The NL844 is a 4 channel AC coupled preamplifier which replaces the NL824. Unlike the NL824, filter and gain settings are controlled in pairs (i.e channels 1 & 2 and channels 3 & 4 share settings. As well as amplifying 4 channels, the unit can also be operated in a single or two channel mode (channels 1 & 3 or 2 & 4). The NL844 needs to be connected to the NL820A Isolator module. NL844’s are ideally suited as a multi-channel EMG amplifiers or EEG amplifiers.