FE126E enclosure question

Skitch72 · 17th March 2005, 05:39 PM

I think more of a simple math question but I can't seem to get it straight. I am working on the recommended FE126E enclosure which is a hybrid back loaded horn / bass reflex design. Anyway I want to convert the port to english units from millimeters (don't have an 30 mm pipe!)

I know the port is 30mm diameter and 115 mm in length and Fb is 55 Hz

Due to the design I don't know what to include to calculate the enclosure volume.

What would the length need to be to use 1.5" port?

Thanks in advance,
Tim

Here is a link to the design:
http://www.madisound.com/pdf/fostexcabs/fe126e_encl.pdf

baggystevo82 · 18th March 2005, 10:40 AM

If you use the ratio 1"=25.4mm that's close enough for most applications. I've started a thread on the enclosure you want to build here, where I think a few of us are considering it:
Fostex FE126E reference design opinions
Feel free to join us and let us know how you get on.
Good luck,
Steve

Skitch72 · 18th March 2005, 01:18 PM

Thanks for the reply and I will keep an eye on that thread to see what others are trying out.

I don't have any issue converting the mm to inches but the port comes out to 1.18" in diameter and 4.5" long. I don't have any material that is that diameter and wondered how to calculate the new length if I change the diameter to 1.5"..

Maybe I'm not making sense...
(wouldn't be the first time)

Tim

GM · 18th March 2005, 04:34 PM

Greets!

Ron E's take on scaling vents:

.........L1/L2 = A1/A2, where L1, A1 are the original length and area, and L2,A2 are the new length and area... rearranging again, and Realizing that area is proportional to diameter squared:

L2 = L1*(D2^2/D1^2), where D2 is new diameter and D1 is the original diameter.

FWIW, *in sims* using MJK's WSs I found that accounting for the end correction difference was more accurate, probably audibly so if a big change in diameter was made, but as always YMMV:

L2 = L1*(D2^2/D1^2)+(D2-D1)^2

GM

Skitch72 · 18th March 2005, 04:55 PM

Thanks! that is exactly what I needed!

Tim

17th March 2005, 05:39 PM	#1
Skitch72 diyAudio Member Join Date: Jan 2004 Location: Indiana	FE126E enclosure question I think more of a simple math question but I can't seem to get it straight. I am working on the recommended FE126E enclosure which is a hybrid back loaded horn / bass reflex design. Anyway I want to convert the port to english units from millimeters (don't have an 30 mm pipe!) I know the port is 30mm diameter and 115 mm in length and Fb is 55 Hz Due to the design I don't know what to include to calculate the enclosure volume. What would the length need to be to use 1.5" port? Thanks in advance, Tim Here is a link to the design: http://www.madisound.com/pdf/fostexcabs/fe126e_encl.pdf

18th March 2005, 04:34 PM	#4
GM diyAudio Member Join Date: Jun 2003 Location: Chamblee, Ga.	Greets! Ron E's take on scaling vents: .........L1/L2 = A1/A2, where L1, A1 are the original length and area, and L2,A2 are the new length and area... rearranging again, and Realizing that area is proportional to diameter squared: L2 = L1(D2^2/D1^2), where D2 is new diameter and D1 is the original diameter. FWIW, in sims* using MJK's WSs I found that accounting for the end correction difference was more accurate, probably audibly so if a big change in diameter was made, but as always YMMV: L2 = L1*(D2^2/D1^2)+(D2-D1)^2 GM __________________ Loud is Beautiful if it's Clean! As always though, the usual disclaimers apply to this post's contents.

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18th March 2005, 10:40 AM	#2
baggystevo82 diyAudio Member Join Date: Dec 2003 Location: Herefordshire	If you use the ratio 1"=25.4mm that's close enough for most applications. I've started a thread on the enclosure you want to build here, where I think a few of us are considering it: Fostex FE126E reference design opinions Feel free to join us and let us know how you get on. Good luck, Steve

18th March 2005, 01:18 PM	#3
Skitch72 diyAudio Member Join Date: Jan 2004 Location: Indiana	Thanks for the reply and I will keep an eye on that thread to see what others are trying out. I don't have any issue converting the mm to inches but the port comes out to 1.18" in diameter and 4.5" long. I don't have any material that is that diameter and wondered how to calculate the new length if I change the diameter to 1.5".. Maybe I'm not making sense... (wouldn't be the first time) Tim

18th March 2005, 04:55 PM	#5
Skitch72 diyAudio Member Join Date: Jan 2004 Location: Indiana	Thanks! that is exactly what I needed! Tim

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