Recording - August 2015 - 43

Going deeper
There are a lot of audio/MIDI interfaces
with basic front-panel control and built-in
mix settings out there. What makes the
iCA4+ so special? The answer lies in what
you can do with those three USB jacks.
There are two Device Jacks and one Host
Jack. The former are USB-B jacks, as you'd
find on an external USB device like a controller or keyboard, and the latter is a USBA jack, as you'd find on a computer. They
have very different uses, as we'll see.
Each Device Jack connects to a computer via either a standard USB cable (for
Windows PCs and Macs) or a special
cable that converts a USB-B connection to
either 30-pin or Lightning (for iOS). The
iOS cables contain special electronics;
they can't be replaced by just connecting
a conventional USB cable to a Camera

At this point, experienced DAW users
are scratching their heads and muttering
to themselves, because what I've just
described is supposed to be impossible.
USB is a "dumb" standard, with a computer at the center of a network making
all the decisions and cables fanning out
to peripherals that just send USB data
and do what they're told. Even if they
made cables to allow it, you can't hook
two computers up to each other through a
USB network; they'd fight over who had
control, and probably both would crash.
Well, usually. In this case, however, the
internal "brain" of the iCA4+ manages all
of this data, routing and sorting it per your
needs and instructions... and it does so
while convincing each of the computers
that it's actually the one in control and the
other computer is just a peripheral. So if

iConfig has a tabbed interface for routing and mixing audio, routing and processing MIDI, setting overall system parameters, updating firmware, and much
more. The two main tabs most folks will
be interested in are the ones shown in
Figures 1 and 2, the Audio Patchbay and
the Audio Mixer. Changes made to one
will be reflected in the other.
The iCA4+ can work with a variable
number of buses and input channels per
computer. The total number available
depends on the selected sample rate and
resolution; for every combination short of
24/96, the total number of inputs and outputs per device is 16, either as the default
of 8 ins and 8 outs or any combination that
adds up to 16 (e.g. 12 ins and 4 outs).
The figures reflect the factory default
layout of 6 buses with 8 mixer inputs
each. In the Audio Patchbay, each device
appears as a source of 8 output signals
that can be routed to any combination of
inputs on the other devices; the only limitation is that you can't "stack jacks", i.e.
hook up two output signals to go into the
same input at the same time. Signals can
be split and multed, but not summed or
mixed, in the patchbay. You use the
Audio Mixer for that.
Have a look at Figure 1 and follow
along. The two Devices are normally

Connection Kit or Lightning/USB-A adaptor. Both ports provide current for charging iOS devices; one provides 1.0 Amps,
enough to charge an iPhone or keep an
iPad from losing charge too quickly, and
the other provides 2.1 Amps, which will
charge any iOS device in short order.
The Host Jack connects to any USB
MIDI peripheral you may wish to use,
such as a keyboard, drum pad box, or
control surface. It supplies sufficient current to power one bus-powered device; if
you'd like to use more than one, you'll
have to connect a USB powered hub to
the Host Jack, which can then take up to
eight such MIDI devices (but not a mouse
or printer or other non-MIDI USB device).
Now, here's where it gets interesting. The
two Device Jacks provide a large number of
audio and MIDI input and output streams to
and from each of the two connected computers, and the Host Jack can route MIDI
from any or all of the attached controllers to
either or both of the computers as well. And
all three are active simultaneously.

you have a PC and a Mac hooked up to
it, each machine sees the iCA4+ as an
audio/MIDI interface, with the inputs and
outputs from the other machine as available I/O in said interface. The iCA4+
manages data so each computer thinks it's
in charge and passes information back
and forth without slipping and falling.
Once you wrap your head around that,
the possibilities start to unfold...

labeled USB1 and USB2; they can be
renamed as I've done, for my iPad and
my MacBook, so you can remember
which cable goes where. Each of the two
Devices sends up to 8 channels of audio
into the Patchbay (from the top down),
which are then routed to the inputs of various destinations (from left to right). You'll
also see the physical inputs and outputs
on the iCA4+, which I've labeled "Analog
I/O": four audio inputs, and six outputs.
Finally, there are eight inputs and six outputs for the Analog Mixer; we'll take a
closer look at that in a moment.
In this example, I am sending two outputs from my iPad (1/2) into two inputs
on my MacBook (5/6). At the same time,
I am sending two outputs from my
MacBook (1/2) to two inputs on my iPad
(5/6). Even before we get the Mixer
involved, these direct connections let me
route stereo audio between the two computers without going through a pair of
external interfaces or converters, all at
very low latency. If I set up my ins and

iConfig and audio
To route all this data (and do a bunch
more stuff as well), the iCA4+ uses a software application called iConfig. As of
this writing, the Mac and PC versions of
iConfig are available and fully functional
(I did my work on the Mac version for this
review), but an iOS compatible version is
not yet shipping. I'm keeping my fingers
crossed for that one, as the older version
of iConfig that worked with the MIDI interfaces was a real dream on iOS and
made all-iOS rigs a possibility without the
need for a laptop at all.

RECORDING August 2015

Table of Contents for the Digital Edition of Recording - August 2015