It can of course be done actively but as I said not with a reasonable solution. In order to achieve a delay od 300us that is flat up to the highest audio frequencies you need an allpass of about the twentieth order. => not for the faint at heart and definitely not very advantageaous for signal quality (=> noise and distortion).
Even worse: you will have to use the same thing again for the delay between 2nd and third driver and again between 3rd and 4th and ......... You see what I mean ?
Now do this one in passive ! Just some hint: Signal loss.
Regards
Charles
Even worse: you will have to use the same thing again for the delay between 2nd and third driver and again between 3rd and 4th and ......... You see what I mean ?
Now do this one in passive ! Just some hint: Signal loss.
Regards
Charles
I see, how about delay of 0.3 ms flat up to, say, 1500 Hz?
would it be more feasible?
regards
graaf
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thank You!
it's interesting because it reminds me of the thing showed below which, it's weaknesses aside, proves that stereophonic highs are not necessary for stereo imaging, the tweeter is just summed L+R
so perhaps it could be that Jordan delay array was effectively mono L+R in the highs yet it was capable of soundstaging and imaging as claimed?
it's interesting because it reminds me of the thing showed below which, it's weaknesses aside, proves that stereophonic highs are not necessary for stereo imaging, the tweeter is just summed L+R
so perhaps it could be that Jordan delay array was effectively mono L+R in the highs yet it was capable of soundstaging and imaging as claimed?
An externally hosted image should be here but it was not working when we last tested it.
So once it has been shown that 300uS delay over the full bandwidth is impractical both analog actively and most certainly passively, you back track to a device that is only uniform delay up to 1500Hz, missing nearly 4 octaves? And even at that, a 4th order passive delay line would be quite complex, especialy since 20 of these would be required.
As for my experiments with the line source, I don't know how you get the idea that an equal delay applied sequentially between the discrete drivers produces a curved wavefront. It produces a plane wavefront angled backwards at an angle determined by the total delay.
This was all discussed in Walkers ariginal electrostic articles in Wireless World.
My experiments were somewhat limited in scope admittedly, only a 6' line, not 10', but I tried both crossing them in an X arrangement and also put into a simple V arrangement, end to end, and I listened both close in and far away.
In the Jordan paper that was referenced, he doen't even show a direct implentation of a true delay line. He shows the center part of the line source facing down, with the extreme left and right drivers facing forward. Those extreme drivers left and right would almost certainly improve stereo imaging, as they would act substantially as a conventional stereo pair, particularly as the line source drivers, facing downwards, would have very little treble energy radiating forward.
I just don't see from his publication how what he shows matches the theory he espouses.
As for my experiments with the line source, I don't know how you get the idea that an equal delay applied sequentially between the discrete drivers produces a curved wavefront. It produces a plane wavefront angled backwards at an angle determined by the total delay.
This was all discussed in Walkers ariginal electrostic articles in Wireless World.
My experiments were somewhat limited in scope admittedly, only a 6' line, not 10', but I tried both crossing them in an X arrangement and also put into a simple V arrangement, end to end, and I listened both close in and far away.
In the Jordan paper that was referenced, he doen't even show a direct implentation of a true delay line. He shows the center part of the line source facing down, with the extreme left and right drivers facing forward. Those extreme drivers left and right would almost certainly improve stereo imaging, as they would act substantially as a conventional stereo pair, particularly as the line source drivers, facing downwards, would have very little treble energy radiating forward.
I just don't see from his publication how what he shows matches the theory he espouses.
why not?
I am just trying to understand because I do not assume - as You seem to implicitly do - that Jordan was simply making false claims - I can't see any reason to simply discredit such renown engineer, can You?
therefore I am trying to understand, looking for possible explanation, is it ok?
yes, complex, expensive but feasible
my intention with the scheme was to illustrate a curved line source not a curved wavefront, the scheme was not clear - I apologize
why a curved line source and not just angled back? well, You tell me please - why Keele's CBTs are not just angled back - curved back instead?
it was a popular article - not patent application, right?
I think that we - Colin and me - have given enough reasons explaining why this popular article could be intentionally unclear
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And lets not ignore the most obvious one, that he never made the unit work as described.
He speaks of a sequential delay line but neither the diagram nor the text imply that he understands what would truly be required.
Jordan was a good driver designer and seemed to know his way pretty well around a woofer equivalent circuit. He designed products that enthusiasts still love. That he wasn't much of a network designer and didn't understand delay lines is perfectly okay.
David S.
yes, not as described in the popular article
but custom installed units that worked as declared were certainly built - Colin remembers Jordan's advertisements of such custom installations
yeah! smart move, isn't it? like yeah I know exactly what to do but no I won't tell You how to do it - You have to pay for such expertise
Let's not put Him in the coffin to early - please don't be scared too much but He is still alive and still designs!
are You sure? ask Tony Hooley!
who? Andrew? Are You so blinded by Your negative attitude that You missed the fact that the excellent One Limited paper had been linked by Yours truly and that the first reference in it is Jordan's article from the subsequent 1971 issue of Wireless World?
geezz - how can there be any meaningful discussion with people of such negative attitude?
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One Limited is the company associated with the Hooley paper you referenced. Note that Hooley briefly mentions Jordan in the text as previously discussing an array like loudspeaker. No details are given. It is conventional in writing such papers to cite the earliest paper you can find that references your topic. It doesn't speak to the development of the invention.
Hooley actually developed the speaker that Jordan dreamed about.
Here is an interesting interview with Jordan. He mentions a conventional vertical array with 4 of his units (no delay, or even level tapering mentioned) and also talks of PA line arrays.
TNT-Audio inter.views Ted Jordan
But oddly no mention of his greatest invention, the dual ended progressive delay line. Still being coy about the details after all these years.
David S.
Hooley actually developed the speaker that Jordan dreamed about.
Here is an interesting interview with Jordan. He mentions a conventional vertical array with 4 of his units (no delay, or even level tapering mentioned) and also talks of PA line arrays.
TNT-Audio inter.views Ted Jordan
But oddly no mention of his greatest invention, the dual ended progressive delay line. Still being coy about the details after all these years.
David S.
but normally You won't use as reference in an article concerning delay lines an earlier article by someone who wasn't much of a network designer and didn't understand delay lines?
it is symptomatic how You try again to depreciate Jordan by saying that Hooley mentions Jordan as previously discussing an array like loudspeaker when in fact it is not just an array like loudspeaker but much more specifically phased-array antenna-like array loudspeaker
what is wrong with You? problems with self-esteem? You just cannot live without depreciating other people?
Is He questioned about it?
furthermore - He couldn't claim any invention because He hadn't got any patents. Why not? Who knows - I gave possible pratical explanations somewhere above.
It happens that I know a bit about patent law and IP protection strategies and I can say that patenting is not always an optimal IP protection strategy, sometimes it is much more convenient to protect IP as a trade secret (know-how)
besides Jordan's measure of greatness is perhaps different than Yours - it is not to impress as many professional colleagues as possible but to make high quality music reproduction available to as many music lovers as possible
from such - perhaps old fashioned - perspective anything pricey and custom installed simply cannot be the greatest
Attachments
Those pics are interesting. The stereola was the product from the advert, as far as I recall, but I suspect it's not a delay line. It's four drivers a side, which is Jordan's preferred series/parallel arrangement for his current, vertical arrays.
Jordan talked of running the drivers facing down (or up in the case of the ones in the pic) to roll off HF. That would give something like a centre channel speaker used in home theatre today; stereo either side, mono in the middle.
Jordan talked of running the drivers facing down (or up in the case of the ones in the pic) to roll off HF. That would give something like a centre channel speaker used in home theatre today; stereo either side, mono in the middle.
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but with Stereola there is nothing to install and You have said that You remember
the japanese description strongly suggests that this is not the case - the Japanese guys took a look inside and they say that the drivers are not driven fullrange but that they "are all connected to different networks"
I see, he is holding back details on his greatest invention until he patents it.
I'd suggest he should get going on that.
David
Found a patent for the system that I remember having read about (in German though):
Arrangement for the acoustic reproduction of signals, presented by means of a right and a left stereo-channel.
Jordan is also mentioned. I wonder how they achieved the delay in these days.
Regards
Charles
Arrangement for the acoustic reproduction of signals, presented by means of a right and a left stereo-channel.
Jordan is also mentioned. I wonder how they achieved the delay in these days.
Regards
Charles
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You think there would be significant market for such a loudspeaker system (expensive, custom installed)?
well, apparently there wasn't, and perhaps it was the main cause of demise of the project,
and costs of patent protection are substantial, and were even more substantial in the 70s
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Tape loops?
Yes, that looks exactly like an active implementation of what Jordan had described.
I have no doubt that an active implementation could be made to work, but will say again that it will perform the same as two crossed line arrays, arrays in this case alligned parallel to the wavefronts he shows in his diagram.
We should also consider what happens with a mono signal. It becomes two crossing angled wavefronts, not a special wavefront eminating from the center as some seem to think. All of the interference usually noted for listeners sitting off the center line will remain.
David S.
Some further info: The Braun system was called Holophonie. A newer expression for the same thing is "Ambisonics".
In the patent they write about "delay ICs". At this time these must have been of the bucket brigade type. These were often used for sound effects back then.
Regards
Charles
In the patent they write about "delay ICs". At this time these must have been of the bucket brigade type. These were often used for sound effects back then.
Regards
Charles
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Re the Stereola - if someone read the WW article & contacted Jordan direct, they could presumably get details to build it. I'm not sure if he was selling consultancy or drive units in those days. The article from WW in Nov 1970 mentions working with a Leicester company on a titanium cone fullrange unit.
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 … The effect of this system is astonishing to listen to. As with Mr Jordan's phase delay technique it is possible to stand at one end of the enclosure and be 'run over' by the train … The most notable feature is the increase in 'breadth' and definition, when listening to a large orchestral piece."
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.
As stereo imaging is a strong interest of mine, I've also been reading up on Edgar Choueiri's work on 3D sound from just two speakers. There's a good intro on the Princeton University site which may be of interest:
3D3A Lab at Princeton University
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 … The effect of this system is astonishing to listen to. As with Mr Jordan's phase delay technique it is possible to stand at one end of the enclosure and be 'run over' by the train … The most notable feature is the increase in 'breadth' and definition, when listening to a large orchestral piece."
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.
As stereo imaging is a strong interest of mine, I've also been reading up on Edgar Choueiri's work on 3D sound from just two speakers. There's a good intro on the Princeton University site which may be of interest:
3D3A Lab at Princeton University
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