Originally Posted by luisdent
I was checking out some earphone distortion specs, and came across this. I thought it was interesting. PFE112 on top ER4S on bottom. The PFE112 is surprisingly similar frequency response, which is probably why I find it easy enough to EQ them to sound practically identical to the ER4S. However, you can see the distortion is indeed a bit higher all around. Not bad, but definitely higher in the mid area. Bah. Go ER4S though! :)
Yes, the PFE has significantly higher distortion --- two reasons:
(1) The PFE uses a vented 2354 driver, plugged up. Vented drivers usually have higher distortion figures. They should've used the 2389, which is supposed to be the Sonion functional equivalent of the ED-29689, but didn't, not sure why.
(2) Phonak utilizes electrical underdamping to get the target response as well, but it does so with the cable itself. The 2354 is about 10 ohm impedance, so the other 22 ohm is in the cable. I don't know whether there are SMD resistors within the Y-split or not, but it's probably what they're doing. Anyway, they probably don't take the time to match noise and tolerances with the cable as much as Ety does.