Guide to Wadia Technology

Technology of the Wadia products

Use the chart below to compare the technology of the Wadia products. Descriptions of each technical element can be found by following the links in the chart.

Table of Contents	3 series	5 and 7 series	9 series	Transports
Digital Filter System	DigiMaster™ 3.1	DigiMaster™ 2.1	DigiMaster™ 1.3	N/A
Direct-Connect™ with Digital Volume Control	Yes	Yes	Yes	N/A
Adjustable Maximum Output Level	Yes	Yes	Yes	N/A
Swift Current	Yes	Yes	Yes	N/A
Modular Architechure	Yes	Yes	Yes	Yes
Modular Rear Panel	Yes	Yes	Yes	Yes
ClockLink™ Jitter Reduction	Yes	Yes	Yes	Yes
NoiseBlock™ Analog Circuit	Yes	Yes	Yes	N/A
Resolution-Matched™ Digital and Analog Stages	Yes	Yes	Yes	N/A
Digital Input	Optional	Yes	Yes	N/A
Digital Output	Yes	Yes	No	Yes
Configurable Digital Outputs	No	Yes	Yes	N/A
RockLock™ Inputs	No	Yes	Yes	N/A
Sleeping Inputs™	Yes	Yes	Yes	N/A
Ferrite RFI Noise Filtering	Yes	Yes	Yes	Yes
Schaffner AC Filter	Yes	Yes	Yes	Yes
Power Supply Transformer	Single Toroid	Dual Toroids	Dual Toroids	Single Toroid
Power Transformer Isolation Sub-Enclosure	No	Yes	Yes	Yes
Transport Mechanism	Phillips VAE 1250	Wadia Hybrid	N/A	Wadia Hybrid
Digital Servo Control	Yes	Yes	N/A	Yes
Separate Servo Power Supply	Yes	Yes	N/A	Yes
Volume Control Display	LED	Alpha-Numeric	Alpha-Numeric	Alpha-Numeric
Balance Control	No	Yes	Yes	N/A
Remote Control	Plastic	Plastic w/ optional metal remote available	Machined Aluminum	Machined Aluminum
Chassis Construction	Hybrid	Monolithic	Monolithic	Monolithic

The Wadia Technical Philosophy

Without doubt, the most important technical feature of these new Players is Wadia's philosophy of design. As with all Wadia products, these designs evolved through a balance of technology guided by a passion for, and understanding of, the power of music.

This design method is a fascinating process. As each new product is created, Wadia engineers develop new technical concepts that they believe will ensure great performance. These new concepts result from Wadia's previous work on digital playback, but also from broad research of leading-edge techniques from other digital fields, such as telecommunications and image processing. Hypotheses are constructed as to why these concepts should provide improvements over existing techniques. These hypotheses are then tested by measurement and extensive listening. Often, even the most advanced technical understanding does not fully correlate with the sonic results. In these instances, the design process continues with more experiments and listening until a more thorough understanding of the interaction between the technology and sonic performance is reached. In many cases, this results in breakthroughs that increase our overall understanding of the digital playback process.

Many measured and sonically evaluated parameters are assessed during the design process, but there is one that receives overwhelming priority - the ability of a CD player to communicate the power and intent of music. Wadia's goal is to produce equipment that makes the message of the composer and performer clear and accessible to the listener. A Wadia product must meet many criteria, but if it fails to communicate music it cannot be considered a success.

This unique design process has continued for over 17 years. The result is playback systems that set the industry standard for both performance and value.

DigiMaster™ Filter System

In 1989, Wadia introduced the DigiMaster filter system, a patented digital re-construction filter designed to specifically address the requirements of music reproduction. The DigiMaster system has become the heart of Wadia's approach, providing the best sonic performance of any re-construction filter currently available.

Digital filter systems used in most digital playback systems are designed to perform well on a small number of "bench" tests, such as frequency response, while sacrificing performance in other areas. The DigiMaster system provides balanced performance, producing excellent results in a wide range of tests, including phase and impulse response, which are critical to accurate and realistic reproduction of music.

Since the introduction of the original DigiMaster 1.0 in 1989, which featured 64-times re-sampling, Wadia has refined and improved the DigiMaster system. The current state-of-the-art is the DigiMaster 1.2, used in the Wadia Decoding Computers.

In 1992, a 32-time re-sampled system called DigiMaster 2.0 was developed for use in Wadia's mid-priced products. This was followed in 1994 by the 16-times re-sampled DigiMaster 3.0, used in Wadia's entry-level products.

The Wadia 5 and 7 series products utilize the most recent version of the 32-times re-sampled DigiMaster system. DigiMaster 2.5 offers great performance in its current configuration, along with processing power that allows future upgrades as well.

The Wadia 3 series product features the most recent implementation of Wadia's DigiMaster 3 series, the DigiMaster 3.1. Due to advances in DSP chip power, the DigiMaster 3.1 outperforms the original version of the DigiMaster 2.0.

Wadia Swift Current Technology

Conventional digital-to-analog converters perform current-to-voltage (I/V) conversion using feedback circuits based on operational amplifiers. Because the signal from the DAC chip consists of a series of step changes, the distortion introduced by this feedback circuit is a significant limitation on sonic performance.

In contrast, the Swift Current circuit performs this I/V conversion with Wadia’s patented current-conveyor integrated circuit (IC) that eliminates feedback. This bipolar IC consists of an innovative connection of Wilson current mirrors, an emitter degeneration compensation scheme to optimize transient response and stability, and a novel current mirror arrangement to enhance output impedance.

Direct-Connect™ Technology
The Wadia 3 series and 5 series players feature the latest iteration of Wadia's Direct-Connect Technology. With Direct-Connect, the output from the CD player is connected directly to the power amplifier, bypassing the preamplifier. This eliminates several stages of analog circuitry, the analog volume control, and cables from the audio signal path providing a distinct improvement in sound quality. There are many features of the Direct-Connect system, each of which is necessary, but not sufficient by itself, for proper performance. It is the combination of all of these elements that allows the Direct-Connect system to perform at such a high level.
1.	Digital volume control (with adjustable maximum output level)
	Since 1992, Wadia has continued to refine the first audiophile-quality digital volume control. It remains the only volume control that delivers the theoretical advantages of volume control in the digital domain. Although less sophisticated digital volume controls can sacrifice resolution, Wadia's volume control with adjustable maximum output level can be optimized to match a wide range of systems, ensuring greater than 16-bit resolution over the majority of the volume range. For a complete description of the WADIA Volume Control, refer to Guide to Wadia Technology Number 2.
2.	High-current output stage
	Wadia's Direct-Connect output stage can provide up to one-quarter amp (250 mA) of current, to drive very long cables, and low input impedance amplifiers.
3.	High-voltage output stage
	The Direct-Connect output stage can produce up to 4.25 Volts RMS, producing sufficiently loud volume levels even in low-sensitivity systems.
4.	Low output impedance
	With less than 15 ohms output impedance, the Direct-Connect output stage can drive highly capacitive and low-impedance loads with ease.
5.	Quiet digital circuitry
	Since the CD player output is connected directly to the amplifier, any high-frequency noise coming from the audio outputs can cause audible distortion. Direct-Connect circuitry uses the most recent techniques to minimize this noise. (See NoiseBlock)
6.	True-balanced output
	Fully-balanced circuit design - with the inverted signal produced in the digital domain, balanced DACs, and analog output - realizes the benefits of amplifiers with balanced inputs.
7.	Digital inputs
	Although CD is the reference source for most listeners, Direct-Connect components have provisions for additional digital inputs as well. These allow alternative digital sources, such as Laser Disc, DVD, DSS, DAT or Digital FM, to benefit from the Wadia decoding and Direct-Connect technology. As an alternative, listeners can connect analog sources by using a Wadia analog-to-digital converter.

Modular Architecture
The Wadia 3 and 5 series disc players are designed in a modular fashion so they can be upgraded to accommodate new technology.
1.	Multiple circuit boards
	These disc players feature separate circuit boards for each discrete function: input and output circuitry, digital-to-analog conversion, display/control, and transport servo-controller. This allows specific parts of the unit to be upgraded at the lowest possible cost.
2.	Software re-programming
	The main program chip in every Wadia design holds the operating software for the major system components. By changing this chip, the unit can be reconfigured in a wide variety of ways. This chip holds the instructions for three circuit sections: Control Microprocessor: The display, input and output circuitry, and remote functions are controlled by a single microprocessor. Changing the program that controls the microprocessor can modify any of these functions. Software-Based Digital-Signal Processing: Wadia's patented DigiMaster filtering systems in the Wadia 3 and 5 sesries currently operate at 32 times re-sampling with 24-bit resolution. These systems can easily be upgraded to operate at 96 KHz or 192 KHz, simply by changing the main program chip. Field-Programmable Gate Arrays: Every Wadia product utilizes these re-programmable devices for input circuitry, clocking, and data handling. Changing the main program chip allows any of this circuitry to be re-configured.
3.	Modular rear panel
	All three of these units have modular rear panels so connectors can be added or changed. A format change could easily require new rear panel connectors. Using conventional chassis design, this requires expensive re-machining and modification of the chassis. With Wadia's modular rear panel, these changes are inexpensive and easy to perform.
4.	A commitment to upgrades
	Most importantly, Wadia has a proven track record of providing cost-effective upgrades. While other manufacturers offer claims, we offer the most comprehensive history of upgrades in the industry.

ClockLink™ Jitter Reduction

Wadia's ClockLink provides the most effective jitter reduction of any technique available. With ClockLink, the master clock is in close proximity to the DAC section, rather than at the transport. This eliminates the need to transmit the clock from the transport section to the DAC, resulting in lower jitter and improved sonic performance.

Jitter, or clock timing error, causes uneven spacing of successive pulses from the DAC. These clock timing errors are cumulative; as the clock signal travels from the master clock, each additional circuit board trace, connection, and circuit element adds more jitter to the clock signal. This jitter is easily audible in the form of an artificial haze, harshness, as well as overall lack of resolution.

Conventional CD player with clock at transport
In conventional designs, the clock circuit is constructed as part of the transport mechanism so that it can control the transport speed. The clock signal is then combined with the data and transmitted to the DAC section. Along the way, jitter contaminates the signal resulting in audible distortion.

Wadia ClockLink System with clock at DAC
Wadia's ClockLink system positions the master clock directly adjacent to the DAC chips on the main circuit board. This results in the absolute shortest signal path between the clock and DACs, eliminating jitter that would be added during clock transmission to the DAC board.

The sonic result is immediately recognizable. Experienced listeners will notice a greater degree of immediacy, focus, and clarity. Instrumental images are more convincingly realistic. High frequencies are pure and well integrated into the rest of the sonic spectrum.

NoiseBlock™ Output Stage

One of the difficult challenges faced by all CD player designers is that digital circuitry creates high-frequency noise. If this noise is allowed to contaminate the audio signal, it can degrade musical performance. NoiseBlock is a proprietary Wadia design technique that effectively prevents high-frequency digital noise from contaminating the audio outputs.

The Compact Disc format only produces musical information up to 22.05 KHz. Yet most CD players have output stages which reproduce high-frequency signals and noise up to hundreds of KHz or higher. Although it is critical that the analog circuit preserves all information up to the upper limit of the CD format, it is unnecessary to reproduce frequencies far beyond this range. In fact, circuits that do serve only to pass noise from the digital circuit on to the analog signal. This noise can cause amplifier input-stages and many loudspeakers to produce distortions that are clearly audible in the form of hazy, grainy coloration.

Some designers believe that ultra-wide bandwidth analog output stages are required to ensure that high-frequency detail is preserved. However, extensive listening and research, including a deep exploration into the relationship between wide bandwidth and the use of negative feedback, have shown that wide bandwidth is not necessary for excellent sound quality. In many cases, wide bandwidth circuits cause more harm than good by allowing high-frequency noise to pass through to the amplifier.

Wadia's NoiseBlock analog stage starts with a high-speed analog circuit with extremely wide bandwidth. During listening tests, Wadia engineers gradually limited the high-frequency limit of this circuit. Each increment brought a noticeable improvement in sound quality. As the upper frequency limit was reduced, there was no discernable loss of high-frequency information. Instead, there was an increased clarity and purity in the upper musical ranges, owing to a reduction of high-frequency noise being passed into the amplifier.

Over a period of many hours of listening on a wide variety of music, equipment, and listening environments, it became obvious that there was a threshold such that if the response was limited below this point there was a noticeable loss of high-frequency musical detail. The NoiseBlock circuit was set to limit noise at a sufficiently higher frequency than this threshold, ensuring complete transfer of all high-frequency detail.

It is not possible to discern the effect of NoiseBlock circuit using conventional measurement techniques, since NoiseBlock only affects signals far above the upper limit of the CD format. It is easy to notice the improvement in sound quality of the NoiseBlock circuitry, described by listeners as a more natural portrayal of high-frequency information. Massed violins, for example, have the appropriate degree of texture, clarity, and body. Triangles and cymbals have a clear, metallic character, without grit or haze. Percussive sounds and transients are reproduced with a balance of leading edge and decay. The overall character of the upper ranges is significantly more relaxed, while simultaneously being more detailed.

Resolution-Matched™ Digital and Analog Stages

The Wadia 3 and 5 series disc players feature Resolution-Matched digital and analog stages to eliminate the sonic degradation from correlated digital noise.

All audio components produce residual low-level noise, called a "noise floor". Even though this noise is not audible under normal listening conditions, the character of the noise floor has a large affect on sound quality. For example, un-correlated noise, such as pure "white" noise, has a comparatively pleasing effect on sound quality, whereas correlated noise, as produced by digital circuitry, can create distracting distortions and unnatural sonic character.

Noise in a CD player has two sources: the digital circuitry and the analog circuitry. In the pursuit of ever-quieter analog circuitry, Wadia engineers discovered an interesting phenomenon. As soon as the resolution of the analog circuitry exceeds that of the digital circuitry (e.g. the analog noise floor is lower than the digital noise floor), the sound quality is compromised. Like looking through a clear window at a blurry image, the analog circuit can reveal the limitations of the digital circuitry.

To overcome this, Wadia engineers used a new approach in designing digital-to-analog circuitry. They began by designing the highest resolution digital stage possible, in this case true 21-bit digital resolution, ensuring that maximum information is extracted from the CD. Next, Wadia engineers designed an analog circuit that has adjustable resolution level. Through both listening and measurement, it was possible to match the resolution level of the analog circuit so that the noise floor is slightly higher than the digital resolution limit.

With this Resolution-Matched analog and digital circuitry, the high-resolution digital stage extracts maximum detail from the CD, while the noise floor is dominated by sonically pleasing un-correlated analog noise. The sonic result is a perfect balance between retrieval of subtle musical information and natural musical sweetness.

Digital Inputs and Outputs
The Wadia Disc Players include digital inputs and outputs as standard equipment. The Wadia 3 series CD Player includes a digital output and can be equipped with optional digital inputs and at the time of purchase, or as an upgrade later. These digital inputs and outputs include several innovative features:
1.	Configurable Digital Outputs
	The digital outputs on the Wadia 5 series players can be configured as either tape monitor outputs (playing the input that is selected) or CD player outputs (playing the CD transport, no matter what input is selected). In addition, unused outputs can be disabled, reducing noise and resulting in a noticeable improvement in sound.
2.	RockLok™ Digital Inputs
	The Wadia 5 series player uses Wadia's RockLok technology to reduce jitter on sources fed via the digital inputs. The RockLok circuitry is located close to the DAC chips on the main board for best performance.
3.	Sleeping Inputs™
	When any input is not being used, the input circuitry and the associated power supply are disconnected. This reduces digital noise and improves sound quality.

Power Supply Noise Reduction
With digital and analog circuitry in such close proximity, CD players are ripe with opportunities for digital noise to contaminate analog music signals. Over the past ten years, Wadia has developed many techniques for reducing this contamination. In these new CD players, great strides were made in blocking one of the most insidious routes for noise contamination - through the power supply.
1.	Ferrite Filtering
	Through careful listening tests and measurements, Wadia engineers were able to track the progression of noise through the unit. Carefully applying ferrite filters in key locations provided a dramatic reduction of noise. Ferrites are particularly useful at preventing high-frequency noise from escaping from noisy circuitry, such as fluorescent displays and microprocessors.
2.	Schaffner AC Filter
	This costly, high-quality AC input filter serves two purposes. First, it helps prevent high-frequency noise from the AC line from entering the CD player chassis. In addition, this filter prevents noise from the digital circuitry inside the CD player from being transmitted, via the AC power cable, into other sensitive audio components, such as the power amplifier.
3.	Dual Transformers
	One transformer powers the CD transport mechanism and servo controller; one drives the digital-to-analog circuitry. This separation reduces the chance for digital noise to pass to the analog circuits.

Power Transformer Sub-Enclosure

Transformer positioning is a difficult design choice filled with potential for compromise. Positioning the transformer within the main chassis allows for low-impedance, rapid delivery of instantaneous current to the circuits. Transformers, however, produce mechanical vibrations and stray fields that affect the performance of delicate circuitry nearby. In addition, transformer vibration can create objectionable noise in a quiet listening room.

Wadia engineers developed an elegant solution to this conundrum - the internal transformer sub-enclosure. This approach allows the transformer to be mounted close to the circuitry for instantaneous power delivery, but protects internal circuitry from interference.

The transformer sub-enclosure is constructed from machined aluminum plates. Affixed to the top and bottom surface are closed-cell neoprene damping sheets. This material combines excellent damping and thermal stability. A bolt, mounted to the bottom of the sub-enclosure, holds the transformer in position. However, the transformer is not connected to this bolt - it is effectively floating in place, clamped in position by the neoprene damping material.

This arrangement completely isolates the transformer. It absorbs vibration, prevents unwanted mechanical noise, and shields all other circuitry from stray electric fields caused by the transformer.

Power Transformer Isolation Sub-enclosure allows transformer to be mounted inside main chassis
for instant power delivery, but shields transformer to prevent interference.

Separate Servo Power Supply

Wadia's extensive listening tests reveal that the quality of the transport servo-control power supply directly affects sonic performance. Wadia products use a large, carefully pre-regulated power supply with substantial filter capacitance.

Alphanumeric Display
The Wadia products use a 80 or more character fluorescent alphanumeric display that allows for greater flexibility and more detailed display information:
1.	Software Upgrades
	Because the microprocessor program controls display information, new features can be displayed with simple software upgrades.
2.	Balance Control
	The right/left channel balance can be controlled and displayed in increments of one-tenth of a dB.
3.	Status Information
	The display indicates which input is being used, whether the phase is normal or inverted, sampling rate, emphasis, and whether ClockLink is engaged.

Chassis Construction

All Wadia products are built using Wadia's trademark monolithic machined aluminum construction. This produces a chassis that offers remarkable mechanical stability, protecting sensitive electronics from vibrations that can adversely affect performance. In addition, this chassis functions as a highly effective shield against radio frequency interference. Last but not least, this design makes an aesthetic statement that has been lauded around the world for combining beauty, craftsmanship, and unparalleled finish quality.

Remote Control

The metal remote control is machined from a solid billet of aluminum, using a carefully designed shape that fits comfortably into one's hand.

The Wadia 3 and 5 series standard remote control is made of high-density plastic, and shaped in an ergonomically friendly full featured design. The machined aluminum remote is available as an option.