How large should be my port

[batata004]

Hi my friends! I am complete new into this hobby of building speaker boxes and after making a lot of research I still couldnt discover how to solve this question.

I have 2 speakers (125w RMS - Taramps 7driver HD 250S) which have a really really really nice sound (from low-high). I built a box with the following inner dimensions: 30 cm wide, 20 cm tall and 15 cm depth = 9 liters. The wood is 1cm thick however the front panel is not thick so I could easily cut the holes (it's 3mm and I will surely improve the thickness of the front wood in the coming days). Picture below:

I know I should use a much larger box with these speakers, however I dont have any space left for the place where this box will be placed in my house.

My question is this: I already made a hole in the box with a diameter or 6cm to put the port. My question is: how long must be the tube that I will insert into this box in order to get a good low bass (30 hz? maybe 40?). You can see in the picture below I 3D printed a tube with 6cm diameter and 10cm long, but I still dont like the bass (it does not improve much when compared to have the box sealed).

 

[puppet]

This isn't happening. At the absolute minimum you're about 22l short on volume .. using just one driver. Total Vb =30.5l Fb=44hz F3=40hz 6cm(dia) x 10cm(long) vent tube.
This gets you a +1.5dB ripple at 115hz. Below that, response looks just like EBS3. Limited to around 94dB SPL at 1m unless you have a HP solution to apply below tuning.

 

[Zek]

When you make a speaker box, you have to know the Thiele/Small parameters of the speakers you are installing and then you must use one of the programs to calculate the volume of the box and the bass reflex opening.
This way no one can tell you what is good for your project.

 

[Rick Sykora]

For quick estimates, I use an iOS app called Speaker Box Lite. At 9 liters all you really can do is a sealed box and eq it for more bass. If you are able to apply some specific filtering, might try applying a Linkwitz transform.

 

[fineMen]

Hi my friends! I am complete new into this hobby of building speaker boxes ...

It won't work at all. Not only is the so called Thiele/Small alignment far off, but also in such a small volume a port will not behave. It will either be too long to fit length and volume wise, or it would be so small of a diameter that it will generate more of a wind noise than actual bass.