You can solve many ground loop problems by plugging all the equipment into the same grounded AC source, such as a power strip that feeds an AC outlet through a short cord, as this attaches all ground leads to a single ground point. But if you're on a gig, and it's an emergency and temporary, and you’re really careful, you can try this method as a quick fix. In other words, you risk getting shocked. This is definitely not recommended since it eliminates the safety protection afforded by a grounded chassis. Some musicians simply “lift” the AC ground by plugging a 3-wire cord into a 3-to-2 adapter. The preferred method depends on the nature of the problem, so let's look at various options. There are two main fixes: 1) break the loop by interrupting the audio ground or 2) break it by interrupting the AC ground line. Ground loops cause the most problems with high-gain circuits, since massive amplification of even a couple millivolts of noise can be objectionable. If that ground is “dirty,” this noise might get picked up by the circuit. Furthermore, many components in a circuit connect to ground. The loop can also act like an antenna for hum and radio frequencies (called the loop antenna effect). This signal may get induced into the hot conductor. The reason that path exists is twofold: 1) both the AC and audio grounds are connected via the device's metal chassis and 2) the voltage is not 0, on one or both of the lines.īecause ground wires have some resistance, a potential difference in voltage between the two ground lines can exist, and that causes current to flow through the ground paths. In Figure 1 above, one path goes from device A to ground via the AC power cord’s ground terminal (in red), but A also sees a path to ground through the shielded audio ground cable (also red) via AC ground of device B. A ground loop occurs when a signal finds more than one ground path available. Any device should have only one AC path to ground. But bear with me a moment to see why your music will get a buzz on (in a bad way). And really, you don’t even have to understand ground loops if you just memorize the steps to fixing them should they occur. Ground loops are easy to eliminate, once you understand them. More than a few people have reported that their AC-powered multimedia speakers buzz when the computer is plugged in, but are quiet as mice when the computer is unplugged and running on its internal battery. But ground loops can happen in a setup as simple as your laptop computer and powered speakers. You’re even more vulnerable if these multiple units are plugged into different wall outlets around your studio. You find them whenever your audio hookups start to get complicated-such as multiple pieces of plugged in gear all linked by audio cables. Ground loops produce that noisy, low-pitched dirt that plagues your audio signals. Jon Chappell_1 | FebruHow to Identify and Eradicate the Different Hum Gremlins that Haunt Your Studio
0 Comments
Leave a Reply. |