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Welcome
NetworkAmp Manager—Owner’s Manual
What is CobraNet?
CobraNet is technology developed by Peak Audio (Cirrus Logic, USA) that transmits
uncompressed digital audio signals in realtime over a fast Ethernet cable. It can carry up to
64 channels in each direction or 128 channels total for both directions (64 channels total for
both directions in a network that uses a repeater hub). (However, the number of channels
is limited by conditions such as the performance of your equipment and on the type of
audio signal.)
Transmission of up to 100 meters is possible with Category 5 metal cable, or up to 2 km with
multi-mode optical fiber cable.
A CobraNet network can carry digital audio at sampling frequencies of 48 kHz or 96 kHz
and 16/20/24 bit resolutions, but the ACU16-C/NHB32-C support the 48 kHz sampling
frequency at 20/24 bit resolutions. A fixed latency is added to the audio data each time it
passes through a CobraNet network. You can select this latency from 5.33 ms / 2.67 ms /
1.33 ms.
A CobraNet network can carry audio over an existing Fast Ethernet network to which other
devices such as computers and printers are already connected, but we strongly recommend
that you set up a dedicated network for CobraNet.
In a CobraNet network, digital audio is distributed in packets called “bundles.” Each bundle
contains between three and eight channels of audio, depending on conditions such as the
bit depth and latency.
Bundles are assigned a number in the range of 0 through 65,279. Bundles can be transmit-
ted either as “multicast bundles” which occupy more network bandwidth but allow audio
to be distributed to multiple devices simultaneously, or as “unicast bundles” which use less
network bandwidth but can distribute audio to only a single device. The number assigned
to the bundle determines which of these two types it is. Number 0 indicates a null setting
that disables transmission or reception of bundles, numbers 1 through 255 indicate multi-
cast bundles, and numbers 256 through 65,279 indicate unicast bundles. The
ACU16-C/NHB32-C support bundle numbers 0 through 16,383.
The ACU16-C can accept up to four input bundles simultaneously, and the NHB32-C can
use four input bundles and four output bundles simultaneously. However if you set the
latency to 1.33 ms, the number of bundles usable on the NHB32-C will be a maximum of
four (total for input and output).
A CobraNet network also provides a Serial Bridge feature that allows serial data to be trans-
mitted over the network. The ACU16-C and NHB32-C normally use the Serial Bridge to
transmit amp control data, but you can also use COM mode or MIDI mode to send other
data between two NHB32-C units via the Serial Bridge.
A glossary of CobraNet, NetworkAmp Manager, ACU16-C, and NHB32-C related terms is
provided in this manual (see
). A wealth of information about CobraNet, with sec-
tions especially for designers and installers, is available on the Peak Audio Web site at
. If you are designing a CobraNet network, we strongly recom-
mend that you visit this Web site and study the information available in order to take full
advantage of the CobraNet technology. Peak Audio also provide a list of Ethernet devices
that have been tested with CobraNet, including switching hubs and media converters.