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Inside the cryostat, each bolometer line is connected to a low-noise, unity-gain JFET amplifier to transform it to much lower impedance, thus reducing its susceptibility to microphonics and some other sources of noise. The JFETs (aka source followers) are self-heated to a temperature of about 120 K, at which they show minimum noise, and heat sunk to the liquid nitrogen bath. Upon exiting the cryostat, after some EMI filtering, the signals go to room temperature low-noise amplifiers and electronics.

The 295 signals are distributed to 4 identical, custom made, amplification units, providing 80 channels each for a total of 320 available channels. The extra 25 channels are used for technical purposes like noise monitoring, calibrations and so on. The amplification units are equipped with microprocessors providing a digial interface to almost all the functions, accessible remotely via the local network. The amplification gain can be set in the range 270 - 17280. At the beginning of each observation, the DC offset is removed from each channel to avoid the risk of saturation. The values of the 320 removed offsets are temporarily stored in a local memory and, at the end of the observation, they will be written in the corresponding data file, to be used during data reduction process.

The 320 channels are digitized by 4 National Instrument PCI 6225M multifunction DAQ boards (providing 4 x 80 analog inputs over 16 bits) mounted into an industrial computer (1 x Intel Pentium 4 at 3.0 GHz CPU, SBC IEI SAGP-8650EVG, IEI PIAGP-13S3 backplane, 2 GB RAM 533 MHz FSB). The data acquisition software is interely written unsing LabVIEW. It provides a CORBA object interfaced to the APEX control software used to set up the DAQ hardware (sample rate, ADC dynamic range, channel selection, ...) and a TCP data server accessible from the FITS writer for the data output.