The Atlantis Reference DAC and Server offer several user-adjustable parameters to contour the sound to your system and your listening preference. I would like to start a discussion on this to offer a greater understanding of the sonic effect each one of these offers. I will offer my experience based on the systems I have set up for various dealers, clients, and shows. I look forward to anyone else offering their perspective as well. I understand this has been written about in reviews, but I am curious to hear other peoples' experience regarding these settings.
While this might be an obvious statement, I would recommend adjusting these settings only after a system is completely set up - that is, speakers are positioned and all equipment is shelved/housed where it will stay. As many of you have experienced, when you get to a certain level of performance, anything you do to a system changes it.
The Atlantis Reference DAC has two parameters to consider: output voltage and impedance. Each of these offer the ability to tune the DAC to your system without making any changes to the actual signal. Output voltage not only changes the output, or 'volume' of the analog signal, but I have found it affects impact and rhythm. 4V output is has the most 'slam' and in a system with an overall softer sound, can be a nice balance. As you move to 2V and 1V, some of the percussiveness of 4V is reduced, but in exchange the sound becomes more subtle and nuanced. I find that, in most systems, I use 2V as a balance between these points. The impedance changes the electrical impedance of the output signal, which is a dynamic relationship between the DAC and the connected preamplifier or other device. While it may seem most logical to consider the impedance of the input device and try to match the DAC to it, I haven't found this to be the optimal solution. At default, the DAC is set to 0, which offers a general level of performance. Moving the impedance setting across its range creates a sliding scale between pacing and timing, and fluidity and 'smoothness' or flow. I find it to be more like a see-saw with a balance point somewhere along the scale. The lower the impedance, the more pace and timing the music has. Higher impedances flow more and sound more ethereal. I typically start at 0, and listen to each setting one at at time. It does take a minute for the DAC to 'settle in' to the new impedance since it is switching in a new circuit, but the differences are apparent. I keep moving up the scale until I find a tipping point - that is, where I feel the timing has given way to more fluidity. This balance is personal, though when I demonstrate this feature to a group of people, most usually agree on one setting sounding better than the rest. When connected to a preamp, the impedance is usually in the 7s or 8s range; when connecting to a higher impedance device such as an amplifier, the impedance is typically near the top end of the range.
The Atlantis Reference Server has a feature called Digital Waveform Control, or DWC. DWC was developed to correct anomalies in the digital signal which occur naturally as it moves across traces and wires (a normal occurrence in electrical circuits). What starts as a perfect square wave (which is what all digital signals are) doesn't end up as one. DWC is designed to correct the waveform while maintaining a bit-perfect signal. While some might suggest that ‘bits are bits’ and that this should have no appreciable effect on sound, consider waveform anomalies in the same sense as jitter. From a theoretical perspective, jitter should not matter - but we know that it eventually translates into the analog domain. We have found that similar mechanisms with the waveform geometry affect sound, hence the implementation of DWC. There are three adjustable parameters available for both the optical fiber and USB connections. The first parameter is speed; this affects the rise time of the square wave. A perfect square wave has a 90 degree vertical rise to the maximum value (the upper, horizontal part of the square wave), but the verticality of this is affected across a circuit. The speed corrects the rise to make it closer to the original signal. Sonically it provides more punctuation in attack and also a sense of transparency to the sound as it is increased. The next parameter is input gain which affects the plateau of the waveform. Input gain changes the presence and to a lesser extent, texture of the sound. Output gain controls the back propagation from the DAC to the server as it is an asynchronous design. Adjusting the output gain changes the body and weight of the sound.
As I mentioned, much of this is personal and system dependent. Try adjusting these parameters and let us know what your findings are.
While this might be an obvious statement, I would recommend adjusting these settings only after a system is completely set up - that is, speakers are positioned and all equipment is shelved/housed where it will stay. As many of you have experienced, when you get to a certain level of performance, anything you do to a system changes it.
The Atlantis Reference DAC has two parameters to consider: output voltage and impedance. Each of these offer the ability to tune the DAC to your system without making any changes to the actual signal. Output voltage not only changes the output, or 'volume' of the analog signal, but I have found it affects impact and rhythm. 4V output is has the most 'slam' and in a system with an overall softer sound, can be a nice balance. As you move to 2V and 1V, some of the percussiveness of 4V is reduced, but in exchange the sound becomes more subtle and nuanced. I find that, in most systems, I use 2V as a balance between these points. The impedance changes the electrical impedance of the output signal, which is a dynamic relationship between the DAC and the connected preamplifier or other device. While it may seem most logical to consider the impedance of the input device and try to match the DAC to it, I haven't found this to be the optimal solution. At default, the DAC is set to 0, which offers a general level of performance. Moving the impedance setting across its range creates a sliding scale between pacing and timing, and fluidity and 'smoothness' or flow. I find it to be more like a see-saw with a balance point somewhere along the scale. The lower the impedance, the more pace and timing the music has. Higher impedances flow more and sound more ethereal. I typically start at 0, and listen to each setting one at at time. It does take a minute for the DAC to 'settle in' to the new impedance since it is switching in a new circuit, but the differences are apparent. I keep moving up the scale until I find a tipping point - that is, where I feel the timing has given way to more fluidity. This balance is personal, though when I demonstrate this feature to a group of people, most usually agree on one setting sounding better than the rest. When connected to a preamp, the impedance is usually in the 7s or 8s range; when connecting to a higher impedance device such as an amplifier, the impedance is typically near the top end of the range.
The Atlantis Reference Server has a feature called Digital Waveform Control, or DWC. DWC was developed to correct anomalies in the digital signal which occur naturally as it moves across traces and wires (a normal occurrence in electrical circuits). What starts as a perfect square wave (which is what all digital signals are) doesn't end up as one. DWC is designed to correct the waveform while maintaining a bit-perfect signal. While some might suggest that ‘bits are bits’ and that this should have no appreciable effect on sound, consider waveform anomalies in the same sense as jitter. From a theoretical perspective, jitter should not matter - but we know that it eventually translates into the analog domain. We have found that similar mechanisms with the waveform geometry affect sound, hence the implementation of DWC. There are three adjustable parameters available for both the optical fiber and USB connections. The first parameter is speed; this affects the rise time of the square wave. A perfect square wave has a 90 degree vertical rise to the maximum value (the upper, horizontal part of the square wave), but the verticality of this is affected across a circuit. The speed corrects the rise to make it closer to the original signal. Sonically it provides more punctuation in attack and also a sense of transparency to the sound as it is increased. The next parameter is input gain which affects the plateau of the waveform. Input gain changes the presence and to a lesser extent, texture of the sound. Output gain controls the back propagation from the DAC to the server as it is an asynchronous design. Adjusting the output gain changes the body and weight of the sound.
As I mentioned, much of this is personal and system dependent. Try adjusting these parameters and let us know what your findings are.
