Archive for February, 2012
In this video, Ian Shepard of Production Advice in the UK compares a CD track to both its “raw” AAC coded form and a “Mastered for iTunes” rendition. I think that most of you will jump to the punchline early on, but the journey is interesting (for audio geeks).
On a related note, I wish that the audiophile industry would do more null testing to answer simple questions like: “does this cable sound different from that one?” It’s really not that difficult.
Continuing on our recent technical theme, here’s a great site for training your ears to detect and describe sonic anomalies. It’s harder than you think. If you like what you hear, please support the author by buying one of the products on Quiztones. (The Golden Ears material is the sine quo non of the field – it’s great.)
One more bit of knowledge that you need to make pronouncements like “the lower mids are muddy” is a working definition of “bass/midrange/treble.” I personally use the mental hook of dividing the audio range into three ranges, separated by two easy-to-remember “corner frequencies”: 150hz and 1500hz. Piece of cake. You can find a more elaborate definition in the graphic.
Finally, it’s fair to ask about how these map to the musical concepts that we know or learned in school. The keyboard graphic below helps with this aspect.
Audiophiles are taught that equalization (EQ) and compression are BAD. However, used judiciously, they are useful or even GOOD.
Joe Gilder’s “Home Studio Corner” web site is one of the best resources on the web for learning how good-sounding recordings are put together. No, Joe’s home studio is neither Skywalker nor Abbey Roads in sophistication. But it’s quite nice, and Joe is a natural and giving teacher.
The material on EQ is a good building-block for the room correction work that we’ll do. The compression video is also quite interesting, showing that the technique has uses beyond the “loudness wars.”
Few audiophiles share my passion for listening to test signals when evaluating equipment. That’s quite understandable.
But all would agree – from JA on down – that test signals are vital in measuring equipment and rooms. When measuring, the most common test signal in use is “pink noise.” But why?
Common answers include:
- It contains all frequency components
- It’s easy to use/generate
- It contains equal power per octave, and humans “hear” power; and
- It is natural
All of these are, of course, correct. But there’s a reason far closer to the audiophiles’ world: the pink noise spectral signature closely resembles that of music. It’s just that simple.
Not convinced? Compare the pink spectrum above to that of this Corinne May song that I chose at random. Except for the bottom few octaves, they share similar 10dB-per-decade falling slopes. This is not a coincidence.
The relatively weak bottom end (compared to pink noise) of this song is typical. Many recordings do not match the pink spectra down low. I believe this is a combination of music lacking sustained bass, EQ choices when mastering, and some loss of resolution of the FFT. But I don’t know for sure.
Lest you lose all hope for bass on CD’s and digital analysis thereof, check out Cowboy Junkies’ “Helpless” and Sting’s “Fields of Gold” (at bottom). These tracks are two of my bass references. And finally, we come to Max Richter’s “Blue Notebooks.” I know of no cut in my library with more bass extension -it’s nearly flat to 15hz!
You’ll get to hear a bit of pink noise at our upcoming room correction events.
Just lovely. Designed by the inimitable Dieter Rams, it featured a 6-tube amp and cord drive.
Affectionately called the “Snow White Coffin” by some. I wonder why….
BAAS members have had the opportunity to meet several music producers and mastering engineers. The typical content of these meetings has been how to render a true-to-life recording. Clearly, the techniques vary for vinyl, tape, and digital delivery media.
Apple has now taken this concept a step forward (or backward, depending on perspective) with the launch of the “Mastered for iTunes” specification. As reported by Ars Technica, the specified 256K AAC format retains about 3% of the raw information af a 24/192K master.
Note that I use the term “raw information,” as supporters of high-bitrate AAC (or MP3) would claim – with some validity – that these formats retain well over 90% of the musical content. Of course, we audiophiles spend gobs of time and money chasing mils of fidelity. So the 90%+ talk is beside the point on that frame.
My quick perusal of the current “Mastered for iTunes” selections revealed that many of the recent offerings are from the Bowers & Watkins “Society of Sound” library. So presumably Peter Gabriel is on board.
Anyway, the Ars Technica piece summarizes the recent semi-popular embrace af audiophile values by Gabrial, Neil Young and other luminaries. A good read.
Oakland-based Pandora has been a leader, but the space is now quite crowded. How is a person to choose? This infographic, from Gerson Lerman Group, does a nice job in laying out the landscape.
But what does this all mean to audiophiles? My suspicion: not a lot, at least in the near term. Most enthusiasts have invested heavily in vinyl and/or optical media and players. We have seen that these trends are difficult to reverse.
I myself have been surprised by the reluctance of BAAS members in embracing music servers. But it is the “music server” that will ultimately power streaming services in audiophile reference systems. The fact that these devices are close cousins to general purpose computers, including the internet connection, will make it so.
Until then, these services will supplement existing media for audiophiles – and be used mainly when mobile.
What do you think? Please document your experiences and opinions in the comments.
The professional engineer in question has requested anonymity, but here’s what he had to say:
Studios are full of HF signals that alias back into the audio spectrum.
The guess about a TV monitor
somewhere in the mastering studio is valid indeed, as 15,750 * 4 -
44,100 = 18,900 Hz. It could even be a nearby TV transmitter.
Such “birdies” of constant frequency are relatively easy to trace, but
wideband HF is harder. For example, decent condenser mikes and
preamps go well beyond 100kHz at their output. Feeding them to
poorly-filtered ADCs (nearly all of them are!) can produce -40 to -60
dB of aliasing into the audio spectrum. As a side note, this is a
killer justification for ribbon mikes on “comb-spectrum”, high dynamic
range music such as authentic-instruments baroque.
Studio engineers can shrug and call HF birdies “digital sound”, yet to
me everything is analog: some within the audio band as intended, and
the rest just gets there unintentionally. Higher sample rate (192 or
176.4ksps for baroque, 88.2ksps for everything else) dramatically cuts
most of the latter.
See the comments of the previous post for more ideas.
Those of you who have attended events at my house know that I use this version of Sting’s “Fields of Gold” as one of my reference tracks (especially for bass).
I happened to be analyzing those bass peaks today, and noticed intermittent frequency spiking at 19khz (see image). To my knowledge, this behavior doesn’t occur naturally – certainly not in music.
Sure, FM uses a 19khz carrier tone to indicate the presence of stereo information. And Rich Pell has documented this and other high-frequency peaks on CD recordings. He cites speculation regarding the presence of video gear during the recording process. I think that there may be a tie-in to digital-audio tape, but there’s certainly no “smoking gun” in that regard.
My gut tells me that these peaks are simply an artifact of the digital filtering process. They are aliasing or some other frequency fold. But this too is speculation.
One thing that is not speculation is that they are prolific. I frequently (sorry) encounter them in my measurements. What’s worse is that they exist in some high-resolution recordings from famous and well-regarded sources. I don’t want to turn this article into an expose, so I’ll just leave it at that.
The good news is that I believe that these glitches are sonically benign for 99%+ of adult listeners. We simply cannot hear these frequencies, especially when they are narrow-band and 20dB-or-more down from the musical peaks. But they may drive kids crazy.
May not be “audiophile,” but I find it simply remarkable.
(Watch it all…surprising throughout.)
Despite the link-bait title – “Beatles, Pink Floyd Engineer Alan Parsons Rips Audiophiles” – the main message that I got out of the interview had to do with room acoustics and high-resolution downloads. These are where Mr. Parsons recommends spending on home systems. He is also big on surround sound.
Of course, Parsons undeniably knows good sound, having played key roles on Dark Side of the Moon (DSOM) and Year of the Cat (YOTC). Hard to fault the sonics on these babies. To my recollection, the Alan Parsons Project LP’s sounded pretty solid as well.
In any case, while Parsons admittedly is no audiophile, fans of this music will benefit from the read.
Audiophile news has all of the sudden risen on the charts of the blog-o-sphere. To what do we owe this honor?
Chalk most of it up to the timeless “Old Man” – Neil Young.
At a recent News Corp media conference, Young described in some detail about his recent dealings with Apple to bring high(er)-resolution offerings to iTunes. He added that Steve Jobs was taking a personal interest in the project.
Young also approached Bill Ford, asserting that MP3′s sound bad, and suggesting hi-rez alternatives for the car. Ford baulked.
So what’s the ideal hi-rez format? Young claimed that he and Jobs agreed on this one: the LP! He went on to say that Jobs, master of the iPod and $1 compressed download, typically listened to vinyl at home.
Thus, audiophile issues have risen, if for a moment, to the popular consciousness – USA Today, Rolling Stone, HuffPo, Washington Post, PCmag. Like most internet news, the half-life of this issue will likely be measured in hours. But perhaps an impression will be made, boomers remembering just how good that record console sounded and kids wondering whether there’s something to this “quality reproduction” thing. Jobs, having immense street cred across cultures and ages, is probably the ideal messiah for such word.
As an aside, I wrote to Mr Jobs about two years ago, suggesting some audio-friendly tweaks to OSX’s Core Audio package. Alas, my note went unanswered. But I’m no Neil Young.
PS I can hear PeterT and the legions of BAAS vinylphiles now: We told you so! lol
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