06-07-2017, 10:45 AM
Yes, it sounds like you're thinking of the same or similar model. Of course, this approach is not unique. It's actually not a bad plan, and there's a lot to be said for tailoring the amplifier to the speakers, as the components used can be much cheaper, and it's easier to include more elaborate filtering and compensation. Doing it at speaker-level inside the enclosure is not only more expensive in production (because of the need to handle higher powers), but harder to design because of the interaction with the non-constant impedance of the drive unit and lack of flexibility compared to working with op-amps at line-level. Passive speakers are really hard to design well - just look at how complex the crossovers are in the BBC designs.
For a trivial example of EQ'ing an amplifier to a particular (cheap!) drive unit - along with overall measurements made with a measurement mic - see here: http://www.markhennessy.co.uk/activespeaker/mods.htm
It's fair to say that "phase" is one of the most mis-understood and mis-used terms in audio marketing today, and has been for many decades. We're actually very tolerant to phase shifts, and if we weren't, then audio as we know it simply wouldn't work. Every tone control or EQ introduces phase shift, as does every filter, and indeed every loudspeaker enclosure has phase shift along with the LF rolloff (in fact, every peak and trough in the response of a loudspeaker has a phase shift associated with it). Hence, "phase error" is little more than marketing-speak. Along with "linear-phase", et al.
Obviously, signal inversion - often erroneously called "out of phase" - is another matter, quite separate to all this.
When designing loudspeakers, you know the filters will introduce phase shifts, so you design them so the phases align to give the target response through the crossover region(s). Sometimes that calls for the tweeter to be wired in opposite polarity to the woofer, which confuses folk, but many BBC and commercial designs were done that way.
(The mentions of BBC designs is simply because they can be readily looked up as they are in the public domain)
For a trivial example of EQ'ing an amplifier to a particular (cheap!) drive unit - along with overall measurements made with a measurement mic - see here: http://www.markhennessy.co.uk/activespeaker/mods.htm
It's fair to say that "phase" is one of the most mis-understood and mis-used terms in audio marketing today, and has been for many decades. We're actually very tolerant to phase shifts, and if we weren't, then audio as we know it simply wouldn't work. Every tone control or EQ introduces phase shift, as does every filter, and indeed every loudspeaker enclosure has phase shift along with the LF rolloff (in fact, every peak and trough in the response of a loudspeaker has a phase shift associated with it). Hence, "phase error" is little more than marketing-speak. Along with "linear-phase", et al.
Obviously, signal inversion - often erroneously called "out of phase" - is another matter, quite separate to all this.
When designing loudspeakers, you know the filters will introduce phase shifts, so you design them so the phases align to give the target response through the crossover region(s). Sometimes that calls for the tweeter to be wired in opposite polarity to the woofer, which confuses folk, but many BBC and commercial designs were done that way.
(The mentions of BBC designs is simply because they can be readily looked up as they are in the public domain)
