May, 2026

MEETING NOTICE - Sunday, May 17th, 2:00PM - 5:00PM

SUNDAY, MAY 17th MEETING - JIM HIRAKAWA DEMOS 2 SYSTEMS USING HIS OWN ROOM TREATMENT STRATEGY

We are pleased to be meeting with our member Jim Hirakawa at his house in Schaumburg, where he will demo 2 systems that use his room treatment strategy. Jim spent time
researching room treatment and has made his own panels with rock wool. Jim's systems utilize some classic speakers combined with later components.

The 2 Systems are as follows:

Living Room
Receiver: Marantz Stereo 70s
Turntable: DROP - Audio Technica Carbon VTA,
Cartridge: AT-VMN95, Micro-linear Stylus
CD Player: Marantz CD6007
Speakers: AR3a (1969)
Smaller Advent (1972)
Klipsch RS 8000-11

Den
Receiver: Marantz 2270 (1975)
Turntable: Technics SL-C50
Cartridge: Shure V15-111 (1975), Jico HE Stylus, Ortofon 2M Red
CD Player: Marantz CD6007
Speakers: JBL Lancer 77 (1971)
Klipsch Forte (1989)

Receiver controls will be set neutral. No subwoofers will be used.
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Jim describes his room treatment strategy as follows:

Acoustic Treatment Strategy
Identify a location for the speakers and a primary listening position that would be suitable for the room.
Locate the primary listening position in a “low-end sweet spot“, avoiding nodes where standing waves reflecting off of parallel surfaces create low frequency nulls. The Harmon International Industries, Axial Standing Wave Calculator can be a useful tool.
Absorb the first reflection echoes that bounce off the ceiling, floor, side & rear walls, directly to the listening position.
Low frequencies form high pressure zones where two or three surfaces meet. Place absorption bass traps in corners and at various locations where a wall meets the ceiling. The room geometry could form a natural Bass trap.
Place absorption panels at various locations to center imaging and reduce room decay time as necessary.
Adjust speaker placement and toe-in
Notes:
Absorption materials used: Rockwool insulation (3.5lb/cf), Poly-fil Pads
The thickness of the absorption material plus the air gap behind the panel will determine how low of a frequency a panel will treat. The total effective thickness includes the distance the sound rebounds through the panel after striking the wall. As a rule, the ideal total thickness would be 1/4 of the target wavelength. A rockwool panel will treat all frequencies above that wavelength.
Windows have similar acoustic properties to drywall. Heavy curtains have insignificant thickness. They can defuse high frequencies, reducing clarity of high frequencies in a properly treated room.
Thick rugs have insignificant thickness. They can reduce the clarity of high frequencies in a properly treated room.
References:
Jesco Lohan: Acoustic Insider website/Youtube
Harmon International Industries: Axial Standing Wave Calculator

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Do bring along your favorite music on CD (no streaming on hand) to hear a favorite track. Do RSVP to Jim (NOT this email!) for address and directions.
Look forward to seeing all of you for what should be a fun and informative meeting.

Much thanks to Jim for hosting this meeting. Do RSVP!
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