My kinda speaker

[HAL]

Time delay works at all frequencies, where phase delay only works at a specific frequency. That is why digital time delay is used for arrays of drivers or speakers.

[Cogito]

Entire cone area is a single launching point when operated within limits.

[Pelliott321]

So if Shashi is correct one should measure midway back from cone edge

[brombo]

Remember the lily cone tweeter -

http://www.roger-russell.com/omni/omni.htm#onea

My math teacher in college had Hegeman speaker and a fm phono cartridge.

[SoundMods]

Actually time alignment of any speaker is relatively simple if you do it electronically. Doing it multi amped is better but you can also do it with a single amp by doing the alignment in frequency bands that correspond to the ranges in which the drivers are operating. With passive crossovers the result is not as good as there is some overlap of the drivers but it is much better than nothing.

Now that I have moved the eggs up to my living room I will be doing some work with my DEQX on among other things time alignment. Since the eggs also have a passive crossover I will be able to do threee major things that should be interesting. The first is to run the eggs with the DEQX in essentially bypass mode where it basically acts as a high quality DAC feeding a single amp. In this scenario, the passive crossover does all the work. The next condition will be to also use the DEQX as the DAC with a single amp through the passive crossover but use the DEQX to do time alignment within the frequency bands for each driver and also speaker and room EQ as needed. The third condition will be to do a full blown triamped system with all the whistles and bells in the DEQX. The DEQX will be able to store the settings of the three scenarios so we can reproduce the tests anytime at will. It should make for a good meeting at some later date but we would have to do the listening in shifts as my living room is not very large.

If only it actually worked as advertised. You really can't replicate actual acoustic timing with an electronic crossover. Think about my multi-tower example -- does it sound familiar?

[Roscoe Primrose]

Of course Magnepans and electrostatic speakers are time-aligned by default.

Except that they're so large that they're not, unless they're curved. The top & bottom are much further (>4" for a 6' tall driver at a 12' listening distance) away than the middle... Somewhere in the garage I've got a pair of line arrays I built with 18 lousy 3" or so full range drivers, curved so they're all the same distance from the listener. Of course, the curve is only "right" for a specific listening distance, but the design of the speakers is such that it wouldn't be too hard to change the curve. Interesting, despite the lousy drivers...

Roscoe

[SoundMods]

Remember the lily cone tweeter -

http://www.roger-russell.com/omni/omni.htm#onea

My math teacher in college had Hegeman speaker and a fm phono cartridge.

AHHH! The good old days when experiments actually made it to production. Now -- everything is cone this and cone that. Then there is marketing to make the buyers think that the Unobtanium 5000 defies physics and is the greatest thing since sliced bread. Even Dave Wilson's new $600,000 WAMM is nothing more that a boat load of cone drivers. His original WAMM was way more creative. Guys like Peter Walker and Oscar Heil are nothing but memories.

[brombo]

A modern variation?

https://www.morrisonaudio.com/speakers/

[tomp]

Two points. You can actually modify the acoustic time arrival electronically. Remember that the acoustic function does not start until the electrical signal stimulates the voice coil. Delay that electrical arrival and you delay the acoustical arrival.

As far as time differences along the cone, assuming that the cone does not breakup, the speed of sound in the cone is important. That is why beryllium is such a good cone (or dome) material. The speed of sound in beryllium is very high compared to other materials. The only material with a higher speed of sound is diamond but it has twice the density so it takes more energy to move it and also stores more energy. Considering all the factors involved in the materials, beryllium has the highest figure of merit for speaker construction.

[Cogito]

So if Shashi is correct one should measure midway back from cone edge

Don’t think we as DIYers need to worry about cone depths. Cones exist solely for the purpose of providing rigidity to the wave generating surface. Since the cones are attached to the voice coils, aligning them might be good enough. Not sure if any hi-end speaker manufactures take cone depths into consideration.

Cone depth creates a more significant problem, reflections within the cone. Some manufacturers add phase plug to minimize the reflections and improve the directivity.

http://www.lowtherloudspeakers.com/equalizer.html