2 channels or surround: the best of both worlds on an ordinary CD?

[Mallette]

Those of you who've been around awhile are probably all too aware of my recording habit. My latest insanity is taking shape. I am now assembling the components to attempt to get surround sound on the common, garden variety CD without affecting its 2 channel sonics. As I don't want to provoke a debate about its merits I am not going to reveal exactly how I intend to do this, but I can say that the idea is "a novel and unique application of existing concepts."

A while back I posted my Six Cardinal Rules concerning recording/playback of surround. Some got it, others thought I was trying to say this is the one and only way. What I was trying to get across was the basics of how to do it using basic Edisonian technology...i.e., only the basic equipment required to record and reproduce sound. This latest brainstorm leverages that concept with exisiting, common technology to, I hope, provide a satisfying surround playback without any extra steps or expense in the recording or duplication process.

Of course, all this assumes I am not stark raving mad. Now, I am craving a piece of raw chicken...if you will excuse me, I think I hear clucking outside.

Dave

[sfogg]

David,

" My latest insanity is taking shape. I am now assembling the components to attempt to get surround sound on the common, garden variety CD without affecting its 2 channel sonics."

There are numerous ways of doing this already, some that work very effectively.

You have various flavors of matrix encoding (Logic 7, PLII, Dolby Surround..etc..etc..), Ambisonic and so on and so forth.

If you like send me one of you DVD-As and I'll matrix encode it down to 2 channels using a Logic 7 *encoder* for you so you can hear how that works. The real trick though is when you play it back through a Logic 7 decoder to take the two channel encoded source back out to surround. It will sound suprisingly close to what the original DVD-A sounded like and will keep almost all of the same spatial queues intact.

The other option, though I doubt much of anything will support it, is to use the 4 channel capability that was built into CDs.

Shawn

[Mallette]

Neither of the above...nor will I do any matrixing or other processing. Not even a mixer.

Dave

[sfogg]

Dave,

"Neither of the above...nor will I do any matrixing or other processing. Not even a mixer."

I wasn't suggesting you were. I was suggesting you experience some of the work done by the giants in this field before deciding it was time to try and reinvent the wheel.

There are numerous recording techniques and microphone arrays that will in effect passively matrix encode 'surround' info onto a regular CD without actually using any processing or mixing. That isn't new, there are numerous patents describing methods of doing this.

A very common 'audiophile' CD that does this is the Cowboy Junkies 'Trinity Sessions' which uses an Ambisonics 'Soundfield' microphone for the recording. The mic was in 2 channel mode for those recordings so it wasn't doing 'B Format' encoding but was capturing the ambiance and hall sound very well.

Pretty mcuh anyone that has heard that CD will agree what a great recording it is. Those that have expanded it out to surround using a *good* method will likely say it is even better that way.

You can build a DIY 'Soundfield' mic if you wanted to try it.

http://homepage.ntlworld.com/henry01/cheap_soundfield/cheap_soundfield.htm

Shawn

[Mallette]

In thinking about it, I shouldn't have posted before the trials. OTOH, I am interested in the approaches you mentioned and any others. Right now I am locked on the job and need all the "mind expansion" beyond teaching old roughnecks new tricks I can get. I am just beginning the long process of establishing new links in the Houston area to music groups to replace those from Dallas. That is not an easy task as my Dallas "stable" of groups took over 10 years to develop.

I'll leave it at that now and report back on the results when I've stopped talking about it and started doing something about it...

Dave

[sfogg]

Dave,

"OTOH, I am interested in the approaches you mentioned and any others. "

OK, the offer is open if you ever want me to L7 encode one of your DVD-A recordings down to two channel CDs if you want to hear that in action.The real magic is when it is decoded again by L7 though. It sounds very close to the original multi-channel mix even though it uses a 2 channel delivery format. (CD)

Shawn

[Mallette]

That probably sounds great and I would love to hear it. However, my experiments in this area have and continue to be exploring methods of delivering music by the simplest possible path to the equipment most music lovers are likely to have on hand. Don't take this or anything I say to suggest I am against dedicated processors or methods and such (see my signature). It just isn't what interests me as a pursuit. As a LISTENER, I am ready for anything that delivers the music...

Dave

[sfogg]

Dave,

The encoding is full compatible with standard two channel playback. And in fact it sounds very good with two channel playback. There are a few commercial two channel Logic 7 encoded CDs out there but there are a lot more DVDs with Logic 7 encoded 2 channel tracks on them. Most material mixed at 'Mia Casa' has a 2 channel Logic 7 encoded track made from their discrete multi-channel tracks.

BTW, if you wanted to read some more information on the encode/decode method I'm talking about you can find some details on how it works here.

http://world.std.com/~griesngr/AES8A.html'>http://world.std.com/~griesngr/AES8A.html

There are also numerous papers on David Griesingers site about different types of surround recording and all sort of other topics having to do with why halls sound like they do as compared to home playback and a lot of the psychoacoustics of it all. Well worth reading since you are obviously interested in this sort of thing.

http://world.std.com/~griesngr/

Shawn

[psg]

There are numerous recording techniques and microphone arrays that will in effect passively matrix encode 'surround' info onto a regular CD without actually using any processing or mixing. That isn't new, there are numerous patents describing methods of doing this.

A very common 'audiophile' CD that does this is the Cowboy Junkies 'Trinity Sessions' which uses an Ambisonics 'Soundfield' microphone for the recording. The mic was in 2 channel mode for those recordings so it wasn't doing 'B Format' encoding but was capturing the ambiance and hall sound very well.

Pretty mcuh anyone that has heard that CD will agree what a great recording it is.

I listened to it last night. It sounds weird. Yes, you can kind of feel the room acoustics, but did you notice the extreme low frequency content? The beginning of track 2 "almost" makes me sick. That must be in the mid tweenties...

[jt1stcav]

Now I'm intrigued...I gotta get The Trinity Sessions and experience this 2-channel ambience you're all talking about. Are all their recordings done with an Ambisonics Soundfield mic, or just this particular album? Has it been remastered lately, or is this the '88 release?

[sfogg]

Peter,

" Yes, you can kind of feel the room acoustics, but did you notice the extreme low frequency content? "

I believe that is the air conditioner in the church they recorded in.

That deep bass is actually what gives some of the impression of the

hall they are in. If you roll off the recording you loose some of that

effect.

Jim,

I'm not sure if it was just the 'Trinity Sessions' or not. Their other

albums are good too though with a lot of ambiance in them. I have the

1988 version. I doubt they have a remastered version... they never

really mastered that album. It was recorded directly in the hall to two

channel with no mixing or anything happening on later.

Shawn

[Mallette]

OK, now I am intrigued as well. I do not know this group or the recording, but can't help but wonder why air conditioning would be left on during a recording.

Dave

[sfogg]

Dave,

"but can't help but wonder why air conditioning would be left on during a recording."

I may be thinking of a different track. I'll have to listen to it again tomorrow.

The recording was done in a church that was still open to the public during the session.

You can read about it here:

http://www.cowboyjunkies.com/albums/trinitysession/index7.html

Shawn

[Mallette]

Shawn:

Great read. Certainly I'd be at home with these folks and their philosphy. My suspicion is that the noise is from traffic rumble. As one of my favorite recording venues is also a church in an urban setting, I am quite used to this and like to record between midnight and 0600 when practical.

I am also certainly philosphically in step with the aims of the Ambisonics folks. However, my own quest is to accomplish a similar end with no front end encoding not found in nature. Perhaps a quixotic quest, but a great ride nonetheless.

Dave

[jt1stcav]

..."My suspicion is that the noise is from traffic rumble. As one of my favorite recording venues is also a church in an urban setting, I am quite used to this and like to record between midnight and 0600 when practical."

Since the album was recorded live on November 27th, '87, I'm quite certain it was traffic rumble as well, especially since it was recorded during the day with the church still open to the public no less. You'd think the church officials would have been more considerate of the fact that a band rented their sactuary for the explicit use of making a live recording of their music! I'm surprised just from reading their story that The Trinity Sessions sounds as good as it does despite the obstacles they encountered along the way when recording live with tourists and mall shoppers wandering through that sacred building!

[sfogg]

"I am also certainly philosphically in step with the aims of the Ambisonics folks."

Ambisonics is an interesting method of recording/reproduction but it

has some flaws too. For example it tries to reproduce the sound from

one point in space. We hear from two points. Ambisonic decoded material

sounds pretty good but I prefer other methods as the surrounds are too

correlated (un-natural in a hall) compared to other methods. If you

want to hear Ambisonic encoded material anything from 'Nimbus' was done

in B Format Ambisonics. Ambisonic decoding also sound really bad on

non-encoded material.

Gerzon's 'Tri-Field' method works much better on non-encoded material.

"my own quest is to accomplish a similar end with no front end encoding

not found in nature. Perhaps a quixotic quest, but a great ride

nonetheless."

Read some of the patents from those that have already done this.

Shawn

[Mallette]

Good to hear from you, Jim. Its been awhile...

Part my my reasoning, aside from my own experience with traffic rumble and amazement that anyone would leave HVAC on during a session, was the nature of the building. AC is an old church in Toronto, and I would expect any heating in a building of that age and type to be steam or other fanless type.

Dave