Receivers for AE monitoring in multi-anvil experiments. (a) Photograph of the 14/8 octahedral sample assembly on top of four anvils. Transducers are mounted on the back truncation of each tungsten carbide anvil. Note the cable of the bottom receiver (arrow). (b) Photograph of the entire assembly inside the pressure vessel. (c) Closed pressure vessel with exits for transducer cables. (d) Schematic cross-section of a transducer assembly. See text for details.