Flex hose as port in vented cabinet ?

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Does someone out here have any experience with using a flexible hose (e.g. those used in ventilation systems) in your vented woofer cabinet ?

The hose will be firmly attach in both ends, so it keeps the required calculated lenght.
 

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My problem is that I need a port lenght at app. 68 cm = 26.5" so it could be nice to use a flexible hose to make a nice bended port without 90 degree bends.....

The dia. of the port is 10 cm = 2.5", so vacume cleaner hose isn't big enough (not those I've seen)

I was thinking of coating/spraying the hose with some kind of "hardener" after the fitting, so it won't flex.
Could this be an idea ???
 
Hi
I think you could use corrugated flex hose for a tuned port. But you should be careful to keep maximum air speed velocity in the port lower due to non smooth surface of the hose. IMO target air speed say less than 3% speed of sound max.
Then you would be more likely to see a larger diameter and in turn longer port dimensions than the normal calculation.
You could try the program UniBox if you have MS Excel which charts air speed velocity versus frequency in a vented enclosure as you change port dimentions. As always check final tuning with a measurement of impedance minima. IMO Flexing would most likey be a second order effect for such a large port.
regards,
 
I don't think the flexibility is necessarily a bad thing, but the corrugations mean that your port may make noise. A whistling noise is often made by these sorts of pipes. The flexibility may actually reduce this tendency; but this is just conjecture, I have never used one.
 
Hi
Thanks Jan, I guess you have Bang&O engineers on the job already.:D Seems B&O would use a custom driver for that design along with heavy EQ. IMO would be concerned with using just one 10 cm tube with a 15' sub. It's too small for such low tuning with a big driver at 1000W, will be supersonic air flow here. Look around and get other advise on this. OR check the design with UniBox.
Regards,
 
I won't argue with you regarding your calc of air speed ;)

However I know that this driver in a 125 liter (cf ???) cabinet with a single 10 cm flared port (correction from one of my first posts 10 cm = 3.9") plays down to 25 Hz at high power without any port noise...... The guy who calculated this for me has uses such speakers.

However I will of course describe the listining result here soon ;)
 
A better option may be the reinforced plastic hose used for water and 'trash' pumps. its available in sizes from 2" to about 6" dia and is a thicker harder version of what you showed originally. a PVC flexible (quite stiff though) hose with a spiral wire reinforcement. I have considered using it before, but never had a need to. Try Hardware and industrial pump equipment sales.

http://www.machinemart.co.uk/shop/r...ivery-hose/path/hoses-couplers-valves-filters

click on the non existant image in the upper left corner of the main window to see what I'm talking about, I'm sure you can get larger than 3".
 

AKN

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Hi ACD,

Although not your thread subject, i must agree that one 4" port is very little for your box size, tuning and power.
Simulation with one 15" JBL 2235H in 125L box, 25Hz tuning, one 4" port and 150W input.
 

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I promissed to return ;)

Got the complete speaker sets up and running (though at the moment using a passive crossover). So fare no problems with the ports using my AMCRON's DC300 Series II in bridge configuration, however I can imagine using higher power than 300W you just put your face in front of the ports and you don't have to shave :D

More information on www.audio-circuit.dk under my projects
 

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Don't forget you can get 45 degree PVC bends.

There are some Wide radius bends available, these are for electrical conduit to make it easy to pull cables into buildings.. I have seen these in 100mm with a bend radius of about 400mm

These are usually very thick PVC becasue they are designed to be cast into concrete slabs
 
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