Ground loop noise with digital audio?
Many people may wonder how, when using a digital USB interface, this or similar unnatural noise can appear at the speaker output:
Squeaky sounds that change pitch, e.g. when moving the mouse, or noises that intensify when the computer's graphics card is running at higher speeds, are the result of a ground loop , most often closed by the ground of the USB cable .
This is not the case with every connection, because it usually requires three elements: a computer, a USB interface, and amplified speakers (including, for example, active monitors).
In such a system, various phenomena can occur:
- raising the mass level by the flow of high-intensity alternating current (e.g. GPU operation in a computer - when you move the mouse and more),
- flow of equalizing currents to equalize these differences,
- easy propagation of conducted disturbances (an issue related to electromagnetic compatibility).
As a result, the reference level (ground) will change, and thus the analog audio signal measured relative to it. This is possible because the output of a DAC or guitar interface, for example, is generated relative to the ground of the USB cable.
If this is your case, we have good news - there is a simple and safe solution that will remove all unwanted signals from the previously presented recording:
How does it work? Using our isoUSB+ v2 isolator, which galvanically isolates power and USB transmission, neither of these currents can flow. The galvanic barrier means that the circuits are separated by a huge resistance, and the signal and power flow through different phenomena (in our case, magnetic).
It's not about correcting "ones and zeros", we don't need to magically clean up the power supply - we "copy" the USB signal and power supply through an isolation barrier so that analog interference doesn't have a chance to pass through.
Why do insulator parameters matter?
There are various solutions available on the market, but they differ in key parameters that determine whether the isolator will work with your equipment at all.
1. Transmission speed. Cheap, popular isolators based on older chips (ADuM316 0 ) typically only support Full Speed (12 Mbps). In practice, this prevents the use of modern high-resolution audio formats, DSD files, or multi-channel studio interfaces. isoUSB+ v2 supports Full High Speed (480 Mbps) , using the much newer ADuM316 5 .
2. Current capacity and isolation voltage. Many budget designs offer a current capacity of up to 200 mA and isolation of 500-1500 V on the power line. Some better isolators deliver around 300-400 mA, but they are several times more expensive. Unfortunately, this isn't enough – the average interface will draw 500 mA!
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Our isoUSB+ v2 isolator will deliver a stable 500 mA and has a headroom in operation also up to 600 mA, which allows you to operate most audio devices,
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The applied isolation barrier for the power supply is 5.0 kV (5000 V), and for USB transmission - 3.5 kV (3500 V) , which guarantees complete cutting off of the interference path.
When looking for alternatives, you will notice that competitive isolators above 300-400 mA cost at least half as much as our solution.
We also have another advantage for you: the output of our isolator is stabilized using a linear regulator, which gives an output between 5.05 and 4.95 V. Other isolators, even more expensive ones, use unregulated switching converters with an output of 5.5 - 4.8 V , varying depending on the load.
A unique design from A2circuits
isoUSB+ v2 is not a Chinese or audiophile product, but an original engineering project that was created and is manufactured in Poland.
We do not use ready-made, universal power modules - we designed the power supply path from scratch, took care of interference and surge filtration, and were the only ones to introduce current limitation to improve the safety of your equipment.
We test each piece in production - for load (500 mA) and short circuit (>615 mA), high voltage (Hi-pot test: 3750 V) and High Speed transmission.
By choosing this solution, you receive a product tested in real-world conditions, built with high-quality components and supported by the knowledge of the people who created it.
