E. J. Jordan Delay Line

[assembled]

Hello everyone,
Has anyone implemented a delay line from
E. J. Jordan's article "Loudspeaker Stereo Techniques"?
http://www.ejjordan.co.uk/PDFs/Jordan_WW_Feb_71.pdf

What are the results? How many speakers are really required per meter of sound stage? Or rather per some angle?
I suppose the way to go here is line level (analog of digital) delay and an amplifier per speaker.

[graaf]

Originally Posted by assembled

Hello everyone,
Has anyone implemented a delay line from
E. J. Jordan's article "Loudspeaker Stereo Techniques"?
http://www.ejjordan.co.uk/PDFs/Jordan_WW_Feb_71.pdf

What are the results? How many speakers are really required per meter of sound stage? Or rather per some angle?
I suppose the way to go here is line level (analog of digital) delay and an amplifier per speaker.

I subscribe to the above questions

[assembled]

What is the right way of calculating directivity for such array with positions of each driver and their phase?

[graaf]

Originally Posted by assembled

What is the right way of calculating directivity for such array with positions of each driver and their phase?

I second the above questions, where are all wise men of this forum?

[graaf]

I suppose that it was a kind of 1971 soundbar

a bit like Niro Nakamichi's "1000" Surround bar:
Niro Nakamichi 1000 Surround Bar First Look — Reviews and News from Audioholics



only deeper, with at least 2x2 speakers side-firing, and turned on it's back, then mounted on wall

[speaker dave]

A couple of comments on the Jordan system.

He gets the delay line notion from the typical model of propagation delay as a series of sequentially linked masses and compliances. The electrical equivalent would be an L C ladder network. Such a ladder network would have a propogation delay, but at the same time it has to have a low pass nature. Converting it to a sequence of full range drivers with L's in between is not the same and is not exactly a delay line. Each L can provide phase shift but not without considerably response rolloff. In general you will get 3 dB of loss at every 45 degrees of phase shift. In other words it will be much better at rolling off treble (with more rolloff for each sequential unit) than in providing delay. It will not provide broadband delay from unit to unit so it can not operate as described.

Put this aside and consider a full active DSP based version of it. It would be easy to use this technology to give broad band sequential delay from unit. What would you achieve? In the end the sequential delay is identical to angling the far end of the delay further away in the room. Since you feed both the left end and the right end you effectivly have two lines with the left aiming towards the back right corner of the room and the right line facing back to the left. The effective angle comes from the ratio of lateral propogation speed to the speed of sound. The backwards tilt is simply the arctangent of the speed of sound divided by the lateral propagation speed. If they were equal, for example, the lines are effectivly angled back 45 degrees.

I'm not sure why this would be some ideal system. I guess part of the appeal is the thought that left and right are both fed to a common system and mixed signals radiate from some proportionate mid point. This notion is, of course, false.

As to modeling it, all multi-element line arrays are modeled by summing the vector output of each element with regard to the geometry between the various points and the observation point. Whether you have the backwards angled case or the electrically delayed case you would be modeling a conventional line array with a sequential phase rotation for each adjacent element. In the far field the two cases would be identical. In the near field they would be similar.

This was all explained in my paper on the subject.

AES E-Library Discrete-Element Line Arrays-Their Modeling and Optimization

David S.

[Elias]

Originally Posted by speaker dave

What would you achieve? In the end the sequential delay is identical to angling the far end of the delay further away in the room.

David S.

Of course they are not identical. Because of the front wall reflection is absent as suggested in the design. That will not happen if you start angling them across the room.


Why is this ideal:

It provides two horisontal plane waves crossing at the listening position. This is the principal and fundamental assumption of the stereo system, and it is satisfied with this design. Of course the wave front is not plain in vertical dimension, but stereo is horisontal only according to the scriptures.


- Elias

[graaf]

Originally Posted by speaker dave

A couple of comments on the Jordan system.

thank You Dave S.!

[graaf]

Originally Posted by Elias

Why is this ideal:

It provides two horisontal plane waves crossing at the listening position. This is the principal and fundamental assumption of the stereo system, and it is satisfied with this design. Of course the wave front is not plain in vertical dimension, but stereo is horisontal only according to the scriptures.


- Elias

this sounds reasonable!

[graaf]

Originally Posted by speaker dave

A couple of comments on the Jordan system.

...
What would you achieve? In the end the sequential delay is identical to angling the far end of the delay further away in the room. Since you feed both the left end and the right end you effectivly have two lines with the left aiming towards the back right corner of the room and the right line facing back to the left. The effective angle comes from the ratio of lateral propogation speed to the speed of sound. The backwards tilt is simply the arctangent of the speed of sound divided by the lateral propagation speed. If they were equal, for example, the lines are effectivly angled back 45 degrees.
...
Whether you have the backwards angled case or the electrically delayed case you would be modeling a conventional line array with a sequential phase rotation for each adjacent element. In the far field the two cases would be identical. In the near field they would be similar.

This was all explained in my paper on the subject.

AES E-Library Discrete-Element Line Arrays-Their Modeling and Optimization

45 degrees curvature to the back? sounds familiar... yes - now it's more clear, it sounds just like CBT of Don Keele!

now read this:

Originally Posted by gedlee

But neither is actually "constant directivity". CBT is only constant beam height, the horizontal is not constant but falls just like any piston source. IMO they should be placed on their sides, or better yet just make a constant beam width in both directions! Now there is an idea!

Originally Posted by rob g

On sides?

Like this:
Center Speaker

wow! doesn't it look familiar?



the curvature and power tapering in CBT array are just instead of a proper delay line

looks like old uncle Ted outsmarted the gurus of today as early as in 1971

outsmarted because He showed how to make such horizontal array for stereo not just for center channel speaker