I am running multiple amplifiers, each with a CLEARLINK ™ CONVERTER/ISO TRANSFORMER, but (one or) some of them (still) have a buzz/hum, how can I get rid of it?
First, make sure that all the amplifiers are properly grounded with a 3-prong AC power-cord plug! Older amplifiers with 2-prong AC power-cord plugs should be checked for proper grounding, and if necessary, serviced before using them in a guitar rig. Defeating an amplifier’s safety ground may not only be ILLEGAL, but it may also pose a SHOCK or ELECTROCUTION HAZARD. That said, and as you’re probably already aware, the most common cause of buzz, hum, and noise when connecting multiple amplifiers in the same rig, is a ground loop. The isolation transformer inside the CLEARLINK™ CONVERTER/ISO TRANSFORMER and its GROUND switch, work together to safely eliminate a ground loop. With a CLEARLINK™ CONVERTER/ISO TRANSFORMER connected to the input of every amplifier in the rig, the GROUND switch on ONLY one CLEARLINK ™ CONVERTER/ISO TRANSFORMER should be set to the “IN” position, so it can “pass” its earth ground reference to any pedals, and the guitar. The GROUND switch on ALL the remaining CLEARLINK™ CONVERTER/ISO TRANSFORMER’s should be set to the “OUT” position, to eliminate the ground loops that would otherwise form. Try setting each GROUND switch to the “IN” position, individually, and use the combination which results in the least amount of buzz, hum and noise.
Second, remember that any device which contains an audio isolation transformer is susceptible to hum from the magnetic field generated by a power transformer, such as those found in an amplifier, effect processor, “wall-wart” power adapter or universal pedalboard power supply. Even with adequate shielding of the audio transformer and the device itself, there can still be a potential for unexpected hum. So if an unusual hum does occur, which cannot be eliminated by either position of a GROUND switch, try re-locating the CLEARLINK™ CONVERTER/ISO TRANSFORMER. Typically it would only require being moved a short distance in a particular direction to resolve this type of hum.