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If it’s the Czech works you’re after, do not hesitate

  Founder: Len Mullenger
Classical Editor: Rob Barnett

Have you ever wondered how seriously record companies regard comments by reviewers in magazines and web-sites? As can be seen below Dunelm records felt a criticism by Don Satz was an impeachment of their high standards of production and took the complaint very seriously indeed.

 

Ludwig van BEETHOVEN (1770-1827) The Piano Sonatas, Volume 1 Murray McLachlan, piano Recorded at Whiteley Hall, Chetham’s School of Music, Manchester, Summer 2003 DUNELM RECORDS DRD0201 [78:33]

In his review Don Satz commented:

Unfortunately, crackling noises embedded in the soundstage dampen enthusiasm for the production. This is not acceptable for a 21st century recording, and Dunelm needs to address and correct the problem. Otherwise, McLachlan’s Beethoven series has little chance of competing with all the alternative versions on the market.

The results of the investigation by the record company are shown below. July 2004

Ref: 0201ds problem

Dunelm Records: Investigation of review copy of DRD0201:
McLachlan plays the 32 Beethoven Sonatas: Volume1 sent to Classical Musicweb

Contents

Introduction
Problem
Addressing the problem
(1): Request for more information
(2): Tests on the returned CD-R
(3): Examination of the tracks on the music computer
Table: Results of a "glitch search on the Review CD-R and the Master CD-R
(4): Examination of the original manufacture of the Master
(5): Independent examination of the Review CD-R
(6): A new clone
(7): Previous experience

Appendix 1: Optical discs

Further reading

Introduction
Recordings of the Beethoven Piano Sonatas were made in The Whiteley Hall, Chetham’s School of Music, Manchester during 2003 with the pianist Murray McLachlan, Head of the Keyboard Department.
The piano used was the Steinway D, prepared by Peter Lyons, and the microphones used were four AKG 414 B-ULS one at 90 degrees to the keyboard, a stereo pair on the diagonal and one at the tail. The distances from the piano were 250cm and the height from the floor 190cm.

The sound was recorded at 24bit on DAT via a Mackie Designs 1604 VLZ Pro 16-channel MIC/Line mixer [2003] through a TC electronic Triple C signal processor [2001] to a Tascam Professional Digital/Analogue Audio Tape Recorder Model DA-45HR [2001].

Editing was done using Sound Forge 6 and the Master CD was made on a Mitsui gold Ultra low speed CD-R [Serial number 3167 2221 4170*] at a speed of 4 × using a Plexwriter 48/24/48 CD-R writer.
Clones were made from this master using a Marantz CD Recorder / CD player CDR500 at 1× speed.
A Mitsui gold Ultra CD-R clone [Serial number 3167 2221 1844*] was supplied to Classical Music Web on January 14th, 2004 for consideration for review.

* A batch of 300 CD-Rs with serial numbers 3167 2221 XXXX was purchased from The CD Team at Henley-on-Thames in 2003. All have been used on a variety of recording projects. No problems have been reported with the 298 others!

Problem
On June 6th, 2004, a copy of the review written by Don Satz of Albuquerque, New Mexico, USA was received. [
http://www.musicweb.uk/net/classrev/2004/Jun04/Beethoven_Sonatas_Dunelm.htm]

The paragraph causing great concern at Dunelm Records is that placed third from the end of the review together with the first sentence of the final paragraph. These are:

"Unfortunately, crackling noises embedded in the soundstage dampen enthusiasm for the production. This is not acceptable for a 21st century recording, and Dunelm needs to address and correct the problem. Otherwise, McLachlan’s Beethoven series has little chance of competing with all the alternative versions on the market."

Given the sound problem I noted above, my recommendation is to wait and see if Dunelm corrects the crackling soundstage.

[Note: The irony of the situation is that Mr. Satz also reviewed DRD0212: Bernard Roberts: Celebrity recital and, although the method of manufacture of the review CD-R was exactly the same as that with a problem, no "crackling problems were reported. The two copies on file bear serial numbers 3274 2221 0021 and 3274 2221 0013.
http://
www.musicweb-international.com/classrev/2004/Mar04/Roberts_Satz.htm

Addressing the problem (1): Request for more information
1.
Following a request for further elucidation of the "crackling noises", Mr. Satz replied:

"I'll help as best I can.  I used the word "embedded" because the crackling
didn't sound like an extraneous noise but like the crackling that tended to
be prevalent in LPs.
First, it is most noticeable on my best equipment; when using just an
ordinary portable CD player with low-end headphones, there is just a little
projection.
Second, the crackling is fairly persistent, essentially throughout the disc,
although its loudness increases as the program progresses.
…I'll get the disc back to you.

And later,
"I haven’t had any tracking problems with the disc; the noise is most noticeable on my Sennheiser headphones, if that means anything."

2. Jim Pattison replied:
Obviously, I am extremely worried about the (crackling) noise you report.
May I ask one further question? Did you realise that the disc supplied is a custom-made CD-R and not a commercial pressing?  Some CD players may refuse to play CD-Rs because of their hybrid nature. Your third paragraph gives the clue for, if tracking problems were being experienced this is exactly the sound effect it has.
(See New Scientist, 20th May 1999 page 10 "Hi-fi anxiety"; I can send you a copy if you would like to see the article.)
Since that article was written, most manufacturers have improved their laser-tracking specifications and include a little plate on the front of their machines saying CD-R/RW playback. I assume your machines have this.

Addressing the problem (2): Tests on the returned CD-R
1. CD-R Serial number 3167 2221 1844 was received at Glossop on June 16th, 2004.
A visual examination showed nothing untoward.
2. The CD-R was placed in a Sony Super Audio CD Player, Model SCD-XB780 [New on November 16th, 2002] and played back via a Sony Integrated Stereo Amplifier Model TA-FB740R {New on March 27th, 2001]. The sound was heard firstly through headphones – Beyerdynamic Model DT 250 80 ohm / System Serial no. 09156 [New on July 30th, 1999].

These headphones are very "bright" and it was possible to hear – with great clarity – the occasional page turn and pedal application. There was no "crackling" noise.
3. As for paragraph 2 but listening via two wall-mounted B & W Speakers Type DM602 S2.
Listened to at higher volume, nothing untoward was heard.
4. The CD-R was next listened to via a consumer-use (costing about £200) Panasonic CD Stereo System Model SA-PM25 with CD-R / RW playback symbol on the front [New on September 8th, 2001]. Again, the results were clean and of a standard expected from this efficient domestic unit.

Addressing the problem (3): Examination of the tracks on the music computer
Introduction:

To try to locate (I quote) "crackling noises embedded in the soundstage…" – which noises should be visible and audible on each track – each track on the "problem" CD-R was extracted from the CD-R using CD Architect. This procedure was repeated for the Master CD from which the "problem" CD-R was cloned.

Sound recording engineers are aware that unwanted noises – called glitches – can spoil a sound recording. Glitches are commonly the result of analogue audio editing, analogue to digital transfer, or electronic noise. One of the hazards of location recording is that the audio cable(s) which not only carry the "sound" wires but also the phantom power for the microphones, must be really secure. If the XLR plug "droops" (owing to the softening of the plastic sheath in a warm hall) and the phantom power pin separates from its socket – even by an imperceptible amount – an electrical "spike" is caused which gives a massive "glitch" on the waveform. The shape of a glitch is an almost vertical front with an exponential "tailing off".
Because of their shape, they can easily be recognised by a computer algorithm which examines the audio file for instances where the waveform matches the specified threshold slope and sensitivity criteria. The cursor then moves precisely to the location of the glitch to allow it to be repaired. Since the "Find" tool only locates one glitch at a time, all the glitches can be identified sequentially. If the "Find" tool finds no glitches it reports, "No events of the specified type were found" which has been abbreviated in the Table to NE.

There are two possible pitfalls, however! These are:
(i) Where the music is loud and percussive, for example, from a piano, "attack" waveforms can look like glitches to the algorithm when they are not! Thus it is necessary to "listen through" all reported glitches to ascertain if they are real or spurious.
(ii) There are three methods of repairing glitches but each of these is only partially effective, in other words, if the glitch is a small one, it will often be masked by the music. No engineer can "miss" a big glitch!

It follows that, if the source of the "crackling noises" is a series of glitches, they must be large and there must be very many of them!

In the following operation, the code for the Review copy of the CD-R is CD-966703098
and that for the Master CD-R is CD-1796841454. Both codes were "read" by the computer from the discs.

The tracks of the Review copy were examined first. Then those containing "alleged glitches" were checked against the Master to ascertain if they were in the original or whether they had been generated later. Allowing for millisecond differences, if they were in the original the timings would be similar. Every "glitch" was:
(i) listened through on Beyerdynamic headphones for the typical sound of a "glitch", and
(ii) the waveform on either side of the "glitch" was selected, expanded and viewed for its shape.
(iii) This shape was compared with the waveform shape on each side of the "glitch" to decide whether it was "musical" in shape, even though with a sharp (vertical almost) slope at its front.

In addition, if there was "just noise" it could be random as against reproducible if embedded in the soundstage.

Table: Results of a "glitch search on the Review CD-R and the Master CD-R
The Threshold Slope (range –60 60 –6dB) was set at –20dB
The Sensitivity (range 10 to 100) was set at 50

Track

Review CD-R time

Master CD-R time

Comment

1

08:08.186

08:08.140

A very small glitch.

2

NE

   

3

02:27.185

02:27.205

Steep music slope

4

NE

   

5

NE

   

6

01:59.447
02:58.595

01:59.467
02:58.615

Steep music slope
Steep music slope

7

NE

   

8

NE

   

9

NE

   

10

00:33.520

00:33.540

Steep music slope

11

02:42.873

02:42.907

Steep music slope

12

NE

   

13

NE

   

14

04:48.690
05:33.076

04:48.724
05:33.110

Steep music slope
Steep music slope

15

NE

   

Results
There were eight "events" reported in the Review CD-R of which only one was a very small "true" glitch.
These were "matched" – within acceptable mathematical tolerances – by the information from the Master CD-R.

Comment:
The conclusion drawn is that the "crackling noises" could not have come from the embedded audio material or artefacts therein.
In addition, these "noises" have not been reported by anyone else who has purchased this product
.

Addressing the problem (4): Examination of the original manufacture of the Master

Unfortunately, the waveform from which the Master was made on November 11th, 2003 is no longer on the active part of neither the Music Computer nor its Parking Area. However, a 1:1 Safety copy has been retained on DAT.

Because another source of unwanted noise can arise at the Bit-depth Conversion stage, the original records have been checked. These show that the conversion from 24bit to 16bit was done with a Dither setting "Highpass Triangular" and the Noise Shape was "High-pass contour". These are settings that have been used for all of Dunelm’s recordings made at 24bit. No noise will emanate from these settings.

Addressing the problem (5): Independent examination of the Review CD-R
Jim Pattison will give this report – and offer the returned Review CD-R – to Mr. Nigel Winchcombe, an independent sound engineer who formerly worked for the British Broadcasting Corporation, on his return next week from Poland, and ask for an independent assessment of the problem*.


*Another copy of this CD, viz. DRD0201 has been reviewed by David Rothery who commented:
"The recording is clean and well-rounded. The booklet notes by McLachlan and Ian Milnes are interesting. A recording to treasure."


Addressing the problem (6): A new clone
A new clone, on different stock, using the original master on the Marantz copying machine, will be made and sent to Mr. Satz for assessment of the sound quality.

Addressing the problem (7): Previous experience
The use of CD-Rs stock for making CDs in small numbers has been extant since about 1995.

Although it was believed that the manufacturing process was sufficiently developed to enable CD-Rs to be played on conventional CD players without difficulty, it was found that the pseudo-hybrid nature of those CD-Rs which used a dye layer as the recording medium could "fool" the laser-reading/tracking mechanisms of the early player models because the angle of incidence of the laser beam was unprecise and did not focus properly.

In addition, lenses were hardly ever cleaned and a film of condensation, dust/cigarette smoke also diffused the beam.

Further, it was not made clear – for obvious reasons – that, almost imperceptibly, the power of lasers decreased with time and use until a point was reached that "noise" was being created in the playing process. CD-Rs that would not play on an "older" machine, always played on the newer models (whose specifications had tacitly been updated in the meantime by the manufacturers!

Dunelm Records has made more than 5000 music CD-Rs over the twelve years of its existence. In that time there have been approximately 10 reports of playing difficulties. Cleaning the lens or updating to a newer machine cured nine of these. In one case, the laser just failed!

Dunelm’s "no-quibble" guarantee has been invoked twice in all of that time – and one of those was believed to be a "con".

This is the record that this report hopes to restore after the severe censure of the review that started it all.

Jim Pattison
Dunelm Records
June 20th, 2004.

 

 

 

Appendix 1: Optical discs
Optical recorders have the advantage that light can be focused at a distance – something that cannot be done with magnetism – so there need be no physical contact between the pickup and the carrier with no wear mechanism.

Basically, the information on the disc is in a form that simply conveys a series of numbers, which are exactly those recorded on the master tape. The readout of a CD is through the disc thickness and this tolerates scratches very well.


To play an optical disc a drive is needed that has a spindle drive mechanism to revolve the disc, a positioner to give radial access across the disc surface. This positioner carries a collection of items all needed in the reading process. Very accurate track following is required and it takes some time to lock on to a track. For this reason, tracks on laser discs are usually made as a concentric spiral.

To replay any optical disc, a source of monochromatic light is needed. Care must be taken to keep the beam focused on the information layer.

There are two types of "simple" disc:
(i) has a thin metal layer in which holes are punched on recording by heat from a laser
(ii) has a layer of photochemical dye which darkens when struck by a high-powered recording beam.

Whatever the recording principle, light from the pickup is reflected more or less, or absorbed more or less, so that the pickup senses a change in reflectivity.

Conventional CD players should be able to read certain discs, called CD-Rs. However, it was soon realised that the specifications of some "early" CD players were too "loose" and they could not play CD-Rs. There was a theory that the dye used was obscuring/diverting the beam from the information.

This theory was "strengthened" when the industry produced hybrid CDs, called SACDs, at the end of the 20th century. These hybrid CDs contained two recordings at different depths, the lower layer being the conventional CD recording at "Red Book" standard. The laser optics in a standard CD player are designed to focus on the lower layer, ignoring the second semi-reflective layer.

Laser optics in some existing CD players may, in fact, detect the semi reflective layer, fail to make sense of it and either reject the disc as unplayable or give an artefact (noise, in this case).

Some companies cured this by issuing Firmware Updates; some just changed the models and put a plate on the front saying that the player was compatible with CD-R / RW.

 

 

 

 

Further reading
1. The Quiet Revolution: Optical disk and CD-ROM (November, 1995)
http://www.soundonsound.com/sos/1995_articles/nov95/opticaldisks.html?session=eeaf…

2. Creating Audio CDs & the future of CD-R
http://www.soundonsound.com/sos/1996_articles/sep96/pcnotessep96.html?session=eea…

3. Burning Issues: Compiling an album on CD-R (July, 1999)
http://www.soundonsound.com/sos/jul1999/articles/cdrmastering.htm?session=eeaf16b0e2

4. Burning Questions: Getting better performance from your CD drives (January, 2003)
http://www.soundonsopund.com/sos/jul99/articles/cdrmastering.htm?session=eeaf16b0e2


5. Watkinson, J., The Art of Digital Audio, Focal Press, Oxford, 1999 (2nd edition reprinted 1994).


Ref: 0201ds2 problem

Dunelm Records: Investigation of review copy of DRD0201:
McLachlan plays the 32 Beethoven Sonatas: Volume 1 sent to Classical Musicweb:
Examination of the review copy of the CD by Mr. Nigel Winchcombe of Precision Electronic Production: Interim report on progress

Introduction
The work done by Jim Pattison of Dunelm Records to June 20th, 2004, has been reported in the document 0201ds problem.

In that document there is a section entitled:
Addressing the problem (5): Independent examination of the Review CD-R.
Whilst Jim Pattison was on holiday (June 26th to July 3rd, 2004), Mr. Nigel Winchcombe, of Precision Electronic Production – formerly one of the BBC’s* Sound Engineers with 30 years’ experience of sound mixing – has had an opportunity to examine the returned review copy of the CD as well as another copy made from the Original CD Master but on different stock.

By arrangement, Mr. Winchcombe and Jim Pattison held a discussion on Sunday afternoon, July 4th, 2004 and the following interim report was tabled.

1. Mr Winchcombe observed that, of the entire piano repertoire, Beethoven’s "Pathétique" Sonata is probably the most unforgiving work to a recording medium. He had, therefore concentrated his examination at this stage on this sonata.

2. He had played the review CD on six different CD players listening to the playback from an equidistant position between two BBC Monitoring Loudspeakers. He had found that there were very slight "clicks" – somewhat similar to the low-level clicks on a vinyl LP but nothing like as bad as these.

3. Each of the six CD players give very slight variations in the number and quality of the "clicks" as heard at very high playback levels on the speakers.

4. Mr. Winchcombe stressed that the "clicks" he had heard were at a very low level and could not be said to match (or even come near) the description of the defect described by the reviewer. This could be explained by postulating that the error-correction facility on the reviewer’s CD player may not be as sophisticated as that which exists on the players used in this test.

5. Jim Pattison was asked to describe, in some detail, the set-up of the four AKG B-ULS condenser microphones used at the recording session, their recording patterns, heights and lineal distances from the piano. Except for the advice to tilt the centre stereo pair a little more towards the strings of the piano, the set-up described was recognised as an approved one.

Further tests
The discussion then turned to devising a further series of tests after Jim Pattison had made certain variants of CD preparation from the 1:1 DAT Safety Copy of the waveform at 16 bit.

These variants would be prepared whilst Mr. Winchcombe’s was absent on a recording project for the next 14 days.

Based on the results of these tests, Mr. Winchcombe would decide on the next step in the process of " Addressing the problem".

Jim Pattison
July 4th, 2004.

* British Broadcasting Corporation

 

on adds

I did experience some tracking problems on my oldest CD player and discussed the situation with Mr. Pattison of Dunelm Records who asked that I return the disc to him for extensive testing. The testing was accomplished, and no tracking problems were found. Mr. Pattison did comment that the disc is a CD-R and might have tracking problems on older and less sophisticated audio equipment. For my part, I can assure readers that the disc played well on the three more modern CD players that I own.

 



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