January 27, 2010 Video interview with MP3 co-inventor
By
Rich Pell
I've been listening to a lot of MP3s recently (mostly ripped from 128-kbps Internet Radio streams) and have been suprised at just how good many of them sound. Sure, they may suffer when compared directly with the original lossless files, but certainly as a portable format MP3 - despite getting a bad rap from many audiophiles - is a vast improvement over something like the cassette tape.
January 13, 2010 Vinyl vs. CD myths refuse to die
By
Rich Pell
Some time back I blogged about the audio myths surrounding the vinyl and CD formats and how the former simply couldn't compete technically with the latter. Since then, I periodically receive emails from non-technical vinyl fans/audiophiles who have run across my post on the Web, and the discussion usually goes something like this:
Vinylphile: I saw your article about vinyl. You are wrong - vinyl sounds better than CD. There is NO WAY that the digital process can preserve the original analog signal by chopping it up into numbers and reconstituting it.
Me: Hey, if you prefer the sound of vinyl that's great. However that subjective judgment shouldn't be confused with the objective facts, which show that CD/digital does a far more accurate job of reproducing the original musical signal.
Vinylphile: Who says? Vinyl provides a warmth and immediacy that digital can't, and provides more continuity in the music. Digital veils the music. Obviously the reason is because digital is a much more complicated process than analog and results in "digital" music, while analog preserves the analog waveforms that our ears are designed to listen to.
Me: I'm afraid you're mistaken on several points. If you choose not to believe the technical facts regarding CD/digital - which have long since been demonstrated in theory and practice - and instead wish to believe that digital somehow audibly and mysteriously "veils" or fails to "preserve the continuity" of the original signal, or that the end resulting signal isn't just as analog as the original, then that's certainly your prerogative.
Vinylphile: You're talking about using electronic instruments to measure digital's "superiority," but these measurements aren't relevant to what our ears perceive. I let my ears judge - not some sophisticated electronic devices.
Me: [Sigh.] Thanks for your comments.
Obviously the subjective aspects of audio in music recording and playback will continue to remain fertile ground for discussion/debate among audiophiles. However, over 25 years after the introduction of the Compact Disc, there's no reason for there still to be confusion or misunderstanding over the technical basics of digital audio - even among the non-technical public.
So who's to blame? Audiophiles themselves must take some of the responsibility. Good technical information is readily available - on this site as well as many others - but won't benefit those who restrict their "research" on the subject only to resources like subjectivist audiophile publications and like-minded forums.
At the same time, it is possible for the unwary to be led astray by stumbling across authoritative-appearing sites on the Web that contain incorrect or misleading content. For example, several of the emails I've received on this subject have mentioned one url in particular (http://www.howstuffworks.com/question487.htm).
The content on that page, which presumes to answer the question "Is the sound on vinyl records better than on CDs," is, frankly, tripe. On a quick scan I counted six outright errors - mostly uninformed opinion being expressed as fact.
Unfortunately, this is notable because 1.) it appears on what is ostensibly an authoritative site, and 2.) this particular page comes up in the top search results on Google using the terms "vinyl" and "CD." It appears this content has been up for some time and has never been corrected.
Perhaps at some point I'll create a post here specifically refuting the technical errors on that page, as well as listing some of the many good technical resources available on the subject. If anyone has suggested links - or other material/comments - for such a page, please let me know.
February 22, 2009 Networked audio rules!
By
Rich Pell
I've mentioned before how I'm a huge fan of computer-based audio. Specifically I'm referring to network media players like the Squeezebox series that let you conveniently stream your music files (or music content on the Internet) over your wired/wireless home network.
I was so pleased with my original Squeezebox Classic that late last year I bought a Squeezebox Duet - which consists of a handheld controller with a 2.4-in. color display and a separate receiver unit - for use away from my main system. Its initial set-up wasn't as glitch-free as my experience with the original Squeezebox - most likely due to my Wi-Fi-network-dense location - but it has been working fine since.
Here's a good short video demo (1:36) of the Duet:
No sooner had I got the Duet up and running than I had an opportunity to try out a Squeezebox Boom. Unlike the Squeezebox Classic and Duet, which need to be connected to existing audio systems, the Boom (see a white paper on the Squeezebox Boom audio design) is a standalone unit that incorporates built-in amplifiers and speakers.
It also features physical front-panel radio-like controls, including a knob that can be used to navigate menus on the unit's VFD display as well as to control volume. I've seen the Boom called a "Wi-Fi radio" or "Internet radio" in some reviews, but I prefer the company's description of "all-in-one network music player," which more accurately reflects the product's Internet and PC-based music file streaming capabilities and features.
I hadn't previously considered the Boom very seriously for my own use as I tend to use headphones for music listening, and frankly the product's name - "Boom" - put me off a bit, suggesting a "boomy" sound quality that didn't sit well with my audiophile sensibilities. That turned out not to be the case at all.
I ended up setting up the Boom while on vacation visiting family, none of whom had even the faintest idea what a network music player was or why anyone would want one. Their disinterest quickly turned to appreciation and enjoyment as soon as they heard and saw how their music (some of it old LPs that I'd digitized for the occasion) could be played over the Boom anywhere in (or outside) the house.
The Squeezebox Boom enjoying some rest and relaxation in the Florida sun.
Prior to setting up the Boom, I'd installed the company's SqueezeCenter streaming audio server on the PC and imported the various digital music files I'd prepared (mostly high-bit-rate-encoded MP3 files). The set-up for the Boom itself couldn't have been simpler - I was listening to streaming music from the PC within a couple of minutes of taking the unit out of the box. (It took me longer to figure out how to open up the Boom's tiny remote control to install the battery.)
The first thing I noticed was the unit's sound quality - it was quite a bit better than I'd been expecting given the unit's relatively small size and cost. In retrospect, though, after reading the Boom audio design white paper I can see why. The custom-designed drivers (separate woofers and tweeters) are bi-amped with digital crossovers and individual DACs for each speaker - quite impressive for a product in this price category.
The other thing I noticed was that the display size seemed a bit smaller than that of my Squeezebox Classic, and displayed less information than I was used to. While I prefer the original Squeezebox's display size, the Boom's font size, scrolling speed and brightness of the text on the display can all be changed to adjust for various conditions and preferences.
Otherwise, the Boom performed as I expected based on my previous experience with other Squeezebox devices, which is to say it made playing PC-based music files and Internet radio easy and enjoyable. Digital Trends has a good short (1:45) video review of the Boom, which they say is the best-sounding digital streaming media system they've ever tested:
My experience with the Boom wasn't entirely glitch-free however. At one point, after having moved it about to try it in several different locations, it simply stopped working. When powered up, the buttons would light up and flash, but the display remained blank and the unit unresponsive.
I resigned myself to the fact that I'd probably have to return it, but decided to just power everything down overnight (including the network) and try it the next day. Lo and behold the next morning the Boom worked perfectly, as if nothing had ever happened, and the problem never recurred. (Later, one of the Boom's designers told me he thought it might have been due to a flaky internal connection.)
My takeaway from spending time with the Boom and seeing others' reactions to it is further confirmation that this is clearly the direction that home audio (and digital media in general) is heading. While legacy media conversion and networking technology issues present technical hurdles that will undoubtedly hold some people back in the short run, products like the Squeezeboxes are making it easier than ever for non-"geek" consumers to free up their music collections and begin serving them over their home networks.
For more, the following video (11:53) offers an entertaining and informative overview and demonstration of all three of the Squeezebox network media players:
February 16, 2009 How to measure audio quality in portable media players
By
Rich Pell
Several useful training videos on the proper test and measurement set up for audio quality in portable media devices have been produced by Cirrus Logic and cover the following topics:
The basic equipment and source material needed to properly measure portable media players
How to correctly define the test set up and load conditions
Some basics of audio tests
How to figure out what power levels to target in order to measure the player's full potential
Which data you should take and how you can compare it between devices on a level playing field
The first video (9:38) begins with an introduction to the basic equipment and source material needed to properly measure players, as well as an explanation of several standard audio measurement specifications:
The second video (10:25) includes a discussion of measuring THD+N vs. Power and measuring THD+N changes over different volume settings:
The final video (8:22) shows how to calculate the dynamic range of a player from its THD+N vs. Power plot, and how to run a frequency response sweep:
