Advanced Loudspeaker Application Development Project

Multiple-Degree of Freedom Cavity Resonator System

Project MCAP-CR


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Pipe resonator is one of powerful low frequency boost enclosure. This approach adds characteristic frequencies of pipe resonator. Pipe resonators are practical for builders, because design is not difficult.

Here are two approaches of improved pipe resonator technique:
  1. Pipe Rsonator with Additinal Holes (PRAH) to increase number of characteristic frequencies. This is probably my original. There may have been this, but information was not found.
  2. Multiple-Pipe Resonator (MPR). MPR consists of a chamber, some pipes with throttles. This approach aims to increase number of characteristic frequency as well as PRAH. This unique approach was developed by my friend Mr. Osawa.
Pipe resonators are not so complex as generalized cavity resonators, so that I show only principle of PLAH and MPR below.

PRAH and MPR are essentially the same idea. PRAH is more simple, but MPR is better to design. Advantage of PRAH is to be able to modify existing pipe resonator: just to drill holes. And if you do not like PLAH, you just cover the holes.

MPR is more complex, but easy to design. MPR is very theoretical and you will get more accurate characteristic frequencies.

Here is the formula to calculate characteristic frequencies.

Resonant Frequencies[Hz]
Pipe length = L0 c/4L0, 3c/4L0, 5c/4L0, ...

Pipe length = L1 c/4L1, 3c/4L1, 5c/4L1, ...
Pipe length = L2 c/4L2, 3c/4L2, 5c/4L2, ...
Pipe length = L3 c/4L3, 3c/4L3, 5c/4L3, ...

Try them if you are interested in pipe resonator!