Bose QuietComfort 45 Headphone Review

[Maiky76]

As you see, we get noise reduction from 80 to 400 Hz but above that, the headphone electronics is injecting its own noise. Shame that we are stuck between having good frequency response and noise.

The main sources of noise in this type of devices:

1. NC microphones have a finite SNR from 63dB (every other maker) to 73dB (a select few like Infineon and Knowles) so they generate their own noise...
2. Portable electronics also have a finite SNR, Bose usually uses Qualcomm BT IC (QCC51xx) and ADI DSP (ADAU 1777, 1787 and newer)
3. NC function in particular the Feedback (FB) loop (as opposed to the feedforward) where you need to amplify the signal from the FB mic by 15-25dB
4. The FB loop is not perfect: example of the QC35.2 anything above 0dB will actually amplify the noise!
   BTW QC35.x are better than the 45 and 700 in terms of NC.

So yes, for now, you have to trade SNR for accuracy to get portable devices offering NC with decent battery life/weight.
Accuracy is NOT an issue as BT ICs and any DSP will have more than enough EQ capabilities to match pretty much any target.
Therefore no EQ for those.

Score no EQ 55.3
Score with 75.5

Regarding the L/R imbalance that is too much i.e. it barely meets the industry low standard (within 6dB) and way too much for a large maker.
It should be within 3/4dB max up to 5kHz I reckon, above both diaphragm break-up and cavities modes make it trickier.
In the old days prior to iPhone, Nokia bundled earbuds that were within 2dB up to 8kHz and would still be industry leading today.
I would not be surprised at all that someone could pick that up, QA apparatus can 100%, and trained personnel definitively would...
So it is what is it because it fine by their standards and might be related to built-in L/R issues of the design and consistent across production.

 

[amirm]

Regarding the hiss/noise, it is subtle. I had first generation NC headphones that put out a lot more noise.

 

[192kbps]

I once bought a QC35 for gaming, but the noise floor was too noticeable, so I sold it, forever happy.

 

[Koeitje]

As much as I hate Bose's loudspeaker offerings their NC headphones have always been good. When I see people complain about younger people not caring about audio quality anymore I always wonder where that is coming from, because I see a ton of Bose and Apple AirPods Max headphones all over the place.

With regards to noise: when I use NC headphones I'm already in an environment where the noise is way above the noise level of the NC anyway.

 

[KxDx]

Are there even any over-ear headphones that have a direct usb-c connection? Wireless won't work for me because i tend to leave them in the car and I'll inevitably forget to charge them (and the heat wont do any favors either). But I'd also like to be dongle-free.

 

[Morpheus]

@perdido34
Hi, I gifted my wife a couple years back the Sony model you are replacing.I still like them, but the hiss has always been a bit too noticeable. How do they compare in that regard to your new Bose?

 

[perdido34]

@perdido34
Hi, I gifted my wife a couple years back the Sony model you are replacing.I still like them, but the hiss has always been a bit too noticeable. How do they compare in that regard to your new Bose?

The low-level hiss is there when I'm not playing any audio over the headphones. I have never noticed it when playing music or during zoom meetings, but YMMV depending on your hearing and your ability to focus.

 

[Robbo99999]

Yawn. Your problem is obviously obtuseness. Why this useless and irrelevant link to the HD 800s? I have the headphones myself, so I think Amir's review is correct, as is the positive review by rtings. In addition, Amir is not just some narrator of anecdotal stories, but someone with a lot of experience. And he furthermore explained a few posts ago what is going on. As I already wrote, there is no cure for stupid stubbornness: your sacred measurements are in my book 50-80% and in this case maybe more like 50%. I don't care about your opinion.

It's certainly not ideal that your headphones have that imbalance in that part of the frequency range, and in my opinion you'd mark the headphone down for that. The good thing is you've had the headphone measured, so you could do an EQ to correct the channel balance in those areas of the frequency response - albeit you'd ideally want to have had the headphone measured after a number of reseats & averaged to be sure on exactly what the channel balance was, as a single measurement can not always be that representative.

 

[JohnBooty]

Great review. Nice to see some good objective performance from the much-maligned folks at Bose.

One "side benefit" of using popular mainstream models from Bose/Sony/etc is that there is a wonderful ecosystem of:

• 1st and 3rd party replacement earpads (the QC45 pads are compatible with the QC25/QC35 as well, as a bonus... which is good, because they do wear out)
• Repair guides for things like battery replacement
• etc

Interesting that the channel imbalance is so large in passive mode and disappears in the active modes, guess its due to different internal cup volumes due to electronics and nicely corrected by their EQ/DSP.

Ah, that makes so much sense. I was puzzling over that.

 

[617]

The channel imbalance is not due to low quality drivers. Modern drivers generally don't have 6db variations in their piston region.

The channel imbalance is due to the wildly different acoustic context between the side cups (my opinion anyway). One side of the headphone has a pcb with some little mics attached, but the other side has that with a lithium polymer battery as well. This takes up a lot of volume.

Also to those complaining about the noise, I get it, but consider this.

If an audiophile brand created a product which attenuated all room noise, your neighbors, your dishwasher, the guy running his leaf blower, by 30db, and replaced it with a dull whooshing noise that was imperceptible when music was playing, it would be considered the greatest hifi product ever invented.

I find the noise annoying, but to me, my enjoyment of music is vastly improved with Anc headphones. The Anc lets me hear more detail than my sennheiser 650s most of the time I'm inside, and I can wear them when I'm in my garden. My problems with them relate to their durability and difficulty eqing them, but the way they deliver music is incredible.

 

[Robbo99999]

The channel imbalance is not due to low quality drivers. Modern drivers generally don't have 6db variations in their piston region.

The channel imbalance is due to the wildly different acoustic context between the side cups (my opinion anyway). One side of the headphone has a pcb with some little mics attached, but the other side has that with a lithium polymer battery as well. This takes up a lot of volume.

Also to those complaining about the noise, I get it, but consider this.

If an audiophile brand created a product which attenuated all room noise, your neighbors, your dishwasher, the guy running his leaf blower, by 30db, and replaced it with a dull whooshing noise that was imperceptible when music was playing, it would be considered the greatest hifi product ever invented.

I find the noise annoying, but to me, my enjoyment of music is vastly improved with Anc headphones. The Anc lets me hear more detail than my sennheiser 650s most of the time I'm inside, and I can wear them when I'm in my garden. My problems with them relate to their durability and difficulty eqing them, but the way they deliver music is incredible.

That sounds sensible to me. About channel matching & drivers, I have a miniDSP EARS rig (to measure all my headphones) and I've found that pad variation can create channel imbalance (even at specific frequencies like this reviewed headphone exhibits it's issues) - so to me channel matching is about everything that is happening structurally "within" the cup (including the earpads) as well as how the individual drivers themselves are matched.

 

[lewdish]

My takeaway is that most people using this will never be using it in passive mode, so whatever Bose DSP going on is good, but it looks like they didnt bother w/ that huge dip cause its a consumer products and higher frequencies like that can't be bothered w/ . Bose products these days all are more or less harman target of some kind and im sure their engineers recognize the utility of Harman and did their own research to conclude whatever cost effective targets to meet. Tho im curious if an EQ of that degree will have serious impact on battery life which is why they dont bother EQ'ing it out in DSP.

They dont play loud, but loudness in an ANC products is more or less a non-issue. Since a consumer is already attenuating outside noise via ANC you dont really need the extra loudness as a result the high distortion metrics dont really matter anyways, tho looking at Apple's APM they look like they've managed to DSP out the extra distortion and maintain fairly high output still, Amir should consider re-measuring the APM now that its been heavily changed via updates as well.

All in all its a ok engineered product for its target demographic, but I personally wouldn't buy them cause I cant stand the subversive ANC sound. Something werid about the way ANC makes me feel sick typically. I literally wear the exact opposite of ANC , meaning open backs everywhere even in public (Austrian Audio x65). Personally i'm not a harman target guy, but Bose products are fine for their demographic.

On a non-science related topic: I dont see the company taking an aggressive enough of an approach in innovations to sustain w/ growth. I live near Bose HQ, but they're always laying people off all the time & recruiting college interns, but nobody really stays there. Their market share is shrinking to Apple/Sony/etc. Bose isnt really grabbing the attention of Audiophiles like they used to back in the 70s-90s, I think they peaked at DSP research when they started doing Soundbars (arguably losing to Sonos research now) and havent really progressed since. Just my 2 cents~

 

[617]

That sounds sensible to me. About channel matching & drivers, I have a miniDSP EARS rig (to measure all my headphones) and I've found that pad variation can create channel imbalance (even at specific frequencies like this reviewed headphone exhibits it's issues) - so to me channel matching is about everything that is happening structurally "within" the cup (including the earpads) as well as how the individual drivers themselves are matched.

Correct me if I'm wrong - but the channel imbalance created by pad variation and seating is pretty huge - complete difference in tonality. Does it impact the 'intelligibility' region of say 1-5khz much?

 

[Robbo99999]

Correct me if I'm wrong - but the channel imbalance created by pad variation and seating is pretty huge - complete difference in tonality. Does it impact the 'intelligibility' region of say 1-5khz much?

It can do, I've got 4 units of K702 that I've measured, and one of those units that had "genuine AKG pads" which I had purchased said pads as a replacement from Thomann, when they were on one of my K702's it created a dip in one of the channels between 1-3kHz, can't remember if it spanned that whole region but it was certainly in that region and was significant - a dip of at least 3dB or more compared to the other channel in that localised area (it was a definite artifact rather than just a gentle shifting of the balance, a significant change to the shape of the frequency response in that localised area); however, when I bought some aftermarket pads that closely mirrored genuine AKG pads from another manufacturer, and I replaced them on that particular unit and remeasured the headphone, then the channel imbalance was completely gone in that localised 1-3kHz area, the strange & significant dip was no longer there! (in fact the overall channel balance through the whole frequency range was better with the aftermarket replacement pads). Yes, so that's why I know the earpads can have marked effect on the channel balance as well as in the balance in specific localised areas of the frequency response, which corroborates your idea that channel matching is about more than just the driver itself.

 

[617]

My takeaway is that most people using this will never be using it in passive mode, so whatever Bose DSP going on is good, but it looks like they didnt bother w/ that huge dip cause its a consumer products and higher frequencies like that can't be bothered w/ . Bose products these days all are more or less harman target of some kind and im sure their engineers recognize the utility of Harman and did their own research to conclude whatever cost effective targets to meet. Tho im curious if an EQ of that degree will have serious impact on battery life which is why they dont bother EQ'ing it out in DSP.

They dont play loud, but loudness in an ANC products is more or less a non-issue. Since a consumer is already attenuating outside noise via ANC you dont really need the extra loudness as a result the high distortion metrics dont really matter anyways, tho looking at Apple's APM they look like they've managed to DSP out the extra distortion and maintain fairly high output still, Amir should consider re-measuring the APM now that its been heavily changed via updates as well.

All in all its a ok engineered product for its target demographic, but I personally wouldn't buy them cause I cant stand the subversive ANC sound. Something werid about the way ANC makes me feel sick typically. I literally wear the exact opposite of ANC , meaning open backs everywhere even in public (Austrian Audio x65). Personally i'm not a harman target guy, but Bose products are fine for their demographic.

On a non-science related topic: I dont see the company taking an aggressive enough of an approach in innovations to sustain w/ growth. I live near Bose HQ, but they're always laying people off all the time & recruiting college interns, but nobody really stays there. Their market share is shrinking to Apple/Sony/etc. Bose isnt really grabbing the attention of Audiophiles like they used to back in the 70s-90s, I think they peaked at DSP research when they started doing Soundbars (arguably losing to Sonos research now) and havent really progressed since. Just my 2 cents~

Not only will most people be using passive mode...there are many people whose devices don't have headphone jacks to begin with.

I have a desktop computer with an audio interface but I only use it for monitors because I hate dealing with headphone wires. My tablet has a headphone jack but it's super annoying for the same reason, and it has bluetooth. My phone has no headphone jack at all.

My problem with Sony and Bose headphones is not what they deliver in terms of sound, it's that they are produced like, and marketed as 'technology' products rather than audio products. They have pathetic 1-2 year warranties, they're full of computers which are advertised to get better with every generation (which isn't true - the ANC in the newest Sony headphones is not better than version 3 iirc - I think we may be reaching a limit on how good it can be). They have batteries which can't be replaced, and they're made out of plastic.

I have no problem spending $400 on Sennheiser HD600s or whatever because I have a pair of 580s which I bought in the late 90s which would still be working if I could get a new driver for them (which they sold for decades.) Realistically a pair of $400 headphones could last 15 years - $26 dollars a year. Meanwhile my Razer Opus, which were fantastic headphones, just died and it's going in the bin unless I can maybe put a new battery in it. So, I expect them to last 3 or 4 years - $50 - $100 a year.

 

[617]

It can do, I've got 4 units of K702 that I've measured, and one of those units that had "genuine AKG pads" which I had purchased said pads as a replacement from Thomann, when they were on one of my K702's it created a dip in one of the channels between 1-3kHz, can't remember if it spanned that whole region but it was certainly in that region and was significant - a dip of at least 3dB or more compared to the other channel in that localised area; however, when I bought some aftermarket pads that closely mirrored genuine AKG pads from another manufacturer, and I replaced them on that particular unit and remeasured the headphone, then the channel imbalance was completely gone in that localised 1-3kHz area, the strange & significant dip was no longer there! (in fact the overall channel balance through the whole frequency range was better with the aftermarket replacement pads). Yes, so that's why I know the earpads can have marked effect on the channel balance as well as in the balance in specific localised areas of the frequency response, which corroborates your idea that channel matching is about more than just the driver itself.

When I design speakers I always make a 'friendly' space for the mid-driver to radiate into. You know, oversized, nice and long, maybe tapered and full of absorbing fibers. These high tech headphones are the exact opposite. They radiate into little plastic cavities with a PCB 1cm away.

When DSP came out, speaker designers said it shouldn't replace good acoustic engineering, but the truth is that DSP really can fix a multitude of sins.

This is part of the reason why I find it's so silly to measure them playing passively. You wouldn't design a headphone and then cram a thimble, a matchbook, some toothpicks and a 100 yen coin in the earcups and then expect it to sound good.

 

[Robbo99999]

When I design speakers I always make a 'friendly' space for the mid-driver to radiate into. You know, oversized, nice and long, maybe tapered and full of absorbing fibers. These high tech headphones are the exact opposite. They radiate into little plastic cavities with a PCB 1cm away.

When DSP came out, speaker designers said it shouldn't replace good acoustic engineering, but the truth is that DSP really can fix a multitude of sins.

This is part of the reason why I find it's so silly to measure them playing passively. You wouldn't design a headphone and then cram a thimble, a matchbook, some toothpicks and a 100 yen coin in the earcups and then expect it to sound good.

I'm not a speaker designer nor headphone designer and I don't have a detailed understanding of how headphone sound is shaped through the use of the physical structure of the earcup and everything else that surround the driver itself, but you'd have to think (& indeed we know) that the things that surround the driver making up it's earcup will for sure determine the frequency response you get - so you've got production tolerances of the driver itself (maybe the easy part), then you've got the production tolerance & assembly tolerance of every single other component in relation to the earcup physical acoustic design space (pads, foam inserts, other elements I can't list or know about!). So anything that affects the acoustical space associated with the earcup will shape the frequency response in some way.

 

[617]

I'm not a speaker designer nor headphone designer and I don't have a detailed understanding of how headphone sound is shaped through the use of the physical structure of the earcup and everything else that surround the driver itself, but you'd have to think (& indeed we know) that the things that surround the driver making up it's earcup will for sure determine the frequency response you get - so you've got production tolerances of the driver itself (maybe the easy part), then you've got the production tolerance & assembly tolerance of every single other component in relation to the earcup physical acoustic design space (pads, foam inserts, other elements I can't list or know about!). So anything that affects the acoustical space associated with the earcup will shape the frequency response in some way.

I think you're spot on, but I also think that the production tolerances for all these things are really dialed in, especially on products with hybrid ANC, which requires mics both inside and outside the enclosure.

Back in the old days tweeter assemblies would be glued together using a bead of glue from a bottle, applied by hand. Nowadays, the glue is dispensed by a computer controlled syringe in a clean room, cured by UV exposure. Modern transducer manufacturing is really precise, even for materials like paper and paper-like composites.

Also, back to the DSP - there are microphones inside the headphone, so if they can the response of that microphone, they should be able to use it to adjust for macro-tonal issues like incomplete pad seating and so forth. We can't integrate measurement microphones into speakers because they radiate into vastly divergent environments, but the beauty of headphones is that they all radiate into a little cup with an ear in it.

 

[Robbo99999]

I think you're spot on, but I also think that the production tolerances for all these things are really dialed in, especially on products with hybrid ANC, which requires mics both inside and outside the enclosure.

Back in the old days tweeter assemblies would be glued together using a bead of glue from a bottle, applied by hand. Nowadays, the glue is dispensed by a computer controlled syringe in a clean room, cured by UV exposure. Modern transducer manufacturing is really precise, even for materials like paper and paper-like composites.

Also, back to the DSP - there are microphones inside the headphone, so if they can the response of that microphone, they should be able to use it to adjust for macro-tonal issues like incomplete pad seating and so forth. We can't integrate measurement microphones into speakers because they radiate into vastly divergent environments, but the beauty of headphones is that they all radiate into a little cup with an ear in it.

Certainly for some headphone earpads the variation is certainly not dialed in properly, which was the point I brought up that pad variation can affect 1-3kHz in some instances. As you originally said, the variation that can be seen in a headphone is more than just the variation of it's driver component. As for the extent of other tolerances within the manufacturing & assembly process I cannot be certain, but I'm certain that some variation would exist, how big that variation I don't know, and it's likely different dependant on the starting "design variance susceptibility" of any given headphone model (some design models are gonna be more difficult to manufacture to tight tolerances in both production of it's individual parts & the assembly of those parts) combined with the willingness/ability of the manufacturer to commit to assembling it and controlling it properly with Q&A, etc, all of which has cost implications.

 

[amirm]

Let's start with the fact that they did implement channel matching up to 1 kHz and very tightly so. Question is, whey did they not take it to 3 khz. @Robbo99999 may be onto something: if pad variations were large in their factory jig, that would be the reason they didn't think they could reliably EQ to match in that region and left it alone. Based on my subjective testing, which very likely they performed too, this was a non issue so they have gone with it. I think they deserve praise for locking the two channels so well up to 1 kHz. And with appropriate bass boost. This is most of the game and they got it perfectly (and consider the very low distortion as well).