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Meetings and other Notices

JUNE 2022 ONLINE MEETING NOTICE !

Date: Sunday, June 26, 2022, 7:00 PM
Place: ZOOM On-line
Guests: All BAS Members – Assisted by Ken Swartz & John Hajinlian
Topic: Sharing Favorite Recording Links, Web Resources, and Musical Notes

In this special open forum Zoom meeting members will share links for favorite recordings, and web resources related to music and sound. Information by BAS members on recordings, technical issues, software, and playback equipment are encouraged. Come to the meeting with notes to share (through Zoom chat) or send in advance to John Hajinlian jhajin@gmail.com  the items and 25 word-summaries for each to include in slides John Hajinlian will prepare before the meeting.

Join the Zoom Meeting

Ken Schwarz is inviting you to a scheduled Zoom meeting.

Time: Saturday December 18, 2021 from 1:30 - 3:30 PM Eastern (SUGGEST 1:15 PM )

https://us02web.zoom.us/j/89414786087?pwd=aG8wMFFKaXZuejR3TEJQOThISkhrUT09

Meeting ID: 894 1478 6087

Passcode: 989644

If you are using a computer and this is your first time with Zoom, give yourself at least 15-20 minutes prior to the meeting to set things up: you click on the link in the Zoom instructions below and will be guided to download the Zoom software, HERE:
https://zoom.us/download

You can use your computer’s audio if you have a headset attached, or you can dial-in for audio. If you have a smart phone or tablet and a good internet connection, then you should install the Zoom app for your device and connect using it.

THE BAS MESSAGE
May 2022

Compression

I was listening to a Telarc CD and read in the notes: The signal was not passed through any processing device (i.e. compression, limiting or equalization) during production).

They were known for their audiophile quality. However the dynamic range of a full symphony orchestra is simply not comfortable in the home listening environment. I realized that what they were doing was manually riding gain or asking the orchestra to play louder in the soft places and softer in the loud ones. The latter procedure could be seen as interfering with the artistic qualities of the recording.

So technically they are correct, but it is still a form of compression.

Once upon a time I was testing a VHS recorder and found that the input followed the output—a dB increase in input signal caused a dB increase in output--…up to a threshold of 1 volt. Above that the output stayed the same (without distortion) no matter how much the input increased, at least up to 5 volts or so when there was heavy distortion.

This is called limiting and at least on sine waves it works fine. With analog processing there is burst of distortion at the onset of a loud signal. With digital systems, including the internet, there is a delay (up to 25 seconds!) so there is ample time to smoothly decrease the gain just ahead of the peaks.

I looked at the waveform envelope of the Boston Symphony broadcast stream, which sounds quite good without obvious compression, and found that they use peak limiting. The waveforms are normal up to a threshold, then flat-topped. As long as the overall system gain is not too high that works well. In the glory days of BSO broadcasts on WGBH the engineer would follow the score and manually ride gain to bring the dynamics within the capabilities of FM (and the analog recorder). Too much work for producers today.

The waveform image is shown below.


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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 !


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