The BasX Sub8 absolutely
CAN deliver 28 Hz... the published specs are quite real and we
HAVE measured them.
However, the level of output it can deliver at 28 Hz is limited by the amount of air it can physically move.
The Sub8 will go as low as many much larger subs... it just won't play very low frequencies as loudly as they can.
What most people describe as "port chuffing" is simply the sound of air blowing in and out of the port.
At certain frequencies, in a subwoofer design with a tuned port, there will be a lot of air blowing in and out of the port.
This can be minimized by careful design, but many of the design modifications that reduce port noise also increase the overall size of the sub.
Larger diameter ports are quieter, but must be longer in order to be tuned to the same frequency; flared ports are also usually quieter, but also take up more space.
Playing lower frequencies equally loud requires that you move more air than with higher frequencies, which often results in more port noise.
And, since the sensitivity of our ears decreases at very low frequencies, very low frequencies must be played at higher volumes to be perceived as loud.
One of the best ways to reduce port noise is by taking advantage of room gain.
When you put a sub against a wall or in a corner, you allow it to deliver more bass into the room, while doing less work (and making less port noise).
Let's start by sitting your sub on a table in the middle of the room.
The sound wave exiting the sub expands in a sphere around it... and delivers a certain amount of loudness (and a certain amount of port noise).
Put that sub on the floor, and the bass output will go up by 3 dB, but the port noise will remain about the same.
Move it against the wall, and you'll get another 3 dB increase in bass output, but again the port noise will remain the same.
Push it down the wall into a corner, and you'll get another 3 dB increase in bass output, but still the port noise will remain the same.
Before room correction, you usually had to select the spot in the room where the bass output of the sub would balance with everything else.
Today, WITH room correction, you may be able to use that room gain to good advantage.
Putting your sub in a corner will still result in a major boost in bass output at low frequencies.
However, if you're lucky, and it doesn't end up boomy when you do so, room correction may be able to level out the frequency response...
If so, the room correction will lower the bass to the proper relative level... while, at the same time, reducing or eliminating port noise.
