Advanced Loudspeaker Application Development Project

Multiple-Degree of Freedom Cavity Resonator System

Project MCAP-CR


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MCAP-CR is typical application of Multiple-Degree of Freedom Cavity Resonator. You will find more details in Technical Documents.

There are a number of applications of standard MCAP-CR loudspeakeer system. We will see standard MCAP-CR applications, CBS-CR, and AICC-CR applications in this section.

QNDR is as well interesting. See below:

Table of Contents

1. MCAP-CR Family: Standard MCAP-CR / AICC-CR / CBS-CR

2. Standard MCAP-CR applications for 5" Feastrex Driver

3. Standard MCAP-CR applications for 5" Drivers (TB and Feastrax)

4. Standard MCAP-CR with QNDR (Quasi-Non-Dimensional Radiator) - new sound field presentation -

1. MCAP-CR Family: Standard MCAP-CR /AICC-CR / CBS-CR

1.1 MCAP-CR Family

There are three typical Applications:
Standard MCAP-CR (Multiple-Chamber Alligned in Parallel)
CBS-CR (Carbon-Bond Structured)
AICC-CR (Arbitrary Inter-Chamber Connection)

All the application examples were actually designed and built!
They have proven excellent performance of Multiple-Degree of Freedom Systems!
Let us see what were actually made. Following illustration shows how each one is structured.

Fig. 1

Standard MCAP-CR (left one) is already proven structure and there are a number of applications over the world.

AICC-CR is new one. AICC-CR has connections between chambers. Number of characteristic frequency of AICC-CR is more than Standard MCAP-CR, if number of subchamber is same.

CBS-CR is designed to allign chambers in a same plane. In the above figure, main chamber is not directly connected to the chamber on the top.

CBS-CR interests me the most of all! Let us see more details about CBS-CR.

Fig.2 Standard MCAP-CR

Fig.3 Idea of CBS-CR

Fig.4 Simplified CBS-CR
This is standard MCAP-CR with 4 subchambers.
The is original concept of CBS-CR. There are 4 directly connected subchambers and 4 indirectly connected subchambers. All the chambers can be allingned in single plane. CBS-CR may be extended as gray part.
Because left one is too complex, only four chambers are extracted, then simplified.
We tried this simplified structure compared with MCAP & AICC-CR.

Fig.5 Minimum CBS-CR Model
Let us see structure of the simplest CBS-CR in the left hand side.

We may allign all the chambers in a single plane, but actually made one has 3D alligment, in order to compare with MCAP & AICC-CR.

As seen in the picture in the top of this page, all the applications are made as cute cubic style.

1.2 Used Driver

Tangband's 3" model W3-881SJ was chosen as full-range driver. W3-881SJ has neodium magnet with die-cast frame. It has natural sound and price is reasonable.
We may choose other 3" drivers. These applications fit most 3" drivers.

1.3 Drawing

Here is drawing of all three models. TR80b is standard MCAP-CR, AIT080a is AICC-CR, and CBT080a is CBS-CR.
All the model is written in the same drawing, so that you may be very careful. Clicking the figure, you will see enlarged picture, and you may download PDF file. Here is drawing of all three models. TR80b is standard MCAP-CR, AIT080a is AICC-CR, and CBT080a is CBS-CR.
All the model is written in the same drawing, so that you may be very careful. Clicking the figure, you will see enlarged picture, and you may download PDF file.

Write me an email to , if you need cutting plan and more detailed information.

1.4 Manufacturing

These models were manufactured in early 2010 but reported in Japanese only. Now I add this information to English pages.
These models have unique structure as seen in Fig.1. These three models were manufactured at the same time.

In order to maximize efficiency of plate cutting plan, materials of side edges were made separately.  15mm x 15mm squared log was used for side edge and pre-cut.

Used saw is called "precision meiter saw". This is very practical to cut small-sized log precisely.

Squared log was set and clamped as in the left picture and saw was reciplocated by hand, then acurate 45 degree was given as in the picture.

The side edge materials and wood pipe ducts were pre-cut as in the below left picture.

Some materials had to be separated to two pieces, in order to save square log materials.

Pre-cutting these materials are very important to assemble accurately.

Some wood pipe ducts were combined and glued in order to save wood pipe materials.

Wood pipes are very expensive, so that ducts may be made by paper or PVC pipes may be substituted.

Component materials are combined and glued, then left for a few days.

One day is minimum term to secure strength of gluing.

This is the most patient time for loudspeaker builders.

Pre-assembly continues...

Finally, assembly complete.

Then ground down all the edges and corners.

After finishing, finally MCAP-CR family became complete.

All the systems MCAP/AICC/CBS-CR look same.

It was really ideal for comparison.

All the systems were compared with my friend, Mr. Matsu. He was surprized at the exterior of these systems. They looked same for him.

He began listening without knowing deferences of these systems.

His impression was diference among these systems were very small. Changing music sources and listening intensively then difference was detected.

He told me AICC-CR gave the best sound field presence. It regenerated clear drum attackss, according to him.

Lowest end frequency was around 37Hz, so that low frequency range sounded enough using these systems.

After that, all the systems were demonstrated at 1st conference of "Research Institute of Loudspeaker and Related Technologies", most people graded that CBS-CR was the best favorite.

My impression is that standard MCAP-CR is the best favorite. Standard MCAP-CR demonstrates most natural sound for me.

There is no conclusion which is the best, but I guess order changes every time.

All the system became proven.

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