Telos

Digital


DACs


Ypsilon: DAC-100

24-Bit Multi-bit DAC for Ypsilon CDT-100

DAC 100 is a 24bit (Multi-bit) 192Khz D to A converter. It is a non - oversampling, no upsampling design with multi - bit dac chips. The carefully designed power supply is with shunt regulators. I / V conversion is done by a specially designed, in-house built, transformer. Τhe analog stage uses single-ended class A transformer coupled triodes with valve rectification and choke regulation.

The valves are the high mu, high transconductance, low noise SIEMENS C3g NOS tubes.

There are two available inputs:

  • SPDIF coaxial 75 Ω with WBT Nextgen connector. This input can be used with CDT - 100 or other high quality transports.
  • One Neutric 5 - pin analog current input.

When the Neutric 5 Pin input is used with the Ypsilon CDT-100 the digital part of the CDT-100 is disabled and powered off. Only the analog section is used.

With the matching CDT-100 we strongly recommend the use of this input for optimum performance.

The conclusion has been reached that by using this 5-pin connector the signal is transferred to the analogue section of the DAC-100 at an absolute optimum sonic capacity avoiding all the limitations of digital interfacing.

All transformers are designed and built in-house using the best available materials and are wound with sophisticated techniques for a totally transparent sound.

The transformers are of enormous size in order to achieve the absolute performance we seek.

SPECIFICATIONS DAC-100 D/A CONVERTER

DIGITAL INPUTS SPDIF(75 ohm) RCA
ANALOGUE CURRENT INPUT YPSILON 5 Pin Connector
ANALOG OUTPUTS RCA unbalanced
XLR unbalanced(pin1,3grounded)
RESOLUTION 24 bit(multi bit converter) 192khz
maximum sampling rate
NOMINAL OUTPUT 2,8V rms
POWER CONSUMPTION Typically 40 W
DIMENSIONS 400x180x400  (WxHxD)mm
WEIGHT 25 Kgr

Musically this DAC is unbeatable. Compared directly to the competition in even technically much higher specified units, the Ypsilon DAC100 still comes up trumps. Why?

Demetris Baklavas the designer explains "The CDT100 is a CD-Transport/player. We are using the Philips CD-Pro mechanism which we feel it’s still one of the best mechanisms for Red Book CD playback because it uses one of the best CD decoder chips from Philips. It needs some modification though. It’s mounted in a resonating cast metal part with springs.

We remove all that and mount the module in machined stainless steel base. The improvement in rigidity is enormous and it shows in the sound difference. From that point it makes sense not to install it in an outer box but make it a solid and resonant free construction. So all the construction of the CDT100 is an extension to the mechanism. The added mass with the sandwich assembly moves the vibration and resonance control in the feet of the CDT100 so attention must be paid to the rack that is going to be installed. The type of rack will alter the sound character. A Minus-K would be the perfect partner for the CDT100.

The maximum performance can be attained when the interface with the DAC is done with the I2s output of the cd-mechanism. This is a discrete digital data connection meaning that data bit, bit clock, L/R clock and master clock are not multiplexed in one signal as it is in SPDIF connection. SPDIF receivers  recover all four signals with PLL circuits. The SPDIF frequency is very high (Mhz) and even a slight filtering property of the SPDIF cable induces jitter and affects the performance of the receiver. Clearly SPDIF connection is not the highest possible interconnection that can be used (not to mention USB) and it wasn’t developed with absolute quality in mind.

That’s why ASRC (asynchronous sample rate converters) were developed to solve problems of SPDIF. They are using a local clock to re-clock the data at the receiver. The problem is that they up-upsample through oversampling in a higher frequency and then down sample in the clock frequency. This looks good on paper but sounds terrible because it produces other problems.

So in order to connect the cd-mechanism with the DAC chips we preferred I2s connection and the best would be to have the DAC chips right next to the mechanism with very short wires. 

The output of the DAC chips in current form is the ideal way to interface it with a serious analog stage. This we do by connecting the output of the DAC chips through 5-pin Neutric connectors with our DAC-100.The output of the DAC chips are connected to the analog stage of the DAC-100 making a cd-player in two boxes, one digital box and one analog box.

The power supplies in the CDT100 is with a custom made toroidal transformer operating in low flux. The power supply for the mechanism is just what it needs. Any overkill there doesn’t translate to improvements in sound quality. The power supply for the DAC chips is with Mundorf caps and only shunt regulation.

The D to A conversion is done with no oversampling or up-sampling. There are no digital filters used. That’s why the circuit is very simple. Ypsilon feel that digital filters that are done by oversampling in a DAC ( or decimation in A to D) are responsible for what we associate with “digital sound” in cd playback. Digital filters can be found in special chips or can be made with FPGA’s or even high power  DSP. When done with DSP could be better but the result is almost the same.

Older DAC chips were ladder DACS (R-2R). A high accuracy R-2R dac  is expensive and difficult to make because it needs trimming of the internal resistors. In the quest to find a simpler and cost effective way to build DAC's the industry started to produce one bit Sigma-Delta Σ-Δ modulator DACS. Even todays funcy 32 bit DAC chips are internally one bit .

These have internal oversampling blocks. R-2R dacs are no longer produced. Ypsilon found the three best ladder DACS were the 16-bit TDA1541 from Philips, AD1865 from Analog Devices and 24 bit PCM1704 from Burr Brown.

Ypsilon are using the Burr-Brown chip in non oversampling mode, meaning that it’s a 24-bit dac that accepts 16-bit signal in the CDT100. A walk in the park for the DAC100.

The sound produced by a non oversampling high quality multibit DAC chip cannot be matched in ‘analog like’ character with an oversampling DAC.

Since the DAC chips placed inside the transport are high quality it made sense to include a simple and “decent” analog stage so that the CDT100 transport can be used as a player for starters.

This analog stage is with a single-ended low noise j-fet transformer coupled at the output with our own C-core amorphous transformer.

When using our DAC 100 with the 5-pin connector the analog stage inside the CDT100 is disabled and substituted for the analog stage of the DAC100."

In summary if you put the combination of the CDT100 with the DAC100 together you finally get to hear "digital" as "analog". It is "scary good" in colloquial terms. For those with quality CD collections it is an imperative to audition this technology. A sensational answer to the conundrum of returning to owning LP's vs sticking with CD for serious golden-ears. For those with collections of both then finally being able to finish a listening session on digital source awaits.

 



Thrax: Maximinus DAC

DAC 32Bit

DAC with AES/EBU, USB

This is the original multibit DAC concept with the most sophisticated implementation and highest precision.
We based the solution on the best technology available and applied our knowledge and experience taking the design to the extreme.

Features:
• Multibit conversion
• 25 bit resolution
• 4 quadrant sign magnitude operation
• 8 inputs (6 +2 optional)
• Balanced outputs on RCA or XLR (selectable)
• Transformer output
• No I/V conversion or output buffers
• No filtering after dac
• Total galvanic isolation of internal circuits from outside world
• Operates at 32bit/384khz
• Internal clock generators
• Selectable recklocking
• Selectable upsampling
• Selection of 4 digital filters
• Firmware upgradable
• modular design for field upgrades
• 32/384 Asynchronous USB interface (option)
• Sealed solid aluminium enclosure

Maximinus uses a concept called R2R ladder. This is a resistor matrix that is switched for the various output levels outputting a fraction of an internal reference (much like a volume control).

In order to bring the performance of multibit DAC’s to new levels the only solution is to build them from discrete components as there are no off the shelf chips good enough.

This involves the selection of ultra precision resistors, thermally coupling them and building a very fast and sophisticated switching logic to control them. The result is an order of magnitude better performance than what is achievable by IC based solution.


To take advantage of the available resolution and bandwidth we had to implement a state of the art digital pre-processing. This is a suite of algorithms that would apply digital filtering and up sampling to the incoming data stream. After processing a 16bit 44.1kHz CD data stream it is converted to 32bit 352.8kHZ data fed directly to the DAC.

This greatly improves low-level resolution and the sense of space. The process is all user controllable and defeatable for purist and non-oversampling use.
Apart from taking the uncompromising approach of using discrete ladder technology we have taken exceptional care with the construction and operation of each circuit within the DAC.

To keep up with tech development we have 2 internal slots for options to be used when the time calls for it.

We use transformer or optical decoupling of all inputs, meaning that contaminated ground connection and other interfering signals don’t make it to the inside of the unit.
We have no output buffer or filter at the DAC output providing the cleanest possible output signal, just a transformer matching the impedance of the converter resistors to the outside world and isolating them from external influence.

We use completely separate power supplies for each block in the DAC: the Converters, Clock, DSP and Control logic all with floating ground planes and our unique constant current regulator technology.

Then the whole assembly is mounted in a solid aluminum case for vibration damping and EMI/RFI screening following the same construction concept as our preamplifiers.

It’s a different league from all currently available high end DAC’s hence the name of a Roman Emperor!

Specifcations:

• Inputs
- 2 x COAX (RCA) connectors. Limited to 384 kHz, 24 bit data
- 2 x AES/EBU (XLR) connectors
- 2 x TOSLINK (optic) connectors. This format has limited bandwidth
and works for maximum sample rates of 192 kHz
- 1 x USB (optional)

• Output
- 1 pair unbalanced RCA connectors
- 1 pair balanced XLR connectors
• Power supply ………………..............................................…….. 115 or 230 V
• Power consumption ………....................................................…….......... 30W
• Dimensions ……………….........................…….. WxDxH - 432x400x120 mm
• Weight ……………….....................................................................…….. 12Kg
• Finish …….....................................….. Black or Silver anodized aluminium

 

384Khz Ultra performance DAC with analog like performance. Crazy build quality and bass extension that goes lower than what we thought is possible.

Succeeds where a lot of lesser DAC's fail.

Amazing!