Slot ports or round ports .... which is better ...?

[norman bates]

So, a slot port is less long given same in2 (compared to round) ?

Because of frictional losses ?

I think i remember someone mentioning this years ago.

 

[JimT]

I'm lost when it comes time to calculate slot dimensions. Any hints?

 

[GM]

So, a slot port is less long given same in2 (compared to round) ?

Because of frictional losses ?

I think i remember someone mentioning this years ago.

No, round is the most efficient shape, ergo shortest.

If by slot port you mean shelf vent where three sides of the cab plus top plate has a much higher end correction, then yes, for a given vent area [Av], tuning, the top plate will be somewhat shorter than round, but been told that it will still have higher frictional losses, though still desirable for small cabs tuned low.

I first saw one in an early '50s Altec 604 [~50 Hz Fs] consumer custom cab barely big enough to hold the driver, shelf vent [Av = ~Sd], all of which was heavily damped with fiberglass insulation and was shocked at how powerful/'tight' the [mid] bass was with an Fs tuning.

Certainly enough for the radio, TV, mono recordings of the times.

GM

 

[GM]

I'm lost when it comes time to calculate slot dimensions. Any hints?

https://www.diyaudio.com/forums/att...rt-slot-port-math-effective-port-length-1-jpg

GM

 

[norman bates]

That is a wild link.

Long story short, slot port the width of the box needs less length.

Slot port questions -

Techtalk Speaker Building, Audio, Video Discussion Forum

Jeff bagby (rip) agrees too.

 

[JimT]

Those links are great.

Thanks.
Jim

 

[GM]

 

[aceinc]

Hey guys, now i am ongoing building a subwoofer project ...

I need help ... the ports for subwoofer i found locally were too small ..... to make things easy for me to work ..... i know i can use PVC pipes as ports .... but there are no way to make flares for the port ends ....

so therefore considering the use of slot ports came to my mind .... can give advice .... slot port or rounded port is better for subwoofers ....?

I have never done this specifically, but I think it may work and it would be fun to try. To make a flare in a PVC pipe with two tools.

1. Heat source.
2. Form.

The heat source could be something as common as a high powered hair dryer. The form could be a bowling ball, or other spherical object. Press pipe end against form and begin to heat applying constant pressure.

I have used this method to bend PVC pipes and expand them slightly, and have thought about using it to flare it but have never done so.

 

[dannyjmf]

visit this site

Collo's DIY Subwoofer Tools

it already answered here

 

[Jared]

nothing says the PVC has to terminate on the baffle either. A few layers of MDF behind the baffle with the PVC only inserted into the rear most layer allows the front layer(s) to be rounded over with a router.