Experimental measurements of the response of a group of closely spaced heaving devices are reported. Details of the experimental technique are presented and the effect of both array size and configuration on the power output and response of individual floats is reported and compared to an isolated float. Power output measurements relate to a non-linear drivetrain representative of the Manchester Bobber wave energy device in which each float and counterweight is supported from a pulley which drives a flywheel and generator. Net power amplification relative to an equal number of isolated floats is observed at several wave frequencies, generally when the wave period is greater than natural period. Response measurements are also presented with negligible mechanical friction (i.e. free-response) to provide dataset for easy comparison of response to general numerical simulation. As theory suggests, the measurements indicate that response and net power capture is amplified at particular ratios of device spacing to wavelength.