there's a problem with that thumbnail diagram...nothing a good pair of sidecutters can't fix though!
Thanks Norman bates for the stereo matrix post! Every month I get to paste a link to a single speaker stereo concept, and here it is again. Just in case someone is hungry for more info on the connection scheme 🙂 http://elias.altervista.org/html/SingleSpeakerStereo.html
The consumer version originally lacked the steering, so they needed a new brand to explain the difference, so they went with ProLogic.
The steering circuits in early cinema Dolby units (i.e. CP 50) was originally pretty discrete, not even using voltage controlled amplifiers. Also noisy as can be. 🙂
Interestingly, VHS Hi-Fi had really great audio specs. Better than optical film and probably the best analog consumer recording medium at the time, including reel to reel, so it helped push for better ProLogic.
Around this time, DSP starts to become affordable in consumer gear, AND Dolby Digital and DTS were in theaters. The former using a compressed signal on film, the latter putting only an SMPTE time code to synchronize audio which was shipped separately on multiple CDs per movie. Somewhere around this time ProLogic II comes out.
Now we are in the fully digital film era, and movies are streamed to the theaters and played from disk.
Lots of innovation and progress. Lots of tech has come and gone.
The rolling off of the highs was not desirable, but a side effect of the limits of the encoding/decoding mechanism. Remember, this is all being done via simple op amp summing and difference signals. Raise the top frequency and you'd get more leaking from the L and R main signals.
The dipolar thing was stupid, IMHO. It was never done in theaters. There we used at least 2 speakers per side, more if the theater was deeper. AFAIK this was something THX tried to do, and helped to sell more expensive speakers with 2x the parts. You were better off replicating the theater thing, using pairs of standard monopole speakers
I really disagree with this connection. What kept you from being in the scene was Prologic. I'm watching The Expanse right now and I think it's a good example of putting you in the scene with DD 5.1.
Now putting you in an immersive environment that doesn't scream at you is up to the sound editor and much easier to accomlish.
I remember that Dolby marketing at the time was that the small physical separation of home speakers needed more steering than the larger cinema systems to achieve the same effect.
I certainly ran quite a few films thru the trusty old CP-50 back in the analog days. I don't remember much steering or panning at all, except in maybe 2 films. I mentioned it to one film maker and he was surprised, said no one else had even noticed it. 🙂
It was surprisingly good. I remember doing location digital recording onto U-Matic video tape with the Sony PCM rig. A fellow shows up from Radio France with a Hi-Fi VHS deck, saying it was his favorite recording medium. I was shocked, but convinced after I heard it. I bought one.
Seriously Important... to hear the latest Marvel Movie with the best possible dialogue sound reproduction.
Don't forget to crank the volume Up to hearing damage levels in imitation of the Enhanced "theatre" experience.
Don't forget to crank the volume Up to hearing damage levels in imitation of the Enhanced "theatre" experience.
I never realized that Dolby had that much of a grip on movie sound, what a shame. The multi-channel effects always reminded me of the early sci-fi movies where you could see the wires that supported the model spaceships.
My only exposure with that name was in 1983 while noticing how a hearty treble cut with the Dolby selected during playback mode would help while making tapes from distant radio stations.
I sure see a lot of used center speakers show up on Craigslist nowadays, was even looking to see if I could find a matching pair.
My only exposure with that name was in 1983 while noticing how a hearty treble cut with the Dolby selected during playback mode would help while making tapes from distant radio stations.
I sure see a lot of used center speakers show up on Craigslist nowadays, was even looking to see if I could find a matching pair.
I know sometimes there's little between can and can't comprehend but one thing is coming through in my opinion... the strength of the phantom in the first place.
How good is the stereo pair to begin with? (eg. what exactly do you hear when you play mono through them?)
I worked for one of Dolby's competitors. We had a Christie projector and Star Wars as a reference film, along with a CP 50. It steered, pretty hard. We replicated it, but during development we also were able to turn it down via a resistor adjustment.
It was remarkable how much a movie could open up if we reduced the steering. Sadly we didn't ship that as an option, but instead stuck to the CP 50's formula.
We did so with much more modern parts though, in an all analog, through hole board the size of your hand.
One comment we had from sound editors with our earlier gear, which did not steer as much, was you could hear a lot more artifacts which made it to the film which they thought they had removed. Half of that was better power supplies, half was the steering hid noise.
Perhaps it’s more correlation than causation, but I prefer IMAX exhibitions of films because IMAX theaters employ better sound systems and with them, better acoustic treatments to the room. Intelligibility is noticeably better than other conventional theaters which are noticeably more reverberant and unclear. I say this despite sentimentally preferring historic theaters which tend to lack sophisticated sound systems.
I was watching a theatrical demonstration of Meyer Sound equipment at the theater in the Meyer Sound HQ here in Berkeley, CA. We were watching Master and Commander. And while the sound was too loud and the treble too piercing for my ears, the dialogue was astonishingly crisp and decipherable. I stayed after and had a long conversation with the technician who set up the demonstration. The main takeaway was that intelligibility (transient response) is often overlooked in favor of low- and high-frequency extension and that there’s really no reason not to optimize transient response in a center channel, or when possible, a midrange driver in a multi-way enclosure.
I was watching a theatrical demonstration of Meyer Sound equipment at the theater in the Meyer Sound HQ here in Berkeley, CA. We were watching Master and Commander. And while the sound was too loud and the treble too piercing for my ears, the dialogue was astonishingly crisp and decipherable. I stayed after and had a long conversation with the technician who set up the demonstration. The main takeaway was that intelligibility (transient response) is often overlooked in favor of low- and high-frequency extension and that there’s really no reason not to optimize transient response in a center channel, or when possible, a midrange driver in a multi-way enclosure.
Yeah, the quality of the sound system and acoustics matters a great deal.This is where THX got it's start. Trying to bring up the standard of reproduction, so that movie presentations were universally excellent.
I am a big fan of Meyer's tech, but I love to use M&C as a demo at home, mostly to show how good a sub can integrate. None of that harshness here! 🙂
I am a big fan of Meyer's tech, but I love to use M&C as a demo at home, mostly to show how good a sub can integrate. None of that harshness here! 🙂
There’s a few factors I attribute to the harshness. One of them is that I suspect the older gentleman was maybe fine-tuning the system by ear. That’s pure speculation though.
The other was that the levels seemed higher than I’ve ever heard in an exhibition but this was not a packed theater (it was a small group showing). Perhaps in a large, crowded theater where these levels are more appropriate, the HF would be attenuated somewhat through audience absorption.
During the Q&A I brought up Floyd Toole and his “house curve” as mentioned in his book. He scoffed and directed me to the SMPTE X Curve standard. I deserved the rebuff as I only brought it up as a smartass, suggesting that perhaps the balance was a little “hot” as it were.
The other was that the levels seemed higher than I’ve ever heard in an exhibition but this was not a packed theater (it was a small group showing). Perhaps in a large, crowded theater where these levels are more appropriate, the HF would be attenuated somewhat through audience absorption.
During the Q&A I brought up Floyd Toole and his “house curve” as mentioned in his book. He scoffed and directed me to the SMPTE X Curve standard. I deserved the rebuff as I only brought it up as a smartass, suggesting that perhaps the balance was a little “hot” as it were.
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You just debunked your own argument. Anna bob and charlie are mono sources, like a centre speaker, therefore they always sound like they are in the correct place, no matter where you listen to them from because human bin-aural processing is able to use the subtle phase and amplitude differences of sound arriving at each of our ears to give us a directional judgement.
The problem with stereo speakers is that the sound from the left and right speakers arrives at both the left and right ears, unlike headphones where only the left channel reaches the left ear and the right channel to the right ear. Think about what happens if you stand right in front of one of the speakers in a stereo setup. The sound from the speaker right next to you completely swamps both of your ears and it now appears that audio is coming from solely inside that speaker, no longer from a virtual location in between the two speakers. Human audio processing is very good at dismissing the sound from the further speaker which arrives significantly later and at much lower volume as being an echo/reflection.
The same is true for any listening location which is not equidistant between the stereo speakers - the virtual centre becomes increasingly skewed towards the closer stereo speaker as you move closer to it and further away from the other. This becomes a problem particularly in smaller home theater setups with smaller screens and wildly off-axis listening positions because if you are sitting on one side of the room, speech no longer sounds like it is coming directly from the characters mouths on the screen but instead somewhere between their mouth and the nearer of the stereo speakers.
Stereo sweet spot:
Off-centre stereo listening location:
very off centre stereo listening pos:
Centre speaker sweet spot:
Centre speaker off-centre listening location:
If you don't believe this... try it in real life.
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Well that's remarkable Allen. I've heard a few systems that will support a phantom image far off axis, but I'm not sure about a 12:1 ratio off axis. That's extreme.
You got some strange speakers. When i'm 1ft from one of my speakers and 12ft from the other, playing a mono speech source I can barely even detect that the far speaker is producing audio. Sounds like i'm just listening to a mono speaker 1ft away.
You need a low diffraction and reflection speaker, one that when you approach it you can't hear the speaker itself, just the sound, no matter how you try. If you look at the speaker itself, you see silence. There is no clue that the shape you see is related to anything you hear.
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I ran one screen somewhere (maybe S.F.) that has the "other brand" processor. Maybe one of yours? I don't remember it being very different than the Dolby units.
In practice there was sooooo much more going on and going wrong than just the processor. That was usually the least of worries.
Playing mono from between the speakers, the sound is like coming from the next room through a small imaginary window in the wall. This shows an absence of secondary sources, something Earl put me on to some years back. If I move away from the middle the (edit:stereo) image distorts in shape just like a 90's 3d computer game.
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