"Official" Audyssey thread (FAQ in post #1) - Page 607

Hi Gary,

Yes, in the first quote Sanjay is agreeing with you and I, extolling the virtues of 7.1 matrixed surround decoding.

In the later quotes he is responding to my question (see my previous posting) asking whether today's version, of 7.1 "discrete" has some advantages over 7.1 matrixed surrounds, and as Jeff states "extolling the virtues of 7.1 discrete mixes with rear surrounds".

The two opinions are not mutually exclusive.

Larry

Thanks. Now (mostly) unconfused.

Hi John. Yes if you want DynEQ you must renounce the tone control. Again, reference vs preference. However, if you disable DynEQ (no green light, no red light) the Audyssey and Flat curves are available and do allow the tone control to operate. I have not found that desirable and always have DynEQ engaged on my 2809. If you want more bass, there are ways to do this. Normally I would suggest just turning up the SW channel with the remote but in your case with the ext xover I'm not sure how to best accomplish this.
I assume the fronts are run as Large? Perhaps with more details the expets can assist.

John -- it seems the best solution would be to abandon the "5.0" setup and external crossover, and simply switch your dual subs to the SUB OUT channel. They will benefit from the higher rez filters in the sub channel, and then the receiver can set the crossovers as needed for the fronts. Then you can manage the SW volume separately from the other channels.

Hi Jeff,

In either case, 1)with surround back speakers, or 2)with side surround wrapped around back, aren't they departing from the ITU standard?

I know large venue screening rooms can be setup like commercial theaters with surrounds wrapped to the back, but I thought dubbing stages were supposed to conform to the ITU standard, but perhaps I have that wrong.

Larry

Larry, I believe that your research/googling has shown that the various players', e.g. THX, Dolby, ITU, Audyssey, etc, polar graphs for system layout all differ by, umm . . degrees. So pointing to one "standard" as THE standard seems questionable.

Jeff

Right. Discrete channels have always had the advantage over matrix derived channels. Certainly that's nothing new (nor confusing). Likewise, being able to independently mix dialogue, music & effects using professional tools has advantages compared to applying consumer surround processing to a composite soundtrack.

Hi Jeff,

You may be right, there may be some latitude. However, one clarification, regarding my references to THX and Dolby, they were specifically discussing the layout of 7.1 home theater speaker locations for playback. My previous question dealt with speaker locations for mixing, and I believe that standard is still limited to 5.1 speakers.

Larry

Good stuff.

What is not covered here, though, is how well humans deduce phantom (virtual) images from pairs of loudspeakers placed around the head. For example, the ability to resolve between the L/R speakers is very good, and there are those who say a center speaker is superfluous.

How about between L and Lb? It's not nearly as good, as we don't have ears on front/back of our heads. Across the back it's somewhere between these two extremes. What shall we conclude from this? If we want any kind of reliable localization of sounds to the sides, then we'd better put a speaker there. If we put the surround speakers at the sides (the poorest location for phantom imaging), then we have no means to create cues to the rear. Ok, better put some speakers back there, too. Hence, 7.1.

Whether one has to devote a dedicated delivery channel from the mixing stage to each speaker is a wholly separate matter. Accurate spatial coding does not require such extravagance. I submit that we see current 7.1 mixes doing it that way as they have no other thoughts or abilities to use the 7.1 platform to better purposes. That will change as the art improves.

Hi Roger,

Thanks for your insights.

Would you mind briefly elaborating on the paragraph quoted above? I naively assumed that to facilitate mixing 7.1 discrete content, a re-recording engineer ideally needed to be monitoring at a 7.1 mixing stage. Do you feel that the current method is good enough for the foreseeable future and having a 7.1 mixing stage would add little to the final product?

Thanks.

Larry

I remember reading something about the early days when the thinking (Holman's?) was that dipole surrounds would produce a diffuse soundfield and NOT pull the listener's attention from the screen by producing pinpoint sounds. So, do we really want precise sounds from the rear?

To me, this whole discussion (not you personally, Roger) implicitly endorses the concept of the "WIDE" speakers, and a 9.1 setup of [7.1 + WIDE] seems to resolve a lot of the compromises. Especially when we take into account how human hearing is more sensitive across the horizontal plane.

All of the arguments for why people love their rear surrounds in 7.1, seem (to me) by extension also to logically endorse the idea of adding two extra speakers between FL/FR and the surrounds. Close that spatial gap and remove the need for certain compromises between phantom imaging and discrete localization.

When will we get IMAGES all around us???

When we head down to the local Omnimax theater.

LOL ... The reason I finally added the rear surrounds was because of "Resistance FOM." When I went to HDMI from the PS3, I wanted to make sure I could hear all of the tracks from the 7.1 mix. ... No nasty Chimerae silently sneaking up behind me.

Very true. The challenge is to do it with a reasonable number of speakers. With 100 we wouldn't be having this discussion. But, if you only get 7 or 9 there are some placements that are better than others to account for as many of the limitations as possible.

That's not what I got out of this but I may just be again.

well Chris agrees at least

I actually used a SP meter to get the amps "tuned in", but that was on an older Denon model. I do like my music flat, but when you have a Joe Satriani concert going and there is little to no thump in da rump, it's a letdown.


For starts I put quite a bit of money into my Marchand electronic crossover which allows me to set the gain, crossover point level, crossover frequency point with a 24 db slope AND phase adjustment. I guess I could turn down the gain on the subs, run Audyssey, then turn up the gain to suit my tastes.

I have SUBS set to NONE. It is my understanding that the LFE is then directed to the mains which are set to LARGE, therefore getting regular bass as in music and Dolby DD. Can someone chime in on this? I may give Denon a call. Being somewhat of a purist, I'd hate to go with mono bass. Again, these are two high end 15" subs that can take about anything you can throw at them. They are driven by the old Soundcraftsman amp. (Anyone remember that brand!)

Thanks for the input ~

Oops, just saw these responses.....


Yeah, they run as LARGE. Like I said in the previous posts, I'll just have to play with it. May have to cut back on the gain on the subs, run Audyssey, and then go from their with yea ol knobber roo.


Is the LFE directed to main LARGE when you choose "no sub" in the settings? I have a poor repetoire of DVD's, in fact I haven't even played with one. Been too busy with installing my new Epson 1080P 6100 front projector (man is that one fine machine!), Dragonfly screen and 2809.

I custom built these speakers out of quality drivers like Focal, Accuton, etc. and I'd hate to lose some of the output they are capable of. But, anything past 100 hZ for the fronts, center and surrounds gives me the willies. I removed the bass from the fronts years ago for many reasons - it really frees them up to do what they best - mid-bass through to the highs.....cleans them up. IMO, any time you remove the bass from speakers not designed to handle frequencies as low as 30 Hz, you're doing yourself a big favor. Enter the "new" 5.1, 6.1, 7.1 formats.

Regards ~

There's no need to re-run Audyssey with your subs turned down, unless you don't have any further to go to turn them up with your corossover. Just turn them up. Audyssey will have done whatever it can with the bass (it has less resolution available in the main channels than the sub channel) and the correction is made independent of your amp settings. There should be no difference between just turning them up now and turning them down, re-running Audyssey, and then turning them back up. If the balance between the mains and subs was about right pre-Audyssey, turning down the subs (which look to Audyssye like part of the mains) may make it difficult for Audyssey to get the system back to flat overall, anyway, since it would in effect have to shelve up the entire bass region . . .

No, you're correct that the mixing engineer needs to work within the complete environment under his control, be it 5.1, 7.1, 9.1... I don't advocate mixing in the 'dark.'

I'm just saying that once the mix is created for x speakers, there's no need to deliver it over x pipes. I'm not claiming PLIIx is the end-all, but just by way of example, it can deliver 4 surrounds over 2 pipes in the 5.1 format. There are also ways to do it that result in more a discrete performance. Example, the spatial coding techniques developed by Coding Technologies wherein side-chain data is incorporated into the bitstream to control the upmix process, rather than simpler level/phase encoding.

I wonder if it would significantly degrade the DSX Wide signals were they to be split between L and Ls and R/Rs, thereby not needing another pair of speakers. Virtual wides, if you will. Then use the new speaker/amps for heights. 11.1 effect over 9.1 speakers.

Hi Roger,

Interesting idea, but Chris has stated that the Wides need to be at about 60 degrees. So even if this splitting were possible the phantom Wides would image at more than 100 degrees, behind the listener rather than in front. I thought the Wides' primary purpose was to enhance the front soundstage and smoothing front to back pans was merely a bonus.

Larry

I'm saying to place the sound between the 30-deg L and the 90-deg Ls. It will emanate from somewhere in the 60-deg region, and what with MultEQ, the time/phase of the arrivals can be pretty well optimized, and the mix can be predefined to take into account the effects of phantom playback. Ought to be a snap for Chris & Crew.

Hi Roger.

Duh! I should have read more carefully.

Larry

I think Chris has the higher math skillz to place discrete channels wherever he wants.

Funny story: My setup is a "normal" 7.1 system. My equipment rack is on the right side wall about mid-way between the RF and RS speakers. One night I was watching a movie and a (movie) dog barked quite loudly just above the rack. One of my two Golden Retrievers (who normally leave when I watch a movie because it is too loud for them) was asleep on the dog bed in front of the equipment rack. Upon hearing the movie dog bark, Pete jumped up and started barking furiously at my equipment rack. Scared the wee out of my wife and me.

Sounds lika a classic case of DRTF, Doggie Related Tranfer Function.

Hi Roger,

This is the exact experiment that Tom and I did in the lab at USC several years ago. The answer is: it is impossible to create a phantom between L and LS for a listener facing forward. Not even close. It's quite easy to prove with a pair of stereo speakers in front of you. Sit in the middle and listen to the nice phantom. Then turn 90° and listen again with the speakers to your side. Phantom is gone. The same thing basically happens when you try to create a phantom between front and surround speakers. Not to mention, that even if it did work, it would only work for one listener.

Wides are needed and work well to make the front-back more seamless. Furthermore, in experiments by Y. Ando in Japan it was shown that 60° (actually 55°) is the most important direction selected by listeners as "enhancing auditory source width". So, the Wide channels serve two purposes: (1) fill in the perceptual imaging gap between front and surround and (2) provide ASW enhancement.