What we need now is someone explaining to the big masses why the tweeters are not at the ear hight aimed at the listener
oh yeah, good question!
is there any Snell's literature on "Type 1" out there?
I would have ot pull out my RT figures for my room and run the calcs again, but that was my recollection from the last time and also what others have commented on. Your curves with an 8 meter critical distance would be for a large hall, of course.
I have also done draw away response curves from a system in two rooms at PSB. Each curve was divided by the half meter response so it simply showed the response change due to varying room RT and speaker directivity (typical 2-way and typical 3-way tested). By 3 meters the reverberent field (probably direct plus reverberent) had only shelved down by 2dB.
Again, its kind of academic when the ear is so good at pulling out the direct sound.
David S
I find the whole concept of two channel stereo triangle as an academic excercise since it doesn't work very well in practise
By the way, it's very easy to demonstrate the perceptual weakness of direct sound as it can be overruled by few early reflections arriving several ms later. Looks like Haas effect or the law of the first wavefront should be updated
- Elias
You like it, that's all
scientifically it's a failure based on oversimplificating 19th Century theories of hearing and some hit-and-miss experiments from the first half of 20th Century which (in seeming corroboration of those theories) produced some good enough (...to sell) results
Stereo works OK in ideal circumstances but is something of a compromise. You only have to listen to a good binaural recording over headphones to realise what we're missing.
The BBC are currently conducting experiments in surround and their technical blog reported that four speakers were ideal for producing an immersive soundfield, with little improvement in directional cues if more speakers were used.
They've experimented with the Caldrec soundfield mic for many years.
I don't want to divert a valuable thread off-topic, so here are a couple of links which may be of interest:
BBC - The BBC Radio Blog: Whatever happened to surround sound for streaming Radio?
BBC - Radio 3 Blog: The Festival of Nine Lessons and Carols in surround sound
The BBC are currently conducting experiments in surround and their technical blog reported that four speakers were ideal for producing an immersive soundfield, with little improvement in directional cues if more speakers were used.
They've experimented with the Caldrec soundfield mic for many years.
I don't want to divert a valuable thread off-topic, so here are a couple of links which may be of interest:
BBC - The BBC Radio Blog: Whatever happened to surround sound for streaming Radio?
BBC - Radio 3 Blog: The Festival of Nine Lessons and Carols in surround sound
I have found a 1981 review of "Type 1", I believe that reviewers had read the marketing literature
it looks like Snell arguments for such design were similar to my arguments for a flooder - complete elimination of the single one worst room problem - the floor reflection - although He argued in terms of frequency domain and tonality whereas I argue in terms of time domain and spatial sound reproduction in the first place
Attachments
I believe that the main problem is not of a flawed recording technique but of a flawed reproduction technique
it is perfectly possible to raise the level of realism of reproduction of existing conventional stereo recordings with better - scientifically designed - loudspeakers setups
in other words - one only has to listen to a stereo dipole, for example, because apart from the floor reflection the big problem is stereo crosstalk - Linkwitz seems to understand this when He talks about "Optimizing the Phantom Source without XTC [that is "crosstalk cancellation"] & in a Room":
http://www.linkwitzlab.com/TMT-Leipzig'10/TMT-PP-Hearing spatial detail.pdf
interestingly, His proposition - the SEL setup ("stereo enhancement loudspeaker": WATSON-Stereo_Expansion_Loudspeakers ) - in his words: "not a CTC scheme, which requires cancellation, but (...) a left and right channel signal enhancement" is essentially quite similar in it's technical effects (increase of the level of the L signal on the left, and of the R signal on the right) to a flooder in Beveridge placement - the loudspeaker setup I have proposed here years ago
Last edited:
I have just come across this fascinating thread.165 pages!!! I apologise if this has been mentioned already, but it is an interesting idea to try if you have a room big enough (I haven't). It was an idea of a writer for audio magazines called Jimmy Hughe. I have heard his system and all I can say is that this idea works, although I know that 95% of people reading this will say that it can't work, and won't try it. He turned his speakers which were about two feet from the rear wall round so that they were pointing away from the listener, toed in so that the sound off the rear wall was directed towards the llistener. As I say you need a reasonably sized room and an uncluttered wall behind. I seem to remember that he discovered this by accident.
I find your description of "psycho" difficult to equate with the sound from Jimmy Hughes' system. What I found was that
a) the treble was still there (I assumed it would be lost)
b) the stereo image was improved
c) when the speakers were returned to their normal orientation the sound had a glare to it, not noticeable before.
Did the Bose speakers have no direct sound?
a) the treble was still there (I assumed it would be lost)
b) the stereo image was improved
c) when the speakers were returned to their normal orientation the sound had a glare to it, not noticeable before.
Did the Bose speakers have no direct sound?
of course they have
Bose direct/reflecting is an entirely different thing, with purely pseudoscientific, quite absurd "theory" behind it
In that experiment the speaker's stereo triangle locations remained unchanged and they were only rotated ?
I think better is to put the speakers close to each others (touching) in the center and facing towards side walls. This is a fine concept. If you like what you hear then you might find interest of integrating 3 speakers in one and use a linear matrix decoder to generate L-C-R stereo field in the room
- Elias
From memory, Jimmy Hughes's loudspeaker system was one of the Impulse designs, which featured a horn operating from 400Hz up. I built a similar DIY version from Wireless World some years ago which had the same mid-treble horn design.
The horn was quite directional so I can see that reflecting from rear walls would spread the sound somewhat. I'm not sure how applicable this technique would be to more conventional designs.
FWIW, I found the Wireless World design gave good stereo over a broad area without the need to have it facing away, although I never had them in a large enough room to try the Hughes trick.
The horn was quite directional so I can see that reflecting from rear walls would spread the sound somewhat. I'm not sure how applicable this technique would be to more conventional designs.
FWIW, I found the Wireless World design gave good stereo over a broad area without the need to have it facing away, although I never had them in a large enough room to try the Hughes trick.
Yes absolutely right, they were (and I think still are) Impulse H1s. I have tried this with a conventional design for a few minutes, and it seemed to be a benefit. If I had a room suitable to try it out, I would give it another go.
On the subject of ideas from the 70s does anyone remember an Alison? speaker that was a conventional shaped box, with which was mounted flush with the rear wall. It had the tweeter centrally mounted on the front face (baffle) and the bass/midrange mounted on the top? face right up against the wall (pointing upwards). The principle I think was that that both drivers effectively had wall loading. I have tried to find out about these and cannot find any reference to them. Have I got false memory syndrome?
On the subject of ideas from the 70s does anyone remember an Alison? speaker that was a conventional shaped box, with which was mounted flush with the rear wall. It had the tweeter centrally mounted on the front face (baffle) and the bass/midrange mounted on the top? face right up against the wall (pointing upwards). The principle I think was that that both drivers effectively had wall loading. I have tried to find out about these and cannot find any reference to them. Have I got false memory syndrome?
His room is very unusual. From memory, I would say it was about 15 ft wide (his walls are completely lined with cds; he used to do cd crits), and the room is about 30ft long on 2 levels. The speakers are on the lower level, and are near the side walls and about 2-4ft from the rear wall. He listens on an upper level about 4 or 5 steps up. The rear wall has a large window, and is flat. He has some pretty classy equipment. He was still doing equipment reviews for Hi Fi magazines until recently.