Update 28.9.09 - Now available with 8 times data interpolation for improved resolution and reproduction of low level detail. This is achieved by driving the 8 dac chips with the same data but at precise time differences. When the output of the DAC chips are summed together the result is an increase of data bit depth from 16 to 19 and increase of sample rate from for example 44.1KHz to 176.8 KHz. This is achieved without digital filtering which is the main reason upsampling or oversampling techniques result in unsatisfying sound quality. These versions of our DAC are designated ‘8i’.

Our Paradox Digital to Analog Converter is the result of 2 years development to evaluate both digital filter free dac design & replay of music stored on a computer. Whilst neither of these techniques are new we believe our implementation of them has resulted in a DAC capable of a very musically involving reproduction from a computer via USB or CD Transport/Player via SPDIF.

Key to the design is the elimination of digital filtering used in most CD systems, as part of the over sampling or up sampling process. The effect of digital filtering is to blur the sound such that it sounds somewhat bland and lacking in dynamics. This is the main reason that reproduction of music via LP records has retained a large following.

The reason for digital filtering is to remove the Alias signals that occur at ultrasonic frequencies as a direct result of the analogue to digital recording process. For example with (redbook) CD the conversion is done 44,000 times per second (44KHz) which allows information to be recorded up to 22KHz but when reproduced there is also a mirror image of the recorded information from 22KHz to 44KHz. This sounds like a bad thing but actually human hearing does not extend beyond 22KHz and it is able to effectively filter out the unwanted information. There is also the risk that the 22KHz-44KHz signals will adversely affect reproduction equipment indirectly leading to sound degradation but in practice this is extremely rare.

The Paradox DAC design uses 16 bit multibit DAC chips without over or up sampling so that the data is not changed in any way. We do however improve the timing of the data to reduce jitter. Jitter can also degrade sound quality. To reduce jitter we have developed our own reclocking circuitry powered by out ChronoClock ultra low noise power supply. This process reduces jitter nearly as low as can be achieved with crystal oscillators but allows different sample rate data to be received. On listening tests there was no benefit in using a crystal oscillator in our design. The DAC can receive any data rate up to 100KHz.

Actually we use 8 dac chips running in parallel to reduce noise and distortion, subjectively this also gives a more dynamic sound. The dac chips output a current signal is passively converted to a voltage signal, we found this sounded better than active conversion. The voltage signal is however buffered by an active circuit to provide a low output impedance signal capable of driving any interconnect cables.

To receive music from a computer we have developed a USB interface. We found that jitter levels were much too high from available circuits and have adapted them to get jitter low enough. Firstly we developed low noise power supplies to power the USB interface via the DAC rather than via the computer. Ground isolation is also used to prevent possible ground loop noise. Finally we developed a jitter reduction circuit (mentioned earlier) to clean up the signals before feeding to the dac chips. The jitter reduction circuit also works to improve SPDIF input data. The resulting sound quality via USB or SPDIF is comparable. In general terms a £200 laptop will be very slightly better than a £200 CD transport as the input source to the Paradox DAC. However a top quality CD tansport may be slightly better than using USB input. Mainly its down to whether you like to use a computer or prefer conventional disc handling.

Multiple torroidal transformers power the Paradox DAC, there are 5 isolated power supplies to minimise undesirable interaction between circuits. All voltage regulators are fast high bandwidth types combined with low impedance capacitors to give low noise at audio & Radio frequencies. As mentioned earlier the master clock is powered by our ultra low noise ChronoClock supply.

Inputs - USB type B, SPDIF coax 75R and Toslink optical. Balanced input is optional.

Outputs - RCA unbalanced stereo.

Contols - Phase can be inverted 180 deg. Some recording give a better sound-stage with phase inverted.

The Paradox DAC is available in 4 versions, its possible to upgrade to the better versions at a later date.

Standard Paradox DAC uses a high performance opamp output stage. Price - £520.

Paradox 8i DAC adds 8 times interpolation. Price - £610.

Paradox 8i Plus DAC uses a non opamp output stage powered by Hypex regulators. Price - £750.

Paradox 8i DAC Deluxe same as Plus DAC but with an external power supply. This arrangement isolates any electrical noise radiated by the transformers or rectifiers from the DAC circuits. Also included in this power supply are additional active ripple reduction circuits which allow the voltage regulators in the DAC to work more effectively. Price £970.

Customer Feedback:-

“Many thanks, Colin, for the DAC: it is astounding. We compared it to our ModWright-ed Perpetual Technologies DAC and upsampler and thought it might come close to them. We were astounded with the sound of the Chevron DAC which was better in all aspects that the Perpetual Technologies units. It reveals more detail, seems to have no digital glare at all (!), and reveals ‘texture’ in sounds in a way I have not heard CD do. It does the usual hifi soundstage and depth stuff extremely well too. We are absolutely delighted with our unit and consider it a bargain, especially when compared with the cost of the Perpetual Technologies units

David, Derbyshire”
 

Hi Colin

Just had a five hr marathon listening session with the dac. I have
played a lot of tunes I am very familiar with through both usb and
toslink and I am very pleased with the results, very "undigital", lots
of power and detail but not fatiguing, its also very dynamic sounding,

Regards
Andy