CD-1 Liner Notes

The Boston Audio Society Test CD-1 contains 71 minutes of contributions by members.

The Boston Audio Society TEST CD-1   1  Jabberwocky 2  Jabberwocky Finale 3  Saint-Saëns: Organ Symphony 4  Bach: Concerto in a after Vivaldi 5 Brahms: Geistliches Lied, op.30 6  Bruckner: Symphony No. 4 7  At Christmas All Be Merry 8  Soler: G minor sonata 9  Schumann: Kreisleriana 10  Mahler: Das Lied von der Erde 11  Verdi: Requiem 12  “Shop Talk”, WBUR-FM 13  Stereo pink noise 14  Mono pink noise 15  Mono pink noise, out of phase 16  Surround sound pan 17  Third-octave bands of mono pink noise 18  50-second sweep 19  150-second sweep 19  150-second sweep 20  Hollywood Edge test (reversed) 21  Hollywood Edge test 22  Slow downward sweep, 200-80 Hz 23  Slow downward sweep, 80-10 Hz 24  High warning 25  Picket fence test 26  Multitone test 27-32  Low-level crackle tests 33  Low-level chime 34  Warning 35  Frogs! Production Completed January 2001 Boston Audio Society PO BOX 260211 Boston MA 02126 603-899-5121 www.bostonaudiosociety.org

1. Jabberwocky
An arrangement by Sam Pottle of the Lewis Carroll nonsense poem. (" 'Twas brillig, and the slithy toves / Did gyre and gimble in the wabe / All mimsy were the borogoves / and the mome raths outgrabe...") It was performed in Bowker Auditorium at the University of Massachusetts, Amherst, MA, by the Chamber Choir conducted by E. Wayne Abercrombie on May 11, 1997. It was recorded with two Shure SM80 spaced omni mikes. [DBH]

2. Jabberwocky Finale
Finale from above with professional Lexicon reverberation added. Many times we record in small venues works written for larger ones. This is the last minute of cut 1, with a little bit of digital acoustic space added using a Lexicon 300 processor. Many commercial acoustic recordings made in reputable, or even famous, spaces end up with a touch of this same treatment. [EBM]

3. Saint-Saëns: Organ Symphony, excerpt from second movement
(Poco Adagio)
WARNING: When playing this track for the first time, lower the volume as your woofers may be at risk. The bottom octave of this recording may damage vented or planar loudspeakers. (The opening string passage should be quite soft.)

Boston Civic Symphony conducted by Max Hobart, James David Christie, organist. Two AKG 414 ORTF cardioids, about the third row in Boston's Jordan Hall, spring 1983. This was one of the last times that the Jordan Hall organ, already showing signs of serious asthma, was heard in a public performance. [MS]

4. Bach: Concerto in a after Vivaldi, BWV 593, first movement
James Johnson at the Busch-Reisinger organ, Harvard University, March 1987. An earlier analog recording by Peter Mitchell and me was excerpted for two Stereophile test CDs, and this later digital session can be compared with it. The important differences do not originate in the digital recorder; the center cardioid array is about a foot higher here, giving it a clear view of the main pipes over the stone railing and a brighter direct sound. This recording was made during a warm humid spell in early spring, which gave the space an audibly longer reverberation time at high frequencies. [EBM]

5. Brahms: Geistliches Lied, op. 30
Soli Deo Gloria (the group's new name is New World Chorale), Holly Krafka conducting. This piece was written as an exercise in counterpoint; it is built as a double canon* (soprano/tenor, alto/bass) at the interval of a ninth below (which would be very dissonant if the musical lines occurred simultaneously). Having set himself this formidable challenge, Brahms creates a remarkably expressive piece whose text begins "Lass dich nur nichts nicht dauern mit Trauern" ("Let nothing afflict thee with grief"), dedicated to Clara Schumann after her husband Robert was confined to an asylum. (The introduction quotes from Robert Schumann's Fourth Symphony, which he had dedicated to Clara.) The final "Amen" abandons the canon and unfolds over a held low E-flat from the organ.

The organ is behind and above the chorus in Arlington's First Baptist Church, and the recording was made with a near-coincident pair of AKG 414 microphones in figure-8 pattern at a 90-degree angle, to capture the diction of the chorus along with the reverberation of the room. An Apogee AD-1000SE provided phantom power, preamplification, and A/D conversion with UV-22 noise-shaping, feeding a portable DAT for storage. The recording equipment ran unattended, as the engineer was singing! [SO]

*A canon is a composition or passage where the melody is repeated by one or more voices, overlapping in time in the same or a related key.

6. Bruckner: Symphony No. 4 (original version), conclusion
The New Hampshire Symphony Orchestra conducted by James Bolle in the Palace Theatre, Manchester, NH, on November 16, 1979. It was recorded with two Nakamichi CM-1000 cardioid mikes using Dolby A on analog tape. The venue is quite dry, but one hardly notices since the music almost never stops. This version portrays Bruckner before the revisons by well-meaning friends not the amiable bucolic peasant but a person with apocalyptic visons of angels and terrifying demons. I've been recording the NHSO since 1977 and Maestro Bolle is retiring next year. [DBH]

7. At Christmas All Be Merry
This track is recorded in Logic 7, Lexicon's seven-channel encoding system. The primary goal of Logic 7 is to mix down five channels into two such that the energy (loudness) of each track in the original is preserved in the two channel mix, and at the same time give the tracks an identifiable phase relationship so they can be reassigned to their original spatial position with a Logic 7 decoder.

The major consequence of this goal is that a five-channel recording can be played on ordinary two-channel equipment and retain the instrumental balances in the original. Thus the Logic 7-encoded recording is compatible with two-channel stereo equipment.

A secondary goal but an important one is to make the phase relationship compatible with Dolby Surround, so people with Pro-Logic decoders can play the recording with some of the spatial properties present in the original. Conversely, a Logic 7 decoder can play back Dolby Surround recordings with improved performance over a Pro-Logic decoder. (Available on A Victorian Christmas, Revels CD #2000.) [DG]

8. Soler: G minor sonata
Performed by Irma Rogell. This is a 16' instrument, the last one built by Eric Herz. The recording is with two spaced Schoeps CMC 56 omni microphones about 6.5' from the floor, close to the 7'4" ceiling and literally above the instrument. It is in a living room acoustic augmented with Lexicon reverb. (Available on Iberia, AFKA SK434.) [MS]

9. Schumann: Kreisleriana, VIII. Vivace et scherzando
The pianist is the late Luise Vosgerchian, recorded on a seven-foot Bechstein piano in the very reverberant courtyard of the Fogg Museum at Harvard, June 1990. Two small Neumann cardioid microphones in an ORTF array were supplemented with a "shuffler" circuit (built by David Griesinger) that adds a small amount of bass and lower midrange to the L-R part of the signal. The piano's slightly nasal tone, distinctively different from a Steinway, is pretty well represented in the recording, and the miking is closer than usual because of the reverberant room. Since early reflections were suppressed acoustically and by mike placement, the effect in most rooms is of the piano, followed by the listening room, followed by a long, lower-level reverb from the space. (Available on Titanic Ti-210). [EBM]

10. Mahler: Das Lied von der Erde (arr. Schoenberg)
Marian Dry, contralto, Arlene Zalman conducting. Recorded in Houghton Chapel, Wellesley College, Wellesley, MA in spring 1999, using two Schoeps CMC 56 omnis. This is Schoenberg's chamber reduction of the Mahler orchestral work. [MS]

11. Verdi: Requiem: Dies Irae, Mors stupebit.
Boston Philharmonic Orchestra, Benjamin Zander, conducting, Boston Symphony Hall, March 8, 1981. Four Nakamichi 700's two omnis for overall pickup and two cardioids used at lower levels as chorus accent mikes. [PM, EBM]

We could not issue this CD without a recording by our late founder, Peter Mitchell. This work is one of the hardest to record with natural dynamic range. The original was captured on videotape using a PCM-1, an early 14-bit Sony professional encoder. Fearing that the quiet passages would be lost in the dithering noise of the processor, we had Rene Jaeger build a custom dbx I encoder with a mild 1.5:1 companding ratio. This type of signal processing actually works better with digital encoding than with analog, since digital is extremely consistent in frequency response and signal levels, eliminating the most common sources of decoding errors. The recording was later decoded and transferred to a 16-bit PCM-F1.

Even once it is captured, few systems can handle the true dynamic range of this work. Play the section from 4:30 to 5:00 and set your system so that the singer reaches a natural maximum level at 4:58 of around 76 dB SPL (broad band). Then, if you think your amplifier and speakers can take it, try playing the track from the beginning. (The BAS assumes no responsibility for any damages.) If your system survives, you will be able to hear the door open and close as the off-stage trumpeters rejoin the ensemble at 4:25-4:28. [EBM]

12. "Shop Talk", WHRB-FM, November 5, 1984.
Peter Mitchell (on the left), Richard Goldwater, MD (center) and E. Brad Meyer (right) introduce the show with a 1932 stereo recording and prepare to talk with guests Mark Davis and David Moran, both then of dbx corporation.

Shop Talk, which through most of its ten-year life on WBUR featured just Mitchell and Goldwater, was the precursor of Tom and Ray Magliozzi's "Car Talk". As we finished our 9:00-10:30 stint every Saturday morning, Tom and Ray would take our places and begin joking with each other. Eventually the station manager figured out that they were funnier than we were, and that more people drove cars than owned hi-fi equipment, and fired us. Until then, the show publicized the Boston Audio Society, vastly increasing attendance at our monthly meetings. The show came back for a time during the '80's on the Harvard station WHRB, where we appeared once a month as guests of HRB stalwart David Elliott. [EBM]

13. Stereo Pink Noise will put flat energy into your room without interference between the channels as the listener's ear or microphone moves across the room, so it gives a better idea than mono noise of the overall performance of the system with both channels operating. [EBM]

14. Mono Pink Noise is useful when you're seated in the sweet spot on the center line between the speakers. The noise should appear to come from a single point at dead center. Any asymmetry in the system or room will reveal itself as a displacement or horizontal smearing of the apparent source. (Results in this test can be improved by getting out a tape measure and making the speakers truly equidistant from the center of your chair.) With the mono noise you will also hear the 2k response error that is generated by a phantom center image, since the virtual source is being generated by two real sources neither of which is straight ahead of you. [EBM]

15. Mono out of phase Pink Noise. It will produce an uncomfortable hollow-headed feeling in a system with accurate geometry and symmetrical response. In a surround system it will be entirely in the surround speakers. [EBM]

16. Surround sound pan
This noise (modified from a signal supplied by David Griesinger of Lexicon) begins in the left channel and sweeps from left to right and around the room. It will describe a continuing circle in systems with split surrounds. [EBM]

17. Third-octave bands of mono pink noise
This test is very useful for a quick by-ear survey of a system's response. Upward movement is slower in the lower frequencies where systems and rooms take longer to settle, becoming more rapid as the test progresses. The test is very revealing of response limitations and problems, but is over quickly enough to prevent serious annoyance in salesmen, presenters and other customers in stores and at trade shows. The frequencies are the ISO standard bands, with brief tones before 1, 2 and 5: you will hear 25 Hz, 31.5, 40, tone/50, 63, 80, tone/100, 125, 160, tone/200, 250, 315, 400, tone/500 and so on. With a little practice you'll learn the sequence. (See appendix for indexes and times). [EBM]

18. 50-second sweep
This is a log sweep from 20 Hz to 20 kHz. There are blips in the 1-2-5 sequence, i.e. at 20, 50, 100, etc. The blip is 20 msec of silence followed by 20 msec of 1 kHz, repeated. Note that when the sweep reaches 1 kHz the blips are almost inaudible. It is preceded by a 1 kHz reference tone. [DBH]

19. 150-second sweep
This is a log sweep from 20 Hz to 20 kHz. There are double blips in the 1-2-5 sequence and single blips on the other 1/3 octave centers, i.e. 25, 31.5, 40, 63, 80 etc. It is preceded by a 1 kHz reference tone. [DBH]

20, 21. Hearing Test
Track 21 is borrowed with permission from Tomlinson Holman's Hollywood Edge test CDs, where it is billed as a high-frequency limit test for your system. It is of course no such thing, as Holman admits with little prodding; modern tweeters all go out to 20 kHz or beyond, but aging listeners do not. Holman's test is a tone that starts at 8 kHz and sweeps upward. You track the sound, starting at 8 kHz and reading the index points that occur every 0.5 kHz, noting when the tone seems to disappear.

The test works, but it requires the listener to say when he or she stops hearing sound — which is more difficult than the opposite, so we reversed the signal and put our version first, on track 20. Our tone begins at 20 kHz, and you can find out how badly you've treated your hearing over the years by reading the numberof seconds from the beginning of the track at which the tone becomes audible and consulting the table below.

22, 23. Slow downward sweep
This is two joined linear sweeps a sweep from 200 Hz to 80 Hz (track 22), 25 sec long, and from 80 Hz to 10 Hz (track 23), 50 sec long. There are double blips in the 1-2-5 sequence and single blips on the other 1/3 octave centers as in 19. [DBH]

24. High Warning

25. Picket fence test
A sum of sine waves at all 1/3 octave centers from 20 Hz to 20 kHz, except for omitted 1.25 kHz to 3.15 kHz. It is a severe test for bit-reduced systems (like MP3) since it contains energy spread across the spectrum. [DBH]

26. Multitone test
An in-band test for high frequency distortion suggested by Robert Cordell and discussed in the 9/81 AES Journal. It comprises three equal amplitude tones at 20.00, 10.05, and 9.00 kHz. The distortion components are at 950 and 1050 Hz. Unlike the CCIR test with 19 and 20 kHz, it allows easy measurement of both even- and odd-order distortion without the use of a spectrum analyzer. The suggested test fixture comprises two 3rd-order low pass filters at 2 kHz followed by a 4th-order bandpass filter centered at 1 kHz, with gain in between each filter pair. Cordell notes: "Because the test does not resort to unrealistically high rates of change to stress the amplifier under test, good subjective correlation can be expected." [DBH]

27-32. Low-level crackle tests
A short sound selection, such as you might hear in a concert, repeated 5 times at successively decremented 10 dB levels. It was made by playing the original recording through passive attenuation into the Sony SBM-1 Super Mapper (A/D converter). The Sony uses noise shaping to lower the audible noise in the 3 kHz region at the expense of extra noise at 20 kHz, resulting in a 6 dB improvement over standard 16 bit PCM (by my measurements). The last track represents the quietest a CD can be. Play the loudest music on this CD at the highest level you can stand and then compare track 32 to your ambient noise. In the unlikely event you can hear the track noise, then you need more than 16 bits of dynamic range (with proper dithering, distortion drops at low levels, just like analog, in all bit formats).

I have found that 3 of the 4 digital workstations tried, including my own, were unable to accurately copy the lowest level tracks without altering them (adding a ph..ph..ph sound, or extraneous beats). [DBH]

Note: Word lengths in excess of 16 bits do one thing, and one thing only, for the digital channel: they lower the noise floor. To demonstrate whether this is significant with actual recorded music, play track 32 on your system, and set the volume control so that you can just hear the noise disappear in PAUSE mode. At the same volume setting, play the beginning of track 5, or from 3:48 in track 9 through the beginning of cut 10 (or any quiet passage on another CD). Room tone and preamp noise in real recordings swamps anything that happens at the 16-bit level. [EBM]

33. Low-level chime
A small metal chime was recorded at a relatively high initial level and reduced digitally so it peaks at about -40 dBFS. You can leave the system turned up from the previous tracks and hear what your D/A converter does with a delicate acoustic sound at very low levels. [EBM]

34. Warning

35. Frogs!
This is a brief selection from the four-hour opus The Frogs of Jaffrey, New Hampshire. Next to the tennis courts is a small bog where the frogs make their marvelous sounds in the spring and early summer. After hearing this for years, I finally showed up on a Friday morning (June 2, 2000) at 7:15am with a marine battery, invertor, DAT machine, and a pair of Shure SM81 cardioid mikes (with windscreens) in an ORTF configuration, and recorded all morning. By late summer they were quiet rumor has it their agent advised them not to utter another peep without a contract. [DBH]

Track 17. Third-octave bands of mono pink noise
Frequencies with a "T" have a brief tone before the start.

High-frequency limit, downward sweep
Note: If your player displays index marks subtract one from the mark at which the tone becomes audible and read the frequency from the table.

21. High-frequency limit, upward sweep
Note: If your player does not display index marks,
add 1 to the seconds display and look up the result in the table.

Produced by David Hadaway and E. Brad Meyer
Editing and mastering by E. Brad Meyer, Point One Audio
Original Typesetting by Matthew Packwood
Track 1 Copyright © 1972 Triune Music
Reproduced by Permission
Permit 690642