Visual alignment of the heads will only take an Echorec so far along the path to attaining its peak audio performance. The minute tolerances, dimensions that are in the order of just a few microns one way or another, required to align the head gap accurately against the drum are beyond human ability to resolve, yet alone manipulate. Or, to put another way, the task is somewhat akin to attempting to assemble a pocket watch, whilst blindfolded and wearing oven gloves. Further, subjective audio testing by listening alone is a hit and miss process, especially if using a guitar amp instead of a hi-fidelity audio reproduction system.
But there is an easier way of tackling the climb to audio nirvana where all the heads are perfectly aligned and the machine is producing crystal-clear repeats: use the same procedures that Binson used. Back in the day Binson production engineers utilised electronic test equipment, a signal generator and oscilloscope to measure the audio performance of the heads whilst the machine was operating. A pure sine wave signal from the generator is fed into the input of the Echorec and then the ‘wet’ signal level (from the playback amplifier circuitry) monitored on the ‘scope display. The frequency response of the memory system (heads and drum) can be determined by taking spot measurements at 1KHz and 10KHz (note: the Echorec’s bias oscillator circuitry generates an A.C. bias signal between 50KHz to 60KHz, setting the upper frequency limit of the machine at 10KHz to 12KHz).
