Problem: Ground loop creates DC hum and buzz

Problem: ground loop creates
DC hum and buzz.

Solved: transformer isolation eliminates DC noise

Solved: Transformer isolation disconnects the 'hard wire' electrical input from the output while allowing the audio signal to pass. Ground loops are eliminated.

JPC™ Development

Let us be the first to break the news: Computers are not designed for audio. Hard to believe… but it is true. Computers are designed to crunch numbers. Yes, they can be equipped with microphones, audio outputs and video capabilities, but this in no way should lead you to believe that they are optimized to work in a professional audio environment. It’s no wonder that folks constantly complain about system noise. Most computers are made from plastic that does not provide any shielding from stray electromagnetic fields. Further, the audio inputs and outputs do not always follow proper audio grounding convention and the built-in audio interface is rarely, if ever, balanced. As soon as you connect a computer to the PA system, you are basically opening a big wide door to allow noise to get in.

The JPC was designed from the ground up to provide an effective analogue interface for computers and other consumer grade devices to connect to the audio system. Noise reduction, while delivering excellent audio, is central to the JPC’s design.

Eliminating noise at the source
Audio noise comes from many sources. The most common is known as a ground loop. This usually occurs when two devices are connected together that share the same audio and electrical grounds. DC offsets or the internal working voltages usually differ from one piece of equipment to the next and when interfaced, they will often cause a disruption that will generate hum and buzz in the audio system known as a ground loop. The most effective solution is to isolate one device from the other using a transformer. Transformers allow audio to pass while blocking stray DC voltage. These magical devices eliminate so-called ground loops, providing an immediate remedy. The JPC is equipped with two isolation transformers at the input to prevent ground loops from occurring.

The next problem is somewhat more convoluted. Even without computers, sound technicians are constantly battling system noise from entering the PA system. Electro-magnetic noise from light system dimmers, motor power supplies and amplifier power transformers have a nasty habit of polluting the air, causing magnetic waves to collide with every piece of equipment and connecting cable. Once noise gets into the system, it seems to travel at will. Computers are particularly vulnerable. While passive transformers block DC, active circuits have a distinct advantage - they employ blocking capacitors that prevent AC from traveling backwards into the source device. In other words, noise that may be present in the PA system is blocked so that it cannot travel back into the computer.

This is the reason why the JPC is so effective at preventing noise… it combines transformer isolation with active buffering. This hybrid approach gives you the best of both worlds.

Maximising connectivity
The AV world is inundated with connector options. Computers and portable music players like iPods are equipped with mini 3.5mm TRS connectors; hi-fi gear is equipped with RCAs while DJ equipment and keyboards are often outfitted with ¼” jacks. And for the field technician, always having the right adaptor is next to impossible. To address the inevitable, we equipped the Radial JPC with a full array of connector inputs and since they are all wired in parallel, you can use any input as a throughput should you need to route the audio source to a second destination. And because the JPC can be rack mounted or desk-top mounted using the J-Rak or J-clamp, it can be safely used anywhere!

Flexible, easy to use and quiet. These are the hallmarks that have made the JPC the most effective computer DI made today.