Preface Ground Loops Sometimes currents flowing through the ground line generate a signal seen by another part of the circuit sharing the same ground. In other words, if there are two identical signal paths within a circuit, they can form a loop which can result in hum and/or noise. If you are using equipment that has 3-prong “grounded” AC power cords, you may suffer from a ground loop resulting from the interconnection of this equipment. The following diagram shows how cascading or “chaining” the output of one 3-prong grounded system into the input of another 3-prong grounded system with a standard unbalanced 2 conductor cord (like a 1/4” guitar cable) can result in a ground loop.
Unbalanced Output to Unbalanced Input. Single conductor shielded cable SIGNAL PATH Unbalanced Output to Unbalanced Input. Single conductor shielded cable SIGNAL PATH (circuit ground) + 3-Prong "Grounded" System (circuit ground) + 2-Prong "UNGrounded" System Ground Loop > Earth Ground Earth Ground FIG. 2 Fig. 1 depicts a system interconnection where a ground loop can exist. Fig. 2 depicts a system interconnection where a ground loop does NOT exist. When interconnecting 3-prong grounded systems, you can use signal isolation transformers to prevent ground loops.
This coupling transformer effectively isolates two interconnected system signal grounds, while still allowing the signal to pass through. FIG. 1 AC Line Conditioning As is the case with any computer device, the ASR-10 is sensitive to sharp peaks and drops in the AC line voltage. Lightning strikes, power drops or sudden and erratic surges in the AC line voltage can scramble the internal memory and, in some cases, damage the unit’s hardware. Here are a few suggestions to help guard against such occurrences: A Surge/Spike Suppressor. The cheaper of the options, a surge/spike suppressor absorbs surges and protects your gear from all but the most severe over-voltage conditions.
You can get multi-outlet power strips with built-in surge/spike suppressors for little more than the cost of unprotected power strips, so using one is a good investment for all your electronic equipment. A Line Conditioner. This is the best, but by far the more expensive, way to protect your gear. In addition to protecting against surges and spikes, a line conditioner guards the equipment against excessively high or low line voltages. If you use the ASR-10 in lots of different locations with varying or unknown AC line conditions, you might consider investing in a line conditioner. Disk Care v 3-Prong "Grounded"+ System 3-Prong "Grounded"+ System