The Musical Fidelity was part of a of a limited edition
of 1300 pieces based on the military-spec 5703 triode tube, also known as a
Tri-Vista or "Trivistor". Tube output stages for CD players are not
new at Musical Fidelity, the FCD CD player used the Telefunken E88CC tubes as
output buffers, the Tri-Vista being its successor
Sharing similar design philosophy to the Tri-Vista SACD player, the 21 DAC features two large linear power supplies using a pair of toroidal transformers. The first toroid supplies the lower voltage DC supply and a hefty bank of reservoir capacitors totalling 90,000µF does the AC smoothing. The second, higher voltage supply is solely for the triode output stage, with 8,800µF of reservoir capacitors to smooth the 90V supply rails. The unregulated DC is followed by two large choke regulators.
On the signal side, the digital input is handled by the CS8420 sample rate converter. The digital signal can be upsampled to either 96KHz or 192KHz courteously of the SM5849 asynchronous sample rate converter. A single, high performance Burr Brown DSD1792 DAC does the digital to analogue processing with an op-amp based current-to-voltage converter & analogue filter stage. The audio signal is then buffered a line driven by the triode tune output and capacitor coupled.
Digital Makeover
The 21 DAC contains a vast amount of general purpose components which deprive the product from performing anywhere close to its potential. Having meticulously examined the 21 DAC’s circuits we have developed a range of upgrades to wring every last ounce of performance out of this product. Each ‘level’ of upgrade has been calculated to provide scalable performance increases between levels
The Tri-Vista DAC’s circuits has a high capacitor count and the PCB’s are littered with general purpose Jamicon SK electrolytic capacitors types for de-coupling and signal coupling Jamicon LP general purpose types for main power supply reservoir. Ceramic leaded capacitors are used to bypass the electroytics at high frequencies as well as bypassing the input of the fixed voltage regulators and local digital de-coupling.
These cheap general purpose capacitors used throughout and where very low impedance; very low E.S.R., low distortion is required and seriously limit performance. With the level-2 upgrade we replace all the SK electrolytic on the main PCB with high performance cocktail of OS-CON SP, Rubycon ZA & ZL type. The optimal capacitor type is selected for individual circuit requirements based on a balanced and synergistic approach to upgrading.
Burr Brown’s high grade DAC is followed by 3 pairs of NE5532 operational amplifiers, an industry standard that measures well but is clearly outdated and outclassed compared to modern types. For I/V conversion were use the LM4562, a new op-amp that can deliver remarkable sound when used correctly. The filter stage uses the excellent ADxxx from Analog Device; all are fitted with high quality Gold plated, Beryllium Copper sockets for future upgraded when available.
The Tri-Vista’s DC regulated power supplies are supplied by 78xx & 79xx generic regulators. The output noise of the 7805 is typically 40µV, with a ripple rejection (AC noise) of 80db at low frequencies which worsens considerably as frequency increases. This noise riding on the DC rails arrives at the power input pins of every digital & analogue processing stage; noise on the input of the DAC = noise/errors on the output.
In the level-2 upgrade we replace 3 stages of generic regulation for the DAC, digital circuitry and analogue output stage with ultra-low noise, wide bandwidth discrete regulator boards. These regulators feature (1) very wide bandwidth (2) ultra-low noise (3) high PSRR. The new regulators design means noise is rejected at the input so the circuit being powered is "isolated" from input noise. Compared to the best standard regulator which at best offers 80db rejection, the new regulators provide a PSRR of 130db across a wide bandwidth.
Tri-Vista 21 DAC Level-1 Upgrades
4x Os-con SP capacitors for DSD1792 DAC current bias and digital de-coupling. 6x Gold plated, Beryllium Copper 8-pin sockets for post DAC current-to-voltage converter & filter stage. 2x LM4562 op-amps to replace NE5532 for current-to-voltage converter stage. 4x OPA2604 op-amps to replace NE5532 for analogue filter stage. 4x Sanyo OS-CON capacitors for +/-15V analogue supply rails. 4x Panasonic FC capacitors for Tri-vista triode tube de-coupling. 1x Sontech SFRT-AL resonance control panel for lid.
Tri-Vista 21 DAC Level-2 Upgrades.
4x Os-con SP capacitors for DSD1792 DAC current bias and digital de-coupling. 6x Gold plated, Beryllium Copper 8-pin sockets for post DAC current-to-voltage converter & filter stage. 2x LM49720 op-amps to replace NE5532 for current-to-voltage converter stage. 4x OPA2604 op-amps to replace NE5532 for analogue filter stage. 4x Sanyo OS-CON capacitors for +/-15V analogue supply rails. 4x Panasonic FC capacitors for Tri-vista triode tube de-coupling. 1x Invisus series 2 (PPR2) for 3.3V analogue power supply regulation. 2x Invisus series 2 (NPR2/PPR2) for +/- 15V analogue power supply regulation. 4x OS-CON SP capacitors for voltage regulator input & output bypassing. 4x OS-CON SP capacitors for digital circuitry de-coupling. 2x Rubycon ZA/ZL capacitors for regulator bypassing. 1x Sontech SFRT-AL resonance control panel for lid.
Tri-Vista 21 DAC Level-3 Upgrades.
4x Os-con SP capacitors for DSD1792 DAC current bias and digital de-coupling. 6x Gold plated, Beryllium Copper 8-pin sockets for post DAC current-to-voltage converter & filter stage. 2x LME49720 op-amps to replace NE5532 for current-to-voltage converter stage. 4x AD825 op-amps on Brown Dog adapters to replace NE5532 for analogue filter stage. 4x Sanyo OS-CON capacitors for +/-15V analogue supply rails. 4x Panasonic FC capacitors for Tri-vista triode tube de-coupling. 1x Invisus series 2 (PPR2) for 3.3V analogue power supply regulation. 1x Invisus series 2 (PPR2) for 5.0V digital power supply regulation. 2x Invisus series 2 (NPR2/PPR2) for +/- 15V analogue power supply regulation. 1x Bybee Slipstream purifier for digital input. 4x OS-CON SP capacitors for voltage regulator input & output bypassing. 4x OS-CON SP capacitors for digital circuitry de-coupling. 2x Black Gate NX Hi-Q for DAC decoupling. 2x Rubycon ZA/ZL capacitors for regulator bypassing. 1x Sontech SFRT-AL resonance control panel for lid.
How does it Sound?
Even with a modest Sony CD player as a transport the upgraded Tri-Vista takes incredible strides forward in sound quality; partner it with a high performance CD transport like the Teac P30 or Sony CDP-R1 and it is difficult to comprehend the level of improvements.
Where to start?? Instantly you are aware of a lower noise floor, a silence between notes that is eerily atmospheric. Every note is cleaner, crisper clearer with a hint of digital glare, hardening or insipidness. The sound is so much more ‘analogue’ that you are detached from the fact that you are actually playing compact disc. Every inner detail and nuance is presented, shift in tempo felt, emotive clues, the sound has a charismatic quality considered absent with CD; the music is enthralling.
For existing owners of the DAC 21 then the step on to this upgrade path should be without reservation, if you do not yet own a DAC 21 seeking one out is fiercely recommended, 1299 left and counting.
