WANTED: 56mm ID port

[peterpan]

Please help me find this size port, I have searched everywhere I know. Thank you. 56mm internal diameter x 185 long

[kelticwizard]

Are you making a box up new or replacing a damaged or missing port in an existing box?

If you want, I or some other member here can give you the dimensions for a port with an Internal Diameter of 50mm, 60mm or any size to give the exact equivalent tuning for your 56mm X 185mm port. It's just a case of running it through any program.

Internal dimensions-or even external dimensions of a speaker with the thickness of building material would help as a double-check, but are not really necessary.

You might also want to know that a mm here or there in diameter will not-repeat will not change the tuning to any real extent.

Still, you want to get the tuning exactly right for your project.

Don't forget to give the Internal Dimensions of whatever port material you have available.

For instance, in a 42.8 liter box, a 60mm X 215.5 mm port gives the exact tuning of a 56mm X 185mm port.

Similarly, a 54mm X 170.6mm port gives the exact same tuning as a 56 X 185mm port.

Things will vary slightly from program to program, but this issue is not quite so dead-on critical as all that.

Post the diameter of pipe you have available, adn I or someone else will give you the equivalent length.

[peterpan]

Thank you for reply. the box is h=40mm w=20mm d=23mm, INTERNAL VOLUME, ports available nearest==62mm ID and 75mm ID. peterpan

[kelticwizard]

Originally posted by peterpan
Thank you for reply. the box is h=40mm w=20mm d=23mm, INTERNAL VOLUME . peterpan

Err, by any chance, do you mean cubic centimeters? Because at 25.4 mm per inch, your enclosure would be an inch and a half by an inch by an inch or so.

I know they are coming with some really good mini-enclosures these days, but this would really be something.

[kelticwizard]

What you have is a box that is 18.4 liters. You might want to double check-I'm not that familiar with Metric.

According to WinISD, an 18.4 liter box will be tuned to 41.77 Hz by a port that is 56mm dia by 185mm long.

Also according to WinISD, that same 18.4 liter box is tuned to 41.77 Hz by a 62 mm diameter port 231 mm long.

Also, you get the same tuning with a 75 mm port 350.4mm long.

If you haven't built the box yet, I would suggest using the 75 mm vent-using an easily available elbow if necessary-and increasing the volume 2.5 liters or so. The 62 mm pipe's noise figure is good. The 75mm pipe's noise figure is even better. If you add the 75mm vent to the 18.4 liter enclosure, the tuning will go up to about 44 Hz, which isn't much.

[Vigier]

Hi,

can you get your hands on a 60mm reflex-port? Since simulation-programs always use the inner-diameter of the port and the products-info always give the outer-diameter, the 60mm will do fine (since a 2 mm thickness is pretty usual).

Grtz, Joris

[moses]

If you have a drill press you could easily grind down an old large spade bit to 56mm, or use a fostner bit at near that size.

[kelticwizard]

I would point out that in an 18.4 liter box, with a 185mm long port: enlarging the diameter of the port from 56mm to 60 mm only increases the port tuning by 2.5 Hz, from 41.7 Hz to 44.2 Hz. That should not really change the sound.

In many aspects of the ported box, approximations will get you through.

[peterpan]

Thank you all for your help. peterpan