still don't really understand SDA...

madmax

Can we at least say that doing it passivly like polk does is most likely going to be the reference to hold other forms to?
madmax

Dennis Gardner

I think George is right. "Correctly" is still a matter of personal judgement and is measured by the degree the spatial qualities of the original signal have been adjusted without destroying the credible soundstage of the recording. Going beyond credible is what made quadrophonic fail in the '70s. We all know that musicians rarely sit behind the audience during a performance.

Front and center has always been the preferred seats at concerts for most live performances. SDA gives you the same feeling on normal recordings by making the stage wider and deeper. Polk's crosstalk cancellation in the SDA line was done at a level that makes most listeners believe they have the best seats in the house.

Audiophile purists dismiss the effect simply on principle that the engineer of the recording didn't intend on the soundstage being manipulated in a manner unheard in the studio or venue. I get a kick out of this mindset since recording in stereo itself is already a manipulation of the signal to achieve a wider soundstage than a simple acoustic setting. Even the greatest concert halls "add" their own acoustic identities to the performance.

I always found SDA to add realism to most all recorded materials without making it sound fake or processed as many of the DSP fields do. Polk's method sounded credible.

Dennis

Larry Chanin

For a little more background on electronic approaches to Interaural Crosstalk Cancellation, here's an excerpt from a Lexicon white paper. It quite candidly discusses the limitations which I have highlighted in Bold.

One other minor point, in the Lexicon community, it is the 2-channel audiophiles who love the Panorama effect, not the Home Theater enthusiasts. This is because the small sweet spot makes it a solatary listening experience, and more importantly it is not compatible with multi-channel soundtracks.

Panorama primarily relies on a technique called interaural crosstalk cancellation, first popularized in 2-channel products such as the Carver Sonic Holography circuit. The processor analyzes the stereo content of a source, then, for signals present in one channel or the other, generates a corresponding out-of-phase signal that cancels any leakage into the other channel. The generated cancellation signal varies in strength according to how far the original signal was mixed to one side or the other. Unlike past products that used interaural crosstalk cancellation techniques, Lexicon’s Panorama is performed entirely in the digital domain, resulting in a cleaner sound and eliminating the distortion and phase artifacts that often plagued analog implementations.

Although some supplemental signal is generated for the center and surrounds, Panorama is primarily created from the front left (L) and front right (R) channels using these phase cancellation techniques. It is every bit as enveloping as the multi-channel effects on almost every source, and produces an enhanced traditional front soundstage–one reason for the popularity of this effect among two-channel fans. A notable limitation is in stereo miked piano recordings, where the lower octaves are sent to the left and treble to the right–this tends to produce a 30-ft wide piano–not very natural!

With most recordings, however, Panorama enhances the natural soundstage without introducing overt steering to the surrounds. The catch is that because Panorama depends on carefully controlled phase cancellation to create these effects, it has a very narrow sweet spot–your ears have to be positioned at the point where the cancellation occurs. Only one “sweet spot” will be able to get the full imaging enhancement of Panorama (though it can contribute a slightly improved sense of air when listening from off-axis). Still, for group listening conditions, true multichannel effects such as Music Logic, Music Surround, and the ambience creation modes are more sociable. For solo listening, however, Panorama, when properly set up, evokes an amazingly wide frontal soundstage that extends well beyond the edges of the ‘speakers, and seems to lock individual instruments to realistic points in space.

This need for precisely balanced crosstalk cancellation is why it is so important to calibrate Panorama for a specific listening position.

Larry

gmorris

Great post Larry, and cool site too. After reading your post, I realized another question.

What is DTS Neo:6 Music & Dolby PLII Music trying to accomplish? It seems to me Neo:6 Music & PLII Music are trying to do the same thing you described about the Lexicon. Maybe not, I'm not really sure. The owners manual for my Onkyo receiver doesn't tell squat about what these two modes are actually doing, only how to turn them own & access the controls.

Does anyone know anything about Neo:6 & PLII Music, other than what is described in owners manual? Is it at all related to interaural crosstalk cancelation, or is it completely different?

Terrax

One thing to bare in mind, is that with digital signal processing, multiple speakers are used to create soundfields. And the soundfield incompasses the listener within the field from multiple angles. Yamaha, has done extensive amounts of research, to the point of going around the world to exotic locations and setting up mics around different venues, to be able to record and analyze the acoustic make-up of the venue, in an attempt to at recreating this enviorment in your home through DSP technology. DTS Neo:6 and DPL II Music are using multiple speakers to create soundfields. It is not IMO the same as creating a soundstage with 2 channels. Which again, IMO, is more natural and pleasing.

Terrax

And FWIW, I would much prefer to have two top-notch quality speakers that can create a pleasing, natural soundstage, than to have any type of multiple speaker set-up try to do that. As has been mentioned already, concerts, in fact, any type of live perfomance, will not have the performers in the back of the listener. Which, from all the DSP modes I've heard, there is sounds of music that will be unnaturally coming from those locations. The only exception to this will be perhaps, the recreation of a Nite Club, Jazz Club, or something of this nature, where you would be hearing the ambience of the venue. Like the chattering of patrons close by, echos, reverberations, but would still be able to hear the performers in their natural locations relevant to your listening position.

gmorris

Alot of good points, but I get it already, SDA is NOT a DSP mode.

My question was if you could achieve the results of SDA electronically (whether this is possible or not is not the point) would you be interested?

I think I now understand what SDA is doing, but I still need to hear a pair for myself.


I guess what I'm thinking is: if you could take 4 speakers, set two side by side (to emulate the SDA design) then have a processor send signals to each of the 4 speakers, would you be happy? I'm not proposing an idea, just thinking out loud........

Terrax

I have heard a few electronic attempts at this in the past, and was not impressed. However I have not had a chance to hear the Carver's version, yet. But unless vast improvements could be made, I would not be interested. Which was what I was trying to say before. Sorry, I made it so long and drawn out.

gmorris

I guess I need to stop being such a nerd and trying to figure this all out & just hear the damn things. Now I just have to find somewhere to hear a pair.

It must be majic. Matthew Polk must have worked a deal with the Keebler Elves....:p

PolkWannabie

Originally posted by hoosier21
Doesn't seem like the same thing to me.

You're right, it doesn't seem like the same thing ... but it is ... except of course unless for some reason 7.5" is a mandatory requirement ...

Larry Chanin

[

Originally posted by gmorris
Great post Larry, and cool site too. After reading your post, I realized another question.

What is DTS Neo:6 Music & Dolby PLII Music trying to accomplish? It seems to me Neo:6 Music & PLII Music are trying to do the same thing you described about the Lexicon. Maybe not, I'm not really sure. The owners manual for my Onkyo receiver doesn't tell squat about what these two modes are actually doing, only how to turn them own & access the controls.

Does anyone know anything about Neo:6 & PLII Music, other than what is described in owners manual? Is it at all related to interaural crosstalk cancelation, or is it completely different?

Thanks.

I am not a surround sound expert, but DTS Neo and Dolby ProLogic II are not DSP effects, they are surround decoders which derive additional matrixed channels from sources that have a limited number of discrete channel. For example, my preferred surround decoder is Lexicon's LOGIC7. It can derive seven individual channels, including and eighth LFE channel, from 2 to five discrete channels.

This of course has nothing to do with interaural crosstalk cancellation.

Larry

gmorris

What I was refering to in DTS Neo:6 & DPLII Music modes was not the surround channels, but both systems add the center channel in, with some amount of control. Dolby PLII even has an adjustable setting called Panarama, and another called Dimension, that control the front 3 channels. There are controls for the surrounds, but that is not of interest here. I'm wondering if Neo:6 & PLII's controls of the front 3 channels have anything to do with crosstalk cancelation?

George Grand

Max,

Sure we can agree on that. The same day I agree with you that somebody elses version of the Jimi Hendrix original "Little Wing" is the reference for that song.

We could agree that Polk is the reference for attempting it passively.

George Grand (of the Jersey Grands)

Larry Chanin

Originally posted by gmorris
What I was refering to in DTS Neo:6 & DPLII Music modes was not the surround channels, but both systems add the center channel in, with some amount of control. Dolby PLII even has an adjustable setting called Panarama, and another called Dimension, that control the front 3 channels. There are controls for the surrounds, but that is not of interest here. I'm wondering if Neo:6 & PLII's controls of the front 3 channels have anything to do with crosstalk cancelation?

I see your point. I doubt any of of the Dolby's variable music controls have anything to do with interaural crosstalk cancellation. Here is an excerpt from Dolby's Dolby Surround Pro Logic II Decoder Principles of Operation white paper describing the variable control available in music mode.

There are well-known characteristic differences between movie soundtracks and music recordings. For example, movies (and Dolby Surround TV shows) are mixed and monitored in a calibrated multichannel environment, so the desired end result when listening at home can be obtained from a similarly calibrated home theater system. Stereo music, on the other hand, is not monitored through a surround system when being mixed, so it is not really known at that time how it will sound when played on a surround system. For these reasons, the Movie mode of Pro Logic II has preset characteristics to ensure consistent results. The Music mode, however, can be user-adjustable, assuming the decoder manufacturer decides to offer any of the following three optional controls. These controls are useful in any kind of decoder to allow optimization of the soundfield as desired, but are especially effective in automotive applications due to seating and speaker positions.

• Dimension control. Allows the user to gradually adjust the soundfield either towards the front or towards the rear. This can be useful to help achieve a more suitable balance from all the speakers with certain recordings.

• Center Width control. Allows variable adjustment of the center image so it may be heard only from the center speaker, only from the left/right speakers as a “phantom” center image, or various combinations of all three front speakers. With this control it is possible to create a balanced left-center-right stage presentation for both the driver and the front passenger. For home users, it allows improved blending of the center and main speakers, or to control the sense of image width, or “weight.”

• Panorama mode. Extends the front stereo image to include the surround speakers for an exciting “wraparound” effect with side wall imaging.

I suppose this is open to some interpretation, but here's my take on the various controls.

The Dimension control appears to be no more than a fader control like in a car radio.

The Center Width control merely determines how much of the right and left signal is mixed in to the center channel.

The Panorama mode merely determines how much of the front stereo channels are copied into the surround channels.

None of these controls appear to use out of phase signal to cancell interaural crosstalk, they are merely copying signal to different channels in order to spread sound about the room.

Just my 2 cents worth.

Larry

PolkWannabie

Although I've really never played around with this option until this evening the Sunfire TG IV has SH in DSP.

I tried a little listening experiment with stereo playback utilizing SH on a pair of LS90's .vs. only the SDA from a pair of CRS+'s.

Although somewhat similar there are distinct differences in the sound fields between the two with the CRS+'s imho sounding a little more realistic in terms of instrument placement etc.

For an additional comparison I tried playing the CRS+'s with the SH also on. This reaches the point of over kill with the perceived center becoming "echoy" and the sides creeping around far enough that there was sound clearly perceptible as coming from behind the listening area even though there were no surrounds in play.

By comparison in normal mode the SRT's are not quite as wide as the CRS+'s and are somewhat wider and deeper in wide mode.

SRS3.1TLguy

sweet system Rick