Let me begin by saying that I firmly believe that there is no reason why digital audio can’t sound just as good or better than analog audio. While I certainly enjoy the smooth engaging sound of vinyl and also tape, I really appreciate the added benefits of having a library of digital files. However, I have too often experienced digital that sounds just a bit too, well, digital. You know what I mean.
For two years I have been striving to assemble the best music server, and the best DAC (within reason). But when I chose to thoroughly investigate the USB connection between those devices, I realized that the design of the USB link was paramount to achieving that analog flavor that I was after. So, I starting exploring the USB specification documents, and researching the science behind engineering a better USB cable.
During the development of this cable, I made comparisons to numerous other USB cables from different manufacturers and of different designs. Our USB cables are characterized by a very low noise floor, which gives the cable a very smooth and relaxed sound, while maintaining great detail and a controlled bass response. Other cables could be edgy or digital sounding, or lacking in bass, or emphasizing bass frequencies which tended to cause bloom.
Our cables are highly refined, clean and open sounding with a solid bass and good micro-detailing. The music sounds involving and engaging. It is not fatiguing, which is evident when music contains difficult to render instruments like flute, harmonica or violins. An open soundstage is evident with clear imaging and plenty of air and sustain.
For a little background on myself; I am a software engineer, and I’m an avid electronics hobbyist. I Build my own music servers, and have built my own DAC with various tweaks. I’ve also built tube amplifiers and linear power supplies. So it’s with this electronics background and an understanding of the digital realm that I pursued my experimentations with building a better USB cable.
As computer audiophiles, we’ve all heard the adage that bits are bits, so how could a wire that carries digital make any difference. When you hear the difference between USB cables, you soon realize that the digital cable has a significant involvement with the enjoyment of the music. Being curious, I asked how USB cable architecture can make so much difference. When it’s done right, a good USB cable can improve one’s enjoyment of the music.
Digital noise and jitter is prevalent in all digital signals to a lesser or greater extent. It's a critical issue in USB cable communication, because the USB signal travels in real-time between a Music Server and DAC. Moreover, when errors in the music data occur, there is no provision in the USB specification for the DAC to request a re-send. Therefore, the integrity of the digital music must be accurately preserved within the USB cable traffic.
In designing this USB cable, I have carefully chosen the wire metallurgy, gauge, cable architecture and dielectric. I've paid special attention to reducing both digital noise and jitter timing issues in the cable. I carefully chose the wire shielding or the lack thereof. All wires that carry a voltage emit electromagnetic radiation as a field surrounding the wire. To combat this EMI effect, which impacts the wires in proximity to it, I chose to use wire shielding on the 5 Volt (Vbus) lead. However, I chose not to shield the data plus and data negative wires, because I want their EMI to dissipate away. Jitter noise is introduced by the timing of the USB packet transfers across the wire, and the nature of the positive and negative data lines which are utilized by the USB software to subtract noise that may accumulate on the wires. We provide our USB cables in basically two versions. The "Standard" cable has the 5 volt shielded wire for those DACs or USB converters that require voltage to communicate and/or operate. We also offer the "Data Only" cable for those DACS that do not need the 5 volt wire. We recommend using the data only design if your DAC can accommodate it.
The source of noise in computer audio is the most important issue to deal with for discriminating audiophiles. It’s critical to realize that the modern consumer laptop or desktop computer is extremely noisy by nature. They work just fine for everyday use, even though they have noisy power supplies, inaccurate clocks, poor USB timing and inconsistent, shared power delivery. By disconnecting your computer or laptop power from your DAC or USB converter, and supplying clean power externally, you’ll seriously improve your digital sound.
The USB specification clearly defines the design parameters for the cable and transmission protocol. We followed the specs as closely as possible, only diverging when it made sense from an audio standpoint opposed to a computer data position. The two data lines work in a duplex fashion which allows for summing the data to eliminate noise built up during data transmission. The host USB device expects the music data packets to arrive at specifically timed intervals, in the microsecond range, and without phase shifting between the + or – data lines. The cable is supposed to be approximately 90 ohms impedance, give or take 15%. The binary data within the packet stream needs to be within specific voltage tolerances upon arrival to be correctly termed a one or a zero. There is no provision for resending the data if there is a bad read. Timing by the computer clock, the USB clock and the DAC clock are all working together to assure a properly timed stream of bits. This is extremely critical for the music to be rendered accurately. We have paid careful attention to these requirements, as well as other concerns, in the design of our USB cables.