A history of Time Aligned Loudspeakers

[gberchin]

... I do like to use higher-order xovers than MDS allows (or at least allows at my skill of MDS implementation).

In the latest MDS paper (version 20250714) I outline how to achieve basically any transition band slope that one might desire.

 

[norman bates]

You all are so lucky with the digital tools available nowadays !!!!!

 

[KL....]

You all are so lucky with the digital tools available nowadays !!!!!

Thank you, @norman bates, it can be also be suggested that Active Speakers (utiliseing DSP/FPGA PQGA/other) can (easyly) solve/resolve all of the issues mentioned in this thread (no (physical) XOs required) and more (GGNTKT M3), can't they, although/nonetheless, nice/enjoyable to discuss the History....

 

[Thomas_A]

Thank you, @norman bates, it can be also be suggested that Active Speakers (utiliseing DSP/PQGA/other) can (easyly) solve/resolve all of the issues mentioned in this thread (no (physical) XOs required) and more (GGNTKT M3), can't they, although/nonetheless, nice/enjoyable to discuss the History....

What they solve is quite much dependent what you define as "issues". Audible issues? Measurable issues? Distortion issues?

 

[KL....]

What they solve is quite much dependent what you define as "issues". Audible issues? Measurable issues? Distortion issues?

Thank you, @Thomas_A, Yes, but which would you suggest, at this time? It could be suggested as All (the thread posts indicate, possable), and even the Room, although perhaps not quite yet (at least at a reasonable price)....

 

[Thomas_A]

Thank you, @Thomas_A, Yes, but which would you suggest, at this time? It could be suggested as All (the thread posts indicate, possable), and even the Room, although perhaps not quite yet (at least at a reasonable price)....

Frequency response linearity and low distortion (audible stuff). For crossovers < 500 Hz one can have a second look at phase linearity.

 

[Waveform Fidelity]

Can someone comment on "blended' crossovers--initially 1st order then transitioning to higher orders?

The transfer function (order) of XO filters used in loudspeakers is fixed. There are a class of filters that adapt their transfer function (think noise cancelled headphones) based upon a feedback signal - they are called adaptive filters.

Perhaps you are thinking of filters that have a variable attenuation with frequency? Yes one can make different slopes by adding series/parallel R-C, R-L networks to standard filters, which some manufacturer's do to fine tune responses/suppress resonances etc. What ever you can do with passive components, you can do in DSP with IIR filters.

Lastly, FIR filters allow one to design filters with arbitrary gain and phase - so you can create any correction filter that you like to produce any acoustic response you like. Using that type of filter the constraints are the number of filter “taps” and the corresponding delay it produces. At low frequency you need many taps, so its common to combine IIR and FIR filters, or you can use Warped FIR filters which reduces the number of taps by using logarithm spacing in the design process.

Hope this helps

 

[Ultrasonic]

US manufacturer Meadowlark made numerous speakers that qualify for this thread I think. I used a pair of Shearwaters for many years (now sitting surplus to requirements upstairs). Here's a photo of their better-looking Nighthawk as an example:

Edit: I can't quickly find relevant measured data for these but here's some for the Sharwater model including the step-function:

Meadowlark HotRod Shearwater loudspeaker Measurements part 2 | Stereophile.com

In the vertical plane (fig.6), a presence-region suckout that develops immediately above the tweeter axis might balance the off-axis flare. On the other hand, sit lower than the tweeter and more presence-region energy becomes apparent, which will exaggerate the subjective consequences of the...

www.stereophile.com

 

[RetroStereo]

Wouldn't Jon Dahlquist's first speaker released under his own brand fit this category? The DQ10 was a remarkable speaker.

 

[nagster]

Earthworks Sigma 6.2

 

[norman bates]

interesting how the tweeter distances to edges are 3 different distances……. That will smooth out peaks / valleys. Still diffraction, but at least spread out to 3 different times and less due to round overs…

Except for the big diffraction source from the to of the woof cabinet………