Perhaps it's ideal. I actually prefer the sound of DPL2 music mode, which has a width or front blend control, with less than the maximum separation that it can provide. I'm sure it's very speaker, room and listener dependent.
catapult said:
I remember looking at the schematic of a Dolby decoder in a cinema I used to work in. IIRC, it did pretty much that - extract the center from L,R then subtract the center from L,R. All done with opamps. Just how perfect it was, I don't know. Just how perfect does it have to be? Seemed to work pretty well.
FWIW, I like L-C-R, too. Stereo is a nice compromise, but perfect it is not.
Patrick,
"I'm trying to decide if it's worth $88 to find out if that will create the "ultimate waveguide", I have an XT1086 sitting here..."
There's a fellow (penngray) at AVS who made the same offer that I did, so it wouldn't cost you anything.
Does anyone know if any of the available horn s/w can analyze axi-asymmetric geometry?
Or import a 3-D shape and analyze?
I could make another (better) plug of the XT1086 and get it digitally scanned.
"I'm trying to decide if it's worth $88 to find out if that will create the "ultimate waveguide", I have an XT1086 sitting here..."
There's a fellow (penngray) at AVS who made the same offer that I did, so it wouldn't cost you anything.
Does anyone know if any of the available horn s/w can analyze axi-asymmetric geometry?
Or import a 3-D shape and analyze?
I could make another (better) plug of the XT1086 and get it digitally scanned.
If anyone is interested, I have some detailed insight of James Bongiorno's "Trinaural" (a subset of the "Optimum Linear Matrix", as described by Michael Miles). Could even give you the detailed schematic (but I won't, of course. I respect IP).
Basically it's an an ultra-simply analog matrix, completely LTI (if you have balanced connections, 13 resistors will do it damn close to the real thing). And it works like charms... I swear. It creates an artifical but very supportive (for the illusion that stereo is all about, anyway) sensation of a different vertical size/expansion/pattern, giving way more seperation between instruments and between direct and reverberant sounds (as encoded in the recording). It not easy to describe that in words (for me as a non-native speaker, at least).
And the sweet spot is huge (laterally). Toe-In of speakers (that is, "trading" as the effect in stereo psychoacoustics is called, compensating dT with dL) doesn't work for me at all to widen the sweet spot. It still is pretty balanced stereo in the lower registers, but all sensation of space is lost. Sondstage collapses to a straight 1D line between the speakers.
But not in this thread. Better we go here :
http://www.diyaudio.com/forums/showthread.php?threadid=116300
- Klaus
Basically it's an an ultra-simply analog matrix, completely LTI (if you have balanced connections, 13 resistors will do it damn close to the real thing). And it works like charms... I swear. It creates an artifical but very supportive (for the illusion that stereo is all about, anyway) sensation of a different vertical size/expansion/pattern, giving way more seperation between instruments and between direct and reverberant sounds (as encoded in the recording). It not easy to describe that in words (for me as a non-native speaker, at least).
And the sweet spot is huge (laterally). Toe-In of speakers (that is, "trading" as the effect in stereo psychoacoustics is called, compensating dT with dL) doesn't work for me at all to widen the sweet spot. It still is pretty balanced stereo in the lower registers, but all sensation of space is lost. Sondstage collapses to a straight 1D line between the speakers.
But not in this thread. Better we go here :
http://www.diyaudio.com/forums/showthread.php?threadid=116300
- Klaus
KSTR said:
Klaus
This, of course, only works if the speakers are CD that drop off in level at the correct rate with angle. If you do it with any other type of speaker - which is about 99% of the market - it won't work.
Trading is signal dependent. So 99% becomes 100%.
Earl, which trading data did you use? The data from Haas?
Best, Markus
Earl, which trading data did you use? The data from Haas?
Best, Markus
Yes Earl, I know and one set of my speakers are as non-CD as it gets -- simple passive JBL 3-ways. The other, Tannoy coax nearfields are a bit better. I tried to correct for that (and my room is really dry acoustically except for the bass region) by iteratively lowering the level of the closer speaker to the point of best performance, wich wasn't any good. I also counterchecked the situation by staying in the optimum sweetspot and changing level and delay electronically, which is more or less the same situation (ok, there are some minor differences in the crossfeed xfer functions). The problem with the collapsing soundstage remained, in spite of my personal trading curve that I found this way (using wideband music signals. Markus is right with the signal dependence, no way to "trade" a centered cymbal or a picolo flute with regular stereo. Trinaural does much better in this regard for obvoius reasons, even with non-trading-optimized speakers). My stereo sweetspot for best evolvement of spacial sensation is really small, something like 2" in either direction. But maybe my hearing preferences are overly critical in this regard, compared to others, and maybe speakers with a radiation pattern that creates the correct trading relationships would indeed work better. No "hard data" as you like to say, just the impression of what happens in my specific situation.
- Klaus
- Klaus
My experince with my setup is that, if exact center is 100%, then left and right about 4 feet are still 85-90%. There is very little change across the seating area. The large number of auditioners also confirm this as almost everybody comments on it. The fact is that over an area of about 10 feet by 10 feet, there is very little change in the image or tembre at all.
Markus
I didn't use anybodys data, but if I did I would use the chart in Spatial Hearing.
Markus
I didn't use anybodys data, but if I did I would use the chart in Spatial Hearing.
Are there any trading curves in "Spatial Hearing" that derive from experiments using loudspeakers instead of headphones?
I'm speculating here but trading curves might differ more from person to person than psychoacoustic data suggests.
Don't you use a center speaker in your setup?
Best, Markus
I'm speculating here but trading curves might differ more from person to person than psychoacoustic data suggests.
Don't you use a center speaker in your setup?
Best, Markus
markus76 said:
A) the ones in that text used headphones.
B) I do use a center channel in 5.1, but I have been leary of using a derived center channel until I know more about HOW they are done. The simple vector steering does not sound like a good idea to me.
gedlee said:
Values for headphones and loudspeakers are completely different! Here's data from Haas and Meyer/Schodder for loudspeaker playback – Patrick might want to add this to his diagrams:
An externally hosted image should be here but it was not working when we last tested it.
Best, Markus
P.S. Data from deBoer is "Equivalence" not "Trading".
gedlee said:
Thank you for this post, Earl. It is quite helpful in clarifying the context of your work.
gedlee said:
What waveguides were they working on at the time? That seems to be about when JBL first introduced elliptical oblate spheroids into production:
http://www.jblpro.com/catalog/support/getfile.aspx?doctype=3&docid=1366
ZilchLab said:
In the early 90's, thanks to John Eargle, JBL paid for me to file a patent on my OS work. However, a glitch in the works prevented it from issuing and it was abandoned, which is why the OS waveguide is in the public domain. I did not work directly with JBL at the time, but there is little doubt that the concepts in my work and the patent application were reviewed at JBL and utilized in their work. It would have been necessary for them to work independently of me for the simple reason that it was all my work. Had I worked with them and we came up with something, they would not have been able to patent it very easily. This is one reason why corporations hold consultants at arms length.
Just to be sure I understand you, you're saying that they could not patent it because it was mainly or entirely your work? Did you consider or did they offer to buy you out or buy into a joint deal, if you don't mind my asking?
Pete B.
Pete B.
No, of coarse they could have done that had they wanted to. But remember, only the inventor can get a patent. Others can own it but only I could patent it.
There was an error in the original filing that was missed until it was too late to file a "continuation". Thats because it had been shown publicly and the error was not discovered until after the one year lapse.
This probably could have been resolved, I dont know for sure, but JBL saw it as more expense than they had originally expected and bowed out. I could not afford to prosecute it further.
There was an error in the original filing that was missed until it was too late to file a "continuation". Thats because it had been shown publicly and the error was not discovered until after the one year lapse.
This probably could have been resolved, I dont know for sure, but JBL saw it as more expense than they had originally expected and bowed out. I could not afford to prosecute it further.
gedlee said:
I was unaware of this. I always presumed that you dropped it because you once mentioned that you found the curvature was previously known. Something about a paper way back in the 30s or 40s?
pooge said:
That is true, but there were patentable aspects as I recal. It was all nearly 20 years ago and I'm a little rusty on the details, but I believe it had to do with actually mating an OS contour to an existing driver. That was never discussed in the prior art.
The Peavy "Quadratic Waveguide" patent is actually nothing more than an easy way to do this using a circle instead of a true OS contour. It was discovered when Peavy found that the true OS was difficult to draw in a CAD package of that erra and that a simple "fillet" was pretty close. SO they patented that as if they had actually found a new profile! This patent is a classic example of a waste of time because it claims a throat of 0 degrees, which it isn't in any driver, and the correct "Quadratic Waveguide" (one starting at 6 degrees) wasn't claimed at all
So getting around this patent is as easy as just doing it right!!MethMan said:
I don't know.
Digged deeper and found that trading curves change with level (Blauert "Spatial Hearing"). Furthermore Blauert reports that in trading experiments multiple sound sources were perceived. Looks like there is no single number that describes interaction of interchannel level difference and interchannel time difference.
Best, Markus
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