Axiom Home Page Forums General Discussion Home Theater EP175 or Velodyne DEQ10-R?

Hey Micah. Have you listened to the M80s in pure 2 channel? Hows the base on them, nice and tight? Take a peak around the back near the bottom and what do you see?

Well I'm not saying that the philosophy is correct, only that car audio subwoofers (from the 80's and 90's anyway) were designed this way, and so car audio nuts like myself got used to this being the rule of thumb.

But it seems to me that there must have been some reasoning behind all of this. For instance it still makes sense to me that if you're after MAX SPL, a ported design has advantages in this area. Because you get both the air moved from the front of the speaker, and the air being moved from the rear of the speaker out the port. If there were absolutely no differences in the two designs, then why is the EP600 ported and the EP800 not ported?

I didn't say there were no differences, just that the characteristics depended on a lot more than whether the sub is ported or sealed.

You'll say what I bloody well tell you to say and you'll like it God damn it!!!!

Thbbt.

Wow, when did you become Ken's wife?

If we compare 2 sub that have similar spec and SQ does a sealed one provide less shaking in the surrounding environment than a ported one?

The short answer is no.

As you can see from the response curves I posted earlier, a ported sub rolls off differently than a ported sub. If the driver is of high enough quality and you can use equalization or digital sound processing to shape the response of the sealed sub to be the same as a ported sub AND the driver is of a high enough quality that the equalization does not introduce huge amounts of distortion, they will sound the same.

This thread is a good candidate for the subwoofer myths link.

http://www.audiopulse.com/know-how/subwoofer-driver-guide/myths-about-subwoofers/

Micah. Though the back of the driver is being used, the volume of the enclosure and the port act both as an amplifyer/resonator and as a filter. The frequencies (and loudness of the frequencies) coming out of the port are different than what you get from the front of the driver.
::runs to make a picture::



Think of the output of the front of the driver as the response of that driver in a sealed enclosure. What you get is a summing of the two to produce the response curve of your ported sub. That is why, for the same driver and without EQ, a ported design will play lower than a sealed one.

The reason a proted sub will play louder is efficiency. You are not wasting any energy compressing air in the sealed interior of the sub. I suspect that a ported design is also more effectively coupled to the air mass in your room (acoustic coupling).

As to why spl subs sound crappy, its how they are designed. The designer does not care about the accuracy of the sound reproduced. He only cares about how much sound the sub can generate in the enclosed space of a car. There is no need to worry about damping or linear excursion or even motor noise. Sounds sorta like music? Gets REALLY loud? We're all good!

Why is the EP800 sealed? Check out the size of obsi's ED A7-450s. Most people don't want huge boxes in their living rooms.

Oh, and if you want to get super efficient take a look at horn subs. Be warned though, to get a response close to the EP800 you need a sub the size of a large refrigerator!