08-08-14: Charles1dadThank you Charles.
Bombywalla,
I always find your comments interesting and informative. This topic is no exception, I just came across it very recently. Are first order crossovers a prerequisite for proper time alignment?
Would a single driver crossoverless speaker be another example of true time alignment?
Are you able to consistently hear the results of time alignment?
Thanks,
Charles,
Excluding single-driver speakers, yes, 1st order x-overs are a requirement for time-coherence.
In your post you asked "Are first order crossovers a prerequisite for proper time alignment?"
Notice you wrote "proper time alignment". Time alignment is just a small aspect of time-coherence.
Time alignment refers to aligning the acoustical centers of all the drivers such that sound from them reaches your ears at the same time. You find speakers with sloped baffles do this. At other times, the older Dynaudios, the tweeter is placed at the bottom & the woofer on top while the baffle is exactly vertical - this makes the pathway from the tweeter longer to your ear compared to the woofer. This a 2nd way to solve the time-alignment issue. In the bigger Focals you find the speaker front curved & the manuf provides a crank on the back that can change this curvature. This is a 3rd way to solve the time-alignment issue.
Speakers that don't have a sloped baffle nor the tweeter at the bottom & woofer on the top nor a curved baffle but still claim to be time-coherent are making totally fake claims. If you haven't take into account the most basic attribute of time-aligning the drivers, how can you even come close to achieving time-coherence??
Note that just because the drivers are time-aligned, the speaker is not time-coherent. Time-coherence comes from the fact that the phase relationship amongst all the frequencies as they go thru the speaker remains unchanged from speaker input to speaker output. This means that the drivers do not distort as the music signal passes thru the speaker in the 20Hz-20KHz range, that the x-over circuit does not distort as the music signal passes thru the speaker in the 20Hz-20KHz range.
This means you need to select your drivers very carefully & it also means that your x-over cannot change the phase relationship amongst all the frequencies in the 20Hz-20KHz region. Only the 1st-order x-over circuit has the property of not changing the phase relationship amongst all the frequencies in the 20Hz-20KHz region. The 2nd-order, 3rd-order, 4th-order & higher order circuits do not have this property. So, yes, 1st-order x-over is required for time-coherence.
A time-coherent speaker has it's drivers time-aligned. Plus, a time-coherent speaker is phase-coherent at all frequencies in the 20Hz-20KHz range and not only at the x-over frequencies like most speakers in the market.
Would a single driver crossoverless speaker be another example of true time alignment?yes & no. it depends on the quality of the single-driver. For as long as the single-driver's frequency response remains linear, the speaker will be time-coherent. Notice I am writing "time coherent" & not time aligned. Time alignment is just one small aspect of time coherence.
When the single-driver becomes non-linear - maybe due to the whizzer cone or the woofer driver cone break-up or any other reason, the single-driver will start adding its own phase shift to the music signal & the speaker will become time-INcoherent.
So, a single driver speaker could be time-coherent over a limited freq range or over the entire range depends on how good the single-driver is acoustically. Electrically it does not matter as there is no x-over.
Are you able to consistently hear the results of time alignment?absolutely yes! And, each time one listens one appreciates the time-coherence attribute. Again, I'm using time-coherence & not time-alignment. Time-coherence is the superset of time-alignment.
Time coherent speakers simply sound like real music, they are non-fatiguing & let you concentrate on the nuances of the music rather than wasting your time on audiophile attributes of soundstage height, width, depth, imaging, etc, etc. In time-coherent speakers the imaging is always very good & the images are locked i.e. they do not float in space as the volume goes up/down or when you hear soprano/baritone. Sound from such speakers sounds like it's cut from one cloth - no separate-tweeter-separate-woofer sound. Music of all genres sounds great thru time-coherent speakers even those albums recorded poorly because the speaker is not adding any distortion of its own. Of course, better recorded music sounds better thru time-coherent speakers. Time coherent speakers are largely agnostic to the electronics driving them because the speaker is a benign load to the amplifier - a properly designed time-coherent speaker has very little phase shift in the bulk of the audio band. And, as the electronics improves, the speaker sounds better because the electronics is distorting less (the speaker itself has minimal distortion of its own).
So, the reason I'm talking about time-coherence is because the OP asked if distortions affect the enjoyment of speaker. Choosing time-coherence or not is about deciding how much distortion you want to listen & how much you want your listening pleasure to be bombed by distortions. Everybody wants to spend top-dollar to buy the best electronics but they pay little attention to the speaker. So, you have lower distortion electronics feeding into highly distorting speakers & you have basically undone all your work to selecting lower distortion electronics. what good is that?
Choose time-coherent speakers & enjoy your music to its fullest. And, as Roy Johnson says on his website, "it's about time" (pun intended) that you do so!
hope this helps....
