The Audioquest Jitterbug is a USB passive filter designed to enhance the quality of the audio signal and the electric current transmitted to a USB DAC. This device is therefore useful for both a DAC powered via the USB port and one with its own power supply.
The mere existence of the Jitterbug leads us to question the performance of USB ports used on various devices to play music, desktop computers, laptops, NAS or Android smartphones and tablets for example. Who never experienced micro-cuts while listening to music or heard interference while moving a mouse? For the story, we had to decline selling an exceptional sounding portable audio player because it was too sensitive to interferences in USB DAC mode.
Audioquest Jitterbug: controlling the weaker link of the audio system- the USB port
In order to reach proper hi-fi standards, an electronic component must be protected from electrical interference and radio-frequencies. For this reason, many audiophile CD players separate analog and digital circuits and proceed with a thorough shielding of every sensitive component. The USB controller of a computer unfortunately never benefits from such treatment. By simply opening a desktop computer we can see that the USB control chip is right next to the processor or that the power supply is not shielded. Even worse, USB ports are often linked to the front connectors by non-shielded cables. The consequence of this is that the electric current and data are constantly subject to interference, which can cause transmission errors. In order to solve this problem, data is transmitted with error correction codes so that corrupted data can be sent again. This is why a file (photo, zip, etc.) is always perfectly copied.
When the device which receives the data is an audio converter (DAC), this error correction isn’t carried out as it would interrupt playback.
In the best situation possible, the DAC?s USB controller ensures that the data stream is well synchronized by using one or several clocks but cannot guarantee its integrity. Therefore, in a succession of 1 and 0 which makes up the music, 1 can be mistaken for 0. This only results in a sound artifact when the amount of corrupted data is very important (in which case a ?click? can be heard). Nevertheless, a few corrupted bits will have an impact on the intelligibility of the sound which will be less precise and ?harsher?.
Audioquest Jitterbug: how does it work?
The Audioquest Jitterbug is a passive peripheral device featuring electrical resistors, capacitors and small selfs. Audioquest has kept the Jitterbug?s exact working process secret, but the principle is that it reduces background noise caused by electric signals in order to deliver a signal which is easier to read for the DAC (avoid confusions between 1 and 0). The device requires no driver and all there is to do is to plug it in between the computer and the DAC.
We used three different DACs to test the Jitterbug: the Audioquest DragonFly 1.2 (powered by the computer), the Sony PHA-1AEU (with battery) and the HiFiMAN EF2C (external power supply). The Jitterbug was not compatible with the HiFiMAN EF2C tube DAC, the sound was completely broken and impossible to listen to. There was absolutely no issue with the two other DACs. Used with an Android smartphone USB OTG output, the Audioquest Jitterbug prevented the Sony PHA-1AEU to be recognized (although it works perfectly without it).
Does the Audioquest Jitterbug have an influence on jitter?
There is no reason for this. As a quick reminder, jitter is a phenomenon caused by a poor synchronization between two devices exchanging digital data, the second device converts data into an analog signal (audio or video) in real time. In order to work, a DAC needs to receive audio data in regular intervals. These intervals are determined by one or several clocks in the DAC which impose a certain rhythm to the USB controller. If this rhythm is not respected, some 0 and 1 are received either early or late. The result is a drab and aggressive sound and an insubstantial sound stage. The Jitterbug doesn’t affect data transfer and cannot reduce jitter.
Audioquest Jitterbug: Listening impressions and conclusion
With or without the Jitterbug, it does not make a tremendous difference. The main features of the DAC stay the same and the possible flaws are not fixed. The overall sound does seem more coherent and transparent. The listening experience is thus smoother. The background seems quieter, which gives more room for the notes to fade and for details to be heard.
It seems to us that the Audioquest Jitterbug would mainly be a plus for a computer featuring USB ports which are subject to interference and a USB powered DAC. A DAC with a dedicated or external power supply would nonetheless profit from the treatment applied to the electric audio signal. This small adapter brings a sense of serenity to the listening experience.
