Here are some thoughts regarding the Vega Sound Processor from the designer.
l About the burn-in period
I don’t quite believe in the sound change after ‘burn-in’ for electronics, especially for passive components such as cable. Such kind of sound quality change is totally subjective and purely psychoacoustics (I trust instrument first) as the human ear needs some time to accept new sound, that’s why most people feel the machine sounds smooth after a period of use rather than the feeling of better treble extension. However, I do think the capacitors inside the machine require time to for re-activation through charging and discharging for a period of time without use, so please keep the unit in operation for roughly 48 hours to re-activate the components.
l About the warm-up
VEGA requires a warm-up to achieve best performance for two reasons; First, the Femto-grade clock needs a long time to become stable, like the crystal inside a GPS and communication station. It requires at least one hour powered-on to meet specification. Second, with the Class-A output module, the bias current will reach its correct value when in thermal balance, this requires about one hour to heat-up. One interesting measure is the THD on XLR and USB port jitter performance when the machine is completely cold, and then running for 3 hours. I believe you will see a measureable THD difference when the XLR output is driving heavy load (below 600 ohm); the jitter performance will also be different slightly.
To keep the unit at its best performance, we have designed a function named ‘SLEEP’ (enabled by default). By setting the unit in Sleep status, the clock and analog circuit remain powered on. I suggest using the sleep function during daily play so VEGA will sound best any time you’re ready for a listening session.
l Special care when using USB input
VEGA supports all PCM format from 44.1K to 384K as well as DSD64 and DSD128. But, you may experience trouble locking to 384K sampling rate when the unit is totally cold. This is due to the Femto clock not up to its optimal working temperature. Please allow a few minutes for initial warm-up and it will work perfectly.
To playback DSD64 and DSD128 files though DoP protocol, the host computer should be optimized and the hardware should not be too old or there may be drop off during playback. The actual drop off may be heard as a few seconds of white noise starting from low volume to full scale and going down again. I would suggest using the latest version of Audirvana with a MAC computer and J.River or HQPlayer (with better sound quality) under a Windows OS.
VEGA is more sensitive to the host computer than other USB DAC’s because of the Femto clock. We are optimizing and upgrading the internal firmware for the perfect balance of performance and wider server compatibility.
l Key feature #1: Flexible Filter Mode
The Flexible Filter Mode is the most important software feature of VEGA. There are six groups of filters inside our processor, four for PCM and two for DSD. Each PCM filter mode contains 4 different filters optimized for different group of sampling rate: 44.1k and 48k are within one group, 88.2K and 96K for another group. By using this method, the performance for each sampling rate is maximized, that’s one main reason VEGA sounds so good. I would greatly appreciate it if you can measure the frequency response of different sampling rates under each filter mode, showing the result in a chart and explain to the reader.
For more information (including technical detail) of the Flexible Filter Mode, please read the white paper I am enclosing:
l Key feature #2: Manual Femto Master Clock precision (for pro-user only)
The Femto Master Clock inside VEGA is controlled automatically to optimize lock-in ability and jitter performance, but we also offer advanced users the option to manually setting the clock lock-in parameters. After a one-hour warm-up, there will be additional clock options under ‘SYSTEM’>’CLOCK’ menu, they are ‘EXACT’ and ‘FINE’. By setting one of these two options, the control circuit will force PLL’s bandwidth to a very narrow range for maximum jitter performance. I do hear significant improvement on EXACT option compared to AUTO on specific sound tracks (such as a well recorded classical piano solo), but not all kinds of music can benefit from them.
Keep in mind, the EXACT and FINE options will not work on an older processor, or one with a noisy power supply computer (not just hardware, but mostly dependent on software environment). I have tested many computers for the clock options. The best result is comes from a Windows PC, specially made for audio playback: with a kernel, and disabling unused applications and services. I can play all PCM and DSD format under EXACT mode without issues on such a computer. I have tried the clock options on two Mac computers, one is a vintage mid-2008 Macbook and the other is a mid-2012 Mac Mini. The first was only OK with EXACT mode for 44.1K and 48K sampling rate and totally not possible for higher PCM as well as DSD. The Mac mini is fine up to 176.4K and DSD64 but not for DSD128 and 192K PCM. The EXACT and FINE clock options will be disabled when you play 352.8k or 384k PCM. Whenever you set the clock to EXACT or FINE, it will only works under AUTO mode as I have not found a computer today that can work with these two options.
I would suggest you to try out the best setting on your own system if you wish (purely for fun). We only recommend people use AUTO option when we promote our product and consider these two options as ‘playable’ function for professional users.
l About the XLR and RCA outputs
The XLR and RCA output channels are individualy buffered, but only XLR through our ORFEO Class-A module. Though both output ports’ sound quality are equally the same, I would highly recommend using the XLR if possible. Both ports are designed to drive 600ohm load without compromising the performance, but the XLR can work even lower, to 300ohm and less.
l Attention when you want to remove the cover to take photo
The top cover has a single installation direction (without any indication); if you re-install the wrong direction, the edge will be very sharp and may injure your finger, so please make sure to mark the direction when you move it.
Finally, I hope our VEGA processor will bring you much joy during your review session. If you have any question on anything, please just drop me an email at firstname.lastname@example.org
25th September 2013