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Super Audio CD (SACD) is a read-only optical audio disc format that can provide higher fidelity digital audio reproduction than the Red Book audio CD. Introduced in 1999, it was developed by Sony and Philips Electronics, the same companies that created the Compact Disc. SACD is in a format war with DVD-Audio, but neither format has managed to replace regular audio CDs.

Overview

SACD is a disc of identical physical dimensions to the compact disc but it uses a very different technology from CD and DVD-Audio to encode its audio data, a 1-bit delta-sigma modulation process known as Direct Stream Digital at the very high sampling rate of 2.8224 MHz. This is 64 times the sampling rate used in Compact Disc Digital Audio, which specifies 44.1 kHz at a resolution of 16-bit. Because the resolution of SACD is 16 times smaller than CDDA, the bitrate for a given channel is only 4 times as large.
There are three types of SACDs:
Hybrid: The most popular of the three types, hybrid discs include a “Red Book” layer compatible with most legacy Compact Disc players, dubbed the “CD layer,” and a 4.7 GB SACD layer, dubbed the “HD layer.” It is not uncommon for hybrid discs to carry the “Compact Disc Digital Audio” logo to show that the disc is CDDA-compliant.
Single-layer: Physically a DVD-5 DVD, a single-layer SACD includes a 4.7 GB HD layer with no CD layer.
Dual-layer: Physically a DVD-9 DVD, a dual-layer SACD includes two HD layers totalling 8.5 GB, with no CD layer. This type is rarely used. It enables nearly twice as much data to be stored, but eliminates CD player compatibility.
SACD authoring guidelines suggest that an SACD should always contain a 2-channel stereo mix[citation needed] though not all SACD have it (for example, in 2005 Sony Music Entertainment (Germany) GmbH released Charles Rosen’s performance of the Goldberg Variations as a hybrid SACD with 16-bit PCM and DSD 5.1 surround but no DSD stereo). They may optionally contain a surround mix — either 5.0 or 5.1 layout. Although the disc always stores all channels, the surround mix does not have to use them all, and some may be mute; for example the 2001 SACD release of Mike Oldfield’s Tubular Bells remains in the quadraphonic 4.0 mix made in 1975, and the RCA reissue of the 1957 Chicago Symphony Orchestra recording of Mussorgsky’s Pictures at an Exhibition marks the first time the original 3.0 (three track) recording is available in a consumer format. The correct designation for the surround part of an SACD is “multi-channel”, and usually has either the label “SACD Surround” or its own “Multi-Ch” logo on the back cover.

Integration

As of February 2008, there have been over 5,000 SACD releases, slightly more than 50% of which appear to be classical. Jazz and popular music albums, mainly remastered previous releases, are the next two most common genres released to date. [1][2]. Notable popular artists who have released some or all of their back catalog include Alice In Chains, Aerosmith, Björk, Black Sabbath, Boston, David Bowie, Carpenters, Depeche Mode, Bob Dylan, Peter Gabriel, Genesis, Billie Holiday, Elton John, The Moody Blues, The Rolling Stones, Eleanor McEvoy, Nine Inch Nails, Santana, and Barbra Streisand. Pink Floyd’s seminal album The Dark Side of the Moon (the 30th anniversary edition of 2003), The Who’s seminal album Tommy (the 34th anniversary edition of 2003), and Roxy Music’s Avalon (the 21st anniversary edition, 2003) were released on SACD to take advantage of the format’s multi-channel capability. All three were remixed in 5.1 surround, and released as Hybrid SACDs with a stereo mix on the standard CD layer.
Because most SACDs are issued in a hybrid format only, such as the remastered Rolling Stones and Bob Dylan albums released in 2002, music collectors may build and enjoy an SACD collection even if their only disc player is not designed to read the SACD’s higher fidelity DSD encoding. The ability to play SACD hybrid discs on all standard Red Book CD or DVD video players is considered a significant advantage of the SACD format over DVD-Audio. Today, there are many affordable “universal” multiformat players which play not only SACD but also competing formats DVD-Audio or DualDisc.
Despite relatively wide consumer availability to SACD players, however, high definition audio formats continue to attract few major record labels, which in the mid-2000s increased marketing of low-cost compressed audio formats. The main interest continues to be classical and older remastered albums rather than new releases. The record label Mobile Fidelity focuses on this type of remastering.

Disc reading

Objective lenses in conventional CD players have a longer working distance, or focal length, than lenses designed for SACD players. This means that when a hybrid SACD is placed into a conventional CD player, the laser beam passes the high-resolution layer and is reflected by the conventional layer at the standard 1.2 mm distance, and the high-density layer is out of focus. When the disc is placed into an SACD player, the laser is reflected by the high-resolution layer (at 600 µm distance) before it can reach the conventional layer. Conversely, if a conventional CD is placed into an SACD player, the laser will read the disc without difficulty since there is no high-resolution layer.

Playback hardware

Hybrid Super Audio CDs (which include both a Stereo CD and a Super Audio CD layer) can be played back on CD players. To hear the Super Audio CD Stereo, and on many discs the Super Audio CD Multichannel layer, requires a Super Audio CD player.
As would be expected, Sony and Philips – designers of the CD and SACD formats – have the most players on the market in many guises such as standalone players, combined DVD/SACD players, in-car players,[1] and Sony’s PlayStation 3 game console. (As of the 2.00 upgrade, PS3 is capable of SACD 5.1 playback via an optical cable. It achieves this by converting the audio to a 1.5 Mbit/s DTS format. The immediate revision after this removed the feature.[2])
The Sony SCD-1 is a well-known player which was introduced concurrently with the SACD format in 1999 for a price of approximately US$5,000.[3]. It weighs well over 26 kg (57 lb) and is often modified by its owners to improve the sound. The SCD-1, no longer produced, was introduced before multi-channel SACDs existed and only plays two channel SACDs or red-book CDs.
Many other electronics manufacturers, including mid-level vendors Denon/Marantz, Pioneer, Yamaha offer SACD playback capabilities throughout their product lines. None, however, has offered a portable SACD player capable of playing the high definition layer of an SACD. Most portable CD players will play the conventional CD layer of a Hybrid SACD.
SACD players are not permitted to digitally output an unencrypted stream of DSD. Players initially supported only analog output; later some proprietary digital interfaces such as Denon Link permitted encrypted transmission of DSD. There are now two standard digital connection methods capable of carrying DSD in encrypted form: i.Link and HDMI (version 1.2 or later, standardised in August 2005).
The older i.Link interface is generally found on older mid- to high-end equipment and some current top of the line units from the Japanese manufacturers. HDMI is more common, being the standard digital connection method for high-definition video+audio. Most new mid-level and higher 2007 model year and later A/V processors support the HDMI 1.2 specification’s DSD over HDMI feature. Most boutique manufacturers still do not support DSD. Some HDMI 1.1 spec DVD players convert DSD to LPCM and then pass it to an HDMI 1.1 spec or later processor. Lower end processors usually convert the DSD to LPCM, higher end ones usually convert it to LPCM for bass management or DSP but can also process it natively at the expense of DSP and bass management. Some new DVD players from Oppo Digital, Pioneer, Onkyo, etc. now support HDMI 1.2 or 1.3 and will pass DSD over HDMI as well as LPCM. Be aware that some players, for instance, Onkyo DV-SP504, will not support DSD or LPCM over HDMI without downscaling it to 48kHz. SACD or DVD-A will be played through anlaog outputs instead. The older i.Link interface has been dropped from all but high end A/V processors and DVD players.
Some players, such as the PlayStation 3 (not the 40GB version), do not output DSD over HDMI, but instead convert it to PCM.

DSD

SACD audio is stored in a format called Direct Stream Digital (DSD), which differs from the conventional PCM used by the compact disc or conventional computer audio systems.
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. Promotional materials about SACD supplied by Philips and Sony suggest that the system 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 currently available players list an upper limit of 80–90 kHz.
The process of creating a DSD signal is conceptually similar to taking a 1-bit delta-sigma analog-to-digital (A/D) converter and removing the decimator which converts the 1-bit bitstream into multibit PCM. Instead, the 1-bit signal is recorded directly and in theory only requires a lowpass filter to reconstruct the original analog waveform. In reality it is a little more complex, and the analogy is incomplete in that 1-bit sigma-delta converters are these days rather unusual, one reason being that a 1-bit signal cannot be dithered properly: most modern sigma-delta converters are multibit.
Because of the nature of sigma-delta converters, one cannot make a direct comparison between DSD and PCM. An approximation is possible, though, and would place DSD in some aspects comparable to a PCM format that has a bit depth of 20 bits and a sampling frequency of 192 kHz. PCM sampled at 24 bits provides a (theoretical) additional 24 dB of dynamic range. Due to the effects of quantization noise, the usable bandwidth of the SACD format is approximately 100 kHz, which is similar to 192 kHz PCM.
Because it has been extremely difficult to carry out DSP operations (for example performing EQ, balance, panning and other changes in the digital domain) in a 1-bit environment, and because of the prevalence of studio equipment such as Pro Tools, which is solely PCM-based, the vast majority of SACDs — especially rock and contemporary music which relies on multitrack techniques — are in fact mixed in PCM (or mixed analog and recorded on PCM recorders) and then converted to DSD for SACD mastering.
To address some of these issues, a new studio format has been developed, usually referred to as “DSD-wide”, which retains standard DSD’s high sample rate but uses an 8-bit, rather than single-bit digital word length, but still relies heavily on the noise shaping principle. It becomes almost the same as PCM (it’s sometimes disparagingly referred to as “PCM-narrow") but has the added benefit of making DSP operations in the studio a great deal more practical. The main difference is that “DSD-wide” still retains 2.8224 MHz (64Fs) sampling frequency while the highest frequency in which PCM is being edited is 352.8 kHz (8Fs). The “DSD-wide” signal is down-converted to regular DSD for SACD mastering. As a result of this technique and other developments there are now a few digital audio workstations (DAWs) which operate, or can operate, in the DSD domain, notably Pyramix and some SADiE systems.
Note that high-resolution PCM (DVD-Audio, HD DVD and Blu-ray Disc) and DSD (SACD) may still differ in terms of fidelity at high-frequencies since DSD, owing to its high sampling frequency, does not show the ringing effects that PCM shows with certain types of signals when sharp reconstruction filters are employed[citation needed], but instead it shows constant high levels of noise at the same frequencies this ringing would show in 192 kHz PCM. On the other hand, DSD’s dynamic range decreases quickly at frequencies over 20 kHz due to the use of strong noise shaping techniques which push the noise out of the audio band resulting in a rising noise floor just above 20 kHz. PCM’s dynamic range, on the other hand, is the same at all frequencies. (Some high-end SACD players employ an optional low-pass filter set at 30 kHz for compatibility and safety reasons, suitable for situations where amplifiers or loudspeakers can’t deliver an undistorted output if noise above 30 kHz is present in the signal.)
DST

To reduce the space and bandwidth requirements of DSD (2.8 Mbit/s per channel), 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. This 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.
Pit Signal Processing

SACD includes various copy protection measures of which the most prominent is Pit Signal Processing (PSP), a physical watermarking feature that contains a digital watermark modulated in the width of pits on the disc (data is stored in the pit length). The optical pickup must contain special circuitry to read the PSP watermark, which is then compared to information on the disc to make sure it’s legitimate. Because the majority of DVD players and all DVD-ROM drives use an optical pickup that lacks this specialized watermark detection circuitry they cannot read the data on the SACD layer of a protected SACD disc.[4]
On hybrid SACD discs, PSP is only applied to the SACD layer — not to the CD layer.

Comparing SACD and CD

Many people[who?] feel that even a moderately good system should reveal a significant difference between SACD and either CD or DVD-Audio. The late film composer Jerry Goldsmith, for example, fiercely backed SACD and several albums of his film scores and compositions are available as Hybrid Multichannel SACDs.
Increasingly, home audio playback systems are home cinema multichannel and this single feature may prove to be the most important when considering the differences between Compact Discs and the newer distribution formats. CDs are stereo and both SACD and DVD are multichannel-capable. In addition, SACDs can be authored to be both forward and backward compatible with existing CD players.
Few home audio systems can accurately reproduce sounds above 20 kHz, and most recording chains are designed around this limit. Modern popular music is often compressed during mastering to a small percentage of the maximum available dynamic range, and thus would not significantly benefit from the extended dynamic range available in SACD without remastering the audio for more dynamics. However, electronic and organ music offer a wide natural dynamic range, and audiophiles benefit from the lack of amplitude compression that an extended dynamic range affords.
Conversely, the properties of DSD and the authoring process tend to discourage the kind of extreme compression and unpleasant-sounding hard digital clipping often found on PCM recordings. Unlike CD, which sets the 0 dB level right at the theoretical PCM signal limit, and doesn’t take into account oversampling, SACD sets the 0 dB level at 6 dB below the theoretical full-scale DSD signal, and prohibits peaks above +3 dB. DSD processing is less amenable to simple clipping to meet these limits, forcing more care to be taken during mastering. The extra headroom also eases the job of DACs in playback equipment, which often suffer overload distortion when fed the full-scale PCM common on heavily-compressed CDs.[5][6] Thus, improved quality may result from simply preventing the kinds of poor mastering often found on PCM, rather than from any fundamental audible difference between DSD and PCM.[citation needed] PCM mastered several dB lower would also obtain the same benefit.
A 2007 article published in the Journal of the Audio Engineering Society reported the results of a study, which concluded that listeners could not hear the difference between a high-resolution two-channel recording and a CD-quality downsampling of the same recording except when “unpleasantly (often unbearably) loud."[7] The article concluded that many high-resolution releases sounded better than their CD counterparts, but attributes this to mastering differences.
Copy protection

SACD has several copy prevention features at the physical level which, for the moment, appear to make SACD discs impossible to copy without resorting to the analog hole, or ripping of the conventional 700MB layer on hybrid discs. These include physical pit modulation and 80 bit encryption of the audio data, with a key encoded on a special area of the disk 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, nor can SACDs be created except by the licensed disc replication facilities in Shizuoka and Salzburg.[8]
It is possible to capture the DSD digital audio signal after the decryption stage right before the digital to analog converters of an SACD player, but since there is no practical way for the public to make their own SACDs, this does not pose a major threat.
The failure of the format to gain any significant market share further reduces the incentive, whether commercial (e.g. Slysoft’s payware AnyDVD for DVDs and Hi-Def discs) or curiosity to create copying tools (e.g. “DVD” Jon’s DeCSS for DVDs). The quick defeat of protection methods used on HD DVD and Blu-ray Disc, when they accounted for only 4% of digital movie sales in 2007, shows that even a marginal market share can create demand for technologies that enable consumers to bypass the protection.
A number of new SACD players have encrypted IEEE 1394 (also called FireWire or i.Link) or HDMI digital outputs carrying DSD data, and it may be possible to get the raw DSD data from these links. The protection mechanism used is Digital Transmission Content Protection (DTCP), which can be used in “Copy Once” or “Copy Never” modes. It is unlikely, however, that the SACD license agreement rules permit anything but the “Copy Never” mode to be used.
There seems to be one solution for obtaining digital non-DRM output on SACD as well as DVD-A players. A Switzerland-based company is offering a modified output-board that taps into the digital datastream prior to D/A conversion as well as converting DSD to PCM that the S/PDIF port can transfer. [9]
See also

Audio format
Audio storage
DualDisc
DVD-Audio
Earlier attempts at higher fidelity that stayed within the CDDA standard: XRCD and HDCD.
[edit]References

^ “Sony Announces Three Super Audio CD Car Stereo Players”. HighFidelityReview.com. Retrieved on 2007-01-18.
^ “PS3SACD.com News, November 22, 2007”.
^ “The Sony SCD-1 SACD Player”. @udiophilia. Retrieved on 2006-05-18.
^ “Details of DVD-Audio and SACD”. DVDdemystified.com. Retrieved on 2007-07-12.
^ “Issues with 0dBFS+ Levels On Digital Audio Playback Systems”. Audioholics. Retrieved on 2007-05-10.
^ “Overload in Signal Conversion” (PDF). AES 23rd International Conference. Retrieved on 2007-05-10.
^ Meyer, E. Brad; David Moran (September 2007). “Audibility of a CD-Standard ADA Loop Inserted Into High-Resolution Audio Playback”. Journal of the Audio Engineering Society 55 (9).
^ “Sony Starts Hybrid Super Audio CD Production Facilities in Europe”. SA-CD.net (2003-01-22). Retrieved on 2007-07-12.
^ dvdupgrades.ch
[edit]External links

SA-CD site at Sony Music
SA-CD.net SA-CD Reference (Includes full list of available albums and comprehensive FAQ)
Multichannel SACD Rating: album guide for surround-sound lovers.
PS3SACD.com FAQ: a dedicated FAQ about SACD functionality on PlayStation3
Super Audio Compact Disc: A Technical Proposal (PDF), Sony.
The SA-CD explained
“Breaking the Sound Barrier: Mastering at 96 kHz and Beyond” (PDF) Audio Engineering Society Convention Paper 4357 on “HD” audio.
“A Native Stereo Editing System for Direct-Stream Digital” (PDF) Audio Engineering Society Convention Paper 4719 on the 1st DSD commercial editor.
“Why Direct Stream Digital is the best choice as a digital audio format” (PDF) Audio Engineering Society Convention Paper 5396.
“Why 1-Bit Sigma-Delta Conversion is Unsuitable for High-Quality Applications” (PDF) Audio Engineering Society Convention Paper 5395.
Janssen, E.; Reefman, D. “Super-audio CD: an introduction”. Signal Processing Magazine, IEEE/ Volume 20, Issue 4, July 2003 Page(s): 83 - 90

DVD-Audio

DVD-Audio (commonly abbreviated as DVD-A) is a digital format for delivering very high-fidelity audio content on a DVD. DVD-Audio is not intended to be a video delivery format and should not be confused with video DVDs containing concerts and music videos. The first discs entered the marketplace in 2000. Future occasional DVD-Audio releases are expected and/or have been announced. DVD-Audio is in a format war with Super Audio CD (SACD). Neither has gained a strong position in the marketplace. As media players that can play both DVD-Audio and SACD (and many other formats) are available, both are likely to co-exist.

Audio specifications

DVD-Audio offers many possible configurations of audio channels, ranging from single-channel mono to 5.1-channel surround sound, at various sampling frequencies and sample rates.[1] (The “.1” denotes a Low-frequency effects channel (LFE) for bass and/or special audio effects.)
Compared to the compact disc, the much higher capacity DVD format enables the inclusion of either:
Considerably more music (with respect to total running time and quantity of songs) or
Far higher audio quality, reflected by higher linear sampling rates and higher bit-per-sample resolution, and/or
Additional channels for spatial sound reproduction.
Audio on a DVD-Audio disc can be stored in many different bit-rate/sampling rate/channel combinations:

Different bit-rate/sampling rate/channel combinations can be used on a single disc. For instance, a DVD-Audio disc may contain a 96 kHz/24-bit 5.1-channel audio track as well as a 192 kHz/24-bit stereo audio track. Also, the channels of a track can be split into two groups stored at different resolutions. For example, the front speakers could be 96/24, while the surrounds are 48/20.
Audio is stored on the disc in Linear PCM format, which is either uncompressed or losslessly compressed with Meridian Lossless Packing. The maximum permissible total bitrate is 9.6 Megabits per second. Channel/resolution combinations that would exceed this need to be compressed. In uncompressed modes, it is possible to get up to 96/16 or 48/24 in 5.1, and 192/24 in stereo. To store 5.1 tracks in 88.2/20, 88.2/24, 96/20 or 96/24 MLP encoding is mandatory.
The LFE channel is actually full range, and can be recorded at the same resolution as the other channels. This permits it to be used instead as an extra main channel, for example as a “height” speaker above the listening position; this has been done on some releases. Such usage is non-standard, and will often require special set-up by the end user.
If no native stereo audio exists on the disc, the DVD-Audio player may be able to downmix the 5.1-channel audio to two-channel stereo audio if the listener does not have a surround sound setup (provided that the coefficients were set in the stream at authoring). Downmixing can only be done to two-channel stereo, not to other configurations, such as 4.0 quad. DVD-Audio may also feature menus, text subtitles, still images and video, plus in high end authoring systems it is also possible to link directly into a Video_TS folder that might contain video tracks, as well as PCM stereo and other “bonus” features..
Player compatibility

With the introduction of the DVD-Audio format, some kind of backward compatibility with existing DVD-Video players was desired, although not required. To address this, most DVD-Audio discs contain, a Dolby Digital 5.1-channel audio track on the disc[2] (which can be downmixed to two channels for listeners with no surround sound setup). Some discs also include a native Dolby Digital 2.0 stereo, and even a DTS 96/24 5.1-channel, audio track.[3]
Because the DVD-Audio format is a member of the DVD family, a single disc can have multiple layers and even two sides that contain media. A common configuration includes a “DVD-Video” zone on a DVD-Audio formatted single sided disc. The high-resolution, multichannel audio losslessly encoded using MLP is only playable on DVD-Audio hardware but the DVD-Video zone, which can contain Dolby or DTS 5.1 mixes and even video makes the disc compatible with all DVD players. Other configurations include double layer DVDs (DVD-9) and two-sided discs (DVD-10, DVD-14 or DVD-18). Some labels are releasing DVD titles that are formatted as DVD-Audio on one side and DVD-Video on the other, the DualDisc being one such example.
There are some software players that support the playback of DVD-Audio discs, including WinDVD and PowerDVD.
[4]ELS Surround is one of the few vehicle audio systems which can play DVD-A
Preamplifier/Surround Processor interface

In order to play DVD-Audio, a preamplifier or surround controller with six analog inputs was originally required.[5] Whereas DVD-Video audio formats such as Dolby Digital and DTS can be sent via the player’s digital output to a receiver for conversion to analog form and distribution to speakers, DVD-Audio cannot be delivered via unencrypted digital audio link at sample rates higher than 48 kHz (i.e., ordinary DVD-Video quality) due to concerns about digital copying.[5]
However encrypted digital formats have now been approved by the DVD Forum, the first of which was Meridian Audio’s MHR (Meridian High Resolution). The High Definition Multimedia Interface (HDMI 1.1) also allows encrypted digital audio to be carried up to DVD-Audio specification (6 × 24-bit/96 kHz channels or 2 × 24-bit/192 kHz channels). The six channels of audio information can thus be sent to the amplifier by several different methods:
The 6 audio channels can be decrypted and extracted in the player and sent to the amplifier along 6 standard analog cables.
The 6 audio channels can be decrypted and then re-encrypted into an HDMI or IEEE-1394 (Firewire) signal and sent to the amplifier, which will then decrypt the digital signal and then extract the 6 channels of audio. HDMI and IEEE-1394 encryption are different from the DVD-A encryption and were designed as a general standard for a high quality digital interface. The amplifier has to be equipped with a valid decryption key or it won’t play the disk.
The third option is via the S/PDIF (or TOSLINK) digital interface. However, because of concerns over unauthorized copying, DVD-A players are required to handle this digital interface in one of the following ways:
Turn such an interface off completely. This option is preferred by the music publishers.
Downconvert the audio to a 2-channel 16-bit/48 kHz PCM signal. The music publishers are not enthusiastic about this because it permits the production of a CD-quality copy, something they still expect to sell, besides DVD-A.
Downconvert the audio to 2 channels, but keeping the original sample size and bit rate if the producer sets a flag on the DVD-A disc telling the player to do so.
A final option is to modify the player, capturing the high resolution digital signals before they are fed to internal D/A converters and convert it to S/PDIF, giving full range digital (but only stereo) sound. There exist already do-it-yourself solutions for some players. There also exists an option to equip a DVD-A player with multiple S/PDIF outputs, for full resolution multichannel digital output. See: Six channel S/P-DIF output board.
Sound quality

From a purely technical standpoint, the audio resolution of a DVD-Audio disc can be substantially higher than standard red book CD audio. DVD-Audio supports bit depths up to 24-bit and sample rates up to 192 kHz, while CD audio is 16-bit, 44.1 kHz. In both cases, the source recording may have been made at a much higher bit and sample rate, and down-converted for commercial release.
It is uncertain whether average listeners can hear the difference between DVD-Audio and CD-Audio, and many consumers do not regard any supposed quality improvements offered as sufficient reason to justify purchasing new playback equipment and repurchasing albums in higher-resolution formats. Many DVD-Audio releases are older, standard definition audio recordings that have been remixed in 5.1 and upsampled to DVD-Audio’s higher resolution. However, the fidelity of the upsampled audio will be limited by the source material quality and may not exceed the quality of existing CD releases of the same albums. When new recordings are made using high-resolution PCM encoding, a substantial difference in fidelity can be achieved.[citation needed]
Three of the major music labels, Universal Music, EMI and Warner Bros. Records and several smaller audiophile labels (such as AIX Records and DTS Entertainment) have released or are continuing to release albums on DVD-Audio, but the number is minimal compared to standard CDs. New high-definition titles have been released in standard DVD-Video format (which can contain 2-channel Linear PCM audio data ranging from 48 kHz/16-bit to 96 kHz/24-bit), “HDAD”, which includes a DVD-Video format recording on one side and DVD-Audio on the other, CD/DVD packages, which can include the album on both CD and DVD-Audio, or DualDisc, which can contain DVD-Audio content on the DVD side. In addition, some titles that were initially released as a standalone DVD-Audio disc, such as The Grateful Dead’s American Beauty and R.E.M.’s Automatic for the People, were re-released as a CD/DVD package or as a DualDisc.
Copy protection

DVD-Audio discs may optionally employ a copy protection mechanism called Content Protection for Prerecorded Media (CPPM).[6] CPPM, managed by the 4C Entity, prevents users from extracting audio to computers and portable media players.
Because DVD-Video’s content-scrambling system (CSS) was quickly broken, DVD-Audio’s developers sought a better method of blocking unauthorized duplications. They developed CPPM, which uses a media key block (MKB) to authenticate DVD-Audio players. In order to decrypt the audio, players must obtain a media key from the MKB, which also is encrypted. The player must use its own unique key to decrypt the MKB. If a DVD-Audio player’s decryption key is compromised, that key can be rendered useless for decrypting future DVD-Audio discs. DVD-Audio discs can also utilize digital watermarking technology developed by the Verance Corporation, typically embedded into the audio once every thirty seconds. If a DVD-Audio player encounters a watermark on a disc without a valid MKB, it will halt playback.[7] The 4C Entity also developed a similar specification, Content Protection for Recordable Media (CPRM), which is used on Secure Digital cards.
DVD-Audio’s copy protection was overcome in 2005[7] by tools which allow data to be decrypted or converted to 6 channel .WAV files without going through lossy digital-to-analog conversion. Previously that conversion had required expensive equipment to retain all 6 channels of audio rather than having it downmixed to stereo. In the digital method, the decryption is done by a commercial software player which has been patched to allow access to the unprotected audio.
In 2007 the encryption scheme was overcome with a tool called dvdcpxm. In 12 February 2008 a program called DVD-Audio Explorer 2008 was released, containing aforementioned libdvdcpxm coupled with an open source MLP decoder.[8]
Like DVD-Video decryption, such tools may be illegal to use in the United States under the controversial Digital Millennium Copyright Act. While the Recording Industry Association of America has been successful in keeping these tools off websites, they are still distributed on P2P file sharing networks and newsgroups,[9] Additionally, in 2007 the widely-used commercial software DVDFab Platinum added DVD-Audio decryption, allowing users to backup a full DVD-A image to ISO.[10]
DVD-Audio authoring software

Normal DVD(Video) authoring software usually does not support DVD-Audio creation, so there is some special software:
[edit]Macintosh
Sonic Solutions DVD Creator AV – The first DVD-Audio authoring solution available. A spin off of the popular high end DVD Video authoring package. It allows DVD-Audio authoring at the command line level only. Still widely used but no longer sold or supported by Sonic Solutions.
Sonic Studio SonicStudio HD – Macintosh based tool used for High Density audio mastering and to prepare audio for DVD-A authoring in One Click DVD.
Sonic Studio [1]
Sonic OneClick DVD – Converts prepared Sonic Studio EDLs into binary MLP files to be used in the authoring tool. Also generates scriptFile information to be added to DVD Creator AV projects.
DVD audio Tools: console application dvda-author (version 08.07), see below.
[edit]Windows
Sonic Solutions DVD-Audio Creator
Cirlinca DVD-AUDIO Solo
Minnetonka Audio DiscWelder Bronze, Steel and Chrome II (with SurCode MLP)
Steinberg WaveLab Steinberg
DigiOn Audio 2 DigiOn
Gear Pro Mastering Edition Gear Pro Mastering Edition
DVD audio tools package (see below).
[edit]Linux
A project called DVD audio Tools provides free/open source DVD-Audio authoring tools for Linux and other *nix platforms (FreeBSD, OpenSolaris,...).
Windows (console application) binaries are also available. DVD-Audio/Video discs (aka Hybrid or Universal DVDs) are also supported.
See also

Meridian Lossless Packing
[edit]References

^ “Understanding DVD-Audio” (PDF). Sonic Solutions. Retrieved on 2007-07-12.
^ “SACD & DVD-Audio: Ultra-High-Resolution Music”. Crutchfield Advisor. Retrieved on 2007-07-12.
^ “What is DVD-Audio?”. 5dot1.com. Retrieved on 2007-07-12.
^ www.elssurround.com
^ a b “DVD-Audio Tutorial”. TimeForDVD.com (2002-06-05). Retrieved on 2007-07-12.
^ Labriola, Don (2003-08-25). “Digital Content Protection, Part II”. ExtremeTech. Retrieved on 2007-07-12.
^ a b Robinson, Stuart M (2005-06-07). “DVD-Audio Copy Protection Defeated via WinDVD Software Hack”. HighFidelityReview.com. Retrieved on 2007-07-12.
^ “DVD-Audio ripper”. Retrieved on 2008-04-09.
^ “DVD-Audio’s CPPM Circumvented”. Slashdot.org (2005-07-06). Retrieved on 2007-07-12.
^ “DVDFab updated to support DVD-Audio/CPPM”. Retrieved on 2008-04-15.
[edit]External links

The 4C Entity LLC – Licensors of the Content Protection for Prerecorded Media (CPPM) specification.

An audio amplifier is an electronic amplifier that amplifies low-power audio signals (signals composed primarily of frequencies between 20 hertz to 20,000 hertz, the human range of hearing) to a level suitable for driving loudspeakers and is the final stage in a typical audio playback chain.
The preceding stages in such a chain are low power audio amplifiers which perform tasks like pre-amplification, equalization, tone control, mixing/effects, or audio sources like record players, CD players, and cassette players. Most audio amplifiers require these low-level inputs to adhere to line levels.
While the input signal to an audio amplifier may measure only a few hundred microwatts, its output may be tens, hundreds, or thousands of watts.

History

Three audio amplifiers in a smaller scale application
Early audio amplifiers were based on vacuum tubes (also known as “valves"). Most modern audio amplifiers are based on solid state devices like transistors, FETs and MOSFETs, but there are still aficionados who prefer tube-based amplifiers, due to a perceived ‘warmer’ valve sound. Audio amplifiers based on transistors became practical with the wide availability of inexpensive transistors in the late 1960s.

Design parameters

Key design parameters for audio amplifiers are frequency response, gain, noise, and distortion. These are interdependent; increasing gain often leads to undesirable increases in noise and distortion. While negative feedback actually reduces the gain, it also reduces noise, and distortion. Most audio amplifiers are linear amplifiers operating in class AB.

Filters and preamplifiers

Historically, the majority of commercial audio preamplifiers made had complex filter circuits for equalization and tone adjustment, due to the far from ideal quality of recordings, playback technology, and speakers of the day.
Using today’s high quality (often digital) source material and speakers etc, such filter circuits are usually not needed. Audiophiles generally agree that filter circuits are to be avoided wherever possible. Today’s audiophile amplifiers do not have tone controls or filters.
Since modern digital devices, including CD and DVD players, radio receivers and tape decks already provide a “flat” signal at line level, the preamp is not needed other than as volume control. One alternative to a separate preamp is to simply use passive volume and switching controls, sometimes integrated into a power amp to form an “integrated” amplifier.

Further developments in amplifier design

For some years following the introduction of solid state amplifiers, their perceived sound did not have the excellent audio quality of the best valve amplifiers (see Valve audio amplifier). This led audiophiles to believe that valve sound had an intrinsic quality due to the vacuum tube technology itself. In 1972, Matti Otala demonstrated the origin of a previously unobserved form of distortion: Transitory Intermodulation Distortion (TIM), also called “slew rate distortion”. TIM distortion was found to occur during very rapid increases in amplifier output voltage.[1] TIM did not appear at steady state sine tone measurements, helping to hide it from design engineers prior to 1972. Problems with TIM distortion stem from reduced open loop frequency response of solid state amplifiers. Further works of Otala and other authors found the solution for TIM distortion, including increasing slew rate, decreasing preamp frequency bandwidth, and the insertion of a lag compensation circuit in the input stage of the amplifier.[2][3] In high quality modern amplifiers the open loop response is at least 20 kHz, canceling TIM distortion. However, TIM distortion is still present in most low price home quality amplifiers.[citation needed]
The next step in advanced design was the Baxandall Theorem, created by Peter Baxandall in England.[4] This theorem introduced the concept of comparing the ratio between the input distortion and the output distortion of an audio amplifier. This new idea helped audio design engineers to better evaluate the distortion processes within an audio amplifier.
In 1980, a further improvement by Oscar Bonello at the University of Buenos Aires reduced amplifier distortion by employing “Double Loop Feedback” circuitry.[5] This technology led to solid state amplifier designs which could achieve far better distortion measurements than valve amplifiers, at low cost and with high power. At the same time, Bonello proposed using poles and zeros at the feedback network to get a 9 dB/octave slope instead of the traditional 6 dB/octave. This allowed an audio amplifier to be designed without any perceived distortion in the treble spectrum.
Amplifiers often include operational amplifiers and filters. Key to designing linear amplifiers is the examination and evaluation of the distortion introduced by the Distortion Multiplication Factor (Kd).[6] Optimizing the behavior of this type of operational amplifier is important to achieving low distortion amplifiers and audio consoles for sound recording and reproduction.

Phonograph (vinyl record) equalization

Since the mid-1950s, LP phonograph records have been mastered using RIAA equalization, in which the dynamics of the recording have been altered so that the amplitude of the signal that has been cut into the record increases with increasing frequency. Equalization helps to mask the high frequency noise ("hiss") that is generated as the pickup’s stylus rubs against the groove walls. The RIAA curve also attenuates the bass, which reduces the maximum excursions of the stylus to a practical level during loud passages. This has the desirable effect of reducing distortion, as well as making the grooves narrower and increasing the potential maximum recording time per record side. Also, with less excursion, less stress is applied to the stylus, which helps to reduce record wear.
During playback, the RIAA curve is reversed by preamplification, resulting in nearly flat frequency response. It should also be noted that the preamplifier is employed to boost the weak signal emitted by a magnetic pickup. Piezoelectric pickups generally produce much higher output voltages and seldom require preamplification.
Prior to the adoption of the RIAA curve, a number of competing and partially incompatible equalization schemes were utilized during record mastering. Early high fidelity systems often had an equalization selector switch to match playback characteristics to the recording curve of the particular label being played. The development and acceptance of the RIAA curve eliminated this requirement.

Applications

Important applications include public address systems, theatrical and concert sound reinforcement, and domestic sound systems. The sound card in a personal computer contains several audio amplifiers (depending on number of channels), as does every stereo or home-theatre system.
[edit]References

^ “Circuit Design Modifications for Minimizing Transient Intermodulation Distortion in Audio Amplifiers”, Matti Otala, Journal of Audio Engineering Society, Vol 20 # 5, June 1972
^ Distribution of the Phonograph Signal Rate of Change, Lammasniemi, Jorma; Nieminen, Kari, Journal of Audio Engineering Society, Vol 28 # 5, May 1980.
^ “Psychoacoustic Detection Threshold of Transient Intermodulation Distortion”, Petri-Larmi, M.; Otala, M.; Lammasniemi, J. Journal of Audio Engineering Society, Vol 28 # 3, March 1980
^ “Audio power amplifier design”, Peter Baxandall. Wireless World magazine, February 1979
^ Advanced Negative Feedback Design for High Performance Amplifiers, Oscar Bonello, 67th AES Convention, New York, October 1980.
^ “Distortion in Positive- and Negative-Feedback Filters”, Oscar Bonello. Journal of Audio Engineering Society, New York, Vol 32 # 4, April 1984
[edit]See also

Wikimedia Commons has media related to:
Audio amplifier
Valve audio amplifier
Valve sound
Audiophile
Single-ended triode
Tone control circuits
[edit]External links

Audio Design Guide
Categories: Audio amplifiers

The first question is moving coil or moving magnet? Ultimately low output moving coil cartridges deliver the best performance but you need a decent active phono stage (around $400 and above) to really get the benefit. A lower cost alternative is moving magnet or high output moving coil - these can deliver fine performance into a wide variety of phono stages although it is generally recommended a minimum of the GSP Gram 1 phono stage at $100.

Higher end cartridges

High end cartridges such as Koetsu, Lyra, Clearaudio, Benz Micro, Van den Hul, transfiguration etc all have their various strengths and reviews help to clarify your choice depending on your system and priorities. We particularly recommend the Lyra cartridge range but there are many other excellent cartridges which will work as well depending on your system and phono stage balance.

Mid market cartridges

The Dynavector Karat 17d2 mkII is a moving coil cartridge at $650-700 and represents great value for money. Now upgraded to MkIII. The Lyra Dorian has also gained and excellent reputation and a safe choice.

If you do not have a reasonable moving coil phono stage with adjustable gain settings (above $400) then the moving iron Music Maker cartridge at $750 by “The cartridge man” is almost legendry as a moving magnet design. Otherwise opt for high output moving coil cartridges from companies like Sumiko which makes them. However MC cartridges in general require some form of loading and impedance matching which necessitate a more flexible phono stage.

Cartridges below $300

The high output moving coil Dynavector DV10x5 II at $300 is a truly superb cartridge in any arm and is designed for most moving magnet inputs - this cartridge has consistently been reviewed as the best available at this price point.

The Goldring 1000 Series starts at $100 - we particularly recommend the Goldring 1042 mm cartridge at $100
The Low output Goldring Eroica cartridge at $150 are excellent for a budget moving coil cartridge and in our view the low output Eroica LX is slightly preferable to the 1042 if you have a decent moving coil stage.
The Grado Prestige range high output moving iron cartridges starting at $50 are also excellent - these cartridges have a slightly better bass than the Goldrings but not quite such a good treble performance. The Musicmaker cartridges are based on these series of moving iron cartridges and hence retains the signature ‘voice’ of the Grado Prestige range of cartridges.

Remarks on the sound character of various cartridge makes

Cartridges marked with an * are the ideal choice for Origin Live tonearms. However this is only a rough guide as speakers, amps and phono-stage also play a part in the best choice of cartridge for your system. The remarks below are by no means definitive and are only intended as a guide to help those in no position to audition the multitude of options available.

* Audio Technica OC9 $450 (or $325)- noted for definition, speed, clarity and detail - can be a little lean in the bass in some arms - seems most suited on Linn LP12 / Ittock or Akito combinations. The budget Audio Technica’s are extremely good value.

* Clearaudio - very clean sounding catridge, highly detailed, not exactly warm or deep.

* Dynavector - Excellent all round mc cartridges - high output versions are 10x5 and 20XH suitable for moving magnet inputs, low outputs are also available higher in the range.
Dynavector 17D Karat is a favourite at its price point. The xx-2 seems rather system dependent.

* Goldring - Rich sound with plenty of warmth and bass depth - a popular phono cartridge with Rega arm users - a very safe choice that sounds good on most systems.

* Koetsu - Great all round cartridges that deliver an integrated portrayal along with great sense of power and authoritative bass. Sound slightly “thick"and less free in comparison to “zyx cartridges”.

* Lyra - Great tacking cartridges that deliver an organic presentation - may not go quite as deep as Koetsus or have the same bass warmth but have the edge in other aspects such as transparency and imaging.

Rega cartridges - Tend to work well with Rega decks but can sound dull on other makes.

Reson - Similar to the Goldring but added definition due to closer tolerances (made by Goldring). The Reson cartridges are good if your system has a lot of bass and you like high resolution with a nice top end. There is a slight loss of bass warmth relative to the Goldring 1000 series.

* Grado cartridges are excellent on bass and midband - in treble shy systems they can sound slightly dull.

Sumiko - A good choice for systems that are slightly bass heavy and need speed and agility adding - these cartridges have great resolution and are improved over previous models that tended to be lean in deep bass and low in warmth for some systems

* Transfiguration - Good all round cartridge and a very safe choice, strong on subtlety with wonderful delicacy rather than an emphasis on hard hitting and impact.

* Zyx - Very good tonal balance with slight emphasis on dynamic and deep bass. One of the most natural sounding mid bands available, excellent clarity and seperation of instruments, sweet top end without the explicitness or slight overemphasis of some high end contenders.

Cartridge matching

Most cartridges will be compatible with modern tonearms even those well outside the theoretical ideal effective mass. For medium mass arms a compliance of 10 - 15 x10-6 cm/dyne is ideal.

Exchange cartridges - (your current cartridge has expired or been damaged)

If you have a cartridge that is damaged or simply come to the end of its recommended life (normaly 2000 - 3000 hours of play). There are several options.

a) Trade it in for an exchange cartridge from the same manufacturer - generaly you get between 20 to 25% of the value of the cartridge you send in, offset against the cost of the new cartridge whether it’’s a direct replacement or a trade up to a better model.

b) Purchase a new stylus - this is usually only a small saving on an exchange cartridge and not worth it in our view unless your cartridge is very new and only has a bent cantilever. The reason is that once a cartridge has had a lot of use the inside gets gunged up with debris. Most companies do not offer a new stylus option.

c) Purchase a new cartridge - this is often the best option. Cartridges are advancing in quality steadily and older designs are sometimes poor value in comparison even on an exchange basis.

d) Get the cartridge repaired or retipped by a specialist company - this option will usually be a minimum of $200 but often seems very attractive for more expensive cartridges. It should be carefully noted however that you are highly unlikely to get back a cartridge close to the original. The parts used in rebuilds are rarely from the original manufacturer or of the same specifications. For this reason it is a slightly dubious path although some owners have been pleased with the results. Retipping can be worthwhile providing the catridge insides can be cleaned thoroughly and the cantilever suspension is still in good condition.

There are few companies in high-end audio with the
well-deserved reputation for innovation and perform-
ance that Thiel Audio enjoys. Thiel has been manu-
facturing high performance loudspeakers in the U.S.
since the late 1970s. The Thiel 2.4 is one of the com-
pany’s latest designs, and is a relatively diminutive
three-way floor-stander that sells for just $4,200/pair
in satin black. (Thiel’s typically lavish finishes can be
applied for an additional charge.)
I’m very excited to be reporting on Thiel’s 2.4 loud-
speakers, which are truly high-end, high perform-
ance, time- and phase-correct and hand-crafted in
the USA. In an industry riddled with over-priced and
under-performing components, a speaker like this is a
breath of fresh air.
While many magazine reviewers would have you
believe that the carriage trade products they have on
long-term loan are truly reference-quality, here’s a
speaker that many people can actually afford (without
a second mortgage) that’s demonstrably superior to
those pretenders in a number of respects.
Regular readers also know that the Journal is a big
proponent of time-domain fidelity in loudspeakers and
that Thiel Audio is distinguished as one of the few
remaining manufacturers of time- and phase-accurate
loudspeakers. Since the demise of Dunlavy,
Vandersteen and Meadowlark are the only others I’m
aware of.
I share Richard Hardesty’s opinion that time- and
phase-correct speakers represent a higher standard
of performance and a more sophisticated level of
connoisseurship compared to conventional loud-
speaker designs. For those who value convincing
dimensionality in imaging and soundstaging I don’t
believe there’s a substitute.
By their very nature, time- and phase-accurate
speakers require more work and ingenuity on the part
of the designer, and very high quality parts in the
drivers and crossovers. It’s no wonder most design-
ers prefer to tell you that time-domain performance
isn’t audible—it’s very difficult and expensive to prop-
erly execute a time- and phase-correct design.
If you’re a new subscriber I heartily recommend
Richard Hardesty’s article Time and Phase, Not just a Craze from the Audio Perfectionist Journal combined
issues #6&7;for an outstanding primer on the importance of
time-domain performance. That issue also contains an in-depth
look at Thiel’s design philosophies and an account of Richard
Hardesty’s visit to the Thiel facilities in Lexington, Kentucky.
Design and Construction
Many loudspeaker designs that sell for ludicrous sums are sold
on the alleged integrity of construction in their cabinets and/or
the rarity, quality and expense of the materials used in the cabinets, drivers and crossovers. After reading about the design
techniques and materials used to create this $4,200/pair speaker from Thiel, I hope you’ll cast the same jaundiced eye that I do toward the companies selling 7” two-way speakers (or a 7” two-way on top of a vented woofer box) for over
twenty thousand dollars per pair based on spurious claims of construction/parts quality.Cabinets Perhaps the most unique appearance aspect of the Thiel 2.4 is the sloped and sculpted front baffle.The slope is used to maintain physical
temporal alignment of the drivers,which, along with the coaxially mounted
midrange/tweeter,obviates adjustment of the speaker’s tilt in order to maintain
optimal image focus or tonal balance. The contoured edges of the baffle are
designed to break up any early reflections from the drivers that
could arrive at the listener’s ears close enough in time to the
primary signal to cause degrading time smear. Thiel believes
the contoured baffle results in a more open and focused soundstage and my listening experience with the 2.4 backs up that
assertion.
The 3”-thick MDF front baffle material is robust and rigid.
The rest of the cabinet is 1”-thick MDF, and is braced to a
truly extreme degree. The Thiel 2.4 cabinet is inert.
Rapping the cabinet with your knuckles produces the dullest
of thuds, with no sensation of resonance whatsoever.
I assisted Richard Hardesty a few years back when he updated
the drivers in Widescreen Review’s Thiel CS6 speakers to a
newer model. I haven’t seen any speaker at any price that surpasses Thiel CS6 structural integrity. Although the CS6 front
baffle is made of a more advanced material, the 2.4 cabinet
seems to be constructed to similarly high standards in spite of
the price differential.
I had Thiel send the review speakers in satin black, but for an
additional charge Thiel offers a number of exquisite veneers CS2.4 that are mirror-matched on each speaker pair. You simply won’t
find finer craftsmanship or greater aesthetic appeal in a speaker cabinet no matter how much more you spend.
Drivers and Crossovers
The CS2.4 uses a newly developed coincident aluminum tweeter/midrange driver (1” dome tweeter, 3.5” midrange) that’s
unique among coaxial drivers in that it uses a single voice
coil—the so-called “unicoil” design. This coaxially mounted
midrange/tweeter relies on a mechanical crossover (no electrical network) between the two drivers that Thiel claims conforms to a phase-coherent 6dB/octave acoustical slope.
As with any high quality speaker there is substantial cost tied
up in a Thiel speaker in its drivers and crossovers. The unicoil
system offers a very high performance-to-price ratio by using “...the midrange and tweeter are temporally aligned by sharing the same space...”
only one motor/magnet system and eliminating the electrical
network. Jim Thiel told me that, while this driver is more expensive than a separate midrange and tweeter, it’s not as costly to
implement as a typical dual motor midrange/tweeter, especially
with the crossover eliminated. He essentially considers this
design to offer “three-way performance at a two-way price.”
Coaxial drivers in general have advantages in a time- and
phase-correct speaker. One is that the midrange and tweeter
are temporally aligned by sharing the same space. A gentle
slope of the cabinet is all that’s required to align the coincident
driver’s output with that of the woofer, and the typically narrow
vertical listening window of a time- and phase-correct speaker
is expanded greatly. I’ve never found the narrow vertical window troublesome as my critical listening is done from the same
chair at the same height every time. But some people may
appreciate being freed from the perceived “head in a vice” constraint.
A potential drawback of using a coaxially mounted
midrange/tweeter is whether the drivers stay effectively decoupled from one another and avoid intermodulation distortion. In
other words, does movement from one driver cause unwanted
movement in the other, which results in distortion? Thiel combats this by shaping shallow midrange cones to form a proper
surround for the tweeter.
The 2.4 uses a single-layer aluminum midrange material in its
unicoil driver, where Thiel’s more costly designs (such as the
CS6 and CS7.2) use a three-layer sandwich material for
increased rigidity and damping.
Using aluminum for the midrange driver material has tradeoffs.
Aluminum is lightweight but very stiff and can operate over a
broad range of frequencies with high resolution and low distortion, which is a prerequisite for drivers in a speaker with first-
order crossovers. Aluminum drivers exhibit a so-called “oil can”
resonance at certain frequencies, a malady Jim Thiel engineers
around by making sure the resonances occur beyond the frequency range at which a given aluminum driver operates in his
speakers.
Objectively, an impulse response test will show aluminum drivers as prone to ringing. For example, the driver resonates over
a longer period of time after a transient than drivers made of
softer materials. On the other hand, softer driver materials
don’t operate in linear, pistonic fashion over as broad a range,
and tend to absorb energy, either of which can result in lower
resolution and compressed dynamics.
Subjectively, the most obvious drawback of aluminum in a
midrange driver is that attentive listeners will hear the distinct
sonic signature of the metal cone in this critical band.
Aluminum midrange drivers have a sound that will appeal to
some and turn others off. It’s my opinion that Thiel gets the
most out of this design choice, absolutely minimizing, if not
negating entirely, the potential pitfalls.
The 2.4 uses an 8” aluminum woofer with a 7.5” x 11” passive
radiator. Vented/ported woofers resonate the mass of air in the
port to increase the low frequency output of the driver. A passive radiator does the same thing by using the mass of the
passive radiator instead of the mass of the air column of the
port but has the same time-domain characteristics as a vented
box, which means more phase shift and group delay than a
sealed box. When listening, that translates to bass that plays a
little slower than the band is actually playing, which has obvious repercussions to rhythm and pace.
Passive radiators, however, are superior to vents in eliminating
port chuffing (air moving through the port that’s annoyingly
audible at the listening position), and eliminating any potential
for the backwave from other drivers in the enclosure coming to
the listener through the port too close in time to the primary
signal.
Another unique design choice by Thiel is the use of “underhung” voice coils—short voice coils in a long magnetic gap. A
typical long voice coil/short gap motor system produces distortion in bass drivers because the power of the magnetic field
acting on the coil and the amount of iron in the coil vary as the
voice coil moves back and forth, toward and away from the
magnet structure. With a short coil in a long gap, even when
the coil has moved a long way, it’s still in a uniform magnetic
field within the gap. Thiel further eliminates these distortions by
using copper sleeves over the pole piece and copper shorting
rings around the pole base to stabilize the magnetic field acting
on the coil.
Thiel’s crossover networks are all hard-wired (no circuit
boards) using the finest quality parts, including polypropylene
and polystyrene capacitors, along with very pure, low oxygen
copper, and air core inductors. The network in the 2.4 conforms to a first-order, 6dB/octave acoustic slope between the
woofer and the coaxial midrange/tweeter. Thiel’s networks are
complex as they compensate for impedance and phase deviations between the driver elements as well as damping driver resonances.

All in all, there’s enough engineering innovation and quality
parts and construction in the Thiel 2.4 to flat-out embarrass
many of the ultra expensive designs out there.
Adding Multichannel Capability to a Thiel
Speaker System
Another consideration that may be enticing to some is found in
Thiel’s unique options for adding multichannel based around
their stereo speaker pairs. Their PowerPoint® surround speakers are attractive, versatile beyond belief (they can be easily
installed on floors, ceilings or front, side or rear walls!) and
constructed to Thiel’s exacting standards using high quality
drivers similar to those in their floor standing designs.
Thiel’s MCS1 is designed for center channel use and employs
a coaxial midrange/tweeter very similar to the one used in the
2.4. The long-awaited SmartSub® system is among the most
innovative subwoofer/room correction system designs around,
which I hope will be enough to one day lure Dr. Boom himself
(Richard Hardesty) out of retirement from the field of reviewing
subwoofers.
Setup and Reference System
I achieved the sound I liked best with the 2.4s just under 7 feet
apart (center to center), with a distance of just over 9 feet from
each speaker to the listening position (an included angle
between the speakers and listener of considerably less than 60
degrees, which is less than Thiel’s user manual recommends).
In my 24.5’ x 17.5’ room the distance from the coaxial
mid/tweeter to the respective side wall was just over 5 feet and
each speaker was more than 5 feet from the front wall. This did
not optimize bass performance in the room as there was little if
any boundary reinforcement from this position, but produced
the best soundstage with the most coherent, convincing, precise imaging and best soundstage depth.
The amplification components in my system during the Thiel
review consisted of VTL’s TL7.5 preamp, Theta Citadel
monoblock power amplifiers (both of which I bought after
reviewing them for the Journal), and Ayre’s P-5xe phono
stage. Source components included Ayre’s D-1xe CD/DVD
player, and a Linn LP12 turntable with all the latest accoutrements: Cirkus bearing, Lingo power supply, Ekos tonearm,
Akiva cartridge, and the “Speed” carbon fiber mat from
Extreme Phono.
My system cables are all AudioQuest’s battery-biased lines:
Sky and Cheetah interconnects and Kilimanjaro speaker cable.
My power cords are AudioQuest NRG-5 and Richard Gray’s
Power Company High Tension Wire power cords. I also use
RGPC 400S power line conditioners.
Listening
As soon as the Thiel 2.4s were set up in my room, they made
great sound, immediately exhibiting the expansive soundstage
and convincing image focus that sets time- and phase-coherent
designs completely apart from conventional speakers.
Conventional speakers tend to create a strong image deep in
the center of the soundstage that compresses sharply front to
back at both sides, rather like a triangle. The Thiel 2.4s maintained layered image depth and excellent focus far out to both
sides, and far behind the speakers. The imaging capability of this
speaker can’t be described as anything less than spectacular.
“The Thiel 2.4’s soundstage
was completely and utterly free
of the physical boundaries
of the speakers…”
The Thiel 2.4’s soundstage was completely and utterly free of
the physical boundaries of the speakers, and very open sounding. Not only did this speaker never sound boxy, it never
sounded like it was there at all, even in the bass.
Vandersteen’s 3A Signature, which I owned for nearly three
years, has better bass extension, but that comes at the price of
sounding a tad boxy in the lower registers.
The Thiel 2.4 doesn’t go as low, but you never hear the box
either. I suspect this is a tribute not only to the cabinet construction but also to Thiel’s distortion-minimizing woofer
designs, explained in detail earlier. Superior components like
the Thiel 2.4 make your system sound less mechanical, less
like a system and more like music naturally occurring in space.
To that point, “free” and “open” are two words that pepper my
notes on the listening sessions I spent with this speaker.
Occasionally I felt this speaker gave up a rather teensy bit of
ground to the dense, fully rounded 3-D imaging I get from my
reference speakers. But take this nit-picking in its proper context. No conventional [phase incoherant] design I’ve heard at
any price is even worthy of comparison to the spatial precision
and dimension of the Thiel’s soundstage.
Time is not the only domain in which the Thiels are coherent.
Tonally the 2.4 is exceptionally balanced from top to bottom, as
even and neutral a presentation as I’ve heard from a speaker.
The top is airy and extended without being zingy or calling
undue attention to itself, and the midrange is resolved, if a little
cool (more on that in a minute). The mid-bass (50Hz-100Hz)
sounds noticeably quicker and cleaner than typical vented
designs, if just a tad over-damped. Combined with the aluminum midrange, this gives the 2.4 the cool signature Thiels
are known for.
Low bass (50Hz and below) is where I’d describe this speaker
having a slight subtractive coloration. Although its -3dB point is
specified at 33Hz, low bass lacked size and impact in my room,
but also sounded just a bit loose at the same time.
Big acoustic bass sounds, for example, were a little thin on
body sound and the strings didn’t snap quite as tautly as I’m
used to. I’m certain I could have improved the bass extension
by moving the speakers closer to the room boundaries, but my
biases are such that I’d prefer to maintain the spatial performance derived from having the speakers out in the room.
If you want more bass from this speaker it’s my opinion that
you should add a quality subwoofer to your system and leave
the speakers out in the room where they image best.
What about that aluminum midrange driver? Does it have a
sound? Yes, in my opinion, it does. The Thiel 2.4 unequivocally
does NOT have anything resembling the harsh, metallic sound
of other speakers I’ve heard using aluminum midranges.
(Monitor Audio and RBH are two examples of speakers I’ve
heard using aluminum midranges that sound just plain nasty.)
There is a damped, restrained coolness in these Thiels, and the midrange of the 2.4 is certainly not as relaxed as other
speakers that don’t use aluminum midrange drivers, including
the Vandersteens I own. But there is a big difference between
sounding cool and sounding metallic, and in my system these
Thiels never crossed that line.
On harder recordings there’s definitely less forgiveness than
some are used to hearing, but there was no bite or glare either
and this sound didn’t prevent me from getting deeply involved
with the music and thoroughly enjoying this loudspeaker. So
long as you stay away from components with a pushed, hard
midrange you’ll hear open, highly resolved, slightly-on-the-coolside-of-neutral sound from these speakers.
Further expanding the 2.4’s charm is a very engaging sense of
transient speed, dynamics and lifelike snap. Drum kits had outstanding pop and excellent dynamic contrast. Micro changes in
voice level or the intensity of plucked strings were clearly
apparent.
While the 2.4s were in my system they pulled double-duty for
home theater playback and did an excellent job. I used Theta’s
powerful Citadel amplifiers (400W per channel into 8 ohms),
and was more than pleased with how the Thiels performed in
my system even when driven at demanding levels.
“I think at $4,200 a pair
this speaker is one of the
finest values in audio.”
In terms of overall resolution this speaker outclasses nearly
everything I’ve heard at or near its price point, and is frankly
superior to many speakers I’ve heard that cost multiples of its
price. If pushed I’d admit that I believe the Vandersteen 3A
Signature can take you farther into the recording space, and
reveals more low level detail, but I also think a lot of listeners
will gravitate to Thiel’s clean, open and lively sound. And if form
factor becomes an issue, the Thiel has scoreboard, although
that comes at a price.
Another factor in the valuation of this speaker is what’s happening with the dollar. It is not my intent to get jingoistic here,
but current events dictate that buying speakers made right here
in the US of A has never been a better deal. With the poor
position of the dollar in the world economy, and the fact that
importers and distributors have to add a good percentage to
the price of their products to cover their expenses and make a
profit themselves, the odds are you’ll pay more and get less
from an imported speaker.
Conclusion
The Thiel 2.4 is simply superb. It occupies a small footprint in-
room for a full-range, floor standing loudspeaker and can be
purchased with a gorgeous furniture-grade finish that makes it
an attractive and practical speaker to share your living space
with. I feel compelled to mention the price because I think at
$4,200/pair this speaker is one of the finest values in audio, but
I also feel that mentioning the price denigrates this speaker in
some respect. The Thiel 2.4 is not a terrific speaker at this
price—it’s a terrific speaker in its own right, regardless of all
other factors, and I thoroughly enjoyed listening to it.
The Thiel 2.4 is a hand-crafted, high resolution, time- and
phase-coherent speaker that will simply embarrass many conventional designs costing much, much more. That its looks
match its high standard of performance is the icing on the
cake. The Thiel 2.4 is the kind of product that high-end enthusiasts should celebrate!

The changes to the AR II go much deeper than just new drivers. The enclosure has been fitted with new proprietary technology designed to eliminate cabinet resonances, removing the need for internal stuffing. The midrange and tweeter both receive new crossovers which, as on the original Anat Reference, are individually optimized for each speaker. Old Mundorf Supreme silver and oil capacitors used in critical areas have been replaced with new custom made Supreme silver and gold versions optimized for the AR II, and the tweeter’s internal wiring is custom made Kimber Select. Finally, the old Hypex amplifier which produced 200 watts RMS in the Studio version and 800 watts RMS in the Professional version has been replaced with a new amplifier custom made by Hypex to match the AR II’s subwoofer. It produces 400 watts RMS in the Studio version and 800 watts RMS in the Professional version.