The Wadia 121 Decoding Computer / DAC
In an effort to avoid confusing readers let me state that the Wadia 121 is a DAC with a more descriptive name and extra features such as volume control and a headphone output. When in doubt just think of it as a DAC. The 121 is packed with wonderful design and proprietary technologies developed by Wadia. White papers describing much of these technologies read like an engineering geek's dream and music aficionado's nightmare. Four design elements in the 121 Decoding Computer that most computer audiophiles should understand are ClockLink, filtering & D to A conversion, volume control, and the power supply.
ClockLink, as opposed to Wadia's ClockLock, pertains only to the 121's asynchronous USB input. ClockLink is all about reducing jitter through oscillator placement, master clocking, and flow control. In the 121 Wadia placed a fixed master oscillator as close as physically possible to the actual DAC chip. This close proximity is thought to be extremely critical for best performance by many respected audio engineers. All computer audio sources connected to the 121 via USB are synchronized to this master oscillator's clock signal. The 121, like other async USB DACs, controls the flow of data from the computer to keep its buffer at an optimal level. In layman's terms the DAC controls show by using its clock and signaling the computer when to send data. This is vastly different from traditional audio sources connecting via AES/EBU or S/PDIF. These traditional sources embed a clock signal into the audio stream entering the DAC causing increased jitter. In other DACs using adaptive USB the DAC must adapt to the incoming data stream without the ability to prevent data under-run or overflow and must adjust to the incoming clock signal. In theory asynchronous USB has the upper hand but sound quality is much more about the product as a whole than one design element.
Graphic courtesy of Wadia.
Filtering & Digital to Analog Conversion
The 121 Decoding Computer uses Wadia's proprietary interpolation filtering system called DigiMaster. This filtering technology reconstructs the analog waveform operating at 4x44.1 kHz. Wadia does this by interpolating four samples for every original sample. Readers familiar with CD ripping interpolation may recognize a tiny bit of similarity in that CD ripping interpolation looks at the original bits on a disc to recreate missing bits lost to scratches in the disc. The process is called interpolation and can be enabled in dBpoweramp via a check box. The DigiMaster system isn't recreating missing bits through interpolation rather filling in gaps between samples to smooth out the recreated analog waveform. According to Wadia the original samples used by the interpolation filter are not changed in any way. The 121 uses a 32-bit DAC integrated circuit for completion of upsampling to 1.4 MHZ and final conversion from digital to analog.
Variable Level Outputs
One of my favorite features of the Wadia 121 is its volume control. The 121 user manual states emphatically that this device was design to drive a power amplifier directly. To drive a wide array of amps with varying interconnect lengths Wadia implemented a volume control similar to the Weiss DAC202's coarse analog / fine digital control. The 121 output stage is adjustable to either 4Vrms, 2Vrms, or 1Vrms (the user manual states 0.5Vrms as a fourth level of attenuation). Wadia accomplished this attenuation with a single metal film resistor as opposed to multiple resistor arrays with complex signal paths. Adjusting the output voltage of a DAC can increase resolution of a playback system greatly. Most DAC only allow digital volume attenuation thus reducing bits and eventually resolution. Operating a digital volume control at its highest levels decreases the number of bits reduced. An unadjustable output voltage may require the user to use massive amounts of digital attenuation to reduce volume to a comfortable listening level. This reduces resolution and sound quality. By setting the output voltage lower this same user can keep the digital volume control near its maximum output and not reduce bits in an audible way. The 121 can attenuate a 24-bit signal from a computer by 48dB without losing any of the original information according to Wadia. After setting the output voltage of the 121 all subsequent volume adjustments are done in the digital domain at 0.5 dB increments.
The Wadia 121 Decoding Computer uses a switching power supply. When implemented right an SMPS can be extremely good. CA readers may not realize that the $15,500 EMM Labs DAC2X, the best DAC I've heard in my system, also uses a switch mode power supply. Wadia has taken several steps to reduce the effects of such a supply on the 121's sound quality. Placing the power supply outside the physical 121 chassis not only reduces the DAC's size it also reduces EMI and RFI interference from effecting sensitive analog and digital circuits. Internally the 121 has multiple stages of regulation to stabilize the DC power. The master oscillator has its own dedicated voltage regulator providing a clean DC signal for clock stability.
No single design element, discussed here or elsewhere, is responsible for the sound of a component. Rather it's all design elements when implemented together as a whole greater than the sum of the parts that really matter. This whole is a waveform that enters one's ears for interpretation by the brain as a good, mediocre, or bad sound. This hobby is all about taste. Each person may enjoy a slightly different sonic color or character than the next person. Nobody likes 100% transparency because nobody has heard 100% transparency. Not only that but nobody outside the studio control room can judge accuracy of music reproduced through a given component.
Listening to the Wadia 121 Decoding Computer
I listened to the Wadia 121 Decoding Computer ($1,299) in a number of configurations. Most listening was done using my C.A.P.S. v2.0 server running JRiver Media Center v18 and using my MacBook Pro running OS X Mountain Lion 10.8 and Audirvana Plus v 126.96.36.199.2 in Direct Mode. On the audio side I listened mainly through my reference system consisting of a Spectral Audio DMC-30SS Series 2 preamplifier ($12,000) and DMA-260 amplifier ($10,000), and TAD Labs CR1 loudspeakers ($40,000). This system is very neutral and helps me identify differences between products easily. However, the Wadia 121 was likely designed for systems that cost less than my preamplifier alone and systems with different requirements. Wadia advocates a direct connection from the 121 to an amplifier while at the same time Spectral advocates use of its preamp with its amps. The DMA-260 user manual states a high output current capability of at least 180ma continuous is required. That's not an easy task for a small component with small power supply. I listened both with and without a preamp but preferred the sound with the preamp in this playback chain. Both configurations had pros and cons. There was no free lunch simply bypassing the preamp in my main system. At the end of the review period I changed things up considerably by connecting the Wadia 121 directly to a pair of Bel Canto ref1000m monoblock amplifiers ($5,990 /pair) via AudioQuest balanced interconnects. This was a game changer. These amplifiers are not as resolving as the DMC-30SS / DMA-260 combo but from a system synergy point of view they were a much better fit then running direct to the Spectral amp. This Wadia > balanced AudioQuest > Bel Canto combination is a "must listen" for readers putting together a system in this ballpark of size, price, and performance. I also spent a considerable amount of time listening through Sennheiser HD600 headphones connected to the 121's front headphone output. My headphone use wasn't planned but came more from necessity and a desire to listen while at my desk without routing music to my main system. I frequently purchase music online or fire up MOG to sample the new releases of the week every Tuesday. The Wadia 121 works excellent in this capacity as it supports all relevant sample rates from 44.1 through 192 kHz and sounds very good with the Sennheisers.
Overall the sound reproduced through the Wadia 121 ranged from good to very good. The best sound was had when listening to headphones and using Audirvana Plus in Direct Mode on the Mac. Even lossy 320 kbit/s MP3 was very enjoyable while sitting at my desk. Listening through my Spectral preamp and amp produced the best main system sound followed by the direct DAC to amp connection via balanced XLR cables. Connecting the 121 directly to my DMA-260 amp didn't sound as good as the aforementioned configurations but this is also an extremely rare setup not likely to occur in the real world. The sonic character of the Wadia 121 was very different from other DACs I've had in my system in recent memory. I attribute this to Wadia's unique design and proprietary technologies. My favorite aspect of the 121's sound quality is its lack of warm tube coloration. Granted this is a complete solid state design, but that hasn't stopped manufacturers from injecting a bit of warmth in the past. I am usually annoyed by tube warmth within minutes. Readers like me should audition the 121 for a refreshing tubeless sound. Playback of Rock and Pop was right in this DAC's wheelhouse. Seal's Killer (acoustic version) sounded really good through the 121. The vocal on this track was right up front and didn't require a DAC with ultimate resolution and delicacy to reproduce with great effect. Similarly playback of Tower of Power's Diggin' On James Brown was a great track to turn up the volume and enjoy. All the horns, drums, and backing vocals contributing to the chorus produced a fun and engaging sound through the 121.
Continuing with some of my favorite popular recordings I had a blast listening to Suzanne Vega's Headshots, The Black Key's Sister, Fiona Apple's Limp, and The Doors' The End at 24 bit / 96 kHz high resolution. Headshots had very forward sounding bass right from the start while Suzanne's crystal clear vocal was set out in front of the speakers. This track and others like it with a bit more "production" than traditional audiophile recordings were handled with ease by the 121 Decoding Computer. Sister from The Black Keys was another track I turned up considerably to feel the punch of the drums and enjoy great new Rock n' Roll through the 121. With the volume still at an abnormally high but enjoyable level I moved to Limp from Fiona Apple. From the strange sounds starting the track to the percussion solo at 2:07 to the horns during the chorus the 121's reproduction didn't disappoint. Jim Morrison's dark vocal throughout The End and the seemingly endless repetition of keyboard and drums at 24/96 high resolution sounded really good but not so good that I got lost on Jim's 11:38 musical journey. My experience listening to these recordings through both the full Spectral and Wadia / Bel Canto configurations was very enjoyable.
Playback of some of my favorite audiophile type recordings through the full Spectral system revealed the weaknesses of the 121 Decoding Computer. No component is perfect nor without a color of its own. Randi tytingvåg's Red or Dead was a bit forward, a bit flat, and lacked a bit texture that I'm used to albeit with DACs costing thousands of dollars more than the inexpensive 121. The vocals were right up front and crystal clear as was the guitar. Other instruments had pop to them as if they stuck out a bit too much or at least more than I'm use to hearing. The sound was very reminiscent of solid state electronics without a touch of unnatural warmth. The Kansas City Symphony's version of Passacaglia at 24 bit / 176.4 HRx high resolution requires a playback system that can reproduce the delicacy of fine violins and minute sounds at low levels. The 121 struggled with this track. It reproduced sound more like a melting pot (all sounds gelled together without differentiation) than a salad bowl (every instrument is a distinct sound with delineation). This level of reproduction is expected from a component far down the line from Wadia's reference decoding computers. The huge horns and cymbals in a display of wonderful dynamic range isn't easy to reproduce as well as the best DACs in the business.
The previous two paragraphs detailed my experience with the Spectral DMC-30SS Series 2 preamp between the Wadia 121 and my Spectral DMA-260 amp and the direct Wadia to Bel Canto configuration. I listened to the previous tracks and Ottmar Liebert's Not One, Not Two at 24/96 via a direct DAC to Spectral amp connection as well. On all tracks the sonic character was the same and I heard mixed results. On the plus side I heard more low level detail without the preamp. The negative impact of the direct to Spectral amp connection was both less fullness and a loss of texture. Ottmar's guitar strings sounded a bit off to me without using the Spectral preamp. However, I am used to the sound of this recording through my DMC-30SS Series 2. I won't say a direct DAC to amp connection was wrong as my experience with a different DAC to amp config was very right. I will say this direct to Spectral amp configurations was my least favorite and not recommended.
One additional weakness I heard while using the Wadia 121 was a lack of air and space on some recordings. Diana Krall's Almost Blue was devoid of air and space around the piano in the first 40 seconds of the track. At the end when Diana says, "Almost me, almost you, almost blue" there was no air around her vocals and I didn't hear much separation or depth between the vocal and bass finishing off the track. It's a different sound than I am used to but it was still nice. I'm willing to bet most people without the ability to hear the best DACs on the market wouldn't even notice what I consider the weaknesses of the 121. The concept of relativism is very appropriate.
Relativism: The doctrine that no ideas or beliefs are universally true but that all are, instead, “relative” — that is, their validity depends on the circumstances in which they are applied.
The American Heritage® New Dictionary of Cultural Literacy, Third Edition
Copyright © 2005 by Houghton Mifflin Company.
Published by Houghton Mifflin Company. All rights reserved.
The Wadia 121 Decoding Computer is more than competent and competes with products double, triple, and quadruple its size. Think size doesn't matter? It does when designing audio components. Squeezing more electronics into a smaller box, dampening vibrations, and isolating the delicate analog and digital circuitry is much harder with a tiny form factor. Much of my experience with the 121 was heavily influenced by the component configuration and type of music I selected for playback. The 121 isn't an all-out-assault that enables listeners to hear things on a classical recording they've never heard previously. Fortunately in most system connecting the 121 directly to an amplifier will produce great results. What separates the 121 Decoding Computer from the rarefied air of great but greatly expensive DACs is reduced depth, air, and low level detail when reproducing the best recordings from labels such as Linn Records, Naim, and Reference Recordings. Despite a few anticipated weaknesses I thoroughly enjoyed my time with the exceptionally well designed Wadia 121. Its good sound quality enabled me to enjoy most of my favorite music from old to new Rock n' Roll and everything in between. The Wadia 121 Decoding Computer is recommended for readers putting together high performing yet sensible systems or looking to take an existing system to another level. New computer audiophiles seeking their first entry into this wonderful next phase of high end audio can't go wrong by starting with the 121. They may never need another digital to analog converter.
- Product - Wadia Digital 121 Decoding Computer
- Price - $1,299
- Product Page - Link
- Digital Inputs: AES/EBU (XLR), Coaxial (RCA & BNC), Toslink Optical, USB B
- Input Data Rates: 44.1kHz, 48kHz, 88.2kHz, 96kHz, 176.4kHz, 192kHz (up to 24 bits)
- Operating Systems: Apple Macintosh Apple OS X 10.6.4 and newer, Windows, Linux Kernel 2.6.33 or newer
- Analog Outputs: One Pair Balanced (XLR), One Pair Unbalanced (RCA)
- Dimensions: 2.7 x 8 x 8 in., 6.68 x 20.32 x 20.32 cm
- Finish: Black Powder Coated Aluminum
- Seal - Killer (Acoustic)
- Tower of Power - Diggin' On James Brown
- Suzanne Vega - Headshots
- The Black Keys - Sister
- Fiona Apple - Limp
- The Doors - The End
- Randi Tytingvåg - Red Or Dead
- Diana Krall - Almost Blue
- Ottmar Liebert - Not One, Not Two
- Kansas City Symphony | Michael Stern - Passacaglia
- Source: MacBook Pro, C.A.P.S. v2.0 Server
- DAC: EMM Labs DAC2X, Berkeley Audio Design Alpha USB
- Preamp: Spectral Audio DMC-30SS Series 2
- Amplifier: Spectral Audio DMA-260, Bel Canto Design ref1000m
- Loudspeakers: TAD Labs CR1 Compact Reference
- Remote Control Software: JRemote, Apple Remote
- Remote Control Hardware: iPhone 4, iPad (3rd Generation)
- Playback Software Windows 7: J River Media Center 17
- Playback Software Mac OS X 10.7.4 : Audirvana Plus
- Cables: Spectral Audio MH-770 Ultralinear CVTerminator Series II Loudspeaker Cable, Spectral Audio MI-350 Ultralinear CVTerminator Series II Analog Interconnects (RCA), Mogami W3173 Heavy Duty AES 110, ALO Audio AC6 Power Cables, Wire World Silver Starlight USB Cable, AudioQuest Diamond USB Cable, AudioQuest Niagara Balanced XLR Analog Interconnects
- Network: Cisco SG200-26 Switch, Baaske MI-1005 Ethernet Isolator, Micro Connectors Augmented Cat6A Ethernet Cable, Apple AirPort Extreme, Cisco RVS4000 Router, Cisco DPC3000 Docsis 3.0 cable modem, Comcast Extreme 105 Mbps Internet Service