Hi Fi System Components
Audioquest Rocket 33
Audioquest Rocket 33
Price : £11 per metre
Rating : 6.5/10
Audioquest Rocket 33 is well made and really looks the part, but suffers from a forward, in your face type of sound. What’s needed is more finesse in the delivery, and the brightness in the treble needs sorting out. It has plenty of enthusiasm and the bass is well presented, but needs careful system matching to perform at its best.
Specifications
Biwire Yes
Directional Yes
Flat No
Termination cost n/a
Jitter
Jitter is the nemesis of digital audio and is the single most important factor when considering Hi Fi. You might well ask then what is the point in buying a more expensive player. After all we’re talking about a digital system right? The whole point about using digital is that it can’t be corrupted by signal loss or interference. The simple facts are that whatever player you use the data (0’s and 1’s) remains pretty much identical. When you copy a CD it is a lossless procedure. The CD-audio file that’s copied is identical to your original. The question is why does it sound better on a more expensive player? A cheap player is more susceptible to Jitter. Jitter occurs when the timing of data is not exactly aligned, or it’s not exactly in the right place it should be. It might be slightly earlier or later than it should be. This timing is not enough to cause data loss, fallout, or error. Jitter separates players in terms of quality. There are many factors that affect jitter. One factor is the digital clocks ability to supply precise timings. One part of a digital stream that affects others that follow. Errors in timing as small as 5 ns (nanoseconds) are known to be significant in 16 bit systems. The effects of jitter can be heard from around 10 ns. It’s important to remind ourselves that a nano second is a billionth of a second, or 0.000000001 seconds. What we are talking about is incredibly small variations that have a significant audible effect.
Jitter can also be caused by the digital clock giving inaccurate timing pulses. Amplitude errors and the width of the single pulse can also cause jitter. Power supplies are also a source of jitter when the ripple in the supply causes timings to be inaccurate. Other causes of jitter include electromagnetic interference EMI and crosstalk with other signals. Inaccuracies in the transports generating clock is the main source of jitter.
Audio cable
This is a particularly difficult component to deal with being an integral part of any Hi Fi system all interconnects exhibit their own characteristics. However, one thing is for sure, cheap interconnects that are often supplied free with CD players can be discarded; they will not do justice to any Hi Fi system.
So why do we need to buy expensive interconnects? The answer is because they have a significant effect on the sound of the system and costs must be in proportion to the rest of the system, say around 10%. Because cables have will have an important influence on the sound, also they will benefit from being as short as possible.
Properties of Cables
Most interconnects are shielded to reduce any RF interference. Shielding generally increases capacitance which is undesirable and high capacitance tends to roll off higher frequencies so short is best. In order to maintain flexibility and maintain low electrical resistance cables use many conductors. Better cables often use two separate elements of shielding, braiding to guard against (RFI), and foil to reduce (EMI).
Insulation is necessary to stop the signal shorting out but the type of insulation has a significant effect on the sound. Whereas most cables use PVC as insulation but it’s particularly poor as a dielectric. Teflon (PTFE) is one of the best dielectrics available with its dielectric constant being 100 times better than PVC.
Oxygen Free Copper (OFC) is often used in better cables as a conductor and produces minimal signal loss whilst passing signals accurately.
Silver or silver plated is usually considered the best material for cable conductors. Silver content in solder is proven in to have better conductivity in radio frequency (RF) assemblies and superior for audio.
Skin effect is particularly important when it comes to cables. When electricity flows in a wire it concentrates along the surface of the conductor more so with high frequencies. This phenomena lead to the design of Litz wires which are constructed of many very thin wires sometimes employed by high end interconnects.
Purity of silver and copper cables are often quoted in high end interconnects and result in purity of around 99.99%.
Gold plating is used for connectors because of its low oxidation properties; it makes a reliable connection that tends not to deteriorate over time.
Finally remember that each cables characteristic can suit some systems whilst making others worse, for instance a bright cable in a bright system etc.
DVD-Audio
DVD-Audio is a DVD disc designed specifically for Hi Fi audio; it’s not intended for video. First discs were on sale in 2000 and it is in direct competition with SACD.
There are many configurations for reproducing audio including single channel, stereo, and 5.1 channel for surround sound. DVD-Audio has much higher capacity compared to CD. The system allows for many different audio sampling rates and bit depths, for instance 24 bit depth sampled at 96 kHz (96/24) in stereo, or 24 bit depth sampled at 192 kHz (192/24). Rear speaker in surround sound are sometimes sampled at a different rates for instance 20 bit depth sampled at 48 kHz (48/20) for the rear whilst the front speakers can be 192/24.
The storage of audio is either in uncompressed or lossless compression with Meridian Lossless Packing. The total bit rate is 9.6 Megabits maximum so sometimes compression will be necessary. It possible in uncompressed mode to achieve 192/24 in stereo, and 96/16 or 48/24 in 5.1. Audio in 5.1 can be downmixed to stereo if the listener does not have a 5.1 system.
Backward compatibility is desirable to enable existing DVD players access to DVD-Audio although it’s not mandatory. DVD discs can have multiple layers on two sides of the disc. A popular combination is using a single sided DVD with DVD-Video and DVD-Audio in different directories. Audio in PCM high resolution mode can be played only on DVD players that have the necessary decoding ability. Discs with DVD-Video that can include LPCM, DTS, or Dolby are compatible with all DVD players. Discs are available as double sided with DVD-Video on one side and DVD-Audio on the other. CD/DVD releases have one side for the CD version and the other for the DVD-Video version.
An amplifier with six inputs was originally required to play DVD-Audio. Concerns about copying have restricted unencrypted digital audio delivery to sample rates of 48 kHz or lower which is ordinary DVD-Video quality. This concern restricts available sound quality to a lower level than could be available with this media. The quality of upsampled audio will not exceed the source quality and will not be better than existing CD versions of the same albums.
Although DVD-Audio is capable of excellent results restrictions applied by record companies make this a difficult format to recommend.
SACD
SACD stands for Super Audio Compact Disc. It’s based on Direct Stream Digital (DSD) which is the new type of recording technique. It’s a high resolution audio playback developed by jointly by Sony and Philips the team that brought us CD. The disc has the same physical dimensions as CD and was introduced in 1999. SACD is designed as both stereo and surround sound in high resolution. It uses DSD in addition to an optional layer which is CD compatible using traditional PCM (Pulse Code Modulation). SACD has a dynamic range of 120 dB and a frequency range of 100 kHz which is reduced sensibly to 70 – 90 kHz.
The sampling rate of SACD is 2822.4 kHz in one bit resolution (bitstream). It’s an uncompressed medium and can stream at 5.6 Mbps. SACD has much wider frequency and dynamic range compared to CD.
There are three types of disc available:-
Hybrid: This has two layers, a CD layer that can be played on ordinary CD players, and a HD layer which holds 4.7 GB
Single layer: Which does not have a CD layer and is physically a DVD-5 DVD
Dual layer: With two layers of HD and holds 8.5 GB, and physically DVD-9 DVD.
Most discs released contain mixes of stereo and surround sound. Backwards compatibility is assured by the existence of a secondary CD layer. This secondary layer can be substituted by an additional high resolution layer thus enabling playback well in excess of the normal 80 minute limit.
Output from SACD players are not allowed to offer unencrypted stream of Direct Stream Digital so the first players have analogue only output. Later Denon link had digital interface which allowed encrypted transmission.
The optical laser systems in CD players are focussed to a deeper level of the disc compared to SACD so that when a hybrid SACD is played it passes through the high resolution layer and plays the CD layer normally. SACD players are focussed on the high resolution layer and thus ignores the CD layer.
Many well known artists have released their back catalogue on SACD. One of the more notable releases was Pink Floyd’s Dark Side of the Moon selling over 800,000 by June 2004. Others include Jeff Waynes War Of The Worlds, Dire Straits Brothers In Arms, Elton Johns Honky Chateau, Tommy by The Who and many classical recordings.
There are three basic types of SACD players available.
Stereo SACD: A music only player that plays normal CDs but with upsampling capabilities in two channel only.
Universal player: A DVD player geared mainly towards the replay of video but supporting CD, DVDA. SACD, and MP3 audio disks. All supporting multi channel audio.
High End SACD: Aimed at the audiophile market with some supporting multi channel whist most support two channel playback. Few have video outputs, and can normally be switched out to concentrate on audio.
Notable manufacturers that supply players supporting SACD include Accuphase, Denon, Lexicon, Linn, Marantz, Micromega, Musical Fidelity, Onkyo, Philips, Pioneer, Sharp, and Yamaha . Some higher end Blu-Ray players are also compatible with SACD.
