I'm no tech, but here's how I see it:
1990s-2003
1)Capacitor/inductor/coil based (Shunyata, Audience). Simple components placed over the lines, in the hope of breaking-up noise. I don't think these worked too well. The Teflon-equipped Audience (2008) was an improvement, but at a high cost.
2)Big transformer (Silver Circle, Torus). Something else placed in the power-path and this time more effective. Still not perfect, though.
3)Sine-wave generation (PS Audio, Pure Power). Essentially a power amp and IMO trying to do too much. The reviews were strong, at the time. But some of these (reviewers) now say they're only a partial solution.
2014 -on
4)Pull-away or drain noise (High Fidelity, Entreq, Akiko, Nordost QKore). Using magnets, rare-minerals or secret-ingredients. Some of these are placed in the direct-path of the power. Others are plugged into a power-bar (alongside the components) or into a component's rear ground plug.
5)Balanced power (Equi=Core). It's been tried before, but only in the last few years has it been good enough to get talked about.
6)Re-chargeable power tank (Stromtank, Tesla). It's not a big battery, it doesn't contain the chemistry associated. Great for reserves, but needing an inverter, it's unclear how it removes the noise that came when charging.
Added 7)Low-frequency pulses (that 'tune' electrical fields -Nordost QRT, ADD-Powr)
Hybrids (Audioquest Niagara, Synergistics). Pull noise out, then add reserves.
1990s-2003
1)Capacitor/inductor/coil based (Shunyata, Audience). Simple components placed over the lines, in the hope of breaking-up noise. I don't think these worked too well. The Teflon-equipped Audience (2008) was an improvement, but at a high cost.
2)Big transformer (Silver Circle, Torus). Something else placed in the power-path and this time more effective. Still not perfect, though.
3)Sine-wave generation (PS Audio, Pure Power). Essentially a power amp and IMO trying to do too much. The reviews were strong, at the time. But some of these (reviewers) now say they're only a partial solution.
2014 -on
4)Pull-away or drain noise (High Fidelity, Entreq, Akiko, Nordost QKore). Using magnets, rare-minerals or secret-ingredients. Some of these are placed in the direct-path of the power. Others are plugged into a power-bar (alongside the components) or into a component's rear ground plug.
5)Balanced power (Equi=Core). It's been tried before, but only in the last few years has it been good enough to get talked about.
6)Re-chargeable power tank (Stromtank, Tesla). It's not a big battery, it doesn't contain the chemistry associated. Great for reserves, but needing an inverter, it's unclear how it removes the noise that came when charging.
Added 7)Low-frequency pulses (that 'tune' electrical fields -Nordost QRT, ADD-Powr)
Hybrids (Audioquest Niagara, Synergistics). Pull noise out, then add reserves.
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