Blu Ray 4K UHD players are my new standard for playing audio. The below 2 models from Samsung and LG offer UHD 4K video upscaling, 24-bit/192kHz resolution audio DAC, USB input, and Wi-Fi streaming from Netflix, Pandora, and YouTube. They also offer superior cable connections via HDMI ports. They are readily available on Amazon and eBay. Put your library of FLAC audio and HD video on a 256GB USB drive, and you can listen and watch your entertainment library for days. Highly recommended. You can also find older similar models that have the same features. Samsung had the K8500. LG had the UBK8 series and UBK9 series.
Samsung UBD-M8500 4K Blu Ray Player
If your new 4K TV just arrived, you're probably chomping at the bit to see its best picture. Place an Ultra HD Blu-ray disc into the Samsung UBD-M500 4K Blu-ray player's tray, and savor your movies in true 4K resolution — a staggering 3840 x 2160 pixels. This player delivers an incredibly sharp, realistic picture, even when you sit up close.
The Samsung UBD-M8500 features a sturdy disc drive to prevent vibration.
Beautiful, lifelike picture contrast
I think High Dynamic Range (HDR) is the most exciting aspect of Ultra HD Blu-ray. It allows compatible TVs to display extremely bright and dark black picture content together within the same image. (Think tiny stars peeking through the pitch-black night sky.)
This also has Hollywood buzzing. It's given directors a brilliant visual palette to play with — subtle, delicate lighting, sparks of brightness, and true-to-life shading and shadows.
Samsung gives you more 4K viewing options — yep, including Netflix®
Have you ever seen the vibrant Colombian landscapes of Narcos in 4K? It is really something else. And the deeper shading and detail make scenes in small cafés feel even more claustrophobic.
When you connect this player to your home network via Wi-Fi or Ethernet, you get several 4K streaming options including Netflix, Amazon Instant Video, and M-Go. Plus, you can watch 4K video clips on YouTube.
Don't throw out your old discs!
You can still enjoy all your old standard Blu-rays and DVDs on this player. Samsung made 4K upconversion a top priority for the UBD-M8500. Their UHD Upscaling automatically upconverts any signal to 4K resolution. All of your movies and shows will look better than ever.
Find out how great the picture is on your new QLED TV (sold separately) with the Samsung UBD-M8500
Impressive sound and music options
Along with the state-of-the-art picture, your movies will sound amazing too. The Samsung UBD-M8500 has built-in support for the highest-quality surround sound formats, like Dolby® TrueHD and DTS Master Audio™. It also plays Dolby Atmos®-encoded discs (just set the HDMI audio output to "bitstream" when connected to an Atmos-capable receiver).
This Ultra HD player's no slouch when it comes to music, either. You can play music from a CD or stream tunes from services like Pandora® or Spotify®. You can even wirelessly connect to a compatible networked PC via DLNA technology and play songs from your computer.
Samsung's smart hub is smarter than most
This player's brain is a super-speedy eight-core processor — the same found in Samsung's latest high-end TVs, Galaxy phones, and tablets. It lets you do serious multitasking. You can browse the web without having to interrupt your movie, or use one app while downloading another. Plus Samsung's on-board selection of apps is pretty stacked — streaming video, sports leagues, music, games, you name it.
Project images to your screen
While newer phones are getting harder to cram into pockets, sometimes the screens still aren't large enough for certain tasks. Maybe you want to share a video or picture with a group of people. Wirelessly "push" the display to your TV's big screen through the Samsung UBD-M8500. Allshare™, Samsung's take on Miracast™ technology, mirrors the screen of your compatible mobile device, tablet, or computer screen for everyone to see.
Plays Ultra HD Blu-ray discs, standard Blu-ray discs, DVDs, CDs and rewriteable discs (no 3D playback)
full 4K resolution video for use with Ultra HD TVs
4K video upscaling for standard Blu-ray and DVDs
supports lower resolutions when used with non-4K TVs
HDR (High Dynamic Range)-ready for extended picture contrast and brightness on compatible TVs
supports HDR10 format
plays high-resolution digital music files via USB storage device; PCM files up to 24-bit/192kHz resolution
this player accepts Region A Blu-ray discs and Region 1 DVDs
Dual-band Wi-Fi for streaming video and music (subscriptions required for some services)
streaming video services: Netflix, Amazon Prime, YouTube, Vudu, and more
streaming music services: Spotify, Pandora, SiriusXM, iHeartRadio, and TuneIn
HEVC for watching streamed 4K content from sources like Netflix, Amazon Instant, or YouTube (requires Internet speed of at least 20Mbps)
Samsung's Smart Hub lets you scroll through apps and menu while you watch a disc
AllShare lets you stream content and mirror screens from compatible Samsung smartphones and tablets
Multiroom Link for syncing wirelessly with Samsung Shape wireless speakers
on-board web browser
Technical Specs and General Info:
Selectable video resolution up to 3840 x 2160 pixels
built-in audio decoding for Dolby® Digital, Dolby Digital Plus, Dolby TrueHD, DTS®, and DTS-HD Master Audio
can pass Dolby Atmos and DTS:X soundtracks when HDMI output is set to "bitstream"
plays AAC, AIFF, ALAC, , FLAC, MP3, WMA, and WAV audio file formats
front-panel USB port for use with external storage devices
1 HDMI output
HDMI 2.0a (connected 4K TV and/or receiver must have an HDCP 2.2-compatible HDMI input, and must have HDMI 2.0a to support HDR)
Anynet+ simplifies control of compatible Samsung components via "MAIN" HDMI connection (HDMI-CEC)
optical digital audio output
Ethernet port for wired network connection
16"W x 1-7/8"H x 8-15/16"D
warranty: 1 year
LG UBK90 Streaming 4K Ultra-HD Blu-ray Player with Dolby Vision
Ultra HD Premium, Multi-HDR, 4K Blu-Ray Disc Playback, 3D Blu-Ray/ DVD Playback, 4K Streaming Content, Built-in dual band WiFi, USB media input
Get the best out of your 4K TV
Since I upgraded to my LG OLED 4K TV, everything I watch looks better. But I geek out the most over shows and movies in true 4K. They just seem to pop off the screen. And the LG UBK90 4K Blu-ray player will play Ultra HD Blu-ray discs with Dolby Vision — the absolute best-quality video source available today.
Ready for the best HDR formats
Ultra HD Blu-ray discs with HDR (High Dynamic Range) allow compatible TVs to display extremely bright and dark black picture content together within the same image. HDR content makes for serious eye candy on my new OLED TV — it stands out even among other, stellar-looking 4K videos.
And this player supports the required HDR 10 format, and the more sophisticated Dolby Vision format. Dolby Vision is one of the reasons I ended up going with the LG OLED. Dolby's dynamic system can adjust brightness and color levels on a scene-by-scene basis.
Netflix has a bunch of shows in Dolby Vision, and some of them look so realistic and vibrant that it actually adds to the storytelling. Take the brutal Western show Godless: the beautiful yet nightmarish landscape is practically one of the characters. Watching sunlight peek over a mountain and spill over the dusty terrain with true-to-life shading is truly a sight to see.
Top movie sound formats and flexible connections
This player has built-in support for the highest-quality surround sound formats, like Dolby® TrueHD and DTS Master Audio™. It also plays Dolby Atmos®-encoded discs. You simply set the HDMI audio output to "bitstream" when connected to an Atmos-capable receiver.
There are two HDMI outputs: one for sending audio to your home theater receiver and one for video directly to your TV. That means you can still play sound through receivers that don't have a free HDMI input that's HDCP 2.2 compatible. You can also use an optical digital connection to get surround sound from the player to your receiver.
Dual-band Wi-Fi means smooth 4K video streaming
Along with playing discs, you can use the UBK90 to stream Netflix® and YouTube. These are the two video services that offer the most 4K content available right now. And this player's dual-band Wi-Fi gives you the strong connection needed for streaming 4K. (We recommend having an internet speed of 20Mbps or faster for 4K streaming.)
Plays Ultra HD Blu-ray discs, 3D and standard Blu-ray discs, DVDs, CDs and rewriteable discs
full 4K resolution video for use with Ultra HD TVs
4K video upscaling for standard Blu-ray and DVDs
HDR (High Dynamic Range) for extended picture contrast and brightness on compatible TVs
supports HDR10 and Dolby Vision
Dolby Vision adjusts brightness dynamically for premium shading and depth
supports lower resolutions when used with non-4K TVs
plays Region A Blu-ray discs and Region 1 DVDs
Wireless Features and Technical Specs:
Dual-band 802.11ac Wi-Fi for smooth wireless streaming from Netflix and other video streaming apps
HEVC for watching streamed 4K content from Netflix (requires internet speed of at least 20Mbps)
selectable video resolution up to 3840 x 2160 pixels
built-in audio decoding for Dolby® Digital, Dolby TrueHD, DTS®, and DTS-HD Master Audio
can pass Dolby Atmos and DTS:X soundtracks when HDMI output is set to "bitstream" for decoding by a compatible receiver
Plays AAC, FLAC, MP3, and WMA audio file formats
BD-Live and BonusView support for added bonus features with compatible discs (requires external USB storage device)
Connections and General Info:
Front-panel USB port to play music, movies, and images from external hard drives, thumb drives, or Android phones
2 HDMI outputs for separating audio and video signals
HDMI 1 output is HDMI 2.0a (connected 4K TV and/or receiver must have an HDCP 2.2-compatible HDMI input, and must have HDMI 2.0a to support HDR)
HDMI 2 input does not output video signal (audio only)
optical digital audio output
dual-band 802.11ac Wi-Fi and Ethernet port for downloading firmware updates
16-15/16"W x 1-13/16"H x 9-3/8"D
warranty: 1 year
4K Ultra HD Blu-ray Disc playback provides the ultimate in audio/video quality with a stunning 4K picture and state-of-the-art audio. Pop in a 4K Ultra HD Blu-ray Disc and prepare to be transported
4K streaming content - this internet-ready LG device is capable of delivering an uncompromising Ultra HD 4K streaming experience. (Additional subscriptions services may be required)
High pressure audio playback - this UHD Blu-ray DVD player Supports high Resolution audio
HDR playback - this LG Blu-ray Disc player is HDR compatible with Dolby Vision and HDR10. (HDR/Dolby Vision TV sold separately and required for Dolby Vision playback)
Blu-ray & DVD backward compatible - this LG UHD Blu-ray Disc player is backward compatible supporting both of these popular legacy standards.
Extended Resolution Compact Disc (XRCD) is a mastering and manufacture process patented by JVC (Victor Company of Japan, Ltd) for producing Red Book compact discs. It was first introduced in 1995.
An XRCD is priced about twice as high as a regular full-priced CD. JVC attributes this to the higher cost of quality mastering and manufacturing.
The XRCD definition refers to the mastering and manufacture process; the resulting CD and the contained data conform to the redbook standard and are encoded at 16 bits, 44.1 kHz. Hence, XRCDs are playable on any compact disc player.
JVC uses advanced dither algorithms (though without noise shaping) in their K2 technology to transfer the analog or digital source to physical disc. The company claims to have studied how inferior CD-remastering techniques degrade the master tape sound and strives to minimize this loss.
Unlike HDCD, the extra four bits cannot be recovered, as this method of mastering only aims to improve dithering to 16-bit, rather than to store extra data.
If analog, the source material is first converted to digital via JVC's K2 20-bit or 24-bit analog-to-digital converter.
The musical information is next encoded on a magneto-optical disk for transport to JVC's Yokohama manufacturing plant, where jitter reduction is applied. The musical signal on the disk is down-converted to 16-bit through a K2 "super-coding" process. This 16-bit signal is eight-to-fourteen modulation-encoded (EFM-encoded) before going through a proprietary "Extended Pit Cut" DVD K2 laser technology to produce a glass master. JVC claims this optimizes the linear velocity of the glass master, giving precise pit lengths to eliminate time jitters, controlled by an extremely precise rubidium clock. All CDs are finally stamped directly from this glass master.
XRCD2 and XRCD24 are improved versions of the original XRCD process. XRCD2 is the first to record to a magneto-optical disk via the digital K2 regenerator, while XRCD24 upgrades the original music signal's bit depth signal from 20 to 24 bits.
Super Audio CD (SACD) is an optical disc format for audio storage introduced in 1999. It was developed jointly by Sony and Philips Electronics and intended to be the successor to the Compact Disc (CD) format. It is sometimes referred to DVD audio.
The SACD format allows multiple audio channels (i.e. surround sound or multichannel sound). It also provides a higher bit rate and longer playing time than a conventional CD.
An SACD is designed to be played on an SACD player. A hybrid SACD contains a Compact Disc Digital Audio (CDDA) layer and can also be played on a standard CD player.
The Super Audio CD format was introduced in 1999, and is defined by the Scarlet Book standard document. Philips and Crest Digital partnered in May 2002 to develop and install the first SACD hybrid disc production line in the United States, with a production capacity of up to three million discs per year. SACD did not achieve the level of growth that compact discs enjoyed in the 1980s, and was not accepted by the mainstream market.
By 2007, SACD had failed to make a significant impact in the marketplace; consumers were increasingly downloading low-resolution music files over the internet rather than buying music on physical disc formats. A small and niche market for SACD has remained, serving the audiophile community.
By October 2009, record companies had published more than 6,000 SACD releases, slightly more than half of which were classical music. Jazz and popular music albums, mainly remastered previous releases, were the next two genres most represented.
Many popular artists have released some or all of their back catalog on SACD. Pink Floyd's album The Dark Side of the Moon (1973) sold over 800,000 copies by June 2004 in its SACD Surround Sound edition. The Who's rock opera Tommy (1969), and Roxy Music's Avalon (1982), were released on SACD to take advantage of the format's multi-channel capability. All three albums were remixed in 5.1 surround, and released as hybrid SACDs with a stereo mix on the standard CD layer.
Between 2007 and 2008, the rock band Genesis re-released all of their studio albums across three SACD box sets. Each album in these sets contains both new stereo and 5.1 mixes. The original stereo mixes were not included. The US & Canada versions do not use SACD but CD instead.
By August 2009 443 labels had released one or more SACDs. Instead of depending on major label support, some orchestras and artists have released SACDs on their own. For instance, the Chicago Symphony Orchestra started the Chicago Resound label to provide full and burgeoning support for high-resolution SACD hybrid discs, and the London Symphony Orchestra established their own LSO Live label.
Many SACD discs that were released from 2000-2005 are now out of print and available only on the used market. By 2009, the major record companies were no longer regularly releasing discs in the format, with new releases confined to the smaller labels.
|Characteristic||CD layer (optional)||SACD layer|
|Disc capacity||700 MB||4.7 GB|
|Audio encoding||16-bit pulse-code modulation||1-bit Direct Stream Digital|
|Sampling frequency||44.1 kHz||2,822.4 kHz (2.8224 MHz)|
|Audio channels||2 (stereo)||Up to 6 (discrete surround)|
|Playback time if stereo||80 minutes||110 minutes without DST compression|
- Hybrid: Hybrid SACDs have a 4.7 GB SACD layer (the HD layer), as well as a CD (Red Book) audio layer readable by most conventional Compact Disc players.
- Single-layer: A disc with one 4.7 GB SACD layer.
- Dual-layer: A disc with two SACD layers, totaling 8.5 GB, and no CD layer. Dual-layer SACDs can store nearly twice as much data as a single-layer SACD. Like most dual-layer DVDs, the data spiral for the first layer is encoded from the inside out, and the second layer is encoded starting from the point where the first layer ends and ending at the innermost part of the disc. Unlike hybrid discs, both single- and dual-layer SACDs are incompatible with conventional CD players and cannot be played on them.
Commercial releases commonly include both surround sound (five full-range plus LFE multi-channel) and stereo (dual-channel) mixes on the SACD layer. Some reissues retain the mixes of earlier multi-channel formats (examples include the 1973 quadraphonic mix of Mike Oldfield's Tubular Bells and the 1957 three-channel stereo recording by the Chicago Symphony Orchestra of Mussorgsky's Pictures at an Exhibition, reissued on SACD in 2001 and 2004 respectively).
Objective lenses in conventional CD players have a longer working distance, or focal length, than lenses designed for SACD players. In SACD-capable DVD, Blu-ray and Ultra HD Blu-ray players, the red DVD laser is used for reading SACDs. This means that when a hybrid SACD is placed into a conventional CD player, the infrared laser beam passes through the SACD layer and is reflected by the CD layer at the standard 1.2 mm distance, and the SACD layer is out of focus. When the same disc is placed into an SACD player, the red laser is reflected by the SACD layer (at 0.6 mm distance) before it can reach the CD layer. Conversely, if a conventional CD is placed into an SACD player, the laser will read the disc as a CD since there is no SACD layer.
Direct Stream Digital
SACD audio is stored in Direct Stream Digital (DSD) format using pulse-density modulation (PDM) where audio amplitude is determined by the varying proportion of 1s and 0s. This contrasts with compact disc and conventional computer audio systems using pulse-code modulation (PCM) where audio amplitude is determined by numbers encoded in the bit stream. Both modulations require neighboring samples to reconstruct the original waveform, the more the lower frequency that can be encoded.
DSD is 1-bit, has a sampling rate of 2.8224 MHz, and makes use of noise shaping quantization techniques in order to push 1-bit quantization noise up to inaudible ultrasonic frequencies. This gives the format a greater dynamic range and wider frequency response than the CD. The SACD format is capable of delivering a dynamic range of 120 dB from 20 Hz to 20 kHz and an extended frequency response up to 100 kHz, although most available players list an upper limit of 70–90 kHz, and practical limits reduce this to 50 kHz. Because of the nature of sigma-delta converters, DSD and PCM cannot be directly compared. DSD's frequency response can be as high as 100 kHz, but frequencies that high compete with high levels of ultrasonic quantization noise. With appropriate low-pass filtering, a frequency response of 20 kHz can be achieved along with a dynamic range of nearly 120 dB, which is about the same dynamic range as PCM audio with a resolution of 20 bits.
Direct Stream Transfer
To reduce the space and bandwidth requirements of DSD, a lossless data compression method called Direct Stream Transfer (DST) is used. DST compression is compulsory for multi-channel regions and optional for stereo regions. It typically compresses by a factor of between two and three, allowing a disc to contain 80 minutes of both 2-channel and 5.1-channel sound.
Direct Stream Transfer compression was standardized as an amendment to the MPEG-4 Audio standard, ISO/IEC 14496-3:2001/Amd 6:2005 (Lossless coding of oversampled audio), in 2005. It contains the DSD and DST definitions as described in the Super Audio CD Specification. The MPEG-4 DST provides lossless coding of oversampled audio signals. Target applications of DST are archiving and storage of 1-bit oversampled audio signals and SA-CD.
SACD has several copy protection features at the physical level, which made the digital content of SACD discs difficult to copy until the jailbreak of the PlayStation 3. The content may be copyable without SACD quality by resorting to the analog hole, or ripping the conventional 700 MB layer on hybrid discs. Copy protection schemes include physical pit modulation and 80-bit encryption of the audio data, with a key encoded on a special area of the disc that is only readable by a licensed SACD device. The HD layer of an SACD disc cannot be played back on computer CD/DVD drives, and SACDs can only be manufactured at the disc replication facilities in Shizuoka and Salzburg. Nonetheless, a PlayStation 3 with an SACD drive and appropriate firmware can use specialized software to extract a DSD copy of the HD stream.
Sound quality parameters achievable by the Red Book CD-DA and SACD formats compared with the limits of human hearing are as follows:
- Dynamic range: 90 dB; 120 dB (with shaped dither);  frequency range: 20 Hz—20 kHz
- Dynamic range: 105 dB; frequency range: 20 Hz— 50 kHz
- Human hearing
- Dynamic range: 120 dB; frequency range: 20 Hz—20 kHz (young person); 20 Hz—8-15 kHz (middle-aged adult)
In September 2007, the Audio Engineering Society published the results of a year-long trial, in which a range of subjects including professional recording engineers were asked to discern the difference between high-resolution audio sources (including SACD and DVD-Audio) and a compact disc audio (44.1 kHz/16 bit) conversion of the same source material under double-blind test conditions. Out of 554 trials, there were 276 correct answers, a 49.8% success rate corresponding almost exactly to the 50% that would have been expected by chance guessing alone. When the level of the signal was elevated by 14 dB or more, the test subjects were able to detect the higher noise floor of the CD-quality loop easily. The authors commented:
Now, it is very difficult to use negative results to prove the inaudibility of any given phenomenon or process. There is always the remote possibility that a different system or more finely attuned pair of ears would reveal a difference. But we have gathered enough data, using sufficiently varied and capable systems and listeners, to state that the burden of proof has now shifted. Further claims that careful 16/44.1 encoding audibly degrades high resolution signals must be supported by properly controlled double-blind tests.
Following criticism that the original published results of the study were not sufficiently detailed, the AES published a list of the audio equipment and recordings used during the tests. Since the Meyer-Moran study in 2007, approximately 80 studies have been published on high-resolution audio, about half of which included blind tests. Joshua Reiss performed a meta-analysis on 20 of the published tests that included sufficient experimental detail and data. In a paper published in the July 2016 issue of the AES Journal, Reiss says that, although the individual tests had mixed results, and that the effect was "small and difficult to detect," the overall result was that trained listeners could distinguish between hi-resolution recordings and their CD equivalents under blind conditions: "Overall, there was a small but statistically significant ability to discriminate between standard quality audio (44.1 or 48 kHz, 16 bit) and high-resolution audio (beyond standard quality). When subjects were trained, the ability to discriminate was far more significant." Hiroshi Nittono pointed out that the results in Reiss's paper showed that the ability to distinguish high-resolution audio from CD-quality audio was "only slightly better than chance."
Contradictory results have been found when comparing DSD and high-resolution PCM formats. Double-blind listening tests in 2004 between DSD and 24-bit, 176.4 kHz PCM recordings reported that among test subjects no significant differences could be heard. DSD advocates and equipment manufacturers continue to assert an improvement in sound quality above PCM 24-bit 176.4 kHz. A 2003 study found that despite both formats' extended frequency responses, people could not distinguish audio with information above 21 kHz from audio without such high-frequency content. In a 2014 study, however, Marui et al. found that under double-blind conditions, listeners were able to distinguish between PCM (192 kHz/24 bits) and DSD (2.8 MHz) or DSD (5.6MHz) recording formats, preferring the qualitative features of DSD, but could not discriminate between the two DSD formats.
The Sony SCD-1 player was introduced concurrently with the SACD format in 1999, at a price of approximately US$5,000. It weighed over 26 kilograms (57 lb) and played two-channel SACDs and Red Book CDs only. Electronics manufacturers, including Onkyo, Denon, Marantz, Pioneer and Yamaha offer or offered SACD players. Sony has made in-car SACD players.
SACD players are not permitted to offer an output carrying an unencrypted stream of DSD.
The first two generations of Sony's PlayStation 3 game console were capable of reading SACD discs. Starting with the third generation (introduced October 2007), SACD playback was removed. All PlayStation 3 models, however, will play DSD Disc format. The PlayStation 3 was capable of converting multi-channel DSD to lossy 1.5 Mbit/s DTS for playback over S/PDIF using the 2.00 system software. The subsequent revision removed the feature.
Unofficial playback of SACD disc images on a PC is possible through freeware audio player foobar2000 for Windows using an open source plug-in extension called SACDDecoder. macOS music software Audirvana also supports playback of SACD disc images.
- Extended Resolution Compact Disc (XRCD)
- High Definition Compatible Digital (HDCD)
- Timeline of audio formats
In the late 1990s, one of the original portable music file formats -- the MP3 -- was causing quite a bit of bother mainly due to user's illegal sharing over Napster. While MP3 eventually prevailed, there is an even better choice for high-quality music downloads, and it's playable on your favorite device. It's even in your music streams.
FLAC (Free Lossless Audio Codec) is a musical file format that offers bit-perfect copies of CDs but at half the size. It is compatible with many phones (including the iPhone -- with an app), portable music players (PMP) including the PonoPlayer and hi-fi components. FLAC files are available for roughly the same price as the equivalent MP3 in online stores and sound much better.
To see where FLAC has come from and where it is headed, you only need to look at the history of its "lossy" predecessor. Though MP3.com was one of the first sites to sell MP3s in 1999, dedicated players like the Rio PMP300 were subject to legal action by record companies. Yet when the iPod was released in 2001, it helped to legitimize the format, and today MP3s are now sold by most online music stores. (Disclosure: MP3.com no longer sells MP3s and is now owned by CBS Interactive, parent company of CNET.)
FLAC, ahh-ahhh, it'll save every one of us*
Until recently, the music format FLAC (Free Lossless Audio Codec) enjoyed a similar "pirates-only" reputation to MP3 because of its lack of Digital Rights Management (DRM), but FLAC has the potential to reach a larger audience than just audiophiles and tech enthusiasts. Currently, almost every record label is on board with the format, and consumers can buy lossless music from both major and indie acts for the same price as the iTunes Store.
FLAC first emerged in 2001 as an open-source alternative to other lossless formats emerging at the time. These included Apple Lossless (ALAC), Microsoft's WAV (Waveform Audio Format) and WMA Lossless. But these competitive formats do have their disadvantages. While ALAC has a loyal following among iPod and iPhone users, it hasn't seen much uptake outside of Apple products. The WAV format is also popular, and it's compatible with iOS devices, but its biggest problems are that file sizes are very large, and it can't retain "tag" data -- artist, album name, lyrics, and so on -- in the way the other formats can. FLAC, on the other hand, not only supports tags but is also compatible with most music players. Apple is the only real holdout here, for while there was talk in 2017 of hardware support in both the iPhone 8 and X nothing has materialized. However, there are simple workarounds for iOS and Mac users.
*With apologies to Queen
What's the difference between MP3 and FLAC?
MP3 is a lossy format, which means parts of the music are shaved off to reduce the file size to a more compact level. It is supposed to use "psychoacoustics" to delete overlapping sounds, but it isn't always successful. Typically, cymbals, reverb and guitars are the sounds most affected by MP3 compression and can sound really distorted or "crunchy" when too much compression is applied.
Like MP3 before it, FLAC has been embraced by the music industry as a cost-effective way to distribute CD-or-better-quality music, and it doesn't have the auditory problems of MP3s. FLAC is lossless and more like a ZIP file -- it comes out sounding the same when it is unzipped. Previously the only way to get "lossless" files was via the uncompressed CD formats CDA or WAV, but neither is as space-efficient as FLAC.
While FLAC files are up to six times larger than an MP3, they are half the size of a CD, and can have the same boost in audio quality. Furthermore, FLAC is not just restricted to 16-bit (CD quality), and you can buy files up to 24-bit/192kHz for another potential boost in performance. While the effects of better-than-CD quality are highly debated, companies like Neil Young's Pono staked their reputations on its benefits.
But regardless of whether you are using 16- or 24-bit quality files, FLAC is here to stay. Experts such as Malcolm Hawksford, professor of psychoacoustics at Essex University, say that despite competition from proprietary formats like MQA and DSD the humble FLAC is still competitive.
"FLAC has a place in the future for high-quality audio. It is good for transporting files on the internet as it typically halves download time. It is unlikely that for lossless compression there will be significant improvements," Hawksford wrote on Bowers & Wilkins' Society of Sound blog.
While physical discs are still popular, their usefulness will eventually be eclipsed by the convenience of purely digital files: whether that means streaming or software files stored on your network or in the cloud. As a format FLAC will probably never be as popular a format as CD and DVD were in their heydays, but it's quickly become the format of choice for people who care about sound quality.
FLAC versus streaming
FLAC downloads have one major competitor: streaming. While audiophiles are mostly concerned with music bought from music stores like Bandcamp and HD Tracks, it's not the only option available to people interested in high quality music. At the lower end of the scale, Pandora and Rhapsody have been streaming for years at bit-rates between 128kbps and 192kbps but they're no match for lossless FLAC in the audio department.
However there are several major streaming services that offer very high sound quality -- Spotify, Tidal and soon Qobuz -- and depending on the record, they can be indistinguishable from the CD. While Spotify content is ripped in 320Kbps Ogg Vorbis, it's Tidal that offers the biggest alternative to personal collections as it's also based on FLAC. The company is also able to offer hi-res music by adding Meridian's MQA technology for compatible devices. By contrast, Qobuz offers hi-res FLAC streaming without the use of a proprietary wrapper, but the trade-off is much larger file sizes not suitable for the train. In the meantime, both Spotify and Tidal let you download tracks for offline listening (with a paid subscription), and both catalogs are quite impressive.
But it's not just Tidal and Qobuz that offer lossless streaming: there are othe up-and-comers as well. While CD-ripping service Murfie was one of the first sites to offer true-quality streaming, it's currently only for customers who pay an additional $99 fee (roughly converting to £80 and AU$140), and only for the CDs they currently own. Meanwhile, Deezer Elite is another service that offers lossless streaming but currently only to users of Sonos.
While the world is swiftly moving toward streaming, FLAC does offers several advantages over the Spotifys and Tidals of this world. Firstly, you only need to pay once for a FLAC album. With a streaming service, you'd need to pony up for a subscription fee for the rest of your life or lose access to your carefully curated music collection.
Secondly, you don't need an internet connection to listen to your music, and while the Offline modes of both Tidal and Spotify enable you to use it on the subway, it still needs to be connected to the 'net at some point to get the files. What if your music player doesn't have apps or network capability? For inexpensive music players like the Sony A17, a set of FLAC files make the most sense.
Where can I get FLAC files?
There are two main ways to get your FLAC files legally: ripping from CD or purchasing from a digital store. Ripping is easy to do but you will need the right software for your computer. However, there are some devices that enable you to rip and store FLAC files on a networked hard drive without having to ever touch a PC; the Bluesound Vault is one of these.
If you'd rather pay someone else to do that for you, we cover our favorite sites for buying FLAC files here. If you want to find music and don't know which site the music is on, do a Google search for the name of the artist/album and "digital."
How do I play FLAC files?
iOS: There is still one hurdle preventing FLAC's full-scale adoption: the Apple iPhone and other iOS devices don't support within iTunes. With every major edition of iOS and iTunes, we secretly hope for FLAC support, but we may never get it. While Apple announced its Mastered for iTunes program (24-bit/44.1kHz) several years ago, the company has moved on to more profitable and immediate concerns such as Apple Music.
However, there are several apps available in the iTunes Store that do support the FLAC format and even let you stream them between devices on your network via AirPlay and DLNA. Apps available from the App Store include FLAC Player, MediaConnect and Capriccio.
Android: Users of Google's phone OS don't need to worry as much about FLAC support; from Android 3.1 (Honeycomb) onward the OS supports the file format natively. Even if you have an older Android phone, manufacturers like HTC and Samsung have added FLAC support to their software media players. Nonetheless, good apps to try from Google Play are Rocket Music Player, Player Pro -- which also supports high-res -- and Bubble UPnP (which includes DLNA support and also Tidal integration).
Windows and Mac: If you're a Windows 10 user, you can play FLAC files natively in the operating system. For older Windows versions, there is a Windows Media Player plug-in, but the players most recommended by audiophiles are Roon, Media Monkey and JRiver. Meanwhile Mac users can download Roon, Fluke for basic support for FLAC in iTunes or Songbird (also on PC).
Portable: While Android MP3 players have dwindled in popularity, they have been replaced by high-res portable players like Sony's Walkman NW-WM1 and the now-discontinued PonoPlayer designed to support FLAC natively, up to 24-bit/192kHz. Meanwhile, traditional players by Sony, iRiver and FiiO can typically play back FLAC.
Getting quality that's measurably better than your phone will cost you though, with models from Astell & Kern costing into the thousands. However, players such as the Sony A30 Walkman A Series promise 45 hours of battery life and start at about $220 (roughly £170 and AU$310). See CNET's best players that support FLAC here.
Hi-fi: Of course, the biggest advantage to FLAC files is that they are ideally suited to listening on a hi-fi device. In the last few years, a wealth of streaming audio players have appeared with lossless FLAC playback one of their many benefits. The least expensive of these is the $35, £30 or AU$59 Chromecast Audio but these multiroom music systems also support the format.
If you own a Network Attached Storage (NAS) device, PC or even a phone you can serve FLAC files to any number of DLNA for media streamers--what does it all mean? in your AV system including TVs, Roku boxes, receivers and more. If the device connects to the internet, it's most likely to also support DLNA, and though FLAC isn't officially part of the DLNA specification, it usually comes along for the ride anyway.
Though streaming services may come and go, and even the long-term prospects of Spotify are not assured, a FLAC file is like a CD: once you buy it or rip it, it's yours forever (barring storage catastrophes). FLAC may never actually supplant MP3, but if you care about sound quality, then FLAC is undoubtedly your best option -- both now and into the foreseeable future.
Editors' note, October 28, 2018: This article was originally published in October 2012 and has been updated with new information.
Like a lot of folks today, I have been rediscovering the virtues of CD audio quality sound. Back in the 1990's, CDs were the highest quality source of of music. I have hundreds of CDs, along with several high quality Blu Ray players, but I have to use my TV to play these. The CD player has a place in many hi-fi systems today. Below is a Technics 5 CD Changer Model-SL-PD807. It features a 1 Bit DAC. Below are photos and a discussion from Stereophile Magazine on the virtues of this amazing DAC. Other brands like Phillips and Sony have also introduced Bitstream 1 Bit DACs.
Technics SL-MC4 60 CD Changer (from Amazon.com)
60+1 CD changer, digital optical output, CD text search and scrolling text display. Text edit function, phone-style 10 key enter pad, Quick disc change mechanism. Front loading mechanism allows to play one disc while changing another. Quick single play system, 14 preset grouping files.
Large-capacity CD changers are among the best bargains in today's audio market, and Technics is one of a handful of companies responsible for bringing them to a broad consumer base. The LS-MC4 61-disc changer/player is a well-crafted component that fits neatly into an entertainment rack while offering just enough storage capacity to keep most music lovers content.
This handsome player defies the "jukebox" description of many changers, measuring as it does less than seven inches high (with a standard width). The entire front-panel lifts down manually to reveal all 61 slots, with slot 1 reserved for single-disc play only. We were impressed with the build quality of the door mechanism, which slides down gently but firmly and doesn't appear prone to breakage. This mega-changer includes an optical-digital output for connecting to an outboard digital-to-analog converter or an surround receiver or processor with digital inputs.
We connected the LS-MC4 to an outboard digital-to-analog converter with a Toslink optical cable, plugged it in, slipped a CD in the single-disc slot, hit play, and whistled the tune of simplicity.
Since programming features can be rather complicated with today's computer-reliant changers, operating instructions are a must-read. Technics deserves credit for providing well-written, concise instructions on the multitude of programming options, including how to categorize discs by music genre (choose from 14, from Ballads to Oldies) and how to input customized text to identify discs (though a growing number of discs offer CD Text, which displays track and artist information automatically).
It took approximately 90 minutes to read the instructions and become comfortable with inputting text using both the remote control and the front-panel numeric keypads, which include letters just like a phone. It took a few trial-runs to get the procedure down, which was encumbered by the computer's 7-second limit to perform text entries. Once we got the hang of it, however, we had the procedure memorized after about half-a-dozen discs.
Obviously, programming 60 CDs is cumbersome and requires an afternoon of leisure time, but it's well-worth the effort, since it eliminates the task of searching for the right CD in a five-foot display rack or, worse, shuffling through the changer in search of a specific title. Once this mega-changer is armed and loaded, it brings added pleasure to general music listening, not to mention parties.
The LS-MC4 should top of any host's list of must-have electronics, since it can play a weekend worth of music with the touch of a button. Although sound quality doesn't seem to be a priority in mega-CD changers, the LS-MC4 is more than adequate for most music lovers, particularly when taking advantage of the fiber-optic audio output. Kudos to Technics for simplifying today's large-capacity CD changers with the LS-MC4.
PDM, PWM, Delta-Sigma, 1-Bit DACs Peter W. Mitchell
Peter W. Mitchell wrote about MASH DACs in January 1990 (Vol.13 No.1):
In October 1989, Technics flew a dozen North American hi-fi writers, including myself, to Japan for a busy week including seminars about MASH 1-bit digital decoding. The "1-bit" digital decoder, is suddenly appearing everywhere. In recent years, competition among makers of CD players has taken the form of "bit wars," the use of ever-higher numbers of bits to decode the CD. Linear 16-bit decoders led to pseudo–18-bit decoding, then to real 18-bit decoders, and now several companies claim to be providing 20-bit decoding. If you don't read brochures carefully you may also come away with confused impressions about 24-, 32-, and even 45-bit processing (in digital filters).
The assumption, of course, is that more must be better. Re-sampling digital filters follow the same rule: if 2x re-sampling is good, 4x is better, and many of this year's best players use 8x. Decoder chips can be multiplied as well: early CD players used a single decoder, switched between channels. Now most players use two decoders, one per channel, while the newest high-performance models often use four D/A chips, a back-to-back pair in each channel.
It is possible to find engineering logic behind each of these design choices. The best reason for using 18- or 20-bit decoding, or back-to-back pairs of DACs, is that it can reduce the effect of decoder nonlinearity, providing more accurate decoding of the 16-bit data on the CD. Furthermore, the interpolations involved in "oversampling" digital filters have the effect of turning the original 16-bit data samples into 18-bit or longer digital words; using an 18- or 20-bit decoder reduces the distortion and noise that would be caused by rounding off the longer words or decoding only the topmost 16 bits.
Such improvements actually are realized in some high-priced players. But in midprice players the bit wars are just a marketing contest, a way to gain a competitive advantage by making specifications look better. In some factories the use of 18-bit or back-to-back DACs has become another excuse for avoiding the costly individual MSB fine-tuning that is required to obtain truly linear low-level decoding. The result, 18 months after this "CD cancer" became widely known, is that midprice CD players continue to vary greatly in linearity from sample to sample, and a 20-bit 4-DAC model of one brand may perform less well than another maker's 16-bit 2-DAC player. In this environment, the "bit" rating is little more than fraud.
"1-bit" processing is a fundamentally different approach from decoding the digital signal—a method that promises both finer performance in the very best CD players and more consistent performance in low-cost models. But at first it is sure to add confusion. If 18 bits is allegedly better than 16, how can a 1-bit decoder be considered hi-fi at all?
Two players with 1-bit decoding, the Technics SLP-555 and SLP-222, have been on the market since last spring, but the inclusion of the new decoder was kept a secret because the company wasn't ready to deal with this question. The brochures for those players incorrectly described them as having normal decoders in back-to-back pairs. This deception was intended not only to avoid causing confusion among consumers but also to prevent a rebellion among retail salespeople, who like to have a simple, persuasive description of each product they're trying to sell. In a "more bits is better" environment, 1-bit decoding would be a hard sell. Technics chose to postpone publicity about 1-bit decoding until the new year, and inviting hi-fi writers to a factory seminar was part of the plan.
The name, "1-bit" D/A conversion, is part of the problem because it engenders confusion without explaining anything. Philips's preferred name, "Bit-stream" decoding, is less confusing but still doesn't tell you very much. Fundamentally, the operation of a bit-stream decoder is not difficult to understand.
To appreciate why it's a better idea, let's begin at the beginning. Digital signal processing is inherently precise because it involves only simple on-off switching. Switches are either on or off; the accuracy of the result is not affected by the precision of the electrical parts involved, nor by the temperature, or other factors. If you have a sufficiently large number of electronic switches, operated rapidly, any desired result can be obtained. This is how computers work. And if you have too few switches for exact computation, the errors are predictable; known errors can be compensated (canceled) or can be averaged out by switching much more rapidly. (The latter is the basis of "dithering" to remove quantizing distortion in low-level signals.)
Analog processing is inherently approximate and variable, because the result depends on the physical properties of the parts used. For example, every digital device (recorder, CD player, et al) requires an output filter to reconstruct a smooth waveform and remove the ultrasonic byproducts of the digital switching process. In the early days of digital audio, those filters were complex analog circuits containing a dozen or more capacitors, inductors, and resistors. An analog filter is basically a frequency-dependent voltage divider: the signal is attenuated at each frequency according to the ratio of impedances in the circuit. Since impedances of electronic parts are specified only approximately and often vary with temperature, the response of an analog filter can be predicted only approximately. Even with selected high-precision parts it is impractical to achieve exact response, and a few years ago every digital product had a slightly different response—a built-in, nonadjustable tone control. Analog filters also exhibited a potentially audible group delay (phase shift) at high frequencies.
Then designers adopted digital filtering. A digital filter operates by combining signals after many brief time-delays (typically a few millionths of a second); in this process, unwanted signals simply cancel out. The response is controlled by the mathematical design of the filter, and by the delay times (which are precisely regulated by a crystal oscillator). Consequently manufacturers can mass-produce digital filters at very low cost, all with exactly the same response, accurate to a few thousandths of a dB. As a bonus, since the internal delays are the same for every frequency, digital filters are phase-linear.
Virtually all new CD players use digital filters, not because they contain more accurate parts, but because accurate response is inherent in their design (regardless of parts quality). Initially digital filters are more costly to design, but in mass-production they are less costly to use because they are all identical; there's no need to measure each one, grade them for accuracy, or match response in pairs.
The same reasoning underlies the development of bit-stream decoders. The problem with a conventional digital/analog converter (DAC) is that its operation involves mainly analog processes and is therefore approximate. A 16-bit DAC contains a precision current source and an array of 16 switches. Each switch is connected to a resistor, and the resistors are supposed to be scaled in exact 2:1 ratios so that each switch, when opened, will contribute exactly twice as much current to the output as the switch below it. The switches are controlled by the 16-bit codes from the CD; thus by opening and closing in various combinations, a total of 65,536 different output values can be generated.
But the topmost switch (the most-significant bit, or MSB) contributes 32,768 times as much current as the least-significant bit (LSB). If the MSB current is in error by as little as one part in 32,768, the effect of the LSB is swamped. In most CD players it is; few 16-bit DACs operate to better than 15-bit accuracy. The practical result is that most CD players are non-linear at very low signal levels, reproducing small signals at the wrong levels and with added distortion. Keep in mind that this problem arises not from the digital code itself but from small errors in an analog quantity—the current produced by the DAC for the several most-significant bits.
For comparison, imagine that you were assigned to fill a bucket with a known amount of water, using measuring cups varying in size from one ounce to 64 ounces. Even if you use care in filling the largest cup, it might contain 63.7 or 64.5 ounces instead of 64; you can't be sure that it contains exactly 64 times as much water as the smallest cup. But there is a way to obtain an exact result: use only the one-ounce cup, and transfer its contents to the bucket 64 times. The capacity of the cup may not be exactly one ounce, but as long as you fill it the same way each time, the total amount transferred will be proportional to the number of refills—an exactly linear relationship. This is the idea behind 1-bit decoding. In place of a method whose result depended on slightly uncertain analog quantities (the currents in the DAC), we have adopted a simple counting scheme—a purely digital process.
Of course with a small cup you'll have to work fast, but in modern digital electronics that's not an obstacle. In the Philips bitstream decoder, the output stage generates around ten million pulses per second, the exact rate being determined by the digital code. (This is called "pulse density modulation," or PDM.) A simple analog filter averages out the pulses to form the final analog output signal.
In all of the Japanese 1-bit decoders announced to date, the output stage is a pulse-width modulation (PWM) circuit of some type. In a PWM system the output signal is an on/off waveform in which the analog voltage is represented by the duration of the pulses, ie, the percentage of time the waveform remains in the "on" state. This is analogous to filling the bucket, not with a cup, but with a hose whose high-precision valve allows the water to flow in precisely timed bursts. When we want a larger amount of water, we use wider pulses (longer bursts).
The Technics MASH (multistage) decoder uses pulses of 11 different durations to form the output signal. The timing circuit that controls the pulses operates at a frequency of 33.9MHz, or 768 times higher than the 44.1kHz sampling rate of the digital codes in the CD. The transformation of the CD's original PCM signal into the final PWM waveform is determined mathematically and is accomplished entirely in the digital domain. In principle this can be done to any desired degree of accuracy, preserving all of the information in the original 16-bit code.
Summing up: to obtain exact frequency and phase response, manufacturers abandoned analog filters whose performance depended on inexact circuit impedances, and adopted digital filters whose response is controlled by mathematical operations and precisely timed delays. Now, to obtain consistently exact decoding of low-level signals, they intend to abandon conventional DACs whose accuracy is affected by uncertain analog quantities (currents flowing through resistors of slightly inexact value), and replace them with bitstream decoders whose accuracy, again, is determined by mathematics and timing (the number and duration of pulses).
The essential point is that the performance of a bitstream decoder, like that of a digital filter, depends on its design and is not expected to vary from sample to sample. Unlike PCM decoders, there is no need to quality-grade the chips for accuracy, nor to fine-tune the performance on the production line. Thus the bitstream decoder brings closer the day when CD players, too, can be assembled by robots with no need for individual adjustment or testing.
Conventional current-summing DACs also require a current/voltage conversion stage, which can be a source of slewing-induced distortion, plus a deglitching circuit to suppress the "glitch" (the high-current spike) that occurs when several bits change in imperfect synchrony. A bitstream decoder needs neither.
Stereophile readers have already seen an example of how good 1-bit decoding can be, in Larry Greenhill's review of Sansui's AU-X911DG integrated amplifier (November 1989, pp.144–150). The amplifier's integral D/A converter, called "LDCS" by Sansui, is actually a third-generation Technics MASH chip. LG loved its sound, while Robert Harley measured its linearity as "exceptionally accurate, among the best I have measured...nearly a perfect straight line."
You might reasonably suppose that, while introducing a significant technological advance, manufacturers would present a united front in communicating the benefits of the new approach to consumers. No such luck. A forthright presentation of the advantages of 1-bit decoding would require admitting how variable the performance of previous and current players has been. Besides, manufacturers like to promote the alleged uniqueness of their designs: they are launching 1-bit technology with a dizzying array of jargon aimed at making each version seem unique.
Philips, the first to go public with the new system, calls its version a Bitstream decoder process and uses a pulse density modulation (PDM) output circuit. Technics, which claims to have been working on 1-bit decoding since 1986 but is only going public with it now, calls its process MASH and uses a pulse-width modulation (PWM) output circuit. Harman/Kardon is using the Technics MASH decoder in two new CD players but confused many observers by calling it a "bitstream" decoder and comparing its performance to the Philips circuit. Sansui, as noted earlier, uses the Technics MASH chip in its Vintage series CD player and integrated amplifier, but calls it "LDCS." Sony appears to be using the Philips PDM circuit in several CD players marketed overseas (but not yet in the US), calling it a "High Density Linear Converter."
All of the new 1-bit decoders contain a "noise-shaping" digital filter that suppresses hiss, enhancing the S/N ratio, hence the resolution. Technics' trade name for its decoder is a quasi-acronym for this filter: MultistAge noise SHaping (MASH). The MASH chip that has been available since last spring is a third-generation design with a claimed S/N ratio of 108dB. Sony recently announced a new decoder using Sony Extended Noise Shaping (SENS) to achieve a claimed S/N ratio of 118dB. Not to be outdone, JVC announced a chip that uses PEM (pulse-edge modulation, a sort of one-sided PWM) and VANS (Victor Advanced Noise Shaping) to achieve 120dB. At its seminar for North American hi-fi writers, Technics capped this game of corporate one-upmanship by announcing that its third-generation chip will be used only in midprice players; the company's best players will contain a new fourth-generation MASH chip rated at 123dB.
Note that these specifications apply only to noise generated in the playback process; since virtually no CD has been recorded with a S/N ratio better than 90dB, these claims won't be realized with real recordings. (The measurement is made using a special test CD recorded with an all-zeroes code, with no dithering.)
But to demonstrate the superb linearity of the fourth-generation MASH decoder, Technics conducted a play-off comparing its newest player with current Denon and Sony models using 18- and 20-bit DACs. It was no contest; in the dithered glide tone from –60 to –120dB on the CBS test disc, the Sony produced audible distortion and the Denon generated obvious noise modulation due to nonlinearities in the DACs. (To be fair, these may have been worse-than-average samples off the production line.) The playback of this track by the Technics was the best I've ever heard, with no audible imperfection.
What appeals most to my Yankee soul is that this performance came from a decoder that is actually less costly to produce than a conventional DAC. MASH chips, or the equivalent from other manufacturers, can be used in CD players at virtually every price level. (A low-power version for portables hasn't been developed yet, but will be.) Within a couple of years, 1-bit decoders could be in every new CD player; then the cancer of nonlinear decoding will have been banished.
I don't want to leave the impression that all 1-bit decoders are alike in their performance or sound. There have been many rumors that the original Philips Bitstream decoder was not designed to leapfrog ahead of the best conventional DAC performance, but is just a way of obtaining consistent linearity in low-cost players. Further rumors suggest that Philips is working on a high-performance Bitstream decoder for introduction next year.
But the picture became confused at the British Penta hi-fi show in September, where an A/B comparison carried out by reviewer Paul Miller apparently persuaded many listeners that the present Philips Bitstream decoder sounds better than the best 18- and 20-bit conventional DACs. A friend of mine who heard the Penta demonstration examined the demonstration setup afterward; evidently the CD players were not accurately matched in level, and the comparison may have been invalid. Martin Colloms, writing in HFN/RR, added that in his own listening tests the present Philips circuit is a good mid-level performer but not equal to the best linear DACs.
Two weeks after my visit to Japan, the potential of 1-bit decoding was confirmed in a paper written by British mathematician Michael Gerzon for the New York convention of the Audio Engineering Society. In Gerzon's absence it was introduced and summarized by Stanley Lipshitz, who called it a very important paper (footnote 11). It is a mathematical analysis of the noise-shaping that is a central part of MASH and other 1-bit decoders, showing that with appropriate selection of the noise-shaping filter function, the effective dynamic range of CD playback can be increased by about 11dB, or nearly two bits' worth.
The actual limitation now lies at the recording end of the signal chain, with the nonlinearities and quantizing distortion in the A/D converters used in professional digital recorders. Gerzon's paper shows, and the Technics demonstration confirms, that if the recorded signal is correctly dithered to eliminate quantizing distortion, it is possible to record—and accurately resolve in playback—signals much smaller than the least-significant bit. (In theory this is also true with a conventional DAC, but only if it is precisely adjusted for good linearity, which real DACs usually aren't.) So while the CD is only a 16-bit storage medium, it is capable of 18-bit effective resolution and dynamic range. At the AES convention a designer of high-performance oversampling A/D converters told me that Sony will soon introduce a successor to its PCM-1630 CD mastering recorder, employing those A/D converters. Then the recent improvements in player design will really pay off.—Peter W. Mitchell
Footnote 11: "Optimal Noise Shaping and Dither of Digital Signals," Michael Gerzon and Peter G. Craven, AES Preprint 2822. Preprints are available from the Audio Engineering Society, 60 East 42nd Street, New York, NY 10165. Web: www.aes.org.