SAM effects

[GuillaumeB]

The following was posted on the Linn Forums site by a Linn engineer, by way of an explanation as to how SAM works and contrasting it to the Linn Exakt system:


"The Devialet SAM system functions as a bass extension filter. They match a shelving filter that is equal and opposite to the natural roll-on of the speaker(*), effectively pushing the low frequency response of the speaker down in frequency. The shelving filter will produce an equal and opposite phase response to the natural roll-on of the speaker(*) thereby linearising the low frequency phase response (to some degree).


(*) based on measurement of a single loudspeaker, so not truly accurate when you consider production variance.

At very low playback levels this extension can be pushed to (conceivably) quite low frequencies without end stopping the drive unit. However, as playback level is increased, the influence of the shelving filter applied by Devialet is reduced giving progressively less bass extension as the volume is increased. To claim that the low frequency of the Ninka is extended to 15 Hz is therefore rather disingenuous.

The Exakt filter for the Ninka does feature a bass extension filter as did our analogue Aktiv design, though the Exakt version is a rather better implementation. Unlike the Devialet approach the Exakt extension filter does not vary with the volume setting, so gives the same extension irrespective of playback level. As I recall it pushes the -3dB point down by about an octave from the natural response of the system (~35 Hz). Below this the speaker rolls-off with a 2nd order characteristic, so will be ~12 dB down at 17 Hz.

Having heard what the Devialet does to an Akurate 242 I am quite happy to state that the Exakt Ninka sounds significantly better then a passive Ninka driven by a Devialet amp."


Guillaume