do you get any front to back soundstage?

[Stereo Mic]

I think Anex is saying that you optimise the Stereo image by using the 60 degree rule. I can't see it in Blumlein's patent so there goes another audio myth unless someone else can see it (it's Pat no. 394,325)! But anyone who tries listening in the classic equilateral triangle seating position will apreciate that the stereo image clicks into focus.

Now if you sit further away and toe the speakers slightly out, I wonder if you get a similar result? Logic suggests you would as far as I can see, although by increasing the distance, the likelihood is that you increase the room interference. I can't see how the AP positioning results in a solid image, although I can see how it exaggerates seperation.

 

[zanash]

Bub....naughty bub .....I didn't say that and you know it! I don't pretend to have all the answers. I know what I hear and understand the physics, thought don't think getting wrapped up in an argument over semantics will actually help the thread.

Paul that is the best explination as to what I and other experienced. The dealer who was doing the demo had no explination, though had been at similar demo back at quad hq a couple of years previous , if my memory serves.

I tried the head tilting, head back made the percived image go low. Head up made the percived image go high. In other words as the ears moved through an arc the actual image remained in the same place.....my wife said what she heard had remained completely still ?

 

[The Devil]

yawn.

 

[tones]

http://www.doramusic.com/patentdetails.htm is a start.

Full text is now available for most things on the EPO's Espacenet service. If you know the number, it might well be there.

 

[oedipus]

The easiest way surely would be to get hold of the Alan Blumlein patent from 1931.

A patent is just a number allocated by a government body. A patent means that you've paid some lawyers quite a lot of money to have some legal text approved by some government lawyers.

You'll find quite a lot of "snake oil" has been approved by the various Patent Offices.

On the other hand, a paper in the JAES is peer reviewed by scientists and engineers.

 

[Stereo Mic]

Oedipus,

we are discussing the requirements laid out for optimum stereo playback by the accepted founder of the system.

Now if that has been shown to be hocum, I'm sure there will be an AES paper showing where Blumheim went wrong.

 

[zanash]

Oh dear bub ...lost for words? Perhaps a few constructive comments to help the thread along ....but no you post "yawn" well that certainly lets everyone know where your coming from.

oh yes and that patent everyone is looking for ....

http://www.doramusic.com/patents/394325.htm

 

[zanash]

interesting reading...............

http://www.ambiophonics.org/index.htm

 

[oedipus]

Now if that has been shown to be hocum, I'm sure there will be an AES paper showing where Blumheim went wrong.

Merlin,

I'd rather Anex posted references to AES journals containing the "Stereo Equations" , or other material which shows where Blumlein went right.

 

[Stereo Mic]

Datty,

I'd rather you posted references showing Blumheim was wrong, surely something any self respecting member of AES would be proud to prove?

 

[oedipus]

I'd rather you posted references showing Blumheim was wrong,

I expect that whatever Blumlein did say was right

Blumlein did calculate that for phantom imaging to work (and this is what a true soundstage is), the 60 degree angle (30 degree to the normal) was optimium.

And the issue at hand is whether Blumlein actually did say that, or that it can be inferred from his work, or that someone else has shown this to be the case.

 

[Stereo Mic]

Two-speaker stereo is capable of quite good low frequency localisation ââ'¬â€œ the theory of which was understood by Alan Blumlein in 1931. However, this localisation is somewhat unstable when the listener moves or rotates his/her head. As the speaker separation is widened beyond the usual 60° angle subtended at the listener, this poor stability of phantom images markedly worsens, leaving the famous 'hole in the middle' and also in images that can be perceived as being elevated as discovered by de Boer at Philips in the 1940s.

Oedipus, that's the closest I can get from the internet. It's from a paper by Michael Gerzon. Now if you disagree with it, or indeed have contradictory information from AES, please do let us know.

Otherwise, I fail to see a point to your questioning other than to suggest Blumlein never said anything, something already hinted at by me earlier. That is of little importance if the great minds like Gerzon's and those at AES happen to agree with the theory is it?

 

[oedipus]

Oedipus, that's the closest I can get from the internet. It's from a paper by Michael Gerzon.

Which paper? you need to give the Title and Journal...

I'm interested in what they actually said which is why I'm asking for a reference to a specific paper.

Otherwise, I fail to see a point to your questioning

My point is to get you (and others) to stop handwaving when you refer to other peoples work and actually provide a proper reference.

 

[Stereo Mic]

Oedipus,

Please read the patent. It is fairly clearly laid out in it of you know what you are looking for. We can't do all the work for you!

As this patent is widely accepted as representing the discovery of stereo, and as no one has come forward to dispute any of the equations in 75 years, I would have thought it might pass muster even with you.

 

[oedipus]

I can't see it in Blumlein's patent so there goes another audio myth unless someone else can see it (it's Pat no. 394,325)!

Please read the patent. It is fairly clearly laid out in it of you know what you are looking for.

You seem to be having trouble with the patent yourself...

We can't do all the work for you!

I don't want YOU to do any of the work for me. It's why I want you to supply the proper reference to Gerzon's work..

As this patent is widely accepted as representing the discovery of stereo, and as no one has come forward to dispute any of the equations in 75 years, I would have thought it might pass muster even with you.

Do you even have the equations? They are not in the link Joel posted. They are in the AES reprint of the patent though

The equations are not in dispute. What is in dispute, is the interpretation you are attempting to place upon them.

Provide the link/reference to the Gerzon material so we can see if you've completely mangled what he said...

 

[Stereo Mic]

1. Blumlein's calculations are based on the assumtion that the distance between the loudspeakers is no greater than the distance from speaker to listener. Therefore the widest possible soundstage is acheived where exactly?

2. I posted Gerzon's words verbatum.

Once again, and for the last time, are YOU disputing the interpretation that I, Anex, Gerzon, and most hifi writers have attached to the subject and if so, please produce the evidence to counter.

 

[Paul Ranson]

Are these 'The Stereo Equations' that our young friend introduced and then declined to show? What do they say about speaker toe in?

I infer from the reluctance to elucidate, the inability to reference and the retreat to the authority of a lecturer that they don't show what was claimed.

Paul

 

[oedipus]

1. Blumlein's calculations are based on the assumtion that the distance between the loudspeakers is no greater than the distance from speaker to listener.

As you like quoting people verbatim, please quote the text in Blumlein's patent that makes that assumption...

2. I posted Gerzon's words verbatum.

I want to see the context out of which you extracted it.

Once again, and for the last time, are YOU disputing the interpretation that I, Anex, Gerzon, and most hifi writers have attached to the subject and if so, please produce the evidence to counter.

Anex is refusing to play ball.

You haven't provided a reference to what Gerzon said, so we can rule him out of the game too.

Hifi writers, well, it's hard to know where they get there ideas, and whether they are (mis)interpreting Blumlein, so you can leave them out of this.

In summary, you are on your own.

 

[7_V]

I'm coming to this thread late as my phone lines have been down and I've had no Internet connection for a week (I'm convinced that BT are the worse company in the country). Anyway, with apologies if I've missed anything as I haven't had time to read the whole thread yet but I would like to add my 2p worth...

For some time I've been aware that there is a discrepancy between my preferred cabinet theory which says that a cabinet should be dead and non-vibrational and my belief that some speakers which have ignored this 'rule' have an added realism in practice. Bosendorfer has recently released a speaker with a 'sounding board' (or 'horn resonator') - unsurprising for a piano manufacturer - and they claim they get greater depth in the soundfield as a result.

It could be that Bosendorfer are the first to use this sort of principle in a hi-fi loudspeaker but they certainly won't be the last. In fact the new Seventh Veil speaker will also utilize something in this vein, albeit taking a very different approach.

The way that moving coil loudspeakers disperse the sound is not the same as the way sound is dispersed from actual musical instruments. Taking the piano as an example it's apparent that a fair proportion of the sound emits from vibrations in the piano cabinet itself and the dispersion of a panel of a grand piano is more similar to the dispersion of an NXT speaker than to a moving coil device.

I have experimented with the 'Layered Sound' approach which uses an NXT panel in parallel with the moving coil, albeit at a lower volume. While holding the volume of the NXT at a level where no tonal difference can be heard whether it's on or off, a difference can be heard in terms of soundstage and realism. I am now convinced that this is something well worth doing and so will be including an NXT panel (plus digital amp) built into the stands of my new speaker. I will happily invite ZG members to audition the new design before I release it to the general public, in case anyone's interested to see and hear them.

Meanwhile Rory, if you want to experiment with this, buy a pair of NXT speakers with a digi amp (or similar) and run these in parallel with your main pair of rather interesting looking Vaessens. You need to be able to adjust the volume of the NXTs. With the volume of the NXTs below that of the moving coil speakers, quality is not quite so important so price can be kept reasonable.

 

[7_V]

Now I've read the whole thread I'd like to make a minor comment on the (slightly silly) toe-in/Blumlein right or wrong debate.

1. How far are the speakers (however they are 'toed') from the walls? Surely the timing and proportion of direct to reflected sound will be crucial here. For example, speakers listened to nearfield in the middle of a large hall will sound far more 'stereo' than speakers which reflect off back or side walls.

2. The frequency has a large effect. Deep bass cares little whether speakers are toed in or out while high frequencies are very sensitive to such things.

Regards
Steve

PS: Blumlein was a genius - one of the few in the field.