This is an Ortec Model 570 spectroscopy amplifier with user and service manual. The Ortec Model 570 amplifier is a general-purpose spectroscopy amplifier that offers excellent performance for varying counting rates at an economical price. The low noise, wide-gain range and selectable shaping networks make this instrument ideally suited for operation with semiconductor detectors, proportional counters, and scintillation detectors in a wide variety of high-resolution spectroscopy applications. The Model 570 incorporates an automatic gated baseline restorer, which causes the system resolution to be nearly independent of input counting rates. The gated baseline restorer (BLR) includes a discriminator that operates the sensing circuits that normally establish the baseline reference for the MCA. Performance of the spectrometer often depends on the precision of the setting of the BLR threshold. The Model 570 offers the convenience of an automatic threshold control, which typically gives as good or better results than those the most experienced operator could achieve manually. The active filter networks of the Model 570 generate a very symmetrical unipolar output with optimal signal-to- noise ratio over a wide range of time constants. The excellent DC stability of the Model 570 output eliminates spectrum broadening caused by DC drift and ensures that the high-resolution capability of germanium detectors is realized.