⌈ USB, in full universal serial bus, technology used to connect computers with peripherals, or input/output devices. […] The USB standard was developed by a number of American companies, including IBM, Intel Corporation and Microsoft Corporation, as a simpler way of connecting hardware to Personal Computers (PCs). Source: www.britannica.com, date of access: 1.07.2020. Today, this is the basic method of sending audio signal from computers and file transports to digital-to-analog converters. ⌋

ntroduced in 1995 (according to Wikipedia, on January 24th, 1996), the USB aimed to standardize connections between computers and different peripherals. Its basic task was to send PACKAGES containing commands and data. Nobody thought it would become the basic connection for sending audio SIGNAL. When that happened, the USB was classified as ‘01h’. It transmits digital signal in a balanced form through a twisted pair of signal cables (90 Ω ± 15% specific impedance).

| Universal Serial Bus

The USB standard was developed together (!) by a few American companies, including IBM, Intel Corporation and Microsoft Corporation. It initially received more than a cold welcome and the problem was that operating systems supported it to a minimum degree. It only changed when the first generation of Apple’s iMac PCs was launched in 1998, with just one port: the USB. In this way, the standard was imposed on other manufacturers.

The USB is still being developed, mainly in order to ensure faster and faster data transfer. There are four generations of the USB specification: USB 1.x, USB 2.0 (2001), USB 3.x (2011) and USB4 (2011). The two first generations use the same connectors: Type A (the signal transmitter port) and Type B (the receiver port). The next generations have to be equipped with other types of connectors: Type A SuperSpeed and B SuperSpeed for USB3.0, and with the brand new Type C for the USB3.2 and USB4 versions. Let me add that “mini” versions are also available.


In audio, the USB1.0 connection was initially used, making it possible to connect a computer’s output with an external DAC. It was used to send PCM signal up to 24 bit and 96 kHz, and DACs did not need separate drivers, as the ones included in the iOS and Microsoft operating systems were sufficient. As files with a higher sampling frequency (i.e. from 192 kHz up to DXD, as well as DSD) were becoming more and more common, the audio industry started using the 2.0 connector. Separate drivers had to be installed on computers with Microsoft software at that point. ♦

Audio signal sent through the USB has many limitations, starting from an untypical sampling frequency that subsequently has to be synchronized with the receiver, through problems with maintaining the connector’s impedance, to the necessity to transmit signal parallel to 5 V DC supply voltage. Therefore, a lot of recording studios use network signal transmission systems – see TRPTK.

Old-school engineers, i.e. those who do not listen to music and only rely on their basic knowledge (gathered by computer scientists and not sound engineers in this particular case), will claim that it does not matter what USB cable we use. Actually, this is one of the key elements of any audio system which uses files as the source.

| USB

Specialist companies have been offering USB cables for many years. During this time, a lot of things have been explained and learnt through experiments. It was found out that:

• the conductor type matters,
• the shield type matters,
• cable geometry matters,
• but what matters most is the way power supply is transmitted.

That is why, already at an early stage, attempts were made to physically separate power supply cables from signal cables. It can be done in a few different ways, but the most spectacular example is the Acoustic Revive USB 1.0 SP cable, in which signal is transmitted using one shielded cable and power supply – using another one. At the receiver’s end, both cables connect in a Type B connector, while at the other end each of the cables has a separate Type A (flat) connector. The latter are plugged into separate USB ports in a computer.

Another version of this method consists in using an “adapter” which is used to connect the cable that we have and supplies 5 V from a separate power supply unit, usually a battery-powered one. Such solutions are offered by, for example, the Elijah Audio company (more HERE). Another version of the USB cable has also been developed by the AudioPhase company that has so far been offering loudspeakers and classic analog cables. There are two versions of the cable: the UnPowered (without power section) and the USB, standard one.

| A few simple words with…

KAROL GOLIŃSKI
Owner, constructor

I had waited a long time before I designed a USB cable – I simply had no idea for it. However, the day came when one of my colleagues challenged me to “make a USB cable in the AudioPhase school of sound reproduction”. Under high pressure from the people around me, after developing many prototypes and combinations within the course of two years, I created a cable that I sent for a test. The idea was to develop a USB interconnect that would sound analog and natural, without any digital features.

The cable development process was complicated and full of surprises. Unfortunately, the tricks that are used while developing AC or IC cables often bring about undesired effects in this type of cables. The final structure is based on Teflon-insulated silver-plated mono-crystal copper for both sections – data and power supply. Both sides of the cable have separate copper shielding, vibration dampers and geometry stabilizers, and the whole cable has A and B connectors at the ends, with contacts made of directly gold-plated copper. KG

The AudioPhase cable is simply called the USB. It is quite a rigid connector consisting of two separate conductors that can be felt under a black fabric sheath. As I said before, the AudioPhase company offers two versions of the cable: the UnPowered which costs 1,900 PLN/1 m and Standard one that costs 2,500 PLN/1 m. We are testing the Standard version here.

| THE LISTENING SESSION

The way we listened | The tested cable was listened to in the “High Fidelity” reference system. It connected two sources and two D/A converters. The first source was my “working” laptop, the old HP pavilion hv7, but with two (SSD and HDD) superb disks and a lot of RAM, once configured to work with music by Marcin Ostapowicz, the owner of the JPLAY company. The other source was the Silent Angel RHEIN Z1 file transport. The D/A converters were: the Ayon Audio CD-35 HF Edition (№ 1/50) SACD player and the Mytek Brooklyn Bridge file player.

I used two cables that I consider to be reliable: the medium-priced Curious Cables USB and the more expensive Acoustic Revive USB 1.0 SP. There are new versions of both, but I am still using the old ones.

In A few simple words… Karol talked about the aim that he set for himself – he wanted to obtain sound close to the “analog”. Our understanding of the “analog sound” is not monolithic and each of us understands it in a different way. However, it seems to me, we all agree that it is about the opposite of aggressive and bright music that is associated with the stereotypical term “digital sound”.

Listening to the AudioPhase cable shows that this is not about enclosing sound in a warm cocoon or slowing the attack down. This is not a cable that would warm anything up. So, those who associate analog sound with “tubes” will not be fully satisfied. It quite quickly appeared that the AudioPhase cable offers a broader range, with stronger treble than the Curious USB cable that it was compared to. The Acoustic Revive cable was tonally close to the AudioPhase USB, but sound energy with the Polish cable in the system seemed higher.

So, what is the “analog” all about? It does not mean extinguishing the treble at all. The interconnect developed by Karol Goliński produces large sound, sound that is expansive and strong, and, I would say, solid. It is no coincidence that after it was connected in place of both of the reference cables, the sound seemed louder. It is impossible, as signal level is determined by commands included in digital signal itself and it cannot be changed by correcting the material that the given conductor is made of or by using the geometry of the cables. However…

The impression that I am talking about, i.e. the temporary, subjective increase of “volume” results from something else. First of all, from stronger energy shown in the upper midrange and treble. Looking at it from the outside, without emotions, it would be hard to say that the AudioPhase USB sounds brighter than the Acoustic Revive or the Curious cable, or that it sounds bright at all – as it is not so. It is an excellently tonally balanced cable, better (!) in this respect than both reference interconnect cables. It is only about the fact that sound is more selective and a lot is happening in it with the cable – and that is why the musical message captures our attention more easily and sound seems “louder” when the cable is used in a system.

It is a cable that shows the exciting side of music. In comparison, the Curious cable sounds more distanced, with the foreground further away from us and stronger emphasis on the midrange – the midrange that could be described as “tube-like” in its case. The AudioPhase USB has energy and drive. It amazingly differentiates minor events included in recordings. That is why it excellently showed Leszek Możdżer’s performance in Pasodoble (a track from an album under the same title, recorded with Lars Daniellson) and beautifully emphasized the outstanding recording of Buka from Hania Rani’s album entitled Home. These are small things, but thanks to as good reproduction quality as with the AudioPhase cable, the recording “grows” and becomes more interesting, and emotionally stronger.

As I said before, it is a “broad-sounding” cable. It goes deeper in bass than the Curious USB and is almost as good in this respect as the Acoustic Revive cable. The latter shows the concentration of the lowest sounds better, even though the difference is not large. It is similar with the other side of the range, where the Japanese interconnect goes a little deeper into sound. However, the Curious cable seems to sound “blunter” and does not show as much information as the Polish cable.

Finally, there is perspective that places the performers in front of us, rather than at a distance with the AudioPhase cable. The depth of the soundstage is good, its width – very good, but there is no doubt that the foreground is most important here. The instruments shown there are very vivid, have high energy and are clear. All this is achieved without brightening the sound up and without a hard attack. I would not say that the AudioPhase cable softens the message, as it is not the case, but it does not excessively “format” it, either.

| Conclusions

The AudioPhase USB is the first cable made by this Polish manufacturer. We are testing Standard version, i.e. one with integrated 5 V line power supply. These are the two elements that might lower our expectations of it. Unnecessarily, as it is a very good design that has, in many respects, proved better than my medium-priced reference cable, the Curious USB. The Australian cable is characterized by better sound depth, but it is the only thing that distinguishes it from the Polish cable.

The AudioPhase USB Standard produces strong and open sound, and is characterized by high dynamics – as good as that of the Acoustic Revive cable. It has a wonderfully maintained bass, very nice treble and pleasant colorful midrange. It is not the last word in the domain of bass resolution and selectivity, but a lot more will have to be paid for all that.

I liked this cable a lot and I encourage you to try out its version with an external power supply. I did something like this, using an Elijah Audio company adapter – it was really worth it. I recommend this cable to everyone who likes listening to music for emotions and who finds the energy of the musical message as important as its color. A cool thing to have! ■