!!!!!! wrong wrong wrong wrong wrong...
Do you know what it did? It did not calculate the total internal port displacement like it said it did...
It calculated internal port displacement as if the port NEVER bent.... that is 100% wrong.
And of course we are going by the picture, there is no 45 degree brace in the corner of that port so the whole 4" square is there.
The following is if the port never bent to prove how the calculator is wrong( again, in a minute)
Total INTERNAL port displacement of 22.5" x 4" x 32" = 2880 cu in (this is what it should be, but only if port never bent)
Total INTERNAL port displacement of 22.5" x 4" x 34" = 3060 cu in (this is what it says but it never even reach 34" long... pathetic.
Total INTERNAL port displacement of 22.5" x 4" x 30" = 2700 cu in (this is what it told you to make port but what ti calculated and what it told you length needs to be is different so it confused itself!)
Now, it then calculated that Port displacement, which is after wood thickness... is only 19 cu in more than internal displacement?? WHAT?!?!? this calculator is full of ignorance!
Now you will see what total displacement is after wood thickness-
22.5" x 4.75" x 32" = 3420 cu in (this is what displacement would be if port never bent)
22.5" x 4.75" x 34" = 3633 cu in (RE calculated 3079.8 but it never even achieved this length to begin with...)
22.5" x 4.75" x 30" = 3206 cu in (this is what it told you to make it but still didnt equal it's calculated 3079.8, wrong again....)
Now, you WILL SEE TRUE DISPLACEMENT-
When a port bends, it's displacement compared to a straight port changes obviously.
Compare the total displacements i just showed you above to see how wrong this program is once again.
22.5" x 4.75" x 32" with L bend as shown in pic - 3393.27 cu in
22.5" x 4.75" x 34" with L bend as shown in pic - 3607 cu in
22.5" x 4.75" x 30" with L bend as shown in pic - 3179.5 cu in
Numbers are in fact just slightly different then a straight port, less displacement even..
But small miscalculations consistently can and will eventually change something.
Oh and also, it doesn't account for sub displacement because hey, why would it? they obviously forgot to put that in there too.
So RE's calc is what Mythbusters would say BUSTED!
Since it can't do sub displacement... how are you gonna get a precise calculation? simple the reason way how you are gonna get a precise calculation on every other thing it's off on.
IT likes to use numbers in the .xxxxxxxxxxx value and still can't get simple math right.
I'm ranting but i'm glad i finally tested their calc.
TeamPSI
10+ year member
Super Pimp VIP Member
LMFAO... Jesus
Well does anyone know an accurate one
I kinda like having the cut sheet
I kinda like having the cut sheet
psych0ticnemes1
5,000+ posts
Psych0tic Customs
Someone can create a cut sheet for you if you can't figure it out.
poundindak69
Banned
**** that sucks i use that
TeamPSI
10+ year member
Super Pimp VIP Member
Even still... its not that far off. I doubt any of us are getting any closer than 1-2hz by using winisd or bassbox.
so do you suggest to tune lower or higher on re to get more accurate?
re website also only uses L shaped ports...but it is VERY nice that it gives you the cut sheets..
If you search around the web for subwoofer tuning calculator, or box building calculator you will find a few programs...that's what I did.
If you search around the web for subwoofer tuning calculator, or box building calculator you will find a few programs...that's what I did.
- Thread Starter
- #12
Thx for everyones input. Can you guys look at my box (gallery) and give me a suggestion. Should i scrap it and start all over. If my port is too small how should I fix that???
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