Telos

Digital


CD Players


Ypsilon: CDT-100

CD Player/Transport - Redbook

CDT -100 is YPSILON’s top loader CD Player/Transport. The transport’s primal objective is to retrieve data from the cd-disc with as much accuracy as possible. The laser head is extremely sensitive to vibrations so CDT-100 provides a rigid and resonant free construction.

The mechanism is mechanically modified and assembled within a massive construction of a sandwich of thick stainless steel and aluminum plates. In this way, the traditional box shaped chassis is avoided and along with that the associated resonance problems are greatly reduced.

The CDT 100 is a stand-alone product which will outperform many highly regarded separate Transport and Dac combinations. It carries a Spdif output so it can be linked to any outboard DAC or via a special 5 pin output to the Ypsilon DAC-100.

CDT-100 contains a non-oversampling DAC , with multi-bit Burr Brown DAC chips. Power supply regulation for the DAC section is with shunt regulators.

The current output of the DAC chips is level shifted in the current domain and through an in house manufactured c-core transformer becomes a voltage signal directly at the WBT NextGen output connectors. No feedback is used and only one low noise S-E class A J-FET is involved in the signal path. Purity and transparency is the result,so when inserted in a SET system then one can fully appreciate the full sonic glory.

CDT-100 provides 3 outputs.

  • One SPDIF 75 Ω next gen connector.
  • One pair of RCA , analog connections for use as a CD player.
  • One Neutric 5-pin analog current output for use with DAC-100.

The signal flow within the CDT-100 (while being used as a CD player) is as follows:

·       Raw digital data is read by the Phillips CD-Pro mechanism and this data is transferred to the onboard DAC via an I2S connection.

·       The digital data is processed by the Burr Brown PCM1704 DAC chip and is outputted as an analogue current source.

·       This analogue current then flows to a pair of high quality C-core transformers which act as an I/V stage and convert the current to voltage.

·       This voltage is then sent to an analogue output stage where it is amplified by a single JFET transistor per channel and then sent to the RCA output connectors.

The signal flow within the CDT-100 (while being used as a CD transport) is as follows:

1.      Digital out as S/PDIF:

·       Raw digital data is read by the Phillips CD-Pro mechanism and this data converted to S/PDIF format & directly transferred from the S/PDIF output of the Phillips mechanism to the S/PDIF RCA output. This allows you to use a broad range of external DAC devices from various manufacturers.

2.      Analog Current output on 5 pin connector:

·       Raw digital data is read by the Phillips CD-Pro mechanism and this data is transferred to the DAC board via an I2S connection.

·       The digital data is processed by the Burr Brown PCM1704 DAC chip and is outputted as an analogue current source.

·       This analogue current then bypasses the internal analogue stage of the CDT-100 and is sent directly to the 5 pin analog current output connector on the CDT-100 so it can then be connected to the DAC-100.

The 5-pin output when used with DAC-100 is a way of taking the performance even further. Transmitting audio in the digital domain (SPDIF), even discrete such as I2S format, has its imperfections and adds a certain character to the sound. The DAC-100 removes these imperfections.

SPECIFICATIONS CDT-100 CD TRANSPORT

DIGITAL OUTPUT SPDIF(75 ohm) RCA
ANALOGUE OUTPUT RCA
ANALOGUE CURRENT OUTPUT YPSILON 5 pin CONNECTOR
OUTPUT VOLTAGE 2,5 Vrms
OUTPUT IMPEDANCE 2,5 Kohm
DAC chip 24bit Non-oversampling
POWER CONSUMPTION Typically 20W
DIMENSIONS 400x120x400  (WxHxD)mm
WEIGHT 20 Kgr

The CDT100 is a CD-Transport/Player 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. The CD-Pro needs some modification to remove resonating cast metal parts with springs.

Ypsilon remove all the cast parts and springs and mount the CD-Pro 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 DAC100 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 Ypsilon preferred I2S connection and the best would be to have the DAC chips right next to the mechanism with very short wires. 

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. 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 modern heavily promoted 32-bit DAC chips are still 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.

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 allowed Ypsilon to build a serious analog stage so that the CDT100 transport can be used as a standalone player that would outperform the competition.

This analog stage is with a single-ended low noise j-fet transformer coupled at the output with Ypsilons special amorphous C-core 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 CDT100 into a system with quality CD collections it is 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.