A problem also shared with strain gauge cartridges. In magnetic cartridges the generator for the left channel is connected inverted relative to the right channel generator.
I assume the electret is velocity responding like the typical magnetic cartridge and not a displacement sensitive device like the strain gauges I like to play with - which don't adhere well to the requirements of the RIAA response curve required for playback and need a lot of help. (They are not compatible with standard pre-amps which avoids this issue since they need to be powered to generate an audio signal, and therefore will not work.)
I assume the electret is velocity responding like the typical magnetic cartridge and not a displacement sensitive device like the strain gauges I like to play with - which don't adhere well to the requirements of the RIAA response curve required for playback and need a lot of help. (They are not compatible with standard pre-amps which avoids this issue since they need to be powered to generate an audio signal, and therefore will not work.)