PANNING FOR GOLD
Part one in a Series on Mixing
(for the do-it-yourself audio geek)
1998 by Sir Hound, Eddie Ciletti
updated may 2006
For the purpose of this discussion, there are three flavors of surround:
Passive, Active (Dolby ProLogic) and Discrete (5.1 fully independent channels).
Passive and ProLogic extract "hidden" information from a stereo mix. Thatís
right, even though multiple speakers are used, there are really only two
channels of information. The "center" channel is the sum of Left + Right
("mono") and the "rear" channel is the difference: Left Ė Right. Dolby
ProLogic "steers" the subtracted information ó which consists of ambience,
widely panned and/or out-of-phase information ó into the rear speakers
with a form of fuzzy-dumb logic. You can set up a generic Passive or Discrete
system without buying any processing equipment.
If you already have a Dolby ProLogic system, listen to a stereo music
mix and see what happens. The trick to consumer gear is finding the "plain
vanilla" ProLogic setting. Many receivers have DSP effects like "Concert
Hall," "Stadium," "Basketball" and "Bathroom." You donít want any of that.
Also, the consumer version of ProLogic has a built-in auto-level-balance
detector circuit that can not be bypassed. The system will attempt to correct
gross level discrepancies between left and right. This means it may get
confused if your mix is in a very raw state.
The first system is super basic. You donít need any signal processing
gear to get started, just four identical passive speakers connected as
shown in Figure One.
subwoofer is recommended, but the choices are numerous so follow the directions
provided with that system. Assuming your speakers have three- or four-inch
woofers, place them in a four-foot square with you in the middle. The subwoofer
should be in a nearby corner, either left or right of the front speakers.
(Larger speakers can be spread further apart.)
DIY Passive Surround System using standard stereo amplifier
and four identical speakers.
THAT SPATIAL FEELING
Mono mixing is a similar sort of discipline to live recording. The producer,
arranger and mixer are forced to make choices, up front, as to what is
important and what can fall between the cracks. Stereo makes it easier
to hear "space," but a dense production can still be difficult to balance.
Surround ó in discrete form ó will allow so much more spatial freedom that
it might actually "expose" what formerly were seamless transitions.
SURROUND ® STEREO ®
MONO: HOW IT WORKS
Anything panned center will appear as normal. Hard-panned (full Left
and Right) stereo effects like reverb, a pair of guitars or background
vocals will be very prominent in the rear speakers. So will out-of-phase
material. One acid test for any mix is to listen in mono. Stuff thatís
panned in the middle will seem louder while the hard-panned "pairs" will
take a giant step back.
If compatibility is really important, lessen the panning "width." This
is true whether "folding" surround into stereo or stereo into mono. Iíve
found that a mono-compatible stereo mix translates well to "extracted"
surround. The stereo effect may not seem quite as exciting with two speakers,
but the mix will come alive with four. This is actually better than using
processing to make a stereo mix seem wider on a single pair of speakers.
DYI DISCRETE SURROUND
Not everyone agrees that all the monitors (except the subwoofer) need
to be identical, but itís a safe bet. Self-powered or not, you will ultimately
need a source selector and master monitor level control. Two models are
available from Studio
Technologies (847-676-9177). Itís ok for now to connect
the output of an 8-track recorder directly to the power amps. The
accepted channel assignment can be found in Table One.
Standard channel assignment from mixer-to-tape for 5.1 surround.
Next is the connection from the mixer to the deck. If all you have is
a Mackie 1604 or equivalent, use buses 1, 2, 3 & 4 as left front, right
front, left rear and right rear, respectively. Use two aux sends for the
center and subwoofer channels. It will soon become obvious that pan pots
need to morph into joysticks for precise sonic positioning. Calling all
third-party controllers! In the meantime, have fun and let me know how
you make out.
Click here if you want to learn
more about 5.1 Surround Sound.
I have several passive surround systems. Itís great fun and sometimes
surprising to hear how your favorite mixes will be reinterpreted. One could
argue that an audiophile stereo system would be better than a bunch of
speakers, no matter how good. But consider these motivating factors. We
mix in the "sweet spot." Itís fun, but itís also work. The average listener
is never precisely positioned between two accurately placed speakers. Surround
widens the sweet spot, increases dynamic range and ó with the aid of a
subwoofer ó extends low-frequency response. Many consumers are going to
have the really cheap stuff, but even those systems will be better than
a single 3-inch speaker mounted in a typical plastic TV cabinet.
Donít wait for the manufacturers of consumer gear to decide whatís
best for us. Start experimenting now! The next time the surround show comes
through town youíll know what questions to ask!
Feel free to e-mail with questions
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