Hmm... good point! I've got a BruteFIR-based DSP with a web interface (to add/configure filters) here, so linear-matrixing is very easy to implement. All I need is an extra speaker. Which is sort of a problem at the moment.
Standard is simply 2-ch stereo.
For starters there is no need for DSP. All you need is stereo amplifier with common ground and some wire and use some of the passive schemes from this thread. For this experiment 3 speakers is a must, though. Looks like you have another task for the new year 😀
No I mean what is "the standard linear-matrix upmixing" method you did not find performing well ?
If I'm not mistaken it was Dolby Pro Logic (or perhaps Pro Logic II). I think the receiver was a Marantz SR-7000, but I'm not sure. It was about five years ago. I am still curious about trying centre derivations and/or ambience extraction methods, so yes, I have a new task for this year 😀
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Also please try the side wall setup I've shown. There's something "special" about this.
I've had my Nathan's set up in a standard ±30° stereo triangle away from the walls, with a 45° toe-in. The loud contralateral reflection had a detrimental effect on imaging. With the speakers directly at the wall, the problem is completely gone. The resulting reflection pattern seems to aid reproduction (spaciousness and depth).
One simply needs to experiment with toe-in to get the ratio between direct sound and first reflections right. I've also found that the distance from listener to speakers needs to be exactly the same and it's important the whole setup is symmetrical.
The whole front wall in my room is damped. Not sure how important this is.
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Apart from all the theorizing and “should works” and "special cases", is there any simple matrix technique that will, with a majority (or at least a substantial minority) of recordings currently available and over a reasonable sized listening area (not the “one chair in an otherwise empty room”) provide a consistent improvement in overall imaging and center channel stability when compared to plain old “standard” two channel reproduction?
Is there anything, that is, that you can simply “plug in”, add a center speaker, and expect “better” sound most of the time, and degraded sound rarely if at all?
If we include head turning and/or off center listeners, then any method is an improvement over the standard 2 speaker stereo triangle.
See posts #59 and #60 for a simple how-to.
- Elias
While this does improve the center image stability, simple center sum does not increase spaciousness but rather increase the 'mononity' of the presentation.
I think it is an additional advantage to cross feed negative signals to opposite side channels, too.
- Elias
@marcus
Are those FRS8s in the cardboard at the wall? Where is the nearfield bass crossed in?
I have also wanted to try 3"s in 45cm x 45cm carpet squares that I have lying around, and curve the square a little to terminate well in the corners, but I'm very pressed for time at the moment. 🙁
Are those FRS8s in the cardboard at the wall? Where is the nearfield bass crossed in?
I have also wanted to try 3"s in 45cm x 45cm carpet squares that I have lying around, and curve the square a little to terminate well in the corners, but I'm very pressed for time at the moment. 🙁
OK, here's from #59
Why would I want to put .5R in the left channel? How is that going to help anything?
Yes, those are FRS8's but I got it to "work" with Behringer P2031A's and B200's too. Very different speaker concepts. They simply differed in tonality but not in spatial properties. The important part is level, timing and spectrum of the reflections.
The near field subs are crossed in at 150Hz for the FRS8's.
I agree, but then it's no longer simple, easy to set up, and works well for everything.
There are two important benefits in doing so. First it maximises the signal separation between speaker feeds. Secondly it adds MS stereo side signal to side speakers.
It may help if you rewrite the speaker signals with help of MS stereo notations.
- Elias
Well, but have you forget your own post #60 ? What can be simpler ? 😀
It is simpler to wire the matrix of 0.5 than get summed center only 😉
- Elias
As it happens I actually own a Fostex M20RP MS stereo microphone . . . and even for recordings made with it things just. don't. work. that. way. Matrixing that works at the coincident microphone doesn't work with speakers 2 Meters apart. You really need to get past the simplistic "notations" and think about what really happens. If you can figure out how to make a "one speaker stereo" with driver spacing no greater than the microphone capsule spacing you might have something . . .
With more typical microphones and mixing it only gets worse . . .
No . . . the comment was more sarcastic than serious. MS matrixing only works when capsule/"driver" spacing is a fraction of a wavelength.
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