Tuesday, November 12, 2019

USB DAC Calyx part 1

mars 4, 2012 by · Leave a Comment 



The numbers are impressive on paper, but over time I’ve learned to take them with a grain of salt.
We need to go a little bit beyond appearances if we want to be sure of what we really have.

Top of Calyx box

As a preliminary step before listening, I asked our technical consultant, Eric Juaneda, what he thought of the design of this DAC. With his experience in designing and building this kind of device using proprietary circuitry, he is an expert in the field.

Part 1: Eric Juaneda

The front panel of the Calyx DAC is very discreet. There is a single indicator light which shows that the unit has properly locked on to the digital signal.

Front panel

Most of the controls are on the back panel.
The converter has USB and S/PDIF inputs. A switch selects one or the other. There are balanced and unbalanced outputs.

The USB input is built around an XMOS chip. XMOS is a RISC microprocessor design company based in Britain.

The data stream is asynchronous, in other words it’s the DAC’s clock, not the computer’s, which controls timing.

Question: Is this a good thing?

Answer: It means that jitter won’t be directly affected by the quality of the USB connection.

To control jitter, the chip relies on three quartz oscillators, one for the USB link, one for signals at multiples of 48 kHz (96 kHz, 192 kHz) and the other for signals at 44.1 kHz, 88.2 kHz and 176.4 kHz.

It’s a classic configuration but it ought to be effective.

Back panel

There is a fourth quartz oscillator used for digital-to-analog conversion.
All four run at different frequencies.
This generosity with quartz is the tradeoff involved in this kind of design.
The Calyx is one of the small number of USB converters able to handle 24-bit signals from 44.1 kHz to 192 kHz with both Windows and MacOS.

The board

The digital-to-analog converter circuit comes from ESS Technology. It’s a Sabre ES9018 whose eight channels are here used in a symmetrical stereo configuration. It uses its own quartz timing oscillator to reduce jitter from the S/PDIF link.
It’s a less effective solution than the one used for the USB connection.

You’ll have gathered that it’s not likely you’ll get the best from the Calyx via S/PDIF.

Detail of machined hole connectors

The output stages use the very common 5532 op amp. The circuit design is extremely compact and uses primarily surface-mount components.
Power is supplied by an external transformer or by the USB bus.
A small switch lets you choose between power sources: either the USB connection or the external one needed for S/PDIF. Overall sound quality will be closely linked to the precision and size of the power source, so we can expect differences in sound quality depending on the quality of the power supply used.

The manufacturer’s obvious intention is to demonstrate some particularly advanced technical features.
The USB and S/PDIF inputs accept 32-bit data, but I don’t feel I need to make much of this as it’s hard to see what use it can be in practice.

Inside the box

It’s hard not to notice the purely marketing value of this specification.

Does this panoply of technology really serve the music and the listener?

Only the listener can say.

The big surprise is the chassis.
It’s a magnificent aluminum box, cast or machined from a billet, dense and heavy for the size of the unit and it contrasts greatly with the squeezed dimensions of the electronics.

Alloy machined box

This aspect of its design is what will make the Calyx DAC play well in the market.
The mechanical integrity of a unit is responsible for 50% of its musical quality.
A good chassis doesn’t create the music but it allows the quality of the electronics to show itself.
Chassis, footers and racks are all points not to forget.
The product manual is succinct but provides the basics.

Whether you use Mac OS or Windows, don’t hesitate to ask your dealer how to set up your system to get the best from this converter.

Below, the bottom plate

Conclusion of Part 1

We have now heard the technician’s opinion based on his visual observation of the Calyx DAC.
The next step is to listen to it, and we’ll get back shortly with our impressions.

One point on the subject of the enclosure: I myself would say the chassis contributes about 30% of the sonics. The other 20% ( of the 50% Mr. Juaneda mentioned ) comes from the rack, the cabling and the power supply.

The packaging

I wasn’t impressed by the circuit as such, I expected something quite different, more complex and refined. Not a bit of it, the Calyx designers chose an academic, almost textbook approach, no doubt to avoid risks, which is not a bad idea in mass production when a single mistake can be expensive.
But at $1799, the unit had better play music.

The part 2 follow …


Charisma Audio

Manager : Bernard Li

Suite 86
4261, Highway 7
Markham, Ontario
Canada L3R 9W6
Telephone: (905) 470-0825
Fax: (905) 470-7966

E-mail: charisma@rogers.com

Web site : www.charismaaudio.com

Article by Marc Philip, independent publisher, all rights reserved, copyright 2012, text and photos are the property of the author and the magazine, under creative commons licence.

Have a nice day and happy listening !

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