Chevron Audio

Our Paradox Digital to Analog Converter is the result of many 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/music server pc via SPDIF.

The latest versions (August 2011) include improved circuit including a better spdif receiver chip & new improved second stage jitter reduction circuit.

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. There are many NOS (non over sampling) DAC’s available which don’t use digital filtering and therefore present the raw digital data (typically 16 bit / 44K sample rate) to the DAC chip(s). With our design we generate 8 versions of the digital data each with a precisely controlled time delay. Each of these 8 data signals drives a separate DAC chip, the audio output from the 8 DAC chips is then summed together. This results in linear interpolation of the data, giving a closer approximation of an analogue signal. It does not add information though, the benefit is that the low pass filtering that happens after the DAC chips (by equipment or your ears) is easier.

The Paradox DAC is called NDF (No Digital Filter) to differentiate if from NOS.

The Paradox NDF DAC has 8 TDA1543 multibit dac chips, not the best you can buy from a technical measurement view point but they have a good reputation for sound quality and uniquely can generate a useable output signal without the need for a voltage amplification stage. With the 8 dac chips effectively working in parallel we are able to generate a low impedance output with just a single i/v resistor.

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. New to the NDF DAC’s is a second stage jitter reduction circuit using a Crystal Controlled master clock oscillator to clean up the signals before feeding to the dac chips. The jitter reduction circuit also works to improve SPDIF input data. There will always be differences in sound quality between digital sources but our jitter reduction techniques have made the difference very small. Whether you use a low cost netbook pc, cd transport, custom pc music server or £1000+ cd transport you will get great sound quality from the Paradox DAC.

The DAC works from external power supplies and multiple fast high bandwidth voltage regulators combined with low impedance capacitors to give low noise at audio & radio frequencies. Also master clock power supplies are extremely low noise.

The DAC accepts 44K or 48K data which is automatically detected & displayed. Data is 16 bit (24 bit data is accepted but the 8 least significant bits are ignored).

Inputs - USB type B, 2 - SPDIF coax 75R and Toslink optical. One SPDIF input can be factory set to Balanced 110R input.

Outputs - RCA unbalanced stereo.

Contols - Input selection - selected input is displayed on the 7 segment LED display.

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

       With Deluxe version you can select equalised or non-equalised frequency response.

Paradox NDF DAC Price - £610. It can be upgraded to Deluxe version.

Paradox NDF DAC Deluxe same as the standard DAC but with a custom built external power supply. Also included in this power supply are additional active ripple reduction circuits which allow the voltage regulators in the DAC to work more effectively. Also with this version is a non opamp active output stage which is user selectable to also act as an equaliser stage. The equaliser corrects for the high audio frequency roll off inherent with NDF (and NOS) techniques. 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