Here are the exclusive first look of what will be Phonak latest flagship - the dual balanced armature PFE232. Check out my blog for spec.
Edited by ClieOS - 12/18/11 at 8:23pm
Hmm you're right, the previous impression was via my Touch, now with my computer it really does look more like a vent and I'm sure Phonak has a reason for it. This seems to be the year of dual driver iems, there are so many incoming in this configuration.
Yes, it would. It has the same effect as on dynamic driver, but smaller. It is not as uncommon as you might think - Shure, UE (which actually owns a patent related to this), Creative, and a few other brands have made BA based IEM with either internal or external vent.
Not necessary. Sleek Audio SA6 and Creative Aurvana In-Ear2 both have vent to increase warm and bass but they use the regular type of 'closed' BA. Low end frequency can easily penetrate the thin wall of the BA driver and interact / resonate with the air in the housing. A vent on the housing increases the effect, much like a passive radiator with bass-reflex design in loudspeaker
They really shouldn't make a difference would they? The whole principle of BA drivers is to vibrate the air in order to allow 'direct injection' of sound into the ear via a sound tube.
I'd guess that a tuned vent was under the perferated cover.
I believe vented BAs have been around a lot longer than most are aware. Small hole in the housing opposite the lever and we know Shure has had these for some time in their top model but in a sealed case. No way to augment bass without the hole as far as I can imagine.
Well, won't a dynamic transducer does just about the same thing? The whole point of using a close system has more to do with the miniaturization of the diaphragm and the limitation of piston motion in a BA driver. Because BA is much less efficient in generating a lot of volume, using a closed system maximize the energy transfer. However a close system also greatly reduces resonate in the lower frequency, thus single BA isn't particularly good at bass performance. Note that bass frequency is more or less non-directional (i.e. imagine a sub-woofer) and carries a lot more penetrating power (large wave form) than higher frequency, so if you are able to increase the bass resonate even at the back of a BA driver, it will still have enough energy to re-penetrate the driver and go to your ear. That's why when people party in close room, the first thing you hear coming through the wall is bass note.
I don't think that's it. Getting more backwave would make less bass as it's out of phase and not far enough disassociated to tune that way. Better if it just leaves the can. Venting should simply reduce back pressure, low frequency resonance point and damping to the lever itself, allowing it to have more output and produce lower notes directly. It's not like a ported speaker where it vents to the listening space. As the lever is not absolutely sealed there's also the possibility of the back and front wave not cancelling as much by being forced into the other's chamber (ear/case) as much when the rear chamber is allowed to vent. Simply increasing the sealed volume by venting to a larger sealed chamber could extend/increase output and lower noise and may be why we see some of these in closed IEMs. More like going from an air suspension speaker to an infinite baffle design though not a direct translation.
I am think more in line of double sealed speaker with a vent. But with an actual air volume that small, it is kind of difficult to imagine how the acoustic behavior will be since scaled up model (loudspeaker) might not be a linear example to that of a small system.