[AnyDave]

Yeah that’s what I’m curious about, the graph comparison I posted last year looks interesting now, since both of them indicated a 200mv drive, while sensitivity result was different for around 6dB.
If it’s just an error in the printing of sensitivity definition, I think that could explain though.

Thanks for clarifying. The old test system we used for years to test the ER4 on was 200mV drive level. When we migrated production, we switched it to 100mV (which is what we've long used for the other earphones). We forgot to change the text on the graph, so it says 200mV, but it really was tested at 100mV. Cutting the drive voltage by half, will reduce the sensitivity by 6dB. So this was an engineering mistake by us that the printout says 200mV, but there's nothing actually wrong (or even different) about the earphones themselves.

 

[MOONDROP]

Thanks for clarifying. The old test system we used for years to test the ER4 on was 200mV drive level. When we migrated production, we switched it to 100mV (which is what we've long used for the other earphones). We forgot to change the text on the graph, so it says 200mV, but it really was tested at 100mV. Cutting the drive voltage by half, will reduce the sensitivity by 6dB. So this was an engineering mistake by us that the printout says 200mV, but there's nothing actually wrong (or even different) about the earphones themselves.

That sounds convincing to me. I never experienced sensitivity change on any aspect.