[soundbitten1]

http://www.thewhippinpost.co.uk/audio/ambient-sound-stereo.htm


Has anyone tried this? Is there a possibility of gear damage? I have some extra speakers I'm not using but I want to make sure it's safe to do.

[opnly bafld]

 Dolby Stereo Matrix
A simple 4-channel decoder could simply send the sum signal (L+R) to the center speaker, and the difference signal (L-R) to the surrounds. But such a decoder would provide poor separation between adjacent speaker channels, thus anything intended for the center speaker would also reproduce from left and right speakers only 3dB below the level in the center speaker. Similarly anything intended for the left speaker would be reproduced from both the center and surround speakers, again only 3dB below the level in the left speaker. There is, however complete separation between left and right, and between center and surround channels.
To overcome this problem the cinema decoder uses so-called "logic" circuitry to improve the separation.

[WGH]

Deriving the ambient sounds of a recording by using a a pair of rear speakers has been around since 1970. The passive 4-channel matrix system was popularized by Dynaco's co-founder David Hafler. The Dynaco QD-1 Quadapter enabled a bit of control over the rear channel.



More information is available here



Try it, nothing will blow up. I must have used this system for stereo at one time but it was more of a novelty than a useful setup.

Wayne

[Saturn94]

Deriving the ambient sounds of a recording by using a a pair of rear speakers has been around since 1970. The passive 4-channel matrix system was popularized by Dynaco's co-founder David Hafler. The Dynaco QD-1 Quadapter enabled a bit of control over the rear channel.



More information is available here



Try it, nothing will blow up. I must have used this system for stereo at one time but it was more of a novelty than a useful setup.

Wayne

Ah, the old "Hafler Hookup"; my first foray into "surround sound".  I did this many years ago and thought it worked pretty well.

[Rocket_Ronny]

I get 3-D ambient sound all the time from 2 channel. No processor needed. Only good tubes, speaker positioning, and room.



Rocket_Ronny

[Letitroll98]

I get 3-D ambient sound all the time from 2 channel. No processor needed. Only good tubes, speaker positioning, and room.



Rocket_Ronny

+1 on that!

[JLM]

I get a full soundstage from single driver (point source) speakers.  Monoblocks seem to help, but it's 90% + in the speakers.

Look for time aligned drivers and 1st order/phase corrected crossovers if you must go with multiple drivers.

[Early B.]

One of the hallmarks of a decent mid-fi or high end 2-channel system is in providing a 3-D ambient sound. If it isn't doing that, then there's something wrong with the setup or the room. The design and type of speakers shouldn't matter much.

[mcgsxr]

While I have infrequently experienced true envelopment in sound via stereo vs a well setup surround system, I found that OB single drivers (with electronic Xover and biamped with subs) would do a better job for me in my room than traditional 2 ways or box speakers of any kind.

[JohnR]

Sorry, but surely if you have two speakers in front of you and you hear something from behind you, something is wrong?

[Early B.]

Sorry, but surely if you have two speakers in front of you and you hear something from behind you, something is wrong?

The music isn't merely coming from the two speakers. Sound waves are bouncing off the walls, so some of what you hear is reflected sound. These reflections give the effect of ambient sound.

[PDR]

I wouldnt think 3D would mean behind.....although the word envelope may.

3D in 2ch to me means soundstage height, width and depth.....I can have all 3 in front of me.

[decal]

Sorry, but surely if you have two speakers in front of you and you hear something from behind you, something is wrong?

Come on JohnR, surely you know better than that!!!!

[JohnR]

I wouldnt think 3D would mean behind.....although the word envelope may.

Well, the first few posts had a configuration with speakers behind the listener.

[Russell Dawkins]

Incidentally, the Hafler surround device works very well with pure Blumlein recordings since most of what comes in to the stereo pair of figure -of-eight mics from the two lateral quadrants which, if the mics are used properly is mostly ambiance, emanates from the rear ("difference") set of speakers. This is close to "organic" surround, in that only room ambiance comes from the rear.
This really only pertains to "live" recordings in real spaces of acoustic ensembles, such as jazz ensembles (rarely), orchestra, choir and smaller groups such as trios, quartets and so on.

[Letitroll98]

Sorry, but surely if you have two speakers in front of you and you hear something from behind you, something is wrong?

The music isn't merely coming from the two speakers. Sound waves are bouncing off the walls, so some of what you hear is reflected sound. These reflections give the effect of ambient sound.

I think envelopment is a better word.  Of course JohnR is right, normally stereo images will be in the forward direction, except for a few processed recordings that put images directly to the side and some test discs that can throw an image a touch beyond 180°.  But well set up systems and properly recorded material can envelop one in an ambient soundfield that seems to surround the listener.

However this is nothing like my multi-channel home theater that can put car chases and explosions anywhere in the room.  I don't enjoy music this way unless the surround channels are used strictly and correctly for ambient information.  That's why most of my music listening is on a 2 channel system.

[JLM]

Much (most?) of what we hear via our systems (2 or more channels) is subject to the recording process.  Nowadays the market is primarily into earbuds, PC, or automotive playback so unfortunately for audiophiles that's the production target.

Very few recordings provide a good 3D stereo image via two loudspeakers (the very reason stereo was developed).  Even purist recordings are usually processed.  And don't forget that symphonic/orchestral recordings are typically miked from overhead, thus disorienting the listener and providing extra violin emphasis.

[Rocket_Ronny]

Very few recordings provide a good 3D stereo image via two loudspeakers

Sorry to hear this is your experience. 


Rocket_Ronny

[werd]

Putting a speaker behind is a great exercise in getting a handle on what your final goal should resemble. Stuff like this I enjoy reading about.

The final outcome IMO is to take what you experienced and apply it to stereo.

I have never tried this 3rd speaker but my experiences have shown that every room has a certain playable volume that will get your 3d image. This is what makes pre- amps with great volume controls so valuable. Playing stuff too loud or to soft will collapse the 3d image.  Right speaker choice and a good adjustable volume control is paramount.

Find the right speaker with the right room and the right volume and you got a great 3d image.

[Russell Dawkins]

And don't forget that symphonic/orchestral recordings are typically miked from overhead, thus disorienting the listener and providing extra violin emphasis.

If by "overhead" you mean higher than the audience listening angle, that is the way everyone does it - at least for the main stereo pair or array, in the case of the infamous Decca Tree. But this angle actually provides more of the rear of the orchestra in the balance. If the micing angle for the main pair was, say, horizontal and low - then you would get string emphasis, because the strings are closest and also acoustically block the middle and rear sections of the orchestra. As it is, zone or spot mics are need to help the middle (second violins and violas and, behind them, woodwinds) and rear of the orchestra.