Isobaric Subwoofer

Step 3 Ports

The inner port calculations reveal that the port must be 271mm, this is fairly tight considering that each chamber is just 149.5mm wide plus 36mm for the centre baffle giving a total of 335mm
Assuming we arranged the port so that it was centred on the baffle that would only leave 32mm at each end (less once we fix some wadding/sound-deadening at each end)
It is generally accepted that the ideal is to leave at least one port radius between the opening of the port and any surface. Unfortunately with a straight port located tight in the corner we can't achieve this, so the plan is to bend the port a little.
I suppose it doesn't really matter how you do this as long as some attempt is made to maintain a fairly uniform internal cross section.

Comments

[Koil_1]

One could just as easily use a 90° bend available from most places that sell PVC fittings. It's what I do and it works well because of the uniformity of the curve. They usually cost less than $5. Preping the fittings isn't that hard either if you don't mind the cleaning chemicals and glue. Another added bonus to this is the flange on the end that can be used to further extend the port to match the harmonics of larger drivers.

[toastyboy]

Good point, I did consider using premade fittings, not sure why I opted to make one now...