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Re: surround looping

Rainer Thelonius Balthasar Straschill wrote:
> I'm currently reflecting the possibility of doing looping-related
> performance in a speaker configuration with more than two channels.
> ...
> iv. Laptop: Apart from the fact that I didn't yet find a looper plugin

I've been investigating a laptop-based system for surround looping.  I
don't have all the pieces put together yet, but I can relay what I've
found out so far.

First, understand the difference between 5.1 surround sound encoding,
and just having more than 2 output channels.  If the goal is to create
a 5.1 surround mix to publish on a DVD, then you will need a 5.1
surround encoder.  If you just want to route audio signals to 4 or
more speakers during live performance, then you don't need any special
"surround" support in software or hardware.  You just need a computer
audio interface that has at least four mono analog output channels,
and software that can route signals to each of those channels.

You would probably want to feed the audio interface channels into a
mixer with a 4 channel output bus, then into a pair of stereo power
amps.  There are lots of mixer/amp possibilities, the important thing
is the 4 output audio interface.

If there will only be one performer, then the audio interface only
needs to have one input channel, though it might be more convenient to
have more depending on the choice of software.

Next you need a VST host that supports multi-channel audio interfaces
and multi-port plugins.  Plogue Bidule, Audio Mulch, and EnergyXT are
all very good.  Audio Mulch is free, the others are under $100US.  I'm
not very familiar with Live!, but you should be able to route audio to
all of the output channels provided by the interface.  If you don't
want to use the static loop triggering features of Live, it will be
simpler to use a general VST host like Bidule.

Now you need a looper plugin and a mixer plugin that can balance the
looper output among the 4 audio output channels.  The best mixer plugs
for this purpose were designed for surround mixing, you pan the input
signal in space by moving a puck around a 2 dimensional grid.  A surround
panner isn't required but it makes the job easier, and some support
automated movement which is fun.  There were some great ones here, but
they seem to have been temporarily removed:


Most looping plugins are single channel, meaning they take a stereo
input and produce a stereo output.  If you just want a single looper
positioned in surround, then run one instance of the looper patched
into a surround panner.  Boring.  What is more interesting is running
several instances of the looper and several instances of the panner.
This gives you the ability to have several loops going, each at a
different location in space.

The problem with running multiple looping plugins is that they are
difficult to synchronize.  Since the plugins aren't aware of each
other, they need to support some form of synchronization with the VST
host, usually this means quantizing record start/end on a "beat" or
"bar" boundary.  Not all plugins support this.  This also requires the
use of a timer or sequencer plugin that can generate clocks to be sent
to each looper plugin.  A timer is integrated with Audio Mulch, I
think Bidule has a timer plugin, I'm not sure about EnergyXT.

What would be nice is if there were a looper plugin that supported
more than one concurrent loop internally, maintained it's own
synchronization, and could route each loop to four or more output
ports.  Wait!  What about Mobius?  (Oh, come on, you knew I'd be
bringing that up eventually :-)

With Mobius, you would run a single instance of the plugin, then route
each of the 8 tracks to a different output port.  Patch the Mobius
output ports to 4 or more surround panners, then patch the surround
panners to the 4 channels of the audio interface.

A Mobius track is essentially an autonomous looper with features
similar to that of the EDP.  But the tracks are also aware of each
other so you can initialize them to have exactly the same cycle length
as another, resulting in multiple loops that are always in perfect
sync.  You can control each loop track from the same MIDI controller
and feed them from the same audio input.

If Mobius is on the list of looping plugins you don't like, I'd be
happy to hear what you don't like about it.  Maybe it can be fixed.