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Bose QuietComfort 35 II Review (Noise Cancelling Headphone)

Tks

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An important, and never really measured, aspect of NC headphones is self noise (coming from the electret + electronics).
Not many brands do this well. Sony and Bose do but many cheaper offerings have an audible hiss.

One should only buy such headphones when one needs noise cancelling or a BT/NC with decent to good sound quality. I would not buy one to serve as a 'reference' headphone as none really are. The QC35-II however is certainly one of the better affordable BT/NC headphones out there along with the WH-1000XM. The Sony has better noise reduction the Bose sounds more 'correct'.

One thing about NC, the effect of measuring it properly will have to take into account external cancellation. On something like Airpods Pros the effect heightens as more noise is presented (you get more of the pressurization effect within the ear). What the baseline noise of the effect is, will vary.

Idk jack squat about NC in any capacity outside of anecdotal experiences (for some reason, never bothered to research it, but I think I'm going to dig into the literature and see what is out there, it doesn't help that there aren't standards of sorts as NC tech seems highly guarded between companies, or at least their specific tuning of it).
 

solderdude

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NC basically is similar to Motion Feedback.

See it as a feedback loop where one doesn't use the normal electrical feedback loop but uses a microphone just above or next to the driver and uses that signal as feedback.

Downside is that microphones are limited in their dynamic range, they introduce noise and as there is something as the speed of sound it is rather limited as to how high up in frequency it can be used successfully before phase issues arise.

Those with the mics positioned above the driver (Sony for instance) can work at higher frequencies than those at sides of the driver.
Also when a mic is positioned on the middle you basically only use the 'dome' for feedback. All the break-up stuff happening at higher frequencies in the cone are not corrected.

So in practice the NC only works till 1kHz or somewhat above.
Fortunately it is easy to use 'normal' attenuation of outside noises for higher frequencies.

NC being in the feedback loop thus not only makes the response 'more linear' below 1kHz it also reduces distortion in the lowest frequencies.
A double whammy !
Unfortunately microphones (and mic pre-amps) hiss, have their own distortion (mainly 2nd for electrets) and require electronics running on 3V.
This limits the dynamic range and max output SPL. There is no 'high-end' electronics inside only components made for 3V portable applications.

There are also NC circuits that digitize and manipulate the feedback loop this way.

Just a few days ago a truck for cleaning sewers parked nearby and was running all morning. The WH-1000MX3 completely removed that terrible hum in the house. Total silence. Just like the sounds in buses, planes etc. It works great for those LF sounds.

That sound suppression works because sounds from outside are picked up by the mic inside the cups. That signal is compared to the reference (in this case no signal, but could also be the incoming audio signal) and the driver emits the exact opposite sound (anti-sound) so that the sounds reaching your ear are basically the same as the reference (silence or music).
Also distortion and frequency response deviations are fed back (via the mic) and it's anti-sound is mixed with the original signal thereby removing those variations.

See plot below (WH-1000X-M3)
distortion-1.gif


Isn't the correction always too late? Well it is only too late for higher frequencies as the wavelength is shorter. It will be in time for frequencies below a few hundred Hz. Great technique but limited in practice.
 

Tks

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@solderdude

I wonder, does this actually mean we're not being exposed to the sound itself by way of cancelation, or we're just not properly picking it up in our brains?

Like is this "anti-sound" that's occuring, something that would prevent hearing damage if for instance the external sounds were 110dB or something insane like that (provided we had the requirements of proper mic, and setup of frequencies less than 1Khz to even start a Noise Cancelation of a SPL of that caliber?).

Also, could one make this more reliable or scale with higher frequencies if you used multiple mics, or just better mics?

Like imagine taking a massive horn, and having external mics and ADC's that were hooked up to the horn and then sealed off, while the horn was placed in your ear (the smaller end of the horn nozzle). Would that result in anything appreciable in performance of these NC techniques? I know you wouldn't do this in practice, because it wouldn't serve any market need, I'm just wondering what theoretically can this scale to, given current tech, and not regarding current constraints about market viability.
 

solderdude

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The actual sound entering our ear is original + anti-sound.

The anti sound is limited in amplitude (and why Amir measures huge distortion) as that is limited by the output power of the internal amp + driver efficiency.
Most of these drivers are high efficiency and low power rated (think 20mW to 50mW)

When you have 150dB outside sounds, natural attenuation of say 5dB for low frequencies the anti-sound would have to reach 145dB to get total silence. 30dB attenuation would be great but the system cannot go beyond 100dB for instance. That amp would clip and the resulting sound would still be unpleasant but attenuated a lot. The compounding factor is the mic inside won't handle the 145dB well either.

Going much higher than a few kHz will be very difficult.
The problem with using a horn is the distance between driver and mic will be too big and phase differences will happen (speed of sound).
 
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Don Hills

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I've stood next to a "silent" trailer-mounted air compressor as used for powering jackhammers while wearing NC headphones. With the NC on, I had near silence in my ears while my chest cavity was vibrating to the sound of the compressor. This was with an old set of Blackbox (Phitek) headphones. They had the advantage of sounding the same (for music) whether the NR was on or off. Sadly, they eventually fell apart and I replaced them with Bose QC-25 bought on closeout.
 

hangcheng

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maybe a silly question.... if the bose qc35 2 evaluated high enough, why should we buy separated dac or amp to boost a wired headphone?
if compare with a akg k371 with topping D30pro and A30pro setting with amir's eq, still sounds very close??
 

infinitesymphony

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maybe a silly question.... if the bose qc35 2 evaluated high enough, why should we buy separated dac or amp to boost a wired headphone?
if compare with a akg k371 with topping D30pro and A30pro setting with amir's eq, still sounds very close??
The QC35 II's DAC is only engaged when using Bluetooth. In that mode they have over 200ms of delay, which makes them unsuitable for watching video or for any other purpose where timing is important. This is a common issue with non-aptX Bluetooth headphones.

There is no latency if you use them with a wired connection, but then you're relying on whatever DAC you have.

They also have a battery with a limited lifespan that is not designed to be user-replaceable.
 

Lotus97

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The QC35 II's DAC is only engaged when using Bluetooth. In that mode they have over 200ms of delay, which makes them unsuitable for watching video or for any other purpose where timing is important. This is a common issue with non-aptX Bluetooth headphones.

There is no latency if you use them with a wired connection, but then you're relying on whatever DAC you have.

They also have a battery with a limited lifespan that is not designed to be user-replaceable.
I use these for watching TV super late at night cuz I own a co-op, my tv has latency slider, I am able to perfectly match the audio and video.
 

infinitesymphony

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I use these for watching TV super late at night cuz I own a co-op, my tv has latency slider, I am able to perfectly match the audio and video.
That's a cool feature. Seems like most hardware A/V equipment only allows audio delay, not video delay.
 

Urib

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This is a review and detailed measurements of the Bose QuietComfort 35 II noise cancelling headphone. It was kindly purchased new by a member and drop shipped to me. It costs US $299 on Amazon including Prime shipping. It has an incredible 44,000 reviews on Amazon averaging 4.5 stars! Are the masses right? We are going to find out.

The 35 II doesn't feel fancy, nor cheap:
View attachment 113878

The cups are on the smaller side but fit my ears fine:
View attachment 113879

They are on the softer side and seal well which means they wear warm. Fine right now in winter but I suspect they may get too hot in summer.

I briefly tested the noise cancelling function using my Audio Precision fan noise as stimulus. Just wearing the 35 II was enough to kill 90% of the noise. Turning it on removed the last bit but really, it was fine without it. Noise sources with lower frequency content will likely show off the effect more.

Note: The measurements you are about to see are preformed using standardized GRAS 45CA headphone measurement fixture. Headphone measurements require more interpretation than speaker tests and have more of a requirement for subjective testing as a result. In addition, comparison of measurements between different people performing it using different configurations requires fair bit of skill. So don't look for matching results. Focus on high level picture. Listening tests are performed using RME ADI-2 DAC and its headphone output.

Bose QuietComfort 35 II Measurements
Let's start with frequency response of 35 II and comparison to our preference target to figure out tonality of the headphone, with the unit bot on and off:

View attachment 113880

I first ran it with it powered off and was surprised how bad the response was. Equally so, I was impressed once I turned it on and it not only flattened the variations in bass and mid-range but also pulled up the bass response to below 20 Hz! Here is the powered on response again:

View attachment 113881

That is pretty good tracking of our target response! It is essentially perfect to 1 kHz. Here is the relative variations:
View attachment 113882

Good news extends to very low distortion at decent levels:
View attachment 113883

Considering how much bass we already have -- so we don't have to boost it -- that is excellent level of distortion in that region.

Here it is in absolute level:
View attachment 113884

Again, remember that this is to be compared to post EQ for other headphones that are weak in bass.

Clean, not fuzzy group delay shows that we have one radiator doing its job, not a bunch of other resonances mixing in:
View attachment 113885

The entire curve is lifted up from 0 degree indicating a constant delay of about quarter of a millisecond.

Impedance radically changes when the unit is on or off:
View attachment 113886

Paradoxically, even though we are using the internal amplifier when the unit is on, it is not the most efficient headphone to drive:

View attachment 113887

Bose QuietComfort 35 II Listening Tests and Equalization
I was instantly at ease with the tonality of the 35 II. The clean and appropriate bass response was a delight. Spatial qualities were a bit light and higher frequencies a tad dull so I put in a bit of salt and pepper on it:

View attachment 113888

Once there, toe tapping started and I could listen endlessly to my test tracks. So much so that I did not want to take them off to take the pictures for the review!

As an aside, here is the EQ that I applied to AKG K371 headphone:

index.php


So darn close! Indeed the Bose could also use that broad light boost in pink filter I had in K371. I wonder if Bose measured the response of the K371 and used that as the target for 35 II. Anyone know which came first?

Conclusions
Amazing what happens when you follow the science and tune a headphone to proper target curve. You get a happy Amir who loves the 35 II with just a bit of EQ. What else is there to say?

The Bose QuietComfort 35 II gets my high recommendation if used with recommended EQ. Without it, it is still recommended but just not as highly.

------------
As always, questions, comments, recommendations, etc. are welcome.

Any donations are much appreciated using: https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/
Was it measured with Bluetooth or wired?
 

hangcheng

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The QC35 II's DAC is only engaged when using Bluetooth. In that mode they have over 200ms of delay, which makes them unsuitable for watching video or for any other purpose where timing is important. This is a common issue with non-aptX Bluetooth headphones.

There is no latency if you use them with a wired connection, but then you're relying on whatever DAC you have.

They also have a battery with a limited lifespan that is not designed to be user-replaceable.


but, if we calcualte the price, bose qc35 2 is 200 usd, sounds like a 200usd topping combo(d10s+a30)+200usd akg 371+bluetooth receiver+NC function and with mic........ at least , qc35 2 has a internal dac&amp as good as topping desktop.... but my point is, do they really sound very very similar or close to amir's ear?

they both have a golf pink..... it seems this is a unbeatable choice for headphone.
 

HiFidFan

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That's a cool feature. Seems like most hardware A/V equipment only allows audio delay, not video delay.

I use these for watching TV super late at night cuz I own a co-op, my tv has latency slider, I am able to perfectly match the audio and video.

I too use them to watch TV late night. Our LG OLED has an adjustable "Sync" function, so delay isn't an issue for us.
 

infinitesymphony

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but, if we calcualte the price, bose qc35 2 is 200 usd, sounds like a 200usd topping combo(d10s+a30)+200usd akg 371+bluetooth receiver+NC function and with mic........ at least , qc35 2 has a internal dac&amp as good as topping desktop.... but my point is, do they really sound very very similar or close to amir's ear?

they both have a golf pink..... it seems this is a unbeatable choice for headphone.
Bose QC35 II are $299. No headphones have an internal DAC or amp as good as something like the Topping equipment yet.

AKG K371 are $119 right now, less than half the price (normally $150, half the price). Add a $9 Apple dongle and you're set.
 

hangcheng

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Bose QC35 II are $299. No headphones have an internal DAC or amp as good as something like the Topping equipment yet.

AKG K371 are $119 right now, less than half the price (normally $150, half the price). Add a $9 Apple dongle and you're set.

OK.... I got my pair at 200usd. maybe a unusual price.

anyone feel dizzy with NC on?

and if my ear feel inside pain,annoying and tired, means usually what range of hz should be eq lower,? beyond 1k?

I felt this with hd820 and bose qc352. but fine with arya and hd800s
 

Lotus97

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OK.... I got my pair at 200usd. maybe a unusual price.

anyone feel dizzy with NC on?

and if my ear feel inside pain,annoying and tired, means usually what range of hz should be eq lower,? beyond 1k?

I felt this with hd820 and bose qc352. but fine with arya and hd800s
I think that has to do with cans being closed back, I went thru same like you since they my first closed back cans, all my other cans are open back. Thing is after 2 months of owning them it went away.
 

MayaTlab

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I'm a little bit curious about a design aspect of Bose' NC headphones, and would appreciate anyone's input regarding what it means.

With a lot of ANC headphones the internal mic arrangement looks like something like this (Freebuds Studio) :
Screenshot 2021-03-02 at 09.53.30.png

Basically, the mic sits atop or near the driver, and then on top of them you get your traditional cloth mesh and optional foam (Sony XM3/4 for example).

Bose seems to like to cover their drivers + mic with a sort of aerated semi-rigid (think aluminium foil) metallic mesh, for example here the QC35 and 700 :
Screenshot 2021-03-02 at 09.55.43.png

Screenshot 2021-03-02 at 09.55.20.png


What do you think would be the purpose of this mesh ?

More pictures from 52audio's teardowns of the QC35 and 700 here :
http://www.52audio.com/archives/29931.html
http://www.52audio.com/archives/31642.html
More teardowns from 52audio of over on on-ears BT HPs here (including most of the usual suspects) :
http://www.52audio.com/archives/category/fix/bluetooth_anc
 

Bjpenn88

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So it appears this headphone was measured while it was wired direct to an external headphone amplifier. However, wouldn't it be more reasonable to conduct the review/measurement of Bluetooth,ANC headphones while they are in the state for which they were designed? i.e when connected over bluetooth, using the internal DAC, with ANC on? Or is the intention that we are comparing them to other wired headphones with a proper DAC?
 

svenz

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I was using Oratory’s EQ, but will try @amirm settings. It seems to me that having less -but carefully chosen- PEQ points always make the cans sound more natural.

I don't think oratory has measured these... maybe you mean the QC25?
 
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