Multiple Degree of Freedom Cavity Resonators
Research & Development Project

Most advanced Cavity Resonator Applicatons
by Shigeru Suzuki
News: MCAP-CR Simulator GUI Version is released! Now Windows x86 executable file was released. See this!
Last Update: 2013/03/25
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Design & Application
including Feastrex
Cavity Resonators

Technical Documents
& Simulation Software
MPR: Multiple
Pipe Resonator
Web Site
 was closed
Blog Proposed Drawaings
 (Not tested)
Application Reports Contribition

QNDR Loudspeaker About Myself

Your financial assistance is very much appreciated.
Patrons are eligible to manufacture and sell patented MCAP-CR applications.

Contact at:

Join MDOF-CR Project!

Technical information of MCAP-CR was released in 2008 by myself. It is very new technology and technology is now being developed. You are invited to join this world-premier true Multiple Degree of Freedom Cavity Resonator project. You have no obligation to release personal information, and no payment is required. You do not even have to register yourself to any database. Just send an email to me and express your interest. It is absolutely free. What is expected is just your feedback.

You may request some design of MCAP-CR for some drivers. New design will be provided, if you request by email and agree to terms and conditions written in the next section. It may take a couple of months to release new design depending on my schedule. In this case, all the design documents and drawings are open to public and you are agreed to report your impression about the design to me. Your impression with your name (or handle name, nickname etc.) will be open to public.You do not have to measure frequency response or other specification, but your impression is very important for other readers. Thus everyone can share information and one's success in audio life. All the information in these pages is free for everybody and is given to public domain.

Your feedback is very much appreciated.

You may send your own design documents with drawings to me after you actually made the cabinets with photographs. Your information will be open to public with my comments, unless you do not want to do so.

Terms and Conditions to use information of these pages

All the information in these pages is open to public. Anyone may link any part of these pages from any website.
Readers of these pages may use contents of this site for non-commercial personal or public purposes. You have to reference my name, if you open these contents to public.
Satisfaction is NOT guaranteed. Readers may not claim anything to me.
Anyone who wants to use contents or idea of these pages has to agree to the following conditions:
  1. You may not complain about performance, any error or mistake.
  2. You must understand that there may be any deffects, errors, and uncertainty and potetial risks. You must use any information of this page at your own risk.
  3. You may not use any information of these pages for commercial activities unless separate contract.
Your report of impression, evaluation, any bug, error or mistake is appreciated.
List of Contents
This page is under development -- please go to above links for English information and Japanese information. Please wait for other languages (Deutch or Italiano may appear in next 10 years).
Author of this page: Shigeru Suzuki
Contact me at
  m c a p s p e a k e r s @ g m a i l . c o m
(Spaces in above address are for protection from spam. Please remove all spaces from above email address.)

It has been believed that multiple degree of freedom cavity resonators(MDOF-CRs) such as double bass-reflex cavity resonators are difficult to calculate and design. It has been proven that it is completely myth. We may design any type of MDOF-CRs, if we just derive governing equations and calculate eigen valuses of the system.

You will find that it is very practical to design MDOF-CRs. MDOF-CRs include:
MCAS has been existed as concept, but only double bass reflex CRs have been made somewhat practical.
Other types, MCAP, AICC and CBS, did not exist in the world; it has been, at least, proven that MCAP is well practical.
You might not believe this fact, you should read my pages. They are scientifically analized and some are experimented with measured data and detailed drawings (see Application Reports).

MCAP-CR was breakthrough to realize true MDOF-CR systems.  Why don't you try true MDOF-CRs?
You will see some applications of MDOF-CRs here.


DIY may be joy for some people. It would be a pleaseure to see the progress of one's own work, and hear one's own sound. Speaker system is suitable for DIY. We do not have to do it ourselves, if we have enough fund and skill of mechanical and electrical drawing; however, we may want to verify and tune the system in order for us to make it preferable. Because of this reason, we need somewhat to do it ourselves.

Picture in right shows inside structure of my original speasker system.
This enclosure was an MCAP Cavity Resonator.  Details of this system was discribed in PDF files.
Dan you imagine how this system works? Original systems will bring joy to engineering-minded people. Hand craft can make this kind of complex structure, but complex structure may not be suitable for mass production. This is one advantage of hand craft.
inside TCAPSS

Speaker systems in the left are also my original. You will see four holes in the front panel. They are not just four holes but four independent bass-reflex ducts. This is also an example of MCAP-CR. This system consists of  five chambers and eight ducts inside the enclosure. This system has eight characteristic frequencies, so that it generate low frequency using just 3" full range driver.

Another speaker system below MCAP-CR was just normal bass reflex system. It did not interest me at all, and already thrown away, unfortunately. I love what interests me.

Actual manufacturing report will be helpful for those who want to begin hand craft works. I will upload some.

Multiple-Chamber Aligned in Parallel Cavity Resonator (MCAP-CR)

This is world premier speaker system that extends frequency response over low region.
Patent was submitted to Japan patent office in 2007; I encourage amatuer speaker craft lovers to try this system. Patent will not affect non-commercial personal use.
All the technical details are given in this page, so that anyone could employ the idea and develop one's system. MCAP-CR has complicated structure, but designing and calculating scheme has been well developed. Concepts of MCAP-CR is described here. All the equations are seen here.

Please do not hesitate to write to me. I am willing to communicate with those who are interested in multiple-degree of freedom cavity resonator speaker system.

Bitte geben mir ein Email, wenn Sie etwas interesant in MDOF-CR finden. Ich freue mich Ihnen zu schreiben.


You will see how measurement was done in PDF file.
Here is a note why I insist on using Sweep Signals inatead of Pink Noise or White Noise to check Frequancy Response:

Sweep Signal
Reasons why pink noise was not used but sweep signal was used:
Sweep signal is suitable for tester to capture character of the speakers because we can check the response while listening the signal. We have nothing to know about detailed characteristic while testing pink noise or white noise: they will not give frequency response information just from sound. Response at some frequency may be just emvironmental noise or system's noise. We can separate this kind of noise, if we use sweep signal.
Another advantage to use sweep signal is to view harmonic distortion monitoring FFT window.

harmonic distortion
FFT Window while monitoring Sweep Signal
Some of details of my measurement will be uploaded later.
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