Table 1.

Noise floor testing

Amplifier	Inputs shorted (μV rms)	Connected by 1 kΩ (μV rms)	Connected by 10 kΩ (μV rms)	Connected by 10 kΩ and 30-cm cable (μV rms)	Inputs open (μV rms)
OpBox A	1.322 ± 0.005	1.324 ± 0.009	1.337 ± 0.008	1.342 ± 0.006	1.708 ± 0.011
OpBox B	1.282 ± 0.006	1.284 ± 0.006	1.297 ± 0.006	1.306 ± 0.007	1.896 ± 0.021
Grass	0.554 ± 0.009	0.596 ± 0.046	0.589 ± 0.008	0.529 ± 0.018	12.756 ± 0.122
Intan	2.632 ± 0.009	2.708 ± 0.046	3.032 ± 0.055	22.107 ± 1.034	13.104 ± 0.508

Values from noise floor testing of the different amplifiers; 5-min segments of recordings were taken from each amplifier type with differential inputs shorted using a wire, connected using different resistors, or left completely unconnected. To mimic the effect of having EEG travel via a cable in a tethered subject recording, we also connected the amplifier inputs to a 10-kΩ resistor but at the end of a 30-cm shielded two conductor cable. The shielding of the cable was grounded. Mean RMS values of these 5-min segments were calculated using 10 non-overlapping 30-s windows. Mean and SEM values are reported for each combinations of amplifier type and testing criteria; n = 10 non-overlapping 30-s windows for all table cells.