NNMC Форум радиолюбителей, аудиофилов, меломанов и музыкантов
Almost all amplifiers use "negative feedback" to reduce distortion in the power stage. Sigma Drive uses an extra set of wires to include the speakers in the feedback loop so that the amplifier can use power reserves to ensure the speaker track the signal. Quite effective on bookshelf speaker, up until they reach there maximum power level. Less impressive on really good speakers but at least it seemed to be transparent if it wasn't helping.
Kenwood's Sigma Drive has been widely acclaimed as an effective means of providing optimum speaker control and an extremely high damping factor right up to the speaker input terminals. In addition to the normal speaker leads, a special "Sigma" connection feeds distortion products caused in the speaker wires and in the speakers themselves back into the amplifier's NFB loop for effective compensation. The result is a total control over the speaker's behaviour, with optimum damping of unwanted speaker movement. [...] Sigma Drive is also employed between the pre-amp and power-amp stages where it compensates for any signal loss in the interconnection and permits low impedance drive throughout the frequency range.
A speaker driver when it moves it generate a small amount of voltage what goes back to the amplifier.Normaly the amplifier uses his dampingfactor to controle it.Kenwood uses the sigma drive to do that.That's the basic idea.
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