MASDAC
20 BIT DIGITAL TO ANALOGUE CONVERTER
The MASDAC converts the datastream from today's finest digital transports into a musical experience with detail, speed, accuracy.transparency, authority and sheer emotion rivalling state-of-the-art analogue playback equipment.
What the critics say...
"The first perception of the quality of the MASDAC 2 is the enormous expanse of the sound stage that it gives to the music. Perhaps a normal person would not notice it. With the METAXAS we achieve to open up substantially the physical space where the musician and singers perform which recreates the illusion of reality better than other DACs which may be precise but 'cold sounding'.
The level of timbre of the MAS is superior to my D2 (which is already excellent) by the time it transcribes the middle to high spectrum and extreme low frequencies . Low frequencies combine warmness and precision probably due to UltraAnalog . On the other hand the excellent separation between channels and the overall cleanliness perceived during the performance of our Australian guest justifies the importance of over designed sophisticated power supplies (which was intentionally over designed) in such an important processor .The more bits a processor has, the more demanding the power supply needs to be .
Regarding the reproduction of voices, either individual or group, the MASDAC 2 presents irreproachable performance , articulating perfectly ,even with the most soft and conflicted chorals . In fact it is definitive and natural with credibility.
The MADAC 2 is like most of the Metaxas components, the device is distinctive which speaks for itself because the seriousness that reveals in its conception as well as the freshness exhibited for the musical performance. On top of this we add the price is quite reasonable and fully justifiable you can easily reach the conclusion that Kostas Metaxas has come to create one of the few DA processors that deserve to be defined with the suggestive name of "affordable references"."
Salvador Dangla ALTA FIDELIDAD Spain.
"The converter (MASDAC) was a real surprise. Its sound is full and decidely pleasant, extremely natural, robust without being hard, detailed without the slightest trace of graininess, and definitely rich and warm".
Mario Berlinguer SUONO , Italy.
" Whatever complex, state-of-the-art technology has been embodied in the PHOS/MASDAC combination, the sound is anything but complex. It's a simple, untainted stream of highly naturalistic music with holistic, realistic instrumental timres and convincing spatial recreations that you just can't get with affordable integrated players. Most noticeable was the naturalness of the attack of notes: especially piano, bass and percussion. Bass solidity was stupendous, with ambiguities of pitch only evident on poorly recored material. Almost as striking was the way the PHOS/MASDAC system handles the subtle decay of notes-especially bass notes, which often die suddenly rather than fade away naturally. Place into this illusory enviroment a p;erfectly articulated human voice and you have a private audience with your heroes with such an uncanny sense of physical presence that politeness makes you hesitate to talk or shift in your seat".
Greg Borrowman AUSTRALIAN HI FI, Australia.
MASDAC "The digital highway"
The incoming signal via RCA, BNC or OPTO LINK is buffered by a Linear Technologies high speed input comparator with a 2 nanoseconds response time corresponding to a bandwidth of over 300 MHz. This high speed buffer defines with great precision the edge of the digital data stream and assists in the minimisation of 'jitter'.
By using the LT input buffer, we are also able to incorporate the professional industry standard clock (phase locked loop), 'APOGEE' - designed and produced in Santa Monica, USA by Australian- Bruce Jackson. This clock reduces jitter to negligible values in the PICOSECOND range - within the residual noise of the most advanced test equipment. The first version produced in November 1991, saw its first world application in an audiophile standard DAC in our MAS DAC.
To programme the APOGEE and NPC 8X over sampling filter, we use the XLINX 64,000 gate array with a 4 nanoseconds response time driven by our unique programmable 8 pin EPROM memory. This allows us to update our programming of the circuits at any time ensuring that the MAS DAC is future proof.
The 20 bit DAC from Ultra Analog is already regarded as an industry standard. We have asked designer Richard Powers of Ultra Analog tp customise his DAC to our standards by allowing us to substitute our discrete circuits for the internal TL072 and NE5534 integrated circuits.
The combination of APOGEE and ULTRA-ANALOG in our unique topology allows us to extract for the first time, the full 20 Bit potential resolution of the Data stream (120 dB dynamic range) less the 1 Bit error of 6 dB which is lost through 'uncertainty'.
The converted signal then encounters our proprietory output buffers which feature ultra high impedance F.E.T. complementary devices driving a push-pull, high current bipolar transistor output pair. A third order phase linear Bessel filter using 2% tolerance polystyrene capacitors gently rolls off the frequency response beyond 30 kHz.
In the important aspect of power supply design, the MAS DAC uses essentially two types of regulators: our proprietary MAS discrete capacitorless high speed tracking regulators for the Ultra Analog and dual mono output stage buffers and out unique discrete Super Low Noise digital regulators for 5 volt supply to the Apogee, NPC, XILINX and Linear Technology. In fact, every individual stage in our MAS DAC is furnished with its own discrete regulator circuit.
Then we go one step further by having the supply lines to each regulator totally separated all the way back to the external DC power supply which uses our proprietary balanced transformers.
In this way, digital and analogue crosstalk is virtually eliminated and power supply noises are isolated and kept away from the low level signal.
For the purist who wants to go one step further, we can offer our unique "MAINS ISOLATED POWER SUPPLY" which totally isolates the AC mains from the electronic circuits
..............................................
BASIC SERVICING INFORMATION
'LOCKING CIRCUIT'
To achieve the lowest possible jitter, there is a 18 turn trim control located beside the purple 'APOGEE' low jitter clock which can be finely adjusted (less than 1 turn in either direction) if there is a digital noise when connected to your transport (RV1).
NON OPERATION
Check that the 'sacrificial' resistors R191, 189, 190, 92, 93, 97, 98, 99 are not burnt and therefore not supplying voltage and current to the circuit elements.
1. DIGITAL CIRCUITS
a. Input Comparator LT1016 - Input Voltages Q76 ~ - 12V, Q74 ~ - 16 - 20V
Output Voltages of Regulator U1 Pin 1 = +5.5V, Pin 4 = -5.5V
b. Apogee Clock +15V Q23 ~ +25 -30 VDC Input Volatage
+14.7 to 15.2V Output Voltage (at R62) +5V
Q33 (2219A) ~ +25 V input, R167 +5.1V
c. XLinks/Eprom Q24 Input Voltage ~ +25 to 30V
Output Voltage at R156 ~ +5.1V
d. NPC Chip Q72 = Input Voltage ~ +25V
Output Voltage @ R173 = +5.1Volts
e. Ultra Analog +/-15V for DAC
Input Voltages Q50 = +28V, Q5 = -28V
Output Voltages (measured at "plated through holes' between Q50 and Q5)
= +15V and -15V (near Q5) +5V for digital: Q31 = ~+25V
Output Voltage measured at R126 = +5.1V
