i was told that if u tune anywhere in the low to mid 20's it will sound like a sealed box but it will have the output of a ported box...so if a sealed box does like 20hz at -3db...the ported box (depending on how big it is) tuned in the low to mid 20's should be higher...it would be nice to have a box tune to 22hz that has a +3db bump at 20hz
80
At frequencies much higher than the tuning point, the air mass in the port stops moving and becomes like another wall in your enclosure. So basically, the enclosure starts to act like a sealed box and the driver will react accordingly (speaking in the bass range and I'm ignoring all port resonances above the fundamental). In an enclosure tuned in the 20hz range, the driver will start to act like it is in a sealed enclosure around 40hz and up. That will also help give the setup the sound of a sealed enclosure for a good chunk of the bass range. The bass in my car is very punchy and tight with no traces of stored energy or sloppy transients. I would say it is very similar to the .707 sealed box alignment I have used with exception to 35hz and below, where my current box will play down there effortlessly and clean. No more bottoming out the driver trying to get decent output below 30hz.
Frankly, if you're going to tune to the low 20's you might as well simply go with a sealed design or IB for that matter. There is little point having a port there when its not being used...
So extra bandwidth is a bad thing to have? You would rather throw a ton of power at a driver and try to get all the excursion out of it that you can and drive up all that nonlinear distortion? Also, just because the port is tuned in the 20s does not mean that it will not aid in output above and below tuning. If designed correctly, the setup can sound sealed down to a certain frequency and then below that, the port comes into play to aid in output and help with cone control. The stored energy problems and group delay effects are also minimized by tuning so low and you drive those effects down out of the more common spectrum.
In my testings, the large sealed enclosure rolled off too quickly below 35hz (in car) and lacked definition and output in the 20s. Even IB systems can have this problem (depending on car and equipment) and even so, not many people have an option to run IB in a car environment. IB can also lack in output and power handling which leads to multiple large drivers when a single small driver could have done the same job with lower distortion.
So really, there is no point going sealed if you're looking for REAL bottom end extension. Yes, the port IS used in low tuned enclosures and yes there is a point if you're looking for a solid, low distortion, bottom end.
What are you listening to in car that is dropping down into the low 20's? I don't listen to anything like that, so I've never tuned that low....
It's not very common but it is out there. There are a lot of bass tracks from people like Bassotronics and the like that have a lot of content down there. I am a fan of that style music and listen to it often. There still is content in other genres of music as well and many times, it just goes unnoticed due to being too low amplitude. Avenged Sevenfold's song Almost Easy has some 20hz material in it that sounds pretty interesting. I listen to a lot of Ayreon and Arjen's stuff also contains content in the 15-25hz range. Many classical pieces can get down there as well.
It's not about playing songs with constant bass lines to show off how loud and consistent they are but rather to play music and enjoy the detail and depth to it. For example, I was listening to a blues song the other day that had a constant foot tapping against an old wood floor. There was a nice resonance that dug down very deep and it made my car cabin area appear to be much larger due to the apparent low resonance of the floor. That subtle content (I believe it was from like 18-21hz or so?) added detail that I was not able to get from listening to the track with my headphones that only get down to around 30hz before starting to crap out.
