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Tips on phantom center? UST use case

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tifune

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Can you reference a source for this “upside-down Dolby” technique? It sounds like it might be what I stumbled on: my center channel speakers array is similar to the Magnepan-championed “Tri-field Center” arrangement, with 3 dedicated center channel speakers, independent from the main front left and right channel speakers.

No source, just me. Because I have hardwood floors, I was thinking I could aim a "center" from above the screen to the first reflection point on the floor to create an effect similar to the upfiring Dolby speakers that have become popular. I have no illusions about the compromise there, and probably I'd be better off just pointing straight at LP, but doesn't cost a lot to try. Re: trifield, I'm not opposed to trying it but I think I'd need a processor capable (Meridian?) or more spare time + assistance than I have at my disposal.

I Did notice the UST leaves just enough gap between itself and the projected image that I can insert a kef HTF8003 on the screen's bezel pointed at listeners. Probably going to start there because it doesn't involve drilling holes, but hopefully something more elegant comes my way.

The key to this working well is, the near speaker’s output must fall off smoothly and fairly rapidly as we move off-axis. Earl Geddes, who I learned this technique from, has mentioned both 90-degree and 60-degree (-6 dB @ 45 and 30 degrees off-axis, respectively) radiation patterns as being well- suited for this application.

I believe my Kef R3's fall into this category? On average, what's a good starting point for how far in front the speakers should be aimed? As in, typically you start with aiming speakers at primary listening position. But seems as though I should go a few ft. ahead? Or just a few inches? I know room etc. play into it, just looking for a starting point.

If your receiver is trying to play on a non-existent center channel, it should be pretty obvious. At least in movies you'll hardly hear anything at all because 80% of the sound comes from the center channel.

its strange, so far the phantom center for movie/TV dialogue is picture perfect. Music, not even close. Haven't had enough time to experiment to get to the bottom of it
 

Duke

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I believe my Kef R3's fall into this category? On average, what's a good starting point for how far in front the speakers should be aimed? As in, typically you start with aiming speakers at primary listening position. But seems as though I should go a few ft. ahead? Or just a few inches? I know room etc. play into it, just looking for a starting point.

As a starting point, I would aim them to criss-cross about three feet in front of the "sweet spot". My impression is that the KEF R3 has a bit wider radiation pattern than is "ideal" for a time/intensity trading configuration, so you might need to try a bit more toe-in than that.
 

DavidMcRoy

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As a starting point, I would aim them to criss-cross about three feet in front of the "sweet spot". My impression is that the KEF R3 has a bit wider radiation pattern than is "ideal" for a time/intensity trading configuration, so you might need to try a bit more toe-in than that.

That’s interesting (and intuitive, when one thinks about it.) I started out with JBL 305P MKIIs all aimed directly at the listening position (LP), but gradually started toeing-out the left and right side dedicated center channel speakers some, just to sort of “optimize” room interaction. I found any significant toe-in greater than aiming directly at the LP created too much interaction with the screen and the front wall (the wall behind the screen, and too much toe-out causing excessive side wall interaction.) I’ve always found there’s a “sweet angle” for toe-in/toe-out in any given room and of course that’s speaker-dependent, too. In my case toeing out about 20° or so, or just slightly “in” from straight ahead is best. The JBLs are a constant directivity design, and actually pretty forgiving about all this, anyway.

When I was running an all Magnepan 5.1 system with Trifield center configuration, things were far more critical and ultimately less successful. I‘ve had day-to-day experience with Magnepan and Quad ESLs since the early 80s, so needless to say I’ve tried everything.
 
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DavidMcRoy

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No source, just me. Because I have hardwood floors, I was thinking I could aim a "center" from above the screen to the first reflection point on the floor to create an effect similar to the upfiring Dolby speakers that have become popular. I have no illusions about the compromise there, and probably I'd be better off just pointing straight at LP, but doesn't cost a lot to try. Re: trifield, I'm not opposed to trying it but I think I'd need a processor capable (Meridian?) or more spare time + assistance than I have at my disposal.

I Did notice the UST leaves just enough gap between itself and the projected image that I can insert a kef HTF8003 on the screen's bezel pointed at listeners. Probably going to start there because it doesn't involve drilling holes, but hopefully something more elegant comes my way.



I believe my Kef R3's fall into this category? On average, what's a good starting point for how far in front the speakers should be aimed? As in, typically you start with aiming speakers at primary listening position. But seems as though I should go a few ft. ahead? Or just a few inches? I know room etc. play into it, just looking for a starting point.



its strange, so far the phantom center for movie/TV dialogue is picture perfect. Music, not even close. Haven't had enough time to experiment to get to the bottom of it

I do use DSP to control level and EQ, and delay to within 0.5 cm, and changes in delay are quite audible on pink noise at 0.5 cm increments, manifesting as slight changes in ear pressure and the audible effects of comb filtering among the speakers.
 

dasdoing

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my Samsung TV seams to have the speakers on the bottom. and it sounds like that. but when I EQ it with REW the sound magicly seams to emerge from the middle of the screen
 
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