June 2021


DATE: Sunday, June 27, 2021, 7PM Eastern — Boston time, of course.

PLACE: Zoom online

FEATURED GUEST: Charles Repka, Vocalist & Vanguard Recording Engineer

Topic: A Loudspeaker Audio Test and Microphone Setups Explained

Charles Repka is a well-known Vanguard recording engineer and vocalist. Our Boston Audio Society meeting will require your input for a successful evening. Please complete your listening test before the Sunday meeting where Mr. Repka will provide the correct Track to Microphone match. Your answers will be tabulated during the ZOOM meeting.

Audio Test

A Baroque musical performance was recorded simultaneously with two microphones types. Your charge is to designate/indicate which track (one or two) was recorded with a pair of omnidirectional or a Blumlein stereo ribbon microphone. Both tracks were recorded simultaneously, and all the mics were mounted on the same bar, at the same distance from the performers.

Microphone – Royer SF-12 Blumlein Stereo Ribbon microphone
Microphone – A pair of Earthworks M30 Omni microphones

Track Number 1.wav  115 Mb

Track Number 2.wav  114 Mb

( These are now LOCAL on the BAS site — Barry )
Also note: if you are using a browser each .wav file will open into a new tab. That means you can pause one and jump to the other to compare. If you DOWNLOAD them, you might have a different A/B procedure you prefer.

Match the microphone setup used to record Track Number 1, and Track Number 2. Do not share your results, and do not use any analytical device to decipher or to help make your decision. Headphones can be used. If you prefer, you can download the tracks and record to a CD or Stick for playback on your best hifi setup.

If you can hear the differences between the tracks but cannot assign either microphone type, that’s okay. On Sunday indicate your best match and the Track you prefer. To date, many people taking the tests are unable to assign the correct microphone setup to the correct Track Number. This is an extreme test for loudspeakers, audio training, and experience.

Microphone Setups Discussed & Explained

During the Sunday ZOOM Meeting, Mr. Repka will provide the microphone names, the musical venue/environment, and the setup for the 3 musical demos outlined below. A brief description of the music will also accompany the excerpts.

The 3 different opera recordings were all done in the same church and performance space, but with different mic arrangements:

Puccini - La Boheme  End of Act 2

Orchestra on the floor in front of a raised altar area. All the soloists, as many as 4, standing in a row in the first pew in front of the orchestra. 4 omni AKG 451 mics were hung from a cable over the 3rd pew. The choruses were in the balconies along both sides of the church. The women and children's chorus were in the left balcony, men in the right balcony A cardioid Schoeps mic was placed on a tall stand in front of each balcony.

Bizet - Carmen excerpts 1 and 2 Habanera and entrance of Escamillo

Orchestra on the floor in front of the raised alter area. This performance was semi-staged, and all the soloists were placed on the raised altar area where they moved about during the performance. The chorus was placed behind the altar area on low risers. 2 omni AKG 451's were place on either side of the conductor and hung from a cable over the 3rd pew. A Soundfield ST-250 was hung from another cable behind the orchestra and over the alter area to pick up the soloists. A pair of Schoeps cardioids were placed on a tall stand on each side of the chorus.

Puccini - Tosca End of Act 1

Orchestra was on the floor in front of altar area with soloists in the front pew. 4 omni AKG 451's were hung across over pew 3. A small chorus and children's chorus were placed in the balconies on either side of the church. A Schoeps cardioid mic on a tall stand was placed in front of each chorus. For extra excitement, an electronic cannon was hidden behind the pulpit on the left side of the orchestra.


Ken Schwarz is inviting you to a scheduled Zoom meeting.

Time: Sunday June 27, 2021 - suggest 6:45 PM Eastern Time (US and Canada)


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:

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.

See below for dial-in instructions for the Zoom meeting.

If you do not have a computer or smart phone/tablet, you can just dial one of the numbers and join for audio only; use your touch tone dialer to enter the meeting number and password when prompted.

Dial by your location

+1 646 558 8656 US (New York)

+1 312 626 6799 US (Chicago)

+1 669 900 9128 US (San Jose)

+1 253 215 8782 US

+1 301 715 8592 US

+1 346 248 7799 US (Houston)

or find your local number: https://us02web.zoom.us/u/kcgU8tvYvR
(scroll all the way down to 'United States of America')


The Boston Audio Society
PO BOX 260211
Boston MA 02126

problems? email Barry: webmaster@bostonaudiosociety.org

updated 7/17/21