Hi guys!
I think the problem with the bluetooth dropouts / clicks and pops is related to certain power-saving techniques that certain bluetooth stacks -- namely, Android's, and now OS X's with the latest update -- employ. They're trying to give you better battery life, but what they end up giving you is a jarring, unlistenable experience. It's like they (the device manufacturers, not Sennheiser) don't even test this stuff outside of a lab before shipping it.
Honestly, I would be astonished if Sennheiser did anything at all to change the behavior or logic of their Momentum Wireless cans. The problem is on the playback devices.
Consider my scenario from my testing:
Two environments:
E1. Work: Very high 2.4 GHz band congestion. Lots of WiFi networks in range (and close); several other coworkers using bluetooth, etc.
E2. Home: Low 2.4 GHz band congestion. My own WiFi networks are 100% in the 5 GHz range, and neighbors are far enough away that their WiFi signals are extremely weak.
Three sets of bluetooth headphones:
H1. Sennheiser Momentum 2.0 On-ear Wireless
H2. Meelectronics Air-Fi Matrix 2 (Bluetooth 4.0 + apt-X)
H3. Meelectronics Air-Fi Matrix (Bluetooth 3.0 without apt-X)
Four bluetooth playback devices:
D1. Windows 7 Dell laptop with a Bluetooth 3.0 transmitter built into the Intel WiFi combo card (@ work and home)
D2. Windows 8.1 custom high-end desktop with a Bluetooth 4.0 dongle attached via USB to the front panel of the computer (@ home)
D3. The Samsung Galaxy Note 4 smartphone running (at first) Android 4.4.4, then upgraded to Android 5.0.1 recently-ish (@ work and home)
D4. An Avantree Saturn Pro transmitter (accepts 3.5mm TRS cable and plays the audio back over Bluetooth 4.0 + apt-X) (@ work and home)
Here are the combinations I've tested and the results.
Flawless - no issues, ever
E1/E2 + H1/H2/H3 + D1/D4
or
E2 + H1/H2/H3 + D2
Explanation: Basically, regardless of
where I am, if I use the Dell laptop or the Avantree Saturn Pro, with any of the headphones, I get no audio quality or dropout issues at all.
Minor problems
E2 + H1/H2/H3 + D3
Explanation: Android 4.4.4 / 5.0.1 on the Note 4 tries to save battery by cutting down on transmit power or buffering or both (I'm not sure exactly since I can't observe the internals of Bluedroid). This causes the occasional hiccup, but it's rare -- at home, my wireless environment isn't all that congested, so I only get about one dropout per hour. I can kinda deal with it.
Unlistenable
E1 + H1/H2/H3 + D3
Explanation: At work, the wireless environment is very noisy (as evidenced by the Android wireless heat map app). The 2.4 GHz band is almost completely saturated. However, all my playback devices except for the Android phone seem to deliver enough transmit power that the headphones can still "hear" it over all the noise, no pun intended
Conjectures
1. Since the results are identical across three separate models of headphones,
the problem ain't the headphones.
2. Since the results are
better in a less-noisy wireless environment,
the problem is related to signal strength or protocol negotiation/cooperation with errant bluetooth stacks (like Bluedroid on Android 4.4 and later).
3. Since I get flawless results when I use the Windows bluetooth stack or the built-in system on chip with the Avantree Pro, the problem is not that it is
impossible to get a good, clean signal;
it just requires more TX power than some devices are willing to use. (probably to save battery)
I would be very interested to see people who have severe problems with the "Over-ear" cans to try buying an Avantree Saturn Pro and connect it to your iPhone or Android phone and see if you get the same sound quality problems in an urban environment or other busy wireless environment.
If so, I would be left to conclude that the "Over-ear" cans have a
specific problem that they do not share in common with the on-ear cans. That would be unfortunate if true.