Auro-3D questions

[gene]

I agree with you completely. The latest Dolby DD p mixer is incredibly good. From two channel recordings it manages to reproduce the original acoustic with a realistic perspective from 2 channel audio.

Probably the best demonstration of how good it is, is this two channel recording by Tom Scott of his brother Jonathan playing Bach's Wachet Auf from St. Mary's Petworth. The flute division is on your immediate right and the reed plays from the division ahead. The right division is precisely located on your right and the reed right ahead, as it would if you where in the nave of the church. This could not be better even if it where are discrete five channel recording. I find this incredible.

I know you use center spread. However on this rig center spread ruins the effect. I get really good left right and center localization leaving it off. Not only that, this upmixer increases the sound stage depth of the recording, and on many good recordings the sound stage sounds wider then the speaker spacing. I never ceased to be amazed how good it is.

One other thing I have noticed is that this latest versions works on vinyl playback from my turntables. The previous one did not, and was prone to a curious pumping. I have not heard it with this current version.

Now I suspect results may vary, in that in my rig every speaker is very capable. They all sound really similar right across the acoustic spectrum except the last two octaves. Although five of them reach well into the last octave, and the mains all the way to 20 Hz. Although the center is deliberately conceived to be different to the mains, to give it a cone type dispersion covering the listening area. However when you walk across the front stage all three speakers sound identical and I don't think anyone would suspect they use different drivers.

I don't know, but I suspect you would not get similar results unless all speakers have a really smooth response from 80 Hz upwards. In addition all these speakers have an excellent sharp impulse response. I consider that important and often overlooked, and may be significant in causing this technology to work properly.

Yea The DSU is really magical. Thanks for the song tip.

In my theater room, my front soundstage is very closely matched since they are active speakers with FIR correction. I used anechoic data of the satellite and copied that filter for the left/right speakers. The center channel has it's own filter since the driver topology is slightly different. In my money seat, all 3 track extremely well above about 200Hz. Center spread off sounds OK to me for non vocal tracks but I feel you lose a bit of stereo separation with it turned off for vocals. It really takes a lot of info off the front left/right speakers in this case. Try disconnecting the center channel and listen to the mains toggling center spread on and off and see what you get.

 

[TLS Guy]

Yea The DSU is really magical. Thanks for the song tip.

In my theater room, my front soundstage is very closely matched since they are active speakers with FIR correction. I used anechoic data of the satellite and copied that filter for the left/right speakers. The center channel has it's own filter since the driver topology is slightly different. In my money seat, all 3 track extremely well above about 200Hz. Center spread off sounds OK to me for non vocal tracks but I feel you lose a bit of stereo separation with it turned off for vocals. It really takes a lot of info off the front left/right speakers in this case. Try disconnecting the center channel and listen to the mains toggling center spread on and off and see what you get.

Well our experience of the center spread with my rig using the Marantz 7705 is totally different.

I did these experiments, with good sources, however the most revealing were results from BBC Choral Evensong broadcasts.

With the center amps off, which I can do from the custom amp controller I built, with the center spread off, you only hear the echo of the celebrants voice in the church..

If you toggle center spread to on, then your hear a somewhat disembodied rendition of the celebrants voice, which is most unnatural.

With choir and organ, the organ which is central is much reduced, but the choir in the stalls either side sounds fairly natural. If you add center spread the organ is louder, but the choir not really changed.

Now if I switch off the mains and switch on the center speaker, the celebrant is heard, and not really changed turning on center spread, the organ and choir do not change significantly.

The same impression is with orchestral music, but in an orchestra there is a lot of sound in the center of the orchestra, especially woodwinds.

In my opinion, the Dolby DD upmixer does an excellent job of keeping the right, left and center sound sources discreet from well recorded two channel stereo mixes.

Now I did take spl. measurements, and the right and left mains no center gave an spl. 2 to 3 db. louder than the center alone, which is what I would expect.

Engaging all, seems not to significantly change the spl.

However, center spread with all amps on produces an unnatural sound balance. The celebrant's voice is not natural and does not sound like it would in the church.
Above all center spread collapses the sound stage, and worst of all brings the sound stage forward, and really spoils the realistic reproduction of the space.

This rig can really reproduce the original location acoustics uncannily well, and center spread really reduces that realism.

So in view center spread creates a very significant impediment to realistic reproduction. I strongly counsel against its use.

The other point I would make, is that the center of a sound stage frequently does have a large portion and often the lions share of the action.

Therefore a center speaker has to be accurate and powerful.

I admit, that my center is highly unique and specifically deigned by me, from first principles. It was designed to be powerful and have very low coloration, especially of vocals, to cover the listening area, and create minimal interaction with the mains, to keep the center information as discreet as possible over the listening area.
The crossover was among the most complex I have ever designed. So it is hard to compare this to other center speakers, as there is no close commercial equivalent that I am aware of. I certainly regard the design of this center likely the greatest challenge I have ever attempted.

In addition no equalization is used in this rig, other than voicing the BSC to speaker location in the room. As published before room curves are excellent and no FIR filters are engaged.