api preamps (circa 1970) are classics, and everyone uses them if they are available (especially on drums). they have tone that simply cannot be duplicated by anything else, vintage or modern, with a fat low end (due to the distortion in the old transformer) and a clear, slightly hyped high end. although the more modern 512 sound very similar, the older 312's are slightly fatter and smoother sounding (see figure 3.4)