View Full Version : Just have a small question..

09-18-2012, 10:01 PM
What is the effect of using a 4th order passive radiator enclosure compared to sealed or vented enclosures?:laugh:

09-19-2012, 06:51 PM
Can anyone help me out on this ?

Steve Milton
02-01-2013, 01:23 AM
The same as the difference between a rear-loading horn and a tapered transmission line. It's also the same as the difference between an acoustic suspension coupled bass reflex and a Voigt pipe. All enclosure types (alignments) are a byproduct of the modeling it takes to achieve the target response curve at the listening or microphone position. A simple way to test for yourself is to get an RTA app on your phone, then play pink noise on volume setting 20 (for instance.) Have a buddy take a close up picture of the response graphic display, with your enclosure in its current position. Next, hop in the back, rotate your box 90 degrees in either direction and repeat the process. Put both pics on your PC and then pull them up and put them side by side. Notice that your response curves were different. This means that the impedance curve has changed by rotating the enclosure. If you move the enclosure closer or further away from the side of the trunk and take another pic of the phone display, you'll see it has changed again. That is effectively changing your alignment, though the "box" stayed the same. Nobody can arbitrarily give you a correct answer to your question. That is because it depends on many variables and it must be modeled with a program that can actually calculate those variables. There are literally infinite variables for just a sealed enclosure. Needless to say, a vented or passive radiator or more complex design has that many more times more variables to calculate.