Another kind of multichannel audio: front-end stereophonic multichannel

[par4ken]

I'm pretty convinced that some of the quad recordings back in the day were engineered for 4 front speakers. I don't have all of the Dutton quad sacds, but some of the ones I have make most sense audibly with the speakers in various front configurations. Most notably A Chorus Line

I don't think that they were engineered for four front speakers but if it sounds good to you like that there nothing wrong with arranging your speakers that way. Had those stereo only folk experimented with that sort of placement maybe they would nave become multi channel devotees!

 

[Sonik Wiz]

Does this qualify for front-end stereophonic multichannel ?

Ad for the Sansui QSD-1000. It certainly makes me wonder what it would sound like with the dedicated omnidirectional mic set ups mentioned earlier.

 

[par4ken]

Does this qualify for front-end stereophonic multichannel ?

View attachment 98455

Ad for the Sansui QSD-1000. It certainly makes me wonder what it would sound like with the dedicated omnidirectional mic set ups mentioned earlier.

I think that the inside two speakers should be much closer together. It would create a better wall of sound that way. I'm sure that this is meant to create sort of a Super Stereo! They didn't want to advertise the QSD-1000 as quad.

 

[Electric Moo]

Salut Scytales!

This is an interesting concept that I haven't considered before. Very intriguing. Especially for reproducing a live acoustic concert with multiple instruments. Thanks for the info & history! Merci

Maybe Atmos 2.0 can include a front array option.

 

[Scytales]

Atmos is a kind of mystery for me. And I am concerned by one thing : how to be sure that the decoding processor does not make something weird with the discrete channels. I have read the manual of the software environment of a Dolby Digital decoding processor from Texas Instruments and it is stated that bass management configurations not acknowledged by Dolby can be programmed nevertheless. Hence, it is possible for the unsuspected to mess things up without letting the end user know. That's why, for Hi-fi, I tend to prefer the most straight line between the source material and the loudspeakers. Not that I disregard signal processing, but I prefer to know what is done inside a device and that is not always very well documented. I am a firm believer that the worst enemy of great sound is human errors. The more we can tweak with available settings, the more we can introduced errors in a sound reproduction system.

However, I have read more knowledgeable people who said that Atmos can embed discrete channels indeed.

As far as reproducing concert in high fidelity, that's exactly the point of front-end multichannel as envisioned by W. Snow and practiced, for instance, by Robert Fine or G. Cabasse.

The core idea behind that kind of sound recording is, as far as I can understand the fundamental theory, a form of spatial sampling. Each of the numerous microphones is tasked to sample at its location the sound-wave emanating from the sources and which propagate towards the audience. The loudspeakers do the reverse at the reproduction stage. That's why they have to be laid out the same way that the microphones were or at least homothetically. The Snow's sketch displayed in the first page in enlightening on that matter.

For my part, one of the most striking improvements I have heard is on piano music. According to my experience, the most difficult part to reproduce a properly recorded piano in standard 2 channels stereo is low key tones. The simple addition of a third channels spectacularly improve the faithfulness of low key tones, now effortlessly reproduced at the same level as the rest of the keyboard and with magnificent power. It's as if very well laid out subwoofers were put in service. I suppose with four, five or six channels it would be even better.

 

[Scytales]

https://www.highfidelityreview.com/10-rca-living-stereo-sacds-coming-in-september.html
I bought 1 or 2 of these, I'm not a big classical music fan, but I wanted to hear discrete 3 channel stereo (someday - which is now, since I recently bought several MCH SACD players).

Some QQ members aren't fans of discrete center channels (5.1), I have my A/V receiver set to phantom center channel for playback of 5.1 content (I only bought 4 speakers + subwoofer about 5 years ago).


Kirk Bayne

Sadly, BMG/Universal has ceased to release RCA Living Stereo SA-CDs after a few dozens were put on the market.

Fortunately, Analogue Productions has revived this collection under license, with some new additions in 3 channels : Hybrid 3-Channel Stereo SACD|Acoustic Sounds

As far as the aforementioned Everest record company is concerned, some 3 channels recordings have been released on DVD-V and DVD-A called "HDAD" : HDAD 24/192 24/96 (Beware! Not all titles in the list are 3 channels !)

But so far, the few Everest 3 channels recordings I have listened to are less convincing that the best from RCA or Mercury.

 

[barturtle]

I don't think that they were engineered for four front speakers but if it sounds good to you like that there nothing wrong with arranging your speakers that way. Had those stereo only folk experimented with that sort of placement maybe they would nave become multi channel devotees!

I've been going thru some of my Pentatone classical quads and several of them definitely work better with 4 fronts.

 

[Scytales]

@barturtle, can you please tell us more about the loudspeakers set up you used to listen to these particular quadrophonic recordings and which albums they are ?

 

[par4ken]

I've been going thru some of my Pentatone classical quads and several of them definitely work better with 4 fronts.

I don't doubt what you are saying but I don't think that the original intent was to use that speaker placement, or surely I would have heard or read about it back in the day. It might even be possible that the recording was made with microphones placed across the front, so playback in that manor would be more accurate than with surrounding speakers.

I maintain that speakers should be placed according to the user's preference, and according to the dictates of the actual room. I have long felt that the best sounding and most practical placement involves putting the rear/back speakers more off to the sides. This could be a compromise between fully immersive and full front placement. The side speakers can also be moved forward towed in a bit toward the listener, if desired. As such recordings made for a front speaker array will be stretched a bit, while those full surround releases will compress the sound field a bit but reduce or eliminate holes (so called cogging) in the mix.

One suggestion from the quad era placed the back speakers in front but turned them inward. To me that idea is far from ideal but I guess that it's intent was to bounce sound off the walls, creating a bit of fake ambience. Similar to the idea behind Bose direct/reflecting speakers which some swear by while others scoff at the idea as it blurs the stereo image. My point is that idea is not my cup of tea but it might suit some people's taste.

 

[barturtle]

@barturtle, can you please tell us more about the loudspeakers set up you used to listen to these particular quadrophonic recordings and which albums they are ?

I use a matched set of JBL Stage 170 https://www.stereophile.com/content/jbl-stage-a170-loudspeaker powered by a Yamaha receiver.

How I'm listening:
I arrange the speakers in a 150degree arc, 50degrees in between the LF and RF, and the side speakers 50degree to the side of each. They're set 3.5' from me for this exercise, so I can easily lean between a set of speakers to listen for distinct sounds.

These are mostly large orchestra recordings

What I'm looking for
1) distinct instruments coming from the side speakers only. I call this Conductor's Ear View
2) sounds coming equally from LF and LS or RF and RS, making for imaging of instruments placed between the speaker. This is like a front row seat.
3) sound reflections. this is more of a judgement call. is it a reflection off the side of the stage, or is it room sound? If I believe they were recording the sounds reflecting off the stage, I would consider this a front end recording as well.

I've not been through all of my quads in this manner, but the following few I believe meet one of these conditions

Pentatone 5186127 Bach Liszt Organ Works
Pentatone 5186228 Fritz Kreisler Music for Violin and Piano
Pentatone 5186 211 Symphonie Fantastique
Dutton CDLX 7377 The Firebird

 

[MidiMagic]

I use a matched set of JBL Stage 170 https://www.stereophile.com/content/jbl-stage-a170-loudspeaker powered by a Yamaha receiver.

How I'm listening:
I arrange the speakers in a 150degree arc, 50degrees in between the LF and RF, and the side speakers 50degree to the side of each. They're set 3.5' from me for this exercise, so I can easily lean between a set of speakers to listen for distinct sounds.

These are mostly large orchestra recordings

What I'm looking for
1) distinct instruments coming from the side speakers only. I call this Conductor's Ear View
2) sounds coming equally from LF and LS or RF and RS, making for imaging of instruments placed between the speaker. This is like a front row seat.
3) sound reflections. this is more of a judgement call. is it a reflection off the side of the stage, or is it room sound? If I believe they were recording the sounds reflecting off the stage, I would consider this a front end recording as well.

I've not been through all of my quads in this manner, but the following few I believe meet one of these conditions

Pentatone 5186127 Bach Liszt Organ Works
Pentatone 5186228 Fritz Kreisler Music for Violin and Piano
Pentatone 5186 211 Symphonie Fantastique
Dutton CDLX 7377 The Firebird

Are you turning your head to see where the image is panned?

I can't hear the panning between side speakers without turning my head.

 

[par4ken]

Are you turning your head to see where the image is panned?

I can't hear the panning between side speakers without turning my head.

You should be able to hear perfect panning with the speakers that close together, only 50° apart total of 150°! Works for me with greater spacing! We aren't really talking about side imaging there, more of a wide frontal arc!

 

[barturtle]

I found a youtube video with a shot of the mic setup for a quad recording.

time 27:11

 

[barturtle]

I found a youtube video with a shot of the mic setup for a quad recording.

time 27:11

Intestingly this pic is from the 1971 BSO recording of Má Vlast,

however I found a recent article containing a fragment of an interview where the engineer Thomas Mowrey, who also did the BSO's 1973 Symphonie Fantastique mentions that Berloiz was done "In The Round" (or oval).

https://trackingangle.com/features/...atest-batch-of-original-source-vinyl-reissues
"The entire orchestra was assembled in an oval (almost a circle, but a bit squished), with Ozawa in the center. Strings and woodwinds were on one side of the oval, in a conventional layout, and brass and percussion were on the other side, also conventionally placed. My guess is that we put the bells on the percussion side, but fairly far back from the other percussion.

"With this layout, we were able record 360 degrees of direct sound sources for the quad version (which you can hear on SACD quad release from Pentatone, apparently still available), and then when the rear tracks were folded into the front at a 1:1 ratio, that was the ideal stereo mix."

Honestly, I never imaging there were many large orchestral recordings done this way. The costs alone of removing all the seats from the hall for a recording.

It would be interesting to know which ones were done in the round vs what is pictured. The Ma Vlast seems to have never been released in multichannel

 

[Scytales]

There are not only 4 microphones in the above picture of Ma Vlast recording : there are also much more spot microphones among the orchestra.