Chamber Aligned in Parallel Cavity Resonator (MCAP-CR)
Some reference design
and drawings are listed here.
All the drawings below are based on author's calculation and
design experience but not tested by author unless noted
Some of these are designed per request by certain readers. Most of
designed cabinets are for more general use than for specific
drivers. Suggested drivers are listed as well.
You may use this design or change design by yourself, if you agree
to the condition that all the risk is taken care by youreslf. So
you must not complain about design or drawing errors or sound if
you do not like the sound of your works using these designs. This
applies to all the coontents of my pages. User's satisfaction is
Availability of standard wood material depends on business area.
- It is assumed that standard thickness of plywood is 12mm,
15mm, 18mm, 21mm.
- It is assumed that standard thickness of bonded
pine wood is 12mm, 14mm, 18mm, 24mm.
Your information of available wood materials in your area is very
I wish you good luck with this information.
TR120b1 (design not yet complete)
TR120b2 (drawings checked by
- 6 degree of freedom cavity resonator with 4.5" - 5" drivers.
- b1 is for 15mm thickness woods and b2 is for 18mm thickness
- Chamber sizes are a little smaller than TR130b cabinet,
but larger than TR130a
cabinet. Suggested drivers are F120A, FF125K, and FE126E
by Fostex, W5-1611SA by Tangband, L5 by Omnes Audio,
HX132 by Ciare, and other 4.5" to 5" drivers.
- Some 4" drivers with Neodymium magnets by Tangband may be
used, but may not fit..
- You may try 6" - 6.5" drivers as well, if you understand the
risk and are self-sufficient.
Designed Characteristic Frequencies
30Hz, 40Hz, 53Hz, 66Hz, 74Hz, 99Hz
b1: 900H x 230W x 230D per channel
b2: 900H x 236W x 244D per channel
not yet complete)
TR225a2 (design was checked by author: 2009/05/06)
- 6 degree of freedom cavity resonator with 8" - 9" drivers.
- TR225a2 is all front duct version. It is designed to set
along rear wall.
- This cabinet may be huge for ones who lives in small
apartment like myself. Cabinet will be heavy and may not be
assembled or handled by single person. I cannot manufacture
this cabinet, but may be useful for some special drivers
like limited models by Fostex, Feastrex or other high
performance drivers. Cost of one pair of cabinets will be
2,000 USD, if all the labour is supplied by youreself.
Letting professional carpenters all the manufacturing will
cost 5,000 - 10,000 USD depending on pricing.
- I would rather recommend 5" systems like TR130b or c than
9" system, if you do not require specially high performance.
Designed Characteristic Frequencies
1200H x 400W x 400D (192L or 6.83
cft per channel without double side panels)
checked by author: 2009/05/09)
This is modified version of
TR130c1. TR130c1 has complex structure and even myself made
mistake in one channel (it was modified as version c2). Version
c3 was designed not to make assembly mistakes. Basic design is
same as TR130c1.
Any Feastrex 5" drivers especially
FE138ES-R by Fostex
W5-1611SA by Tangband
Other powerful 5" drivers
6.5" fullrange drivers may be suitable
(design checked by author: 2009/05/10)
This design is for
non-classical music. Lowest characteristic frequency was
designed to 42Hz. Other characteristic frequencies are 58Hz,
82Hz, and 104Hz.
Lowest frequency of 42Hz will suffice for most music sources
except particular classical musics. This is easy to assemble and
Mild 5" drivers are suggested.
L5 by Omnes Audio or HX132 by Ciare may be good to use with
DU130a. TR130c3 is recommended for powerful drivers. Mild 4"
drivers like FE103E by Fostex may fit.
Notes and Tips
Selection of Woods
My design assumes that structure is
rigid enough. It means that vibration of cabinet is not taken
account. From this respect, wood may be selected in any way,
unless material is not rigid enough.
I do not recommend very soft and/or light materials for structural
materials. I prefer relatively heavy (density is bigger than 0.5
Another important thing is availability and price. There are
reasonably priced plywoods and bonded woods. MDF is also
available, but it does not look good. Practically best material is
linden-apiton plywood. It is relatively heavy and proce is
reasonable. Another choice will be birch plywood. Birch plywood is
more expensive than linden-apiton, but heavier.
Bonded pine wood looks better than plywoods. Disadvantage of
bonded pine is its softness and its dimensional change. Even
though pine wood was cut accurately, it changes dimension to 0.x
%. This change makes difficult to assemble.
One advantage of DIY is to save money. We may choose best cost /
performance materials with best drivers to realize best cost /
Absorption materials should be
chosen by users. Function of absorption materials is mainly
abosorb mid-range and higher range sound pressure inside the
chamber. Low-range sound pressure will not be much affected unless
ducts are plugged. Plugging any duct is not recommended, because
MCAP-CR is designed to maximize characteric vibrations of masses
I suggest not to use too much absorption materials, because
it makes the sound dead. Using absorption materials must be based
on user's preference.
Suggested Usage of Absorption Materials:
- Use generally available and less expensive materials like
sponge, cotton, soft cloth, soft paper, etc.
- Begin with nothing then add one by one as you require.
- Hang soft sponge behind the driver in the main chamber.
- Some absorption material layer (10mm - 20mm) may be
laminated to walls in the main chamber, if you feel that
reflected sound from back cavity is annoying.
- Some absorption materials may be set in subchambers;
however, please note that you may not be able to remove
absorption materials from subchambers after assembling the
- Some absorption materials like glass wool may be harmful and
Speaker Wiring Terminals
Setting terminals should be taken
care by users.
Some terminals may release sound pressure from its gap or gap
between terminal and cabinet. Recommended terminals are:
- +/- independent terminals (expensive solution)
- Small flange type terminals (less expensive solution)
- Not to use terminals but drill holes to cabinet for wires
from driver and connect to speaker cable outside the cabinet
or even directly to power amplifier. This is the least
Large and thin plastic terminals are not recommended.
Expensive wires are not recommended.
Cables really affect sound quality, but effect is very small
compared with other reasons like driver selection or cabinet
design & manufacturing. 0.75 - 1.25 square milimeter copper
wire for power handling use may suffice.
You may try very expensive audio wires. It is up to you.