Phase and time alligned speakers

Judit,
It's good that you are asking the question in an engineering context. As stated, your question is too broad for a simple answer, but I suggest that you pose a similar question on one or more of the specialty forums at Audio Asylum (speakers, cables, amps), where it should generate more in depth technical discussion.

Beg to differ. Phase and time coherence is not a priority for the vast majority of speaker manufacturers. Of the hundreds out there only a handfull design for these parameters. The jury seems to be out on the importance of these characteristics and the tradeoffs, at least in loudspeakers, generally involve having the drivers contributing significant energy outside of their optimal bandwidth. Sometimes the medicine kills you while knocking out the cold. That said, compared to loudspeakers, most electronics are significantly more phase coherent, as are most cables.

Viridian,

Quads and Vandersteens are the speakers I had in mind. Your answer makes sense to me ... that electronics and cables preserve phase information far better than loudspeakers are able to.

Judit, Quads like any fullrange electrostat or any fullrange single-driver cone speaker, are inherently time aligned. The phase alignment has to do directly with the phase shift that may occur in the single drive element. The advantages of these types of speakers goes beyond the time and phase characteristics, and into speed and coherence. Disadvantages may include narrow dispersion and intermod distortions, and possibly limited low frequency extension.

Multi-driver systems may use different techniques to create time and phase alignments, but are inherently hampered by the multiple drivers themselves. They try to simulate point source sound, but never really achieve it. In addition, the crossovers and additional drivers create as many or more problems than they solve. Advantages may include wide frequency extension, lower intermod distortion, and possibly higher power handling and SPL. Disadvantages would include crossover distortion, driver matching and overlap problems, and lack of the point source radiation pattern that they seek to simulate.

Much depends upon the system and goals you wish to achieve, and your particular sensitivity to these various disadvantages of each type. Picking the faults that you can live with is as important as picking the strong points. Nothing is perfect, and compromise is going to happen with all designs. The sound is the final arbiter, and designs are simply ways to get there. You must pick your poison.

As far as electronics matching up with these speakers, unfortunately, there is a hodge-podge approach to this in audio today. Components are designed to work with a wide range of other components, and cannot take individual speaker characteristics into account. This leads to the inevitable "synergy" discussions about what amp is best for what speaker. Some basic guidelines can help, but auditioning is really the only solution.

With the present situation, all distortions in the system will add together to give a total system distortion, as well as the same result in total system phase linearity. Some work is being done in distortion cancelling "synergy", but this is very strictly limited to certain amps and speakers that are not "mainstream" products. At least, not yet.

I must be in a disagreeable way today. All single element and single driver systems are not inherently time aligned. In fact, when a cone driver is used above the frequency that it maintains pistonic motion it is operating in breakup mode wherein one part of the cone is moving outward while another is moving in. Interestingly, many very fine systems operate their mid/bass or full range drivers this way. Flat frequency response can be maintained as well as excellent dispersion, however time response is, necessarily, compromised. Virtually all single cone systems with 5" or 6" drivers are in breakup as early as the top of the midrange. The Lowther and several others such as the Phillips even add a whizzer cone to tailor the breakup of the cone. There will not be any passing of square waves on these systems. Not with the integrity of Judit's beloved Thiels and Vandys and certainly not like the Quad 63 which actually uses annular rings and a delay line to yeild both phase coherance and point source dispersion.
Marty