The DVD32R has earned itself a reputation as one of the best performing DVD players money can buy, and the first DVD player to truly offer no-compromise, top class CD replay. However, the top loading construction of DVD32R does not suit all installations. And let's be honest - its performance comes at a price that does not suit all wallets!
The design brief given to the engineering team assembled to design TAG McLaren Audio's first av processor was simple: design a processor which will decode all current and future formats, have outstanding audio and video quality and be easy to set up and use. It took approximately 10 man years of effort to execute the brief and now, after just 10 months of extremely hard work, the av processor AV32R is ready for launch.
A very powerful, flexible Digital Signal Processor (DSP) is required to both support the existing decoding formats (Pro LogicTM, Dolby DigitalTM, DTSTM, MPEG2TM) and provide the ability to support any future format. It can not be a mask programmed device as this would mean that its code could not be upgraded in the field to include new decoding formats.
The design team chose the ADSP21065L SHARCTM, a device which at the start of TAG McLaren Audio's design programme was only a design brief given to the engineers at Analog Devices. To base the AV32R design around a device not already established in the market carried a significant risk, but the promised performance of the SHARCTM DSP and TAG McLaren's Automotive division's positive experience with DSPs1 from Analog devices made the risk one worth taking. The 60 MHz, 32 bit ADSP21065L is now a reality and its outstanding performance means a single chip fulfills all the following design requirements:
- enough power to decode all of today's formats with sufficient spare capacity to deal with any future format
- 32 bit processing to ensure the full dynamic range of the latest 24 bit formats is maintained
- the ability to download new code into the DSP's memory at any time.
The '65L SHARC is partnered by a 16 bit Siemens C161RI microcontroller. Devices from this family of powerful microcontrollers have been used within all of TAG McLaren's Formula One powertrain control systems. The C161RI is responsible for all the control functions of the AV32R (responding to the remote control, selecting audio & video inputs, generating the on screen displays etc). It also manages the task of downloading the programme code into the memory of the SHARC DSP. The power of the C161RI combined with good software and interface design makes these tasks simple and user friendly.
The design team turned to TAG McLaren's automotive division for help in selecting the most appropriate software development tools and methodologies for the project3. Working together, they established the software quality systems and put in place the procedures for rapid, high quality software development. The AV32R customer receives, as a direct result, the highest levels of performance and reliability4. All of the AV32R software is kept in a single, re-programmable, FLASH memory device. This includes the decoding algorithms for the SHARC and the control software for the C161RI. The FLASH can be reprogrammed using a PC connected via the TAGtronicTM Communication Bus5. This allows the AV32R to be upgraded to support new features and formats by a software download without having to open the unit. These upgrades can be performed in the field so that the unit need not be returned to TAG McLaren Audio's factory. Software upgrades will be available via the TAG McLaren web site.
This is a significant advantage over processors which, for cost reasons, cannot offer in-field re-programmability.
To ensure that the AV32R is future proof it is also fully 96kHz / 24 bit compatible. This means that future DVD or other sources with sample rates up to 96kHz and resolutions up to 24bits will be reproduced at their full bandwidth and resolution, offering the best possible detail from the recording. Having ensured that the AV32R could decode these high resolution and high bandwidth recordings it was necessary to ensure that the digital to analogue conversion was of the highest possible standard. To this end the AV32R uses three separate 24 bit, 96kHz, stereo Digital to Analogue Converters (DACs) and a separate Analogue to Digital Converter, rather than a compromise codec solution with all these functions in one chip. Again performance was more important than lowest cost.
TECHNOLOGY APPLIED TO ACHIEVE BEST SOUND QUALITY
The topology and devices used to achieve the excellent sound quality of the AV32R were selected after constructing and evaluating many prototypes of all the available options. Each prototype underwent extensive listening tests to fine tune and compare the options. The final sound characteristics were optimised by cross-referencing with experience built up over thousands of hours listening to and improving the F3 series audio products.
All this hard work resulted in the use of high quality Elna Cerafine bulk decoupling capacitors in the Audio Power supplies, and ultra stable Vishay metal film resistors and low dielectric loss Wima polypropylene capacitors in the audio signal path.
The power supplies
To reduce interference between the analogue and digital sections they have separate power supplies. Within the analogue section, separate supplies are used for the 5V DACs and the 12V analogue output devices. The higher voltage of the output stages gives better headroom and better driving of cables. Separating the supplies prevents output circuit currents from interfering with the highly sensitive digital to analogue conversion process.
To maintain separation of the different sections within the unit, the AV32R uses 15 independent linear supplies in all. Each is optimised using the best type of capacitor decoupling for its function and appropriate noise suppression filtering.
The transformer used within the AV32R is of toroidal construction as this has the benefit of a very low stray magnetic field, reducing the possibility of interference with the audio signals. The transformer is also very quiet, reducing hum to an inaudible level.
Within the digital region it is very important to control the high speed currents drawn by the digital IC's. This control is achieved using surface mounted, ceramic chip capacitors which can be located very close to the digital components. Being close to the IC's they can supply the required currents with the minimum of interference to the rest of the board.
The analogue region required a different approach. Particular care is required around the DACs as there the high speed digital signals must co-exist with the lower speed but very high resolution audio signals. To allow for this, the analogue regions use surface mounted, high speed capacitors near the DACs and the output filter components, combined with a three level scheme of bulk decoupling. The three levels of bulk decoupling consist of large, high quality Cerafine storage capacitors near the linear regulators, slightly smaller high quality storage capacitors by each of the sensitive components and surface mounted Polymer Electrolytic Neocaps very close to the supply pins. The Neocaps have a cathode conductance 100x that of an ordinary tantalum capacitor and 1000x that of a Aluminium Electrolytic capacitor, this gives a greatly improved high frequency response. This three level approach is used for all of the sensitive audio components in the input and output paths. By using these combined methods all of the power delivery problems within the system are addressed to deliver fine detail and stable images, as well as powerful but controlled bass.
The DAC topology
To achieve the best possible sound from the DACs, the quantisation noise present on the output has to be filtered out. This is performed by a combination of a 128x over-sampling filter within the DAC itself and an external analogue filter. The requirements on the analogue filter are greatly relaxed due to the over-sampling. However, listening tests proved that it still had a significant impact on the sound quality. The design was optimised to produce a filter which has very low group delay within the region humans can hear and beyond. The low group delay reduces the phase error between low frequency and high frequency sounds. The actual type used, after considerable optimisation by measurement and listening, is a fourth order Linear Phase with equiripple phase accurate to better than 0.5 . This type of filter has a flat group delay extending past the transition region and is thus ideal for filtering audio signals. By using a fourth order filter rather than the second order filter used in most designs the high frequency noise at the output is considerably lower. Reducing this noise reduces the possibility of distortion due to inter-modulation in the input of the power amplifier and thus improves the focus and detail of the sound.
The filter is implemented using high quality, low distortion operational amplifiers (op-amps) from Burr Brown. They were selected after considerable measurement and listening and are used throughout the F3 range to give a consistently high level of performance. These op-amps, combined with the high quality passive components (Vishay resistors and Wima Capacitors), create a very transparent output path which allows every nuance of the sound and the true depth of the bass to be revealed with complete clarity.
One of the principle causes of distortion in a digital audio product is jitter. Jitter is a distortion caused by errors in the timing of digital signals. Data dependant timing errors are one of the most audible and unpleasant types of jitter, so it is essential to remove these.
The AV32R uses a twin phase lock loop design to reduce the jitter on the master clock to an absolute minimum. The first loop extracts the clock from the bi-phase encoded SPDIF (or TOSLINK) signal. Due to the nature of bi-phase encoding, this signal still contains some time variations caused by the data encoded in the SPDIF signal. The second phase locked loop is based upon a voltage controlled crystal oscillator which provides one of the most stable clock oscillators possible. The phase locked loop filter starts to reject jitter from the clock signal at 6Hz and it is critically damped to provide good stability and the quickest possible lock time. Should this second loop not be able to track the input, such as in vari-speed applications or from particularly unstable source devices, the system will switch seamlessly back to the first loop and continue playing.
Short term spectral analysis of the clock jitter at the DAC reveals that it is below 10 pico seconds across most of the audio spectrum. The overall, long term, integrated jitter figure is 150ps, which would be state of the art for a CD player or standalone DAC and must be considered exceptional for a system containing so much digital processing and three DACs. This has been achieved not only by a high stability phase locked loop but also by careful treatment of the clock signal once it has been extracted. The clock signal is transferred across the PCB using independently buffered and precisely terminated clock traces to each of the DACs and the ADC. This termination prevents reflections along the PCB traces from causing decision threshold uncertainty which would introduce jitter. Careful circuit design, a four layer PCB and the layout and electrical noise suppression experience gathered in F1 racing by TAG McLaren's automotive division, have created a system in which the clock design is optimised in all respects.
The TAGtronicTM Sync Link
The final link in this clock path optimisation is the TAGtronic Sync Link: this unique (for an av processor) link allows the AV32R to lock its clock to provide a low noise, ultra low jitter reference right next to the DACs. A signal is then passed back to any TAGtronicTM Sync Link compatible product to synchronise its clocks to the reference within the AV32R. This system allows us to put the reference clock where it needs to be for optimum sound quality, right next to the DACs. The F3 DVD player DVD32R will feature the TAGtronicTM Sync Link.
The video circuitry within the AV32R offers a no compromise signal path using broadcast quality components. For the best possible picture quality the On Screen Display (OSD) device is switched out of circuit when no OSD information is displayed. A separate recording output is also provided without the on screen display option.
Some televisions allow internal crosstalk to occur between the Composite and S-Video inputs. Independent control of the outputs in the AV32R allows them to be selectively turned off if crosstalk is likely to occur.
The OSD chip has its own reference crystals to allow it to produce a stable output with no video input. This simplifies the system setup as there is no need to find a working video source to see the on screen help system.
Multilayer circuit boards are used in the AV32R to control the complex pattern of return currents from each of the different functional circuit blocks, provide controlled impedances for the high speed digital signals and minimise coupling between signal traces.
The AV32R has a complex power distribution system using an entire layer of the PCB. Power distribution is optimised through the use of very low impedance solid planes. This optimisation reduces distortion in the analogue region and improves the digital signal characteristics and electro magnetic compatibility of the complete AV32R.
Within the analogue audio regions it is important that the very sensitive, high resolution audio signals are not disturbed by the return currents from the high speed digital processing circuits. Separate ground planes are used under the analogue and digital regions to provide low impedance return paths for the currents. To minimise crosstalk and noise, the ground planes are split along the boundaries between the analogue and digital processing circuits.
Multilayer circuit boards are virtually essential if effective planes are to be created. Attempting to create planes using conventional two layer circuit technology inevitably leads to compromises with many ground return current paths having to be constructed out of relatively fine tracks in congested parts of the circuit, resulting in higher impedances and greater crosstalk between power and signal traces. Avoiding this compromise reduces digital noise emissions and significantly reduces the effects of the bass return currents on the high frequency treble components. This improves both the bass transient response and the image stability.
At the very high switching speeds of the digital circuitry the PCB tracks have transmission line characteristics. Multilayer boards, combined with precise control of track dimensions, spacing and layout, are essential to present these digital signals with well-defined, consistent impedances. This, together with correct signal termination, ensures that the signals are not corrupted by reflections and crosstalk. This is particularly critical for the clock signals, where the multilayer board is an essential element in achieving extremely low jitter levels.
The multiple layers of the PCB and the planes within it allow significant reductions in crosstalk to be achieved by routing signals perpendicular to one another on different layers and screened from one another by the ground planes.
A further benefit of the use of multi-layer circuit boards is the ability to increase component density. This leads to shorter tracks and smaller signal loop areas, which in turn reduces sensitivity to external interference and reduces noise emissions.
The advantages of a multilayer PCB construction meant that, despite its relatively high cost, it was the only logical choice to maintain the exceptional level of performance required from the AV32R.
The TAGtronicTM Communication Bus
The AV32R is the first F3 unit to feature the TAGtronicTM Communication Bus. This allows TAG McLaren Audio units to work seamlessly together to form an effective, integrated system. Remote control codes can be transferred over the bus, allowing system components to be operated out of sight. The TAGtronicTM Bus will allow the system to be extended to offer multi-room capability in which the output from sources can be controlled and redirected throughout a home.
One of the most flexible aspects of the AV32R is that both the micro-controller and DSP software are stored in re-programmable FLASH memory. The FLASH can be reprogrammed using a PC connected via the TAGtronicTM Communication Bus.
The bus communications protocols are compatible with standard PC asynchronous serial links (RS232). The electrical interface is RS485, selected because of its use of balanced signals and its suitability for long cable runs. Using balanced signals addresses grounding issues in complex systems and serves to eliminate potentially troublesome sources of hum. RS485 can be converted to the PC standard RS232 levels using a simple adaptor.
TAG McLAREN SURROUND
TAG McLaren Surround is an audiophile processing mode designed specifically for listening to both stereo and mono music sources. A centre channel increases the stability of the front sound stage while a split surround supplements the ambience present on the original recording. The processing is beautiful in its simplicity: The surround channel is derived by using the out of phase components of music, then a small amount of the in phase, mono signal is mixed in to enable mono compatibility. The surround channels are then passed through a proprietary de-localisation technique. The centre channel is derived from the mono component of the audio. This is then delayed and attenuated so it can improve the stability of the front sound stage without reducing its depth and character. The left and right channels reproduce the original recording exactly as intended by the artist. All processing within TAG McLaren Surround is fully dithered producing a high quality algorithm capable of processing 24bit/96kHz recordings with no artifacts.
For best results the surface mount components are placed and soldered in TAG McLaren's automotive division in Woking, using high precision placement robots (accuracy better than 80µm) and an inert gas (nitrogen) infra-red reflow oven. Soldering in a nitrogen atmosphere results in significantly higher quality solder joints compared to conventional atmospheric processing.
The boards are then cleaned before being shipped to Huntingdon where all leaded components are fitted before the printed circuit board is wave soldered. After soldering, component values and tolerances are checked by an automatic roving probe tester. The tested printed circuit boards are then installed in the case together with the other hand-fit components, such as the transformer, switches, connectors etc. Finally, a full performance test of the completed AV32R is conducted to verify perfect operation. The tested AV32R is then thoroughly cleaned before being packed and sealed with its accessories by operators wearing lint-free anti-static gloves. The sealed package is only opened by the final owner.
EASE OF USE
The Set-up Wizard
Inch thick manuals - who actually reads them? Setting up av processors is notoriously long winded and time consuming. To make this as easy as possible the AV32R has a self-explanatory Set-up Wizard that gives detailed, on screen, step by step instructions. This takes even a novice user through each of the stages needed to get the best performance out of the AV32R, without once referring to a user guide. The Wizard explains each stage as the user reaches it, and even gives useful hints when things may not be obvious.
The Power User
For more advanced users, or the retailer, there is a direct access configuration option. This option bypasses all the help screens to allow the speediest set-up by those who are confident about what they are doing.
A Learning Remote Control
The control of a full home cinema system can be a labourious task using several different remote controls which are always getting lost. To overcome this the AV32R comes with a system controlling remote. The remote is preprogrammed to control TAG McLaren Audio Products, however, it can be taught how to control almost any product that uses an infra-red remote. This allows it to become the system controller, controlling up to eight devices6. With this controller only one remote control is needed for a whole AV system. The button for the currently controlled device will flash each time a command is sent to tell the user which device it has been sent to.
To make control of the sources simpler there are individual buttons to select each source. Ten source buttons are provided in all, allow the user to select the input to the AV32R without scrolling through lists or using complicated two button procedures.
Typing in source names is made easier by using the same style of alphanumeric entry as phones. This approach keeps the number of key presses to a minimum and provides an interface that most people are familiar with.
The remote control also has a back light so that it is possible to see the buttons in subdued light. This is selected by a button at the bottom of the control so that it does not flatten the battery when it is not required.
CONCLUSION AND OUTLOOK
The AV32R is TAG McLaren Audio's first audio-visual product, offering an exceptional quality surround sound decoder which is designed to meet the needs of the user now and in the future. The AV32R can be combined perfectly with TAG McLaren Audio's existing range of high-quality power amplifiers or with the forthcoming, all new, 5 channel amplifier 100x5R. And the TAGtronicTM Sync Link (reducing jitter even further, i.e. improving the sound quality) will be put to use when the long awaited, high performance DVD player DVD32R completes the range. All products will be able to communicate with each other, using the TAGtronicTM Communication Bus, making remote and multi-room installations a reality.
At the limit...
The new AV32Rbp-192 THX Ultra2 Dual Processor 7.1 is the most powerful version of the AV32R family, offering what is probably the most advanced, all-channel, parametric room equaliser of all THX Ultra2 processors in the market.
Six times the processing power of the AV32Rbp-192 and an enhanced power supply topology allow many advanced functions, such as Height Channel or Room EQ and better sound than ever.
The AV32Rbp-192 THX Ultra2 Dual Processor 7.1 is the ideal choice for those who demand the best performing surround processor with almost unlimited potential for future growth.
All AV32R can be upgraded to AV32Rbp-192 THX Ultra2 Dual Processor 7.1
THX Ultra2 - the most demanding quality standard in home cinema
The new AV32Rbp-192 is THX Ultra2 certified, the latest and yet most demanding quality standard set by Lucasfilms for surround sound processors.
THX Ultra2 also offers THX Advanced Speaker Array processing, which optimises replay of 5.1 recordings using a 7.1 speaker layout. The result is indeed very impressive, and will probably stop you from ever returning to a mere 5.1 channels.
THX Ultra2 also provides THX MusicMode, which takes into account the fact that music is mixed in a different environment than film soundtracks, resulting in enhanced spaciousness and widening of the listening area.
THX Ultra2 also provides support for the new generation THX Ultra2 subwoofers and the different configurations of back channel speaker layouts.
The AV32Rbp-192 THX Ultra2 also features THX's new Subwoofer Boundary Gain Compensation, dealing with the acoustical side effects when a subwoofer is placed close to a wall - an improvement applicable to all systems, be they 5.1 or more.
The perfect home cinema system reproduces exactly what has been recorded - unfortunately no system can achieve this, as the pressure waves emitted from the speakers interact with the listening room, enhancing some frequencies and cancelling out others.
These phenomena have been known about for a long time, but could not be effectively overcome because of cost or inconvenience.
This is no longer the case...
TAG McLaren's Room EQualiser is most likely the most sophisticated room acoustics correction program found in any THX Ultra2 certifed processor today. It allows you to compensate for many of the detrimental influences of your room.
... it easily pays for itself
Have you ever asked yourself if you should replace your speakers, subwoofer or electronics because you found your system's performance boomy and imprecise?
Quite possibly, this behaviour isn't caused by your components but their interaction with your room.
TMREQ helps to resolve this problem for you!
TMREQ is a comprehensive, 8-channel, 96kHz/24-bit audio equalisation package that allows you to compensate for the detrimental influences of room acoustics and loudspeaker response, producing a sound field that is far more natural and faithful to the original production.
TMREQ modifies the signal sent by the AV32R to your speakers in such a way that the pressure waves emitted from your speakers, combined with the interactions of your room, add up to the sound initially recorded. Room effects can be dramatically reduced, resulting in sound improvements not possible otherwise.Great care has been taken to provide exceptional precision, whilst our algorithms have been tailored to maintain true fidelity. TMREQ will allow you to understand and correct many of your room's deficiencies - make use of it or ask your retailer to set it up for you.
TMREQ is real fun and probably the most cost-effective and powerful upgrade you have ever made to your system!
Enhanced Bass Management
The AV32Rbp-192 THX Ultra2 provides an Enhanced Bass Management, allowing the crossover frequency to be individually defined for the Left & Right Front speakers, Centre speaker, Surround speakers and the Surround Back speakers, with the crossover frequency being selectable from 40 to 150 Hz, in steps of 10 Hz. All processing frequencies up to 192(!) kHz are supported.
Full Specifications And Measured Performance
||Dolby Digital (EX)
|Dolby Pro Logic II
|TAG McLaren Surround
|Digital Signal Processor
||2 x Analog Devices ADSP-21161N SHARC® 32-bit, floating-point DSP
||Three RCA phono socket
|Two rectangular TOSLINK
|Digital Input Formats
|Optical: EIAJ RC-5720
||Two RCA phono coaxial (one if AC-3 RF demodulator option is fitted)
|Digital Output Format
|AC-3 RF Demodulator Input (optional)
||RCA phono socket
||Six stereo (including tape loop)
|Analog Input Impedance
||10 kOhms ±10%
|Analog Input Level
||User-configurable between 3V and 0.1V RMS
|Analog Input and Output Freq. Response, ± 0.5dB
|Analog Input THD and Noise
|Analog Input Channel Separation
||>95dB @ 1kHz
|Analog Input Crosstalk Rejection
||>90dB @ 1kHz
||Six (Left, Right, Centre, Sub, Surround Left, Surround Right)
|Analog Tape Outputs
||One stereo pair
|Analog Output Maximum Level
|Analog Output Impedance (except Tape)
||47 Ohms nominal
|Analog Output Impedance: Tape
|Analog Output Signal To Noise Ratio
|Analog Output THD and Noise (0dB full-scale)
|Analog Output Channel Balance
||<±0.5dB at 1 kHz
|Analog Output Channel Separation
||>100dB at 1kHz
||Two (one with On Screen Display)
|Composite Video inputs
|Composite Video outputs
||Two (one with On Screen Display)
|Video Input Impedance
||75 Ohms ±10%
|Video Output Impedance
||75 Ohms ±10%
||0Hz - 5.5MHz +0.1 -0.6dB