Sprite Boombox Vent Tube Dimensions

[multiholle]

I'm building the Sprite Boombox. To save on costs I would like to use regular PVC pipe for the vent tubes. The available diameters differ from the suggested values available here: https://sites.google.com/site/undefinition/sprite

Instead of 35 mm (1 3/8") I'm using 37 mm. How can I calculate the appropriate length of the vent tube?

At the back of each chamber is a 1 3/8" diameter vent that is 5.75" long. This tunes the enclosure to 63 Hz, and will get an F3 of 51 Hz

 

[mikejennens]

I came up with 6.95 inches using this tool:

Port Length Calculator

Mike

 

[freddi]

I get 160mm (~6.3" length) of 37mm ID to tune 4 liters to 63Hz (~63.2) with George Augspurger's "VENTWRK

 

[Jerms]

Try WinISD.... Though it's a little more involved than simply talking ports.

Or have a read....JL Audio header Support Tutorials Tutorial: Enclosure Ports

 

[multiholle]

The pipe was actually 36 mm so I went with 6,14 inch. Unfortunately I have trouble with kind of a rattling Noise. Especially while playing music with deep bass.

I made a video playing Rihanna at a low volume. Does the driver move to much? What's the problem?

https://youtu.be/P8JlYBF6S-c

 

[Jerms]

It's important that the box is sealed (apart from the port). Running it with the lid off you are running it open baffle. The poor thing is probably bashing itself to pieces.

Don't run it loud (or at all) until each enclosure is buttoned up properly.

 

[multiholle]

It's the same behaviour with the lid closed. Playing deep bass it makes this rattling noise. Does it have to be 100% airtight?

 

[Jerms]

It needs to be liberally glued or screwed down tight onto compressible foam tape.