2-4" vents vs. 1-6" vent? (1 Viewer)

[jeff lam]

I ran over my tempest sonotube ideas over to Dan at Adire and he said:

Anyway, for your design, I'd look at 18" diameter tube, 72" high. With 1.5" thick endcaps inset, you're looking at ~287 liters of internal space. After driver and vent displacement, you'll be around 275 liters net.

I'd tune to around 17 Hz. To do this, and to use flares, I'd go with two 4" flared vents (like our FP4 kits), each with a 17" effective length (overall actual length is 18"). They will equal a 5.66" diameter vent, and are

considerably lower cost than the 6" vent flares (which are available from other suppliers for around $50 for one pair). It is plenty of venting for your application.

What do you think of this design, it's pretty big @ 6ft high. I'm not sure if I want to go quite that high, I may have to use 20" sonotube instead.

Anyway, I know many of you used a single 6" as apposed to 2-4" flared ports. What is the advantage to this(actual sonic difference, not air flow and speed)? Also, where can I get a 6" flared kit and how much do they cost?

Thanks!

 

[Fred Seger]

For what it's worth here's my two cents.
I think two four inch vents is plenty, especially considering they are flared. And you won't notice any difference in the sound. Actually two straight four inch ports or one straight six inch port would probably suffice.
Source's for 6 inch ports
Link Removed
http://www.tune-town.com/Products/Ro...stallation.htm
As far as the size goes, I think you could cut a foot or two off that sub and still have a great sub.

 

[Dustin B]

I don't think you would hear the difference between two flared 4" ports and one straight or flared 6" port. However, a straight 6" port can be done from just plain PVC pipe which will be a fair bit cheaper than two of those FP4 flared port kits.

 

[Neil Joseph]

I was originally comparing two 4" ports for my DIY sub but I changed the design for a single 6" port which not only has more surface area but simplifies the construction process because only 1 port hole must be made in the endcap.

 

[jeff lam]

True, it will be much easier to cut only 1 port hole as opposed to 2. Besides I think 1 port will look better than 2 anyway.
Anyway, what about the size of the enclosure, is there any way I can cut down on the size by about 1ft or so?

At 18" and 6ft tall, it gives me over 10ft^3. Is it possible to get simmilar results from a shorter tube?

 

[Patrick Sun]

You're going to have model shorter tubes (find the volume of each, say, 3" section of tube takes up and subtract off the volume and model those new enclosure volumes) and see where that point is that will diminish low end performance.

What's the point in using a Tempest if you shave off too much enclosure volume and wind up with a F3=30Hz. I would venture to say that 8 ft^3 is probably going to be the break-even point. Any lesser than that, and you'll better off using a different driver.

Also, go with the 6" port (don't even need to flare it, it's plenty wide enough).

 

[Gil D]

Jeff,

18" tube 5'tall is more in line with the 214L (7.510ft^3)Adire alignment. A little less extension than the EBS design but still plenty of output from what I hear from Dan W. This is what I am going with.

Gil

 

[Dustin B]

Double check the actual diameter of your sonotube. My 18" was actually more like 18.75" inner diameter. My calculations gave a 5'2" tube with a Tempest and a 24" long piece of 6" section 40 PVC pipe inside it a net volume of 260L. Add 3" of end cap and 6" (4" would work too) of leg and you get 5'11" for the total height.