Large iron core isolation transformers are very effective in protecting sensitive equipment from AC voltage transients, spikes, and electrical noise appearing on commercial power lines.
Iso transformers are designed to be exactly opposite to audio transformers. While an audio transformer needs to pass all audio frequency power uniformly, an iso transformer is designed to transfer power only at or near 60Hz. Frequencies below that are attenuated by operating the iso at relatively high flux densities, and frequencies above that are reduced by introducing as much leakage inductance as possible, consistent with good power transfer to the output side.
Power line noise exists in two forms: "common mode", which appears between both sides of the power line (hot and common) and ground, and "transverse mode", which appears from line to line. With good design, and the intelligent use of shielding and grounding, an iso can reduce both by as much as 120dB, and this specification is usually stated by the manufacturer, and sometimes stamped on the faceplate.
If the power line ground is shared on both the input and output sides, excessive ground line noise from other circuits can be transfered. In that case, it is advantageous to run a separate clean ground to the transformer frame and output side.
I am using a 4kva Topaz iso on 4 dedicated circuits, one each for CD, phono, pre and amp, and have realized a noticable overall improvement. I am also using a second 125va iso on the CD to keep its noise from getting back into the other dedicated lines.
Iso transformers are designed to be exactly opposite to audio transformers. While an audio transformer needs to pass all audio frequency power uniformly, an iso transformer is designed to transfer power only at or near 60Hz. Frequencies below that are attenuated by operating the iso at relatively high flux densities, and frequencies above that are reduced by introducing as much leakage inductance as possible, consistent with good power transfer to the output side.
Power line noise exists in two forms: "common mode", which appears between both sides of the power line (hot and common) and ground, and "transverse mode", which appears from line to line. With good design, and the intelligent use of shielding and grounding, an iso can reduce both by as much as 120dB, and this specification is usually stated by the manufacturer, and sometimes stamped on the faceplate.
If the power line ground is shared on both the input and output sides, excessive ground line noise from other circuits can be transfered. In that case, it is advantageous to run a separate clean ground to the transformer frame and output side.
I am using a 4kva Topaz iso on 4 dedicated circuits, one each for CD, phono, pre and amp, and have realized a noticable overall improvement. I am also using a second 125va iso on the CD to keep its noise from getting back into the other dedicated lines.