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Bose QuietComfort 35 II Review (Noise Cancelling Headphone)

Using that would require passive operation since the active noise cancelling is an amp unto itself, right?

And these don’t sound very good when in passive mode.

I'm using an amp with these and have the headphones in "on" mode. The amp works as expected (need to turn the Topping DX1 to about 75% in "low" mode to get a nice loud sound) and the noise cancellation still works as expected. I don't think the headphones are really amplifying the incoming sound much.

They actually sound quite impressive this way without the bluetooth sound compression, especially with HiRes audio.
 
Using it wired in on-mode is not the same as passive (off-mode).
In off-mode (so no NC and or when the battery is depleted) so in passive mode you can still use it but the sound quality and seal response is quite (very audible) different.
This is what nathan was talking about.

In active mode the input is 480ohm, in passive mode 40ohm and has a higher sensitivity (118dB/V)
No headphone out will have issues with driving 480ohm where sensitivity is 115dB/V

passive vs active (wired)

nc-off-nc-on.png


Different seal in passive mode:
seal-nc-off.png


same seal changes but in active mode:
seal-nc-on.png
 
Using it wired in on-mode is not the same as passive (off-mode).
In off-mode (so no NC and or when the battery is depleted) so in passive mode you can still use it but the sound quality and seal response is quite (very audible) different.
This is what nathan was talking about.

In active mode the input is 480ohm, in passive mode 40ohm and has a higher sensitivity (118dB/V)
No headphone out will have issues with driving 480ohm where sensitivity is 115dB/V

passive vs active (wired)

nc-off-nc-on.png


Different seal in passive mode:
seal-nc-off.png


same seal changes but in active mode:
seal-nc-on.png

Thanks for clarifying. Maybe I misunderstood what a balanced cable is and why it can't be used in active mode.
 
Maybe I misunderstood what a balanced cable is and why it can't be used in active mode.

The QC35-II can not be used with balanced cable/gear. The Bose is single ended only (3.5mm TRS cable)
 
Using it wired in on-mode is not the same as passive (off-mode).
In off-mode (so no NC and or when the battery is depleted) so in passive mode you can still use it but the sound quality and seal response is quite (very audible) different.
This is what nathan was talking about.

In active mode the input is 480ohm, in passive mode 40ohm and has a higher sensitivity (118dB/V)
No headphone out will have issues with driving 480ohm where sensitivity is 115dB/V

passive vs active (wired)

nc-off-nc-on.png


Different seal in passive mode:
seal-nc-off.png


same seal changes but in active mode:
seal-nc-on.png
This is a really useful post.

My original response was intended more as a leading question than a definitive statement.

Based on this measurement and @mjnichol description I think wired (singled ended cable) and powered on would be a good way to use them. I sold my pair so I cannot try it.
 
Winter is coming . I've started commuting again. Dug my pair of these out again .

Stock sound ain't great so got the eq out . Ended with this .

Sound great , lightweight , very comfortable , great ANC .

I suspect similar results can be had from the 45s if you can find them .Doubt you'll find a new 35 II but if you do and in the ANC market and can eq , snap their hand off.
 

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The EQ at 4 kHz is needed to lift the sound and make it more open. Without it, it can sound dull and closed.
How come you like these better than 45’s? I know it comes down to more than this, but the frequency response on the 45’s was just as good if not, better wasn’t it?
 
Opened mine because the voice mic was not working properly. The mic was almost muted, it did just let some scrambled peaks through.
After replacing the voice mic, things got better but the sound of my QC 35 II is still far worse than in this review, check from minute 2:35.

Even in a quiet environment my speech is almost not understandable.

So Bose put some effort in using two decent mics for noise cancellation but two cheap MEMS mics for speech, one for monitoring
environmental noise, one for picking up the voice. I assume, if both are mismatched, the sound of speech gets degraded.
I made some test calls and covered the "monitoring" MEMS with my finger, my voice got a tad clearer - but just a tad.
Switching ANC On-Off has no effect.
Any Idea how to improve this? Because there is no need in buying a new headphone...

In the pictures:
-Speech-Mic-Main-PCB:
The main PCB with DAC etc. with the ANC-mic on the left and MEMS on the right (U500)
On the back (not visible) is a 30-pin connector to the Speech-Mic-Connecting-PCB.

-Speech-Mic-Connecting-PCB
The connecting Board between MEMS Mic, the NFC board and also the drivers.
It connects to the main pcb with a 30-pin connector (on the back, not visible).
FM+ / FM- / FMB on the left are the connections to the MEMS-mic.
Only FM- has a direct connection to GND. No other "direct" connections to the "solder-blobs" on the right.
(I used the short circuitry function of my voltmeter.)
I wonder if FM+ / FM- are connections to the MEMS and also to FB+ / FB- on the Main PCB
FB+ / FB- are close to a recess rather in the middle of the picture.

-Speech-Mic:
The MEMS for picking up voice. The marking reads MU20 6A04.

-Wiring:
Just to show that I replaced the connecting PCB ( it has some resistors and capacitors on the back)
together with the mic for speech.
And yes, the wires can very easily be mixed up. No Idea how they manage this in the factory.

-Assembled:
The main pcb back in place. Re-soldered like it was before.
On the left you can see U500, the monitoring MEMS - mic.
Do you see the the white and black wires connected to FB+ / FB- ?
To me, black would normally be the color for - (Negative)
But I checked a video where a QC 35 II is disassembled and the wiring is correct , white negative, black positive

Any clues how speech could be improved? As the MEMS for speech is on it's own passive pcb,
can it be replaced? Maybe with a condenser mic?
All the best, Herbert
 

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No ideas how the MEMS - microphone for speech can be improved?
What do the 3 Connectors FM+ / FM- / FMB mean?
They could give me a hint how the MEMS - mic is implemented...
 
Winter is coming . I've started commuting again. Dug my pair of these out again .

Stock sound ain't great so got the eq out . Ended with this .

Sound great , lightweight , very comfortable , great ANC .

I suspect similar results can be had from the 45s if you can find them .Doubt you'll find a new 35 II but if you do and in the ANC market and can eq , snap their hand off.
You using Active mode with a wire or just bluetooth? I'm trying it out Active and wired and it sounds pretty good.
 
You using Active mode with a wire or just bluetooth? I'm trying it out Active and wired and it sounds pretty good.
Just Bluetooth. Not a huge fan of wires to snag on trains etc. Not the last word in fidelity but to get some aural privacy and my tunes in comfort is a good thing.
 
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