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Meetings and other Notices

Meeting Notice for November 2019

    NOTE DATE AND TIME !    

Date: Tuesday, November 19, 2019
Time: 6:30 PM

Place: The Concord Orchestra , The Performing Arts Center,
51 Walden Street, Concord, MA 01742

Featured: Steve Barbar, President of E-Coustic Systems, Belmont MA

In 1978, Dr David Griesinger developed the first commercially viable digital reverb system which became the legendary Lexicon 224. This system and its successor, the Lexicon 480L, became (and remains) the gold standard for audio production throughout the world.

Dr. Griesinger’s extensive published scientific research in room acoustics, made him an ideal candidate to investigate the performance criteria of electro-acoustic enhancement systems. Thus, a research project was formed with Dr. Griesinger investigating the physics required to make a substantial improvement in hall acoustics, while Muncy and Steve Barbar investigated the requirements for transducers and system integration. E-Coustic evolved from the science and implementation of their research.

Steve Barbar will provide a lecture on their system & acoustics in the Grotto Room, located in the basement of 51 Walden St. It will be followed by an orchestra introduction, rehearsal, and demonstrations of E-Coustic’s newest room acoustical enhancement equipment in the concert hall.

Refreshments will be available at 6:15 PM

Directions: Driving from Boston – Take 93 N or 128 N to Route MA-2 W, Concord.

On Rt. 2, proceed for about 12 miles. Take the exit (a sudden right turn) onto Walden St. (a.k.a. MA-126) and continue northward 1.2 miles to 51 Walden Street.

Parking is available.

  GPS:   51 Walden St. Concord MA 01742


The BAS Message
November 2019

1.  V41N1 of the BAS Speaker has been published. It features 2 meeting summaries: the April 2019 Recording Panel by David Hadaway, the Beolab 90 Loudspeaker by John S. Allen; and CES reports by Kenneth Wacks.

2.  Replacing Speaker Surrounds

I’ve owned a pair of Acoustic Research AR-9s for many years. About 10 years ago the woofer surrounds for one speaker rotted out. I had heard of do-it-yourself repair, but decided to buy two new woofers. I installed them and discarded the old drivers.

Recently one of the woofers in the other speaker rotted. I decided to try a kit from SimplySpeakers.com. You get surrounds for two speakers, glue and instructions. The instructions were good, but I watched the recommended video on You Tube just for reassurance. The first step is completely removing the old surround. It is in pieces and you have to scrape it off the cone, then off the frame. If it is stubborn you can use alcohol to soften it. You then apply a bead of the glue on the edge of the cone and spread it smoothly around with your finger, then position the surround and start pressing the two together, working your way around. At first the halves don’t adhere — it is a slow setting adhesive — but eventually they stick together. You need to lift the cone to get room for your fingers to press the halves together. After an hour of curing you do the same for the surround attachment to the frame. Before you glue you want to exercise the cone to make sure it is centered and not rubbing. You can skew it a little by the position of the surround on the frame. You are mainly relying on the spider to center the cone—that is usually OK. In advanced repair the dust cap is removed and shims are used to center the cone. Usually that is not necessary.

At one point I had spilled some glue on the surround so I used some alcohol to easily remove it. Then the surround started puckering from the alcohol! I thought I had damaged the surround. Fortunately after it evaporated the surround returned to normal.

After installing the woofer everything was fine. Then a month later, rattling sounds again—the other woofer had rotted. So I used the 2nd surround kit and all was good. As a test I played the Saint-Saëns from the BAS Test CD 1 at high volume and there were no signs of any distress.

I wish I’d saved the first 2 woofers.


email me here

Webmaster's Note: The two great recone and parts companies are both right near each other: SimplySpeakers.com is in St. Pete and The Speaker Exchange ReconingSpeakers.com is in Tampa. The third, a bit smaller but still fascinating, is SoundSpeakerRepair.com , in Tucson, Az.  — Barry


Local Area Audio News
Frequency Therapeutics in Woburn announces a drug trial for Hearing Restoration

Below, other meetings and notices which may be of interest to BAS members

BAS MICROPHONE CLINIC REPORT !
In September 2009 the B A S held a microphone clinic, testing 37 different microphone models. The ambitious nature of the clinic effort, the extent of data collection, the number of individuals involved in microphone testing and in writing various sections of the report, and the complexity in determining how to construct the clinic report and make it available to members resulted it not being published until now. The dataset is extensive.

Representative samples were included in the abbreviated report in "The B A S Speaker"
(Fall 2015; v37n3)

Go to the MICROPHONE CLINIC PAGE for more...


When collecting and plotting "noisy" data it is often useful to have Microsoft Excel plot a Trend Line through it.  If that data is to be used for further work, it may be necessary to have an X-Y table of the Trend Line. That is not easy to get and this paper will show how to do it.
Joseph DeMarinis has a new article here: Extracting Numerical Data from an Excel Trend Line

Foster's Test Bench !
by Alvin Foster !    Click the logo: —>
The rapidly-becoming-famous BAS Headphone Test Article is now available in the BASS VOLUME 25, ISSUE 4, on Page 17, available HERE   PDF 3mb
Visit our PODCAST PAGE for:
The LIVE video podcast of our meetings,
Archived video of past meetings (only one so far!),
and Audio Podcast interviews by Alvin Foster
There is a supplemental and further explanation addendum paper to the E. Brad Meyer / David Moran paper published in the September, 2007 issue of the AES Journal. That page, which documents the experimental protocol and audio systems/source material is here:
www.bostonaudiosociety.org/explanation.htm   
There is a Power Point Presentation of the lecture given by Dr. Barry Blesser at the March 2007 Meeting. The Meeting page synopsis is HERE; the Power Point Presentation (as a web page) is HERE

Some earlier BASS issues, previously available only directly by mail, are now available online, on the BAS SPEAKER page, HERE

Show your appreciation for the immense amount of dedicated work that went into both the original writing, gathering, editing and printing, PLUS the more recent scanning and conversion to PDF format, by joining the Society, HERE !


A L L   O F F S I T E   L I N K S   O P E N   I N T O   A   N E W   W I N D O W

- AND FOR CONVENIENCE -

AES Future Meetings
www.bostonaes.org

Acoustical Society of America
www.gbcasa.org
SMPTE New England
www.smpte-ne.org

There is a posting of an ABX article, The Digital Challenge by Stanley P. Lipshitz HERE


Webmaster's Corner:

Once again, for 2019 - and on through 2020 (!) here is THE useful industry calendar of audio/related events, with kudos to all who put this list together: www.stiernberg.com/industry-calendar

Separately, AV-IQ has their event page here:
https://www.av-iq.com/avcat/ctl1642/index.cfm?events

Barry

 

The Boston Audio Society
PO BOX 260211
Boston MA 02126


updated 11/15/19