ProSoundWeb Community
Sound Reinforcement - Forums for Live Sound Professionals - Your Displayed Name Must Be Your Real Full Name To Post In The Live Sound Forums => The Basement => Topic started by: kristianjohnsen on January 15, 2014, 05:33:39 AM
-
Some older records have the instruments/vocals hard panned into the two stereo tracks, kinda like listening to an unfinished 2-track mixdown.
Does anyone know the name of this technique, and does anyone have some favourite examples of songs that are mixed this way?
-
I believe this is called split track. Typical use is to supply a recorded backing track for live vocals, à la karaoke. The vocal track may be used for practice, or to supply backgrounds for a live vocalist.
Another interesting technique used for FM broadcast is to mix left plus right (sum) on one track, then left minus right (difference) on another track. This allows a mono receiver to receive the mono signal, while a stereo receiver can decode the stereo signal by adding the sum to the difference to recreate the left channel, and subtracting difference from the sum to recreate the right channel. (Naturally, it's more complicated than that, but this explanation should suffice for purposes of this discussion.) Chances are you won't find any recordings like this, but it's certainly an interesting concept.
http://www.st-andrews.ac.uk/~www_pa/Scots_Guide/RadCom/part21/page1.html
-
Another interesting technique used for FM broadcast is to mix left plus right (sum) on one track, then left minus right (difference) on another track. This allows a mono receiver to receive the mono signal, while a stereo receiver can decode the stereo signal by adding the sum to the difference to recreate the left channel, and subtracting difference from the sum to recreate the right channel.
Is this different to Mid and Side processing? This gives one channel mid + side and the other mid - side. When summed together to mono, the + and - side signals cancel out leaving just the mid. I have done this with a figure of eight microphone for the side and a cardioid for mid.
Steve.
-
Is this different to Mid and Side processing? This gives one channel mid + side and the other mid - side. When summed together to mono, the + and - side signals cancel out leaving just the mid. I have done this with a figure of eight microphone for the side and a cardioid for mid.
It is a similar concept but different purposes. Whereas Mid/Side mic technique captures an acoustic source as mid and side components for variable "width" mixing that combines near perfectly to mono without phase problems, the FM technique mentioned starts with a stereo L/R source and combines the two for mono *so that less bandwidth is required to effectively receive the basic signal. When available, the other track is switched in and the aforementioned math is done for stereo operation.
*the details of how FM does mono & stereo is much more detailed but irrelevant for this discussion.
-
Thanks for the clarification.
Steve.
-
Another interesting technique used for FM broadcast is to mix left plus right (sum) on one track, then left minus right (difference) on another track.
How do you go about doing the left-minus-right mix? I assume this involves some polarity reversals? Or is it more complicated than that? Can it be done in Protools with just the stock plugins?
-
When myself and a friend did some mid/side recording, I made him a box with a few op-amps in which took the signal from two mic pre-amps and gave the two required outputs.
If you're recording with Protools, I think there is a setting to enable M/S recording on two channels without any clever messing about required although you could put the mics to multiple inputs, invert one and sum them.
Steve.
-
I'm familiar with the M/S recording and processing through Protools.
From what I gather, it would be the same process, but without the middle channel...invert the left channel, and then sum them to mono, and that will produce this left-minus-right...how does that get translated to being broadcast?
-
H guys.
Thanks for the interesting info on the stereo decoding for FM radio! I believe German TV meddled about in the 80's with some sort of decoding that allowed you to switch between original language and dubbed German.
It also slightly reminds me about a surround matrix JR talked about, for distributing a L-R feed into a 5-channel surround system.
The technique I had in mind was the one where some early rock artists put vocals and guitar in one channel and bass and drums in the other. The Beatles, perhaps?
PS: One cool feature of the Yamaha PM1D is the built in MS-decoding channes :)
-
I think what you're referring to is not really a technique, but more a limitation of the equipment available at the time.
Four or even three track tape recorders were normal in the early 60s and to avoid bouncing tracks too much, most of it was recorded live with minimal overdubs.
Some of the Beatles early records have some strange panning such as drums on one side, bass on the other etc. I read somewhere that these tracks were intended to be mixed to mono but there was a demand for stereo which was new at the time and this is how they turned out.
Steve.
-
PS: One cool feature of the Yamaha PM1D is the built in MS-decoding channes :)
The PM1D has a built in M/S decoder? :o
That just blew my mind.
-
How do you go about doing the left-minus-right mix? I assume this involves some polarity reversals? Or is it more complicated than that? Can it be done in Protools with just the stock plugins?
I believe that to achieve the difference channel (left minus right), the right channel has polarity reversed then is summed with the left channel.
I'm not familiar with ProTools.
-
L+R/L-R is the same method as M+S/M-S as shown on this page: http://www.uaudio.com/blog/mid-side-mic-recording/
Steve.
-
I have a small video camera with a built in mic that uses M/S recording (using two microphone elements), and decodes it into 5-channel surround sound.
However, I don't have any surround sound playback equipment to see if it really works.