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[This is the second part of a series started in February.  The first part is here.]

A few years ago I took a look at the AC power here at my house on an oscilloscope.  I had done this when I first moved to Yerington, Nevada in 1999 and saw a sine wave with a few glitches here and there.  Now I saw a strange waveform that was far from a sine wave.  To make sure this wasn’t caused by some odd load in the house, I shut off all the power except for the scope, and the waveform was unchanged.  I called my friend Wally in Sunnyvale, California and asked him to check his power, and he found essentially the same waveform.  Here is a waveform I took recently, which is similar to what I saw a few years ago:

What has caused the change over the last ten years?  My theory is that the amount of non-linear loads on the power grid has increased dramatically.  These are almost always power supplies with capacitor-input filters which draw current only at the peak of the waveform, thus flattening the waveform.  The large increase in the use of computers with their cheap switching power supplies as well as the program to replace incandescent light bulbs with CFL lighting is probably driving this.  I saw this “flat-topping” effect on the power line waveform when I worked at Tandem Computers in the 1980s.  The buildings were filled with multi-processor mainframe computers with multiple 1 KW switching power supplies.  However, the waveform at my house in San Jose, in a residential neighborhood, was a sine wave. The waveform I see now is deranged in a more complicated way.

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It’s been over three years since I last described my main home listening system.  There have been several major improvements, which I will describe in this and subsequent posts, but first let me describe what has remained the same.

The speakers are still the old Celestion SL-700s that I purchased back in the mid-1980s.  Their clarity and tonal neutrality are still what keep me listening to them, although they do not have the dynamics and very low-level detail that a good horn system can give.  Their inefficiency (~86dB/W) rules out out low-power amps, but they are quite adequately driven by my home-brew push-pull 300B amplifier, the same since 2004, but with a few small tubes replaced.  They are running on the original Svetlana 300Bs, although the filaments need to be turned on about an hour before the B+, otherwise one of the 300Bs intermittently gets a filament to grid short.  This is a well-know failure of these early Svetlana 300Bs.  I put up with this because I like their sound.

The turntable is the same Randall Museum project turntable designed by Thom Mackris. I had a chance to sand the sides better with a power sander, so it looks better.  As will be explained later, the tonearm and its mounting platform have been changed.  The phono preamp is a prototype Artemis Labs PH-1 that has been used as a test-bed for various design changes.

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Before writing an update on my own “Music Computer” system as well as some of the issues with digital audio today, I want to describe an excellent site for anyone considering using a computer or external DAC to play their music: Computer Audiophile.  This is published by Chis Connaker, out of Minneapolis, Minnesota.  Chris combines digital audio technical knowledge, computer IT savvy, connections in the music industry, and a love of music.  Up until just a few days ago, Chris was the sole contributor to the blog posts, posting usually about once a week.  However, he has just added a second contributor, Kathy Geisler.  Kathy produces recordings and CDs, primarily in the classical music field.  This should add a broader prospective to an already good site.

Even though Chris has, up until a few days ago, been the sole poster of blog entries, most of the action in the site is in the comments area.  There are always the newbies with naive questions, but there are also highly experienced users including key people in the digital audio business, so the discussions are lively and can be highly informative, and are civil, too.  One thing should be mentioned, though, is that digital audio is still going through growing pains and there are always people who like to stick to one opinion or another.  So, when the discussion goes to “how many bits are really needed”, for example, don’t be surprised that someone pipes up saying that the CD Red Book standard is plenty and that 14 bits would suit him fine, too.  Other controversial topics are the sound of digital cables, the effects of upsampling, etc.  This comes with the territory, so, as they say, take these arguments with a grain of salt.  The truth is that there still are a lot of things we don’t definitely know about the defects in digital audio.

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Here is a site selling DRM-free high-def music that I have been meaning to write about for a long time: HDtracks.  Founded by David and Norman Chesky of Chesky records, HDtracks is an on-line store selling down-loadable recordings - virtually all of them versions of existing CDs or SACDs.  Their catalog has been growing over the last year I’ve been visiting them.  It does not carry the mainstream consolidated labels, such as Sony/BMG, Warner, or EMI, but it seems to have collected some of the best of the independents: check out their list of labels.  Notable for classical music lovers are its handling of symphony private labels, such as the Philadelphia Orchestra, Chamber Orichestra of Europe, Chicago Symphony, San Francisco Symphony Orchestra, and the New York Philharmonic.  It sells its recordings either as complete “albums”, or in many cases, as separate tracks or bundles of tracks.  There is a pdf file of the CD artwork and notes and each track has the metadata already added.

Even though the site is called HDtracks, many of the recordings it sells are from conventional CDs, i.e. 44.1K/16 bits.  The cost of these are $11.98 for the album and $1.49 to $3.98 per track, depending on the track size.  This is not bad, considering that the artwork/notes has already been scanned and the metadata is good. The formats offered for these conventional recordings are: AIFF (Apple’s equivalent of .wav), FLAC, and 320kbps MP3 files.  Note that the AIFF versions have no compression, so they are larger than the FLAC files, which are just as good.

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The issue of over-compression in recent pop music is getting around in the business, with the latest reaction being the formation of a non-profit group, named “Turn Me Up™” to encourage better dynamics. From their web site:

Turn Me Up!™ is a non-profit music industry organization campaigning to give artists back the choice to release more dynamic records. To be clear, it’s not our goal to discourage loud records; they are, of course, a valid choice for many artists. We simply want to make the choice for a more dynamic record an option for artists.

Today, artists generally feel they have to master their records to be as loud as everybody else’s. This certainly works for many artists. However, there are many other artists who feel their music would be better served by a more dynamic record, but who don’t feel like that option is available to them.

This all comes down to the moment a consumer hears a record, and the fear that if the record is more dynamic, the consumer won’t know to just turn up the volume. This is an understandable concern, and one Turn Me Up! is working to resolve.

How this will be accomplished is not very clear, although the presence of an official Turn Me Up! certification and cool-looking logo (at the top of this article) may help break the positive feedback cycle that seem to make record labels and artists want to compress their music to the max. The fact that the metric for determining whether a recording merits certification has still not been decided is troubling and needs to decided soon for the effort to take off. I really hope it succeeds, since the industry is killing itself with its current compressed mess.

The front page of Turn Me Up’s home page has a very comprehensive set of links to articles and papers on the issue of over-compression, highly recommended for those interested in this issue.

I recently stumbled across a source of DRM-free music that I hope represents the future of music distribution. Pristine Classical sells music, mostly classical, but some jazz and blues also, in a variety of forms, ranging from MP3 downloads to physical CDs. The prices are not very cheap, especially since they are in Euros, but no protection or DRM is attached, so you can back them up or trade them with your friends forever. (A reminder of the futility of DRM is in this Ars Technica article about how Microsoft will turn of their MSN Music license key servers at the end of the year. Your licensed (not purchased) music will still run on the computer it is licensed to until something changes - i.e. OS upgrade, hardware change, etc. I’ve never had a Windows computer be this stable for more than a year.)

Pristine Classical was started in 2005 by Andrew Rose as a offshoot of his Pristine Audio business of restoring and remastering of old records and tapes. He has apparently made deals with the copyright holders of some of these classic works so that all recordings are fully legitimate. The age of the recordings go from about 1955 back to the early electrical recordings of the late 1920s. As such, you won’t hear stereo spectaculars, but the recording quality of the late 1940s and early 1950s recordings can be quite good, if only mono. An added plus is that the details of each restoration are explained for each recording. A particularly difficult restoration is explained in the notes for this 1950 Decca recording.

An outfit that sold only MP3 downloads would frankly not interest me, since I consider the sound degradation too significant, even for vintage recordings. However, Pristine Audio recently has started offering FLAC lossless encoding on many of their recordings, in a 44.1K/16-bit format. Not only that, but they have just started offering 48K/24-bit FLAC versions that reflect the resolution of their original restoration. These are nearly twice the cost of the ordinary FLAC versions, but would offer the ultimate quality. My own experiments with resolution and sample rate show that higher bit resolution is a bigger improvement than higher sample rate.

I bought several of the classical FLAC recordings while I was on the road (I still don’t have high-speed internet at home), and when I got home played them on my main system. So-called restoration of old records can sometimes take the life out of the recordings, but Pristine’s restorations were tastefully done. No major clicks or pops and the surface noise is low, but the details are there. On the whole, I liked the restorations.

The Pristine Classical site is rather cluttered and busy, but that is partly because they offer many versions and services, including cue lists and color CD insert printouts for each recording. The following screen capture shows the general pricing structure:

With our poor dollar-to-euro exchange rate, the prices seem a bit high, but considering you are getting the full musical and sonic equivalent of a CD, with the cue lists and cover art, and no DRM, it isn’t so bad. I’m impressed with their offerings, and hope they do well.

Lynn Olson recently pointed me to an article in Rolling Stone magazine that digs deeply into the problem of MP-3-quality sound and poor dynamic range in recordings. This six-page article goes deeper than the articles I mentioned in two earlier posts (What Happened to Dynamic Range? and More on Dynamic Range). Also covered are the tweaks that are done in the recording or mastering studio, such as correcting the pitch of a singer’s voice. I won’t go into the excruciating details, but recommend this article, especially since it has a nice on-line bibliography and a selection of “Good” tracks (such as Bob Dylan’s Modern Times) and “Bad” tracks (such as the Red Hot Chili Peppers Californication) so you can actually hear the differences.

With speakers getting more accurate, and high-resolution audio getting better and cheaper, the fact that recordings are being trashed while mastered and then get squeezed through MP-3 lossy compression can only be seen as a dramatic disconnect. We can only hope that a new generation comes along that appreciates and demands good sound.

Apple recently announced a new music player, the iTouch, which is similar to the iPhone, except without the mobile phone feature. At the same time, it “refreshed” the 5G iPod video player (that I described below), calling it the “iPod Classic”, with storage up to 160GB. The external appearance is quite similar, but internally is quite different. Reports have been cropping up on poor sound quality, glitchy software, and incompatibilities with various programs.

Via reddit comes this analysis by Marc Heijligers at his HiFiVoice site. After noting that the new iPod (called the 6G, for 6th generation) sounded tinny and fatiguing. He then proceeded to run tests, comparing it with the 5G iPod, and basically found the following (quoting Heijligers):

• An uplift in treble (about 0.15dB at 15KHz).
• A strong modulation with 22k, causing a peak in the frequency extreme, and intermodulation distortion.
• A group delay that depends on frequency (i.e. non minimum-phase).

The culprit seems to be a change from the Wolfson D/A converter used in the 5G to a Cirrus converter. Heijligers hints that some corrections might be made by a firmware update, but knowing these kinds of converters, I think the problem is inherent in the Cirrus chip. His site has some interesting links related to the problem, including some to Apple Discussion Groups. It’s interesting to see what I would assume to be non-audiophile listeners (at least to the level often discussed here) complaining about “narrow-ness”, “compressed sound”, “confined … and not as warm”, “one dimensional & not musical at all”, and in summary: “… a less harmonic sound, less spatial (the scene is inside your head instead of around your head), a bit too much emphasis on high treble, and ‘less silence between the notes’. It sounds more technical, and less acoustical/realistic.” And these are all comparisons with earlier iPods!

From the very good MacInTouch site is a user summarizing the operational problems:

• VERY Slow menu switching response
• Display of clock rather than song info when ?Now Playing?
• Inability to use existing AUTHORIZED 3rd party dock products (including Apple-advertised)
• Audio skipping during operation
• Slow connection to Macs and PCs
• Inability to disable ?split-screen? menus
• Lagging and unresponsive Click Wheel
• Camera connector not working
• Inability to use EQ settings without skipping and distortion

Via the fascinating Boing-Boing site comes word that the software incompatibilities are due to a bit of encryption added that only allows Apple’s iTunes to access the iPod’s database. This locks out any 3rd-party software and really leaves the Linux folks out in the cold, since there is no iTunes for Linux. Someone may find a way to crack this, but with the DCMA law around, this is legally risky in the U.S. As Cory Doctorow, who wrote about this, said: “I guess my next player won’t be an iPod after all.”

Update: The folks at ipodminusitunes (I wonder if they got the idea of this name from my post below?) have cracked the encryption and offered a solution to the Linux users. This still doesn’t help the sound problems, though.

Its been a while since I reported on my music on computers project. I completed my sister’s classical music iPod project in April - she really likes it. It was done using Apple’s music formats: AAC and ALAC. These work well but are proprietary. I didn’t want to commit a lifetime of collected music to formats that might be shut down or at a minimum aren’t accesible by sound editing tools. After exploring Rockbox, though, I realized that high-quality open-source formats could be used on the iPod. Why the iPod, and not some other “MP3 player”? Well, to put it bluntly, MP3 sucks, both in sonic artifacts and compression size. There are some players that handle other formats as well as the lossless formats like FLAC, but their build quality is not as good as the iPod. So, I got an 80GB iPod and loaded it up with Rockbox.

Rockbox is an open-source software project to replace the software on portable music players (Apple’s as well as many others) with many features, high-quality audio control, and the ability to play many different sound formats. It is in a constant state of flux - new compiles are happening all the time, so minor glitches are to be expected, and indeed, I’ve had a few strange crashes. The user interface has a few rough edges, and the “out-of-the-box” screen appearance is awful. There are many “themes” available, however, and these can greatly clean-up the appearance. The main thing is that it does play my two formats of choice: FLAC (lossless) and ogg vorbis (lossy) very well, and its built-in database function organizes recordings quite nicely by their tag information.

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At the suggestion of reader Bill, I downloaded the J. River Media Center software package and tried it out on my “music computer”. I’m still in the middle of my iPod classical music project, so I didn’t want to convert everything over to this new system, but I thought I’d “kick the tires” and play around with it a bit. Media Center has a huge set of features, so while I tested the music organizer and playback features, I didn’t even look at the TV features, CD labeler, portable player synchronizing, Download manager, among other features. This is why I am calling this a mini review.

The first impression of both the J.River web site and the Media Center software itself is one of slickness and attention to detail. There are extensive help files and FAQs on the web site, and a multitude of different modes for displaying information within the program. The appearance is attractive without too much eye candy. The default screen is similar in content and appearance to the iTunes screen. Upon opening Media Center for the first time, it asked if it could bring in media files on the computer. I agreed, and it scoured the hard drives for all media, in this case mostly music files. Basically what Media Center does is set up a database that points to wherever the files are - thus not duplicating the files the way iTunes does. Metadata (artist, pictures, etc.) are stored in the database, but can be put into the tag fields in the music files. The massive file import showed a problem, though - my FLAC files were ignored. A little study of the help files showed that only the “Monkey’s Audio” lossless compression format was supported. Given the extensive set of features and the fact that FLAC is open source makes this omission odd.

Files can be sorted and played from Media Center just like with iTunes. Unlike iTunes, Media Center preserves sample rate and bit-depth, so my 96KHz recordings played back just fine at 96KHz. (iTunes seems to downsample everything to 44.1KHz). There is lots of flexibility in creating playlists, so more sophisticated groupings of songs can easily be made.

I tried out Media Editor, a separate program that is installed at the same time as Media Center. It provides basic waveform editing with the ability to change volume, add or delete segments, etc. According to the help file, “Media Editor can open and save any of the many, many formats that are supported by Media Center “. This is somewhat misleading, since all formats are converted to .wav files while edited, then reconverted to the original format when saved, which, of course degrades files that use lossy compression. You are warned about this, though. The maneuvering and editing features are a bit clunky compared to my standard sound editor, Sony Sound Forge. There is no “interpolation” command, which is essential for taking out clicks and pops from LP recordings. So Media Editor has some use, but doesn’t replace a full-function sound editor.

On the whole, Media Center is a solid, well-designed program that does most of what I want. A fly in the ointment, though, is its product activation. It is not quite as demanding as Microsoft’s or Adobe’s activation schemes, and it allows up to ten reactivations a year, but as your system ages and eventually gets replaced, it is essential that the product activation be available forever. How many small software companies last forever? For a program that may end up holding a lifetime worth of music, this is a problem. It is also only available on the Windows platform. Since this is what I currently mainly run, this isn’t too bad for me, but I have been flirting with Mac OS X, and may want to run in a UNIX environment someday. I think I’ll hold off adopting the J. River Media Center for now, and keep looking for another, hopefully open-source program.

Its been a while since I reported on my music computer project. No definitive decisions have been made on it, but I have been learning more about iTunes and thinking a lot about music organization. For a somewhat delayed Christmas present for my sister, I bought an Apple iPod (the latest 30Gb model) and have started filling it with classical music from my collection. She already has an iPod with jazz and wanted some classical music, so she is already set-up and familiar with the iPod. I am running iTunes 7 on my “music computer” WinXP system. During the course of this project, my thoughts on the music computer have been clarified.

One of the first things I decided was that all music, wherever possible, would be stored using lossless compression. This significantly cuts the storage capacity, compared to Apple’s compressed storage algorithm, but on a 30Gbyte drive this would still allow about 110 hours of music. Since my sister primarily plays her iPod at home through her stereo, the preservation of sound quality should be noticeable. iTunes’ default setting for importing music is to compress it to AAC, Apple’s compression standard. The default can be changed, but the selection is quite buried (edit > preferences > advanced > importing). I set it to “Apple Lossless Encoder”. Thus all CDs are now ripped automatically to the lossless mode. For the cases where I imported a .wav file, right-clicking on the tune in iTunes gives a option to encode to lossless. There is no option for importing or playing FLAC files, so in the case where I had only FLAC files (e.g. from purchases from the Philadelphia Orchestra website), I had to manually decode to .wav files, then import them into iTunes. The Apple Lossless Encoder compresses about as well as FLAC - a bit better than half size for classical music and a bit worse than half for pop music.

I made some interesting discoveries on what the iPod would handle. All my music I have been transcribing from LPs to my computer have been sampled at 24 bits/96KHz. I could import these into iTunes, but when I tried to synchronize the iPod, it complained that it couldn’t handle the format. I then downsampled the file to 48KHz, and the iPod was happy. It seemed to handle the 24 bit mode, but I don’t know if it is actually playing all 24 bits. At some point I will record some test tones onto the iPod, put it on the test bench and see how well it performs. But the good news is that it handles 48KHz just fine. Update: Itunes plays back all files on my system at 44.1KHz, despite storing the files at the full data rate! Sample rate conversion is fraught with problems and is hard to do just right. As noted in my comment below, this invalidates iTunes as a high-resolution media player. I don’t know what the iPod does.
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There has been more interest in the problems of “clipping” and limited dynamic range in commercial CDs. See my earlier posting (What Happened to Dynamic Range?) to see what the fuss is about. There is an interesting thread at diyAudio.com on this. I recently stumbled across David Torrey’s DRT Mastering site, which has useful tidbits and good background material on the mastering process. In particular, he prints a letter to the editor of Audio Electronics/Elektor magazine concerning an article in their 1/99 issue that claimed that clipping is seldom found on CDs and that engineering and recording company professionals avoid such clipping.

David Torrey begs to differ. In the first of his interesting points, he describes how the Sony 1610/1630, a digitizer ubiquitous up through the early 1990s, only indicates an overload if more than a certain number of sequential samples have exceeded 16 bits. In the default mode, this was 8 samples - thus up to 0.16 milliseconds (7 samples at 44.1KHz) of music could have slammed the rails without indication! The second point was that, in order to not cause an “overload” and to satisfy the customer’s demands for a “hot” recording, the mastering engineer would run the music through one or more clippers and limiters that end up clipping the music just below the overload point. When the customer asks for an even hotter recording the next time, the music gets even more scrunched, leading to the kind of waveforms shown in my first posting. In any case, check out David’s letter.