opaqueice wrote: > In general terms there are two options for the cross-overs - analogue > or digital.
All cross-overs cause changes to the signal. Good EQ is expensive, very expensive. > Third, and this is the issue > I want to ask the forum's opinion about, it's possible to create digital > crossovers which don't introduce any phase changes. For example a > square wave in will be a square wave out. This is not an example of phase changes. And square waves are special, they have infinite frequency. For phase, take a simplier example: a 1000 hz sine wave. It will have 2000 zero crossing points, 1000 on the up slope and 1000 on the down slope. So the zero crossings occur 2000 times a second, or once per 500 microseconds. Phase error is when the output signal is delayed, say by 50 microseconds. The signal can have the same amplitude and frequency, just the phase is changed. > 1) do people believe these phase changes are audible? I believe, IMHO, etc, that Phase truth is the key to audiophile sound. > 2) irrespective of the answer to 1), is it worth trying to preserve > relative phase during audio playback? There are two senses to this question. One is absolute phase for the whole frequency spectrum. There are theological discussions about this. A kick drum's sound comes towards the audience when the drummer hits it. So some folks argue that the first wave of the kickdrum hit from your speaker has to come towards you. I"m not convinced of this one. YMMV The second is the relative phase as frequency varies. Crossovers, EQ, etc. have different phase impact (or destruction) at different frequencies. I believe these are critical to realism. > 3) what digital solutions are available for such an application? The > only one I know of which would work out of the box is the DEQX (TacT > seems to only have two outputs, and I'd need six at least). The probability that you can get six of anything and have them all keep the phase properly aligned between them is vanishingly small. Digital EQ that maintains phase across the frequency sweep is very hard and very compute intensive. Doing that is expensive. Gonna cost more than several SqueezeBoxes. -- Pat http://www.pfarrell.com/music/slimserver/slimsoftware.html _______________________________________________ audiophiles mailing list [email protected] http://lists.slimdevices.com/lists/listinfo/audiophiles
