Unibox help??? (1 Viewer)

[JimHal]

What exactly is the "Port End Correction" field for a Vented Box.

I have chosen a 5" port with two flush ends. It resuls in .85 in this field.

Is this value .85 inches, cenitmeters, or something else?

 

[Jack Gilvey]

What exactly is the "Port End Correction" field for a Vented Box.

I have chosen a 5" port with two flush ends. It resuls in .85 in this field.

Is this value .85 inches, cenitmeters, or something else?

It's a length correction factor that changes automatically as you select port type (flared, flush, etc.) so it's not a number you need to change yourself. I don't know how it's arrived at.

 

[JimHal]

So the "Port Lenght" field will be the actual cut length of the port, right?

Thanks for the help.

 

[Jack Gilvey]

Yup.

 

[JimHal]

Yippee. Almost time to cut.

 

[Jack Gilvey]

If you use flares, it includes the flares.

It's always a good idea, though, to start a little long and fine-tune it since there will be variations in volume, etc.

 

[JimHal]

Another question: This one about F3.

I have a Dayton 12" DVC, I was planning on a 120L enclosure, a 5" port tuned to about 18.5Hz resulting in a length of 76.88cm. This will give an F3 of 20.57.

Would I be better off tuning to 20Hz to lower the F3 to 19.67Hz? Will this difference even be audible without an SPL meter?

I am wanting a sub the will be good for mostly movies.

 

[Jack Gilvey]

I think the 120L/18.5Hz looks great, it's a smoother curve and the 5" port keeps airspeed good with about 250 watts applied. Given the effect your room will have, though,you'd be hard-pressed even to measure a difference between those two tunings, much less actually hear any. Just make sure a 30" port will fit, it's pretty much got to be a tall tube.

 

[Brian Bunge]

Jack,

It's nice to know I wasn't the only one with Unibox questions!

Brian

 

[JimHal]

Great, thanks Jack.

I'm planning on using a tube. I originally wanted to build a box but it is just way too big.

Thanks again for your help.

 

[Brian Bunge]

BTW, you can drop the DVC 12 into the Shiva EBS box (142.5L with 20Hz tuning) and use the standard 4" dual flared port from PE as well. Unibox gives a port length of 37.19cm or 14.64". You get 108dB at 19Hz and 110dB all the way out to 80Hz or so, anechoic of course.

I just placed an order. Both the driver and port are on backorder.

Brian