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Need to buy/Make a port tube


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#1 PhilCookson

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Posted 18 Jul 2016 - 07:18

I need a 3" port tube that is 8.5" in length.

 

All the off the shelf ones only seem to be 155mm length longest, which is lacking 60mm or so.

 

Does anyone know where I can purchase a suitable port, or how to make one? Or is sit a simple case of slipping some drainpipe over it to extend it?



#2 Kei

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Posted 18 Jul 2016 - 08:51

Drain pipe is a good way to go if you want a round port. There is an excellent range of ports here. I used one of the multi part ones on mine, buying just the inner and outer flares and a length of drain pipe to go between as it allowed me to be able to adjust the length.Calculators like winISD and those you find online usually give results that are slightly too long with a tuning frequency that is lower than what you were trying to achieve. Without measurement tools, it's not so easy to work out if you need to tweak the length.

 

The ends are either side in this picture.

gallery_44179_303_443014.jpg


Edited by Kei, 18 Jul 2016 - 09:12.

Headunit - Alpine CDA-137BTi
Crossover Alpine 3672 X-over
Amps - Alpine MRV-F400, Alpine MRV-1000 & Alpine 3553
Speakers - Seas L18RNX/P, Vifa XT25 , Vifa TG9
Sub - Dayton Reference 10" HO


#3 PhilCookson

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Posted 18 Jul 2016 - 12:52

Now I am really confused as there are straight one, bent ones etc.

 

This is the kind of box I am making

 

I need to upload some images, but its saying I cannot use FlickR or Photobucket links



#4 LBaudio

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Posted 18 Jul 2016 - 13:57

You can take a look at Phonocar 3" aero,....looks good and it is cheap. You get two PVC pipes of different lenghts


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#5 MR2FC

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Posted 18 Jul 2016 - 16:29

http://www.conrad.com/ce/en/overview/1312045/Bass-Reflex-Tubes

#6 PhilCookson

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Posted 18 Jul 2016 - 21:38

So, these are the dimensions of the box

 

[url=https://flic.kr/p/HRZBQp][/url][url=https://flic.kr/p/HRZBQp]box[/url] by [url=https://www.flickr.com/photos/95633633@N08/]Phil Cookson[/url], on Flickr

 

Where is the best place for the sub and port?

 

[url=https://flic.kr/p/Jj67aq][/url][url=https://flic.kr/p/Jj67aq]box2[/url] by [url=https://www.flickr.com/photos/95633633@N08/]Phil Cookson[/url], on Flickr

http://www.conrad.com/ce/en/overview/1312045/Bass-Reflex-Tubes

 

Only seem to do 3" in 4.5" or thereabouts, or 2.25" in 8" length



#7 LBaudio

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Posted 24 Jul 2016 - 14:29

Mount port at least one port diameter away from any enclosure wall also port mouth on both ends need the same clearance to perform corectly.


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#8 Bibby

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Posted 24 Jul 2016 - 19:45

Just to confuse you some more, you could actually make the box with a long straight rectangular port, by doubling up the walls where necessary. Along these lines, designed as required of course. Instead of it being S-shaped, it could just run along the back, or the base, of the box.

 



#9 PhilCookson

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Posted 25 Jul 2016 - 07:39

See I much prefer the letterbox style ports, but totally unsure how to calculate the requirements



#10 Bibby

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Posted 25 Jul 2016 - 08:20

Internal width x length gives you the area of the port hole, multiply by the internal length to give you the port overall inner volume.


My brain is fried so I can't remember which software I used to calculating required port volume by box volume, but I'm sure someone else can.


You could try dropping a message to EFMAX, Erksine is the bass master.



#11 bretti_kivi

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Posted 25 Jul 2016 - 09:47

if you have the port dimensions already, that should give you a good indication.. but greeef might be able to help, or go download for example winisd or bassboxpro. 

 

But just from the numbers you've given... this is for 500W or so? A single 3"/75mm will chuff more than Ivor the Engine ever did. A 30s play with WinISD implies you'll need to triple the port area (40Hz tuning?) to get speeds close to where they should be.

8" is also probably not deep enough for the sub if it's a 10", as it should be a decent distance from the back of the box, I've understood 50mm to be a reasonable distance.

 

What's the sub, what's the power, have you got the T/S parameters?

 

 - Bret


from a Precision Power manual:

"Before beginning, disconnect the negative (-) terminal of the battery prior to working on the positive (+) terminal to prevent a short to ground. This is important, unless you want to spend the rest of your life with a nickname like "Sparky," or "Smokey." Reconnect the negative terminal only after all connections have been made".

#12 PhilCookson

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Posted 25 Jul 2016 - 12:17

Sub is a 10" OZ Vector. Original thread was a few down from this one



#13 bretti_kivi

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Posted 25 Jul 2016 - 14:19

OK, so simulating a little with WinISD...... sealed would be good, to be honest. And you *must* go to *at least* 10" internal, as the sub itself is 9.25" deep.... 

 

The port they suggest in the manual will chuff like hell at 40Hz, It's 35m/s or so, which is way too much. Sealed of 0.8 cubes would probably play nicely. 

Ported: the design with a 40Hz tune peaks madly at 50Hz, even without cabin gain. A little better - but still peaky for my liking, but which would probably thump beautifully is 1.25cubes. Tuned to 32Hz. Peak should be around 55Hz. 

 

Port: Slot port the height of the box (12") and most of the way across the back. Total length of 33.8" (so that's 12" back + 21.8+1.5 = 23.3" or so along the back wall. Should give you enough space to jam the sub basket hard against one side and still not have to go much beyond 10.5" internal or so. Wind speeds are kept below 20m/s with that and 1.5" is two material widths so it's easy to space correctly.

 

Does this make sense?

 

 - Bret


from a Precision Power manual:

"Before beginning, disconnect the negative (-) terminal of the battery prior to working on the positive (+) terminal to prevent a short to ground. This is important, unless you want to spend the rest of your life with a nickname like "Sparky," or "Smokey." Reconnect the negative terminal only after all connections have been made".

#14 PhilCookson

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Posted 25 Jul 2016 - 21:35

OK, so simulating a little with WinISD...... sealed would be good, to be honest. And you *must* go to *at least* 10" internal, as the sub itself is 9.25" deep.... 

 

The port they suggest in the manual will chuff like hell at 40Hz, It's 35m/s or so, which is way too much. Sealed of 0.8 cubes would probably play nicely. 

Ported: the design with a 40Hz tune peaks madly at 50Hz, even without cabin gain. A little better - but still peaky for my liking, but which would probably thump beautifully is 1.25cubes. Tuned to 32Hz. Peak should be around 55Hz. 

 

Port: Slot port the height of the box (12") and most of the way across the back. Total length of 33.8" (so that's 12" back + 21.8+1.5 = 23.3" or so along the back wall. Should give you enough space to jam the sub basket hard against one side and still not have to go much beyond 10.5" internal or so. Wind speeds are kept below 20m/s with that and 1.5" is two material widths so it's easy to space correctly.

 

Does this make sense?

 

 - Bret

 

No, lol. Yes, it kinda does

 

I have measured the sub and its not 10" deep, its just under 5". I cannot copy n paste on my works PC, so now I am home, this is the sub

 

http://www.sonicelectronix.com/item_9556_Oz-Audio-OZ-V10.3-4.html?utm_source=ebayenterprise&utm_medium=affiliate&utm_campaign=21181

 

and here are the specs

 

http://www.manualslib.com/manual/576227/Oz-Audio-V10-3-2.html?page=3#manual

 

Reason I didn't want to go more than say 10" deep with the box is I want to keep it as subtle as possible in the boot, so wanted to use the width more. I am stick 12" height max as that's where the shelf roller goes which I cannot modify.



#15 bretti_kivi

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Posted 26 Jul 2016 - 08:43

argh, my apologies, I misread the diameter as depth. d'oh!

 

so yes, that slot port would be my personal preference. The 3" diameter is nuts for wind speed.

 

 - Bret


from a Precision Power manual:

"Before beginning, disconnect the negative (-) terminal of the battery prior to working on the positive (+) terminal to prevent a short to ground. This is important, unless you want to spend the rest of your life with a nickname like "Sparky," or "Smokey." Reconnect the negative terminal only after all connections have been made".

#16 PhilCookson

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Posted 26 Jul 2016 - 11:44

I don't suppose you have a programme that could give me the measurements for the wood I would need to get cut brett?

 

I'm happy building, but awful at calculations



#17 bretti_kivi

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Posted 26 Jul 2016 - 18:55

Sketchup? That would be my choice.

in 3/4" MDF

 

back: 34 x 12

sides: 2 off 12 x 10

top & bottom: 34 x 11.5

front = 31 x 12

port = 8.5 x 12 & 23x12. Round over one end of the 23x12 piece.

 

I think. outside dims are then 34 x 13.5 x 11.5. 

 

- Bret


from a Precision Power manual:

"Before beginning, disconnect the negative (-) terminal of the battery prior to working on the positive (+) terminal to prevent a short to ground. This is important, unless you want to spend the rest of your life with a nickname like "Sparky," or "Smokey." Reconnect the negative terminal only after all connections have been made".

#18 PhilCookson

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Posted 27 Jul 2016 - 07:44

Ahhhh, those externals make it a little too big for my allocated space, which is 34" long x 12" high x 10" deep.



#19 PhilCookson

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Posted 27 Jul 2016 - 07:54

I'm going to try to calculate this up on paper for myself, are we saying the port size should be 3" letterbox which goes 8.5" back from the front, then 23" along the back of the box?



#20 hertzman

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Posted 27 Jul 2016 - 08:24

Its going to be difficult to get a low enough tuned box with those dimensions without loosing out on too much port area. 

 

This is the best I could come up with for your dimensions. Should be around 1.25cuft after sub displacements as port displacement is already took into account. Tuning is around 35hz, maybe a tad higher, however if you extend the port much further then you will loose too much box volume. 

 

The only other way to drop tuning without making the box bigger or port longer would be to reduce the port size to 1.5" however this will probably result in port noise.

 

Re box calculator is a brilliant tool for getting your dimensions and cutting list prepared, just dont reply too much on its tuning figures. However to be fair this isnt far out at all, i just wasnt sure what the exact displacement of the sub would be.

 

[url=http://s1119.photobucket.com/user/hipwell1989/media/philcookson%20box_zpsyo0pedeq.jpg.html]philcookson%20box_zpsyo0pedeq.jpg[/URL]


Edited by hertzman, 27 Jul 2016 - 08:25.

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