E. J. Jordan Delay Line

[speaker dave]

Originally Posted by Colin

I've just re-read the article and I think the delay line is a misnomer. I think it reads that the FR and polar response of the drivers is altered. There was a follow-up letter to the article a couple of months later (WW sent it to me when I requested the original article, years ago). This describes a single, 8 foot long box "Along this length and facing forward were placed five 6.5 inch high-compliance type speakers, with small centre cones … a purely resistive division was used between each speaker. The result is similar to the centre channel technique …

I think that makes a lot more sense. The resistive links would be a form of level tapering that would improve the polar response and would also get around the issue of one amplifier shorting the other. By "centre channel technique" I assume they mean like a 3 channel approach with resistors from L & R feeding the center channel, but in this case it would be split 5 ways rather than 3.

I'm not sure if this advances this thread. Rather than debate whether Jordan achieved it in 1971, it might be more interesting to see what can be done using computer techniques.

I think the One Limited (Hooley) paper shows much of what can be done with computer techniques. With a large array of drivers and a fine pitch from center to center you can create a broad range polar pattern in about any shape desired. They even give the user real time control for aiming the beams around during setup.

The One Limited intent is 5 channels in one box but you could use the technology for other things such as a nice surround only array, or front channels with purpose designed polar response. If you are familiar with Ken Kantors Magic (AR) speaker, you could define a more sophisticated version of that with a primary undelayed beam and multiple steered and delayed beams that mimiced the early reflections of an ideal concert hall.

Interesting stuff,

David S.

[Colin]

Hi David - I think the follow-up letter is referring to the centre channel technique in Jordan's article; which used two speakers back-to-back in the centre, relying on their off-axis HF roll off. He also describes a much earlier GEC system which had a single, forward-facing driver playing a mono signal at lower level than the LR speakers.

I'll have a look at the One Limited paper. It's of academic interest to me rather than any plans for a practical project. But very interesting.

[graaf]

Originally Posted by Colin

Rather than debate whether Jordan achieved it in 1971, it might be more interesting to see what can be done using computer techniques.

OTOH what Jordan achieved in 1971 is interesting from our diy perspective because it probably could be diyable today - which cannot be said about modern computer techniques - from our diy perspective they remain - as You have rightly put it:

Originally Posted by Colin

of academic interest ... rather than any plans for a practical project.

[Colin]

I'd have thought the average PC could work up something like this, or possible use some of the digital processing units now available to the DIYer.

But I can't help on that or the inductor fashioned idea - I'd be more inclined to take Ted Jordan's word for it and experiment further with the vertical arrays, which he said are superior anyway.