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We present further evidence of the presence of acoustic oscillations on theslowly-rotating, over-active G8 sub-giant EK Eri. This star was observed withthe 1-m Hertzsprung SONG telescope, at the Observatorio del Teide for twodifferent runs of 8 and 13 nights, respectively, and separated by about a year.We determined a significant excess of power around $\nu_\mathrm{max} = 253 \pm3\,\mu$Hz in the first observing run and we were able to determine the largeseparation $\Delta\nu = 16.43 \pm 0.22\,\mu$Hz. No significant excess of powerwas instead detected in a subsequent SONG observing season, as also supportedby our analysis of the simultaneous TESS photometric observations. We propose anew amplitude-luminosity relation in order to account for the missing power inthe power spectrum. Based on the evolutionary stage of this object we arguethat standard $\alpha^2\Omega$ dynamo cannot be excluded as a possible originfor the observed magnetic field.

Acoustic oscillations and dynamo action in the G8 sub-giant EK Eri