[carmatic]

  I don't share that sentiment because it doesn't always play out in reality -- sometimes, or for certain types of music, one may find the softness introduced by this extra A/D conversion favorable.
 
 

that is subjective, but objectively the integrity of the signal is always more degraded the more things you have happening to it
Quote:

  Also you're just moving the DAC from within the device to within the headphone, the words pot, kettle, black come to mind. What's to say one DAC will definitely be significantly better than the other in daily use?

one only needs to see the myriad of posts asking about headphone/amp combos to see that its not just about a 'better' DAC, but having a complete package where the headphones are matched to the circuitry
and in the case of the qc20's , this specifically means avoiding the use of 2 DAC's one after another

   
Huawei is already selling a pair of ANC earphones that charge from two of their smartphones..one of them being the Mate 7 I believe? And Apple's created an entire spec for headphones to do exactly what you want via the lightning port. JBL may have in fact launched the product you want at CES this year and then backtracked. But you know what, A) I'd rather keep that port free for charging, B) I don't believe most headphones would use a DAC chip that beats the device's performance by a wide margin, and C) all of this is just really really gimmicky, more than it needs to be.
 

i used to own a Sony Xperia Z3 and their NC31EM noise cancellers which ran off the noise cancelling circuitry built into the phone, and they were kind of mediocre - those earbuds were what i would call a mere gimmick of that phone
what do you mean 'keep that port free for charging' , it is USB so it can send both data and power, and being a pure DAC it would dispense with the battery altogether... you could replace the switch with the volume control
and specifically pertaining to the qc20 , it has a DAC already anyway so why not feed it the raw digital input? 

 

[heatofamatch]

Let me put it this way.
I was once that person who paid full retail on the iPad camera connector kit, paid for an external DAC, paid for the iPhone app, rebooted countless times to try and make it work, just to get what you call a less degraded signal. That reduced degradation was not worth carrying an extra DAC, it was not worth my money, my time, or my trouble, even though I could fully hear and appreciate the qualitative difference.
 
I auditioned a ton of players the other day. The ZX2. The AK Jr. Do they sound that much better? Yes. In my current life, does that difference merit my spending $1300 on a ZX2, or $600 on an AK Jr? Oh Hell No. That's just how I roll these days.
 
Besides if you keep going down that purist road, you're gonna eventually run into people lecturing you on how the QC20's quality is only equal to $100 IEMs. Good luck talking sense into them.I don't mind what they say anymore, because other people's benchmark is not my means of measuring how well an item (in this case the QC20) fits my personal use. I listen to them to get educated, yes, but I always ask, do they truly apply to me? Do they merit my unconditional subservience? 

 
And opinions matter because this is audio, A) a hobby that is inherently highly subjective, B) whose main purpose is to find the best fit for my ears alone. It's never going to be as objective as say, chasing raw horsepower in a computer.
 
Oh, and 'keep that port free for charging', refers to charging the smartphone itself.  

 
Now, going off-topic: I own several Sony NC products -- having used them from first generation way back in 2001 -- and based on real-life use, I suspect Sony intentionally made the noise-cancelling performance of the NC31E and NC31EM (an Xperia accessory) weaker than its walkman-series counterpart, the NWNC33. Their isolation ability are not identical when connected to the same device, and the Walkman version is stronger.
 
I suspect this is also going to be the case with the new version, the NC750 (Xperia accessory) and NW750 (walkman accessory).

 

[carmatic]

That reduced degradation was not worth carrying an extra DAC

but if you are carrying around a pair of qc20's, you are technically already carrying around the DAC thats built into them

Besides if you keep going down that purist road, you're gonna eventually run into people lecturing you on how the QC20's quality is only equal to $100 IEMs.

i am a purist, and the majority of my unease about the qc20 stems from the fact that there are no published specs about the bit depth or bit rate of the internal processing, or even something like the SNR
i think that the ADC of the input signal is the main bottleneck in the performance of the qc20 , and the reason why it sounds like a $100 pair of earphones, the only ADC happening should be the noise cancelling microphone signals
 

 
Oh, and 'keep that port free for charging', refers to charging the smartphone itself.  

 

whoops, my bad
but even still, at least as far as i know for the newer Samsung phones it is possible to charge and use the OTG at the same time http://lavalink.com/products/samsung-galaxy-tab-usb-adapters-hubs-poe-hubs-2/usb-otg-host-charge-adapter-tab4-tabpro/

   
Now, going off-topic: I own several Sony NC products -- having used them from first generation way back in 2001 -- and based on real-life use, I suspect Sony intentionally made the noise-cancelling performance of the NC31E and NC31EM (an Xperia accessory) weaker than its walkman-series counterpart, the NWNC33. Their isolation ability are not identical when connected to the same device, and the Walkman version is stronger.
 
I suspect this is also going to be the case with the new version, the NC750 (Xperia accessory) and NW750 (walkman accessory).
 

ah, thank you for the hint... i had no idea that the NWNC33 even existed ... they look almost the same and have the same 5-connector plug, and for some reason the NWNC33 costs less than the NC31 on Amazon, it seems to be a bargain
it would be interesting to compare the NC750, NW750 and the EX750 (which seems to be Sony's take on the qc20) , although searching about the NW earphones tends to only give Japanese results, but thats better left for another thread...

 

[davidc1]

 .

 

[davidc1]

Hi. Ive been using qc20 from past 1 week and when I recently travelled in cab I noticed some noice from the earphones whenever the cab goes through a rough road. After that I checked that on tapping the earphonesI could hear speaker membranemaking noise.
Is there any way to fix this or is this a problem with all qc20s?

All headphone with noise reduction can sometimes be overwhelmed by road noise, especially in a noisy car. When this happens the affected ear will produce a lot to distortion, usually be louder, and extra "noise". That is a possibility.

 

[jlongg]

Hi guys just came across this thread, and saw that you mentioned sound diffrences between new/old model of the qc20.
So just wanted to ask, I saw 3 different boxes , two of them are with the blue cord, and I got a bit confused which one is the newer-better model. And whats the diffrence between the two blue-cord models?
 
Images:
 blue cord 1 : http://i.ebayimg.com/00/s/MTIwMFgxNjAw/z/xAMAAOSwiwVWR2P0/$_57.JPG
blue cord 2 : http://i.ebayimg.com/images/g/mHoAAOSwT5tWF88u/s-l1600.jpg
 
anyone know whats the difrence between these two? are both "new" model?
 
Thanks

 

[ryanjsoo]

Why would the qc20's have a dac built in? They only accept a signal through 3.5mm so the signal is analog by the time it even reaches the plug. They do have their own amp built in though the qc20s hiss much more than the qc25s so quality may be questionable. Doesn't hamper enjoyement though, i find the sound non fatiguing and plenty smooth for everyday listening, but forget about critical listening and lossless files, due to the hiss, there is much reduced dynamic range. But the bose qc series have always had unbeatable comfort for casual listening, i couldn't be happier with my purchase.

 

[andrewcalo]

Hi all,
 
So just got these - they seem good, but there are sudden unexplainable dips in the sound - like the songs become deeper, like I just stepped into the room next to where the song is playing?

 

[andrewcalo]

Anyone?

 

[bubsdaddy]

I have never experienced what you are describing. Bose has excellent customer service so I would give them a call. 

 

[kennish]

Can you share with us how you opened the unit?  Did you have to slice off the rubber exterior?  Thanks or sharing the images.

 

[Akash]

I found the images on  website / someone was selling bulk loads of genuine faulty battery modulars only for Bose QC20I's..Don't ask why and how and who would buy these...

 

[carmatic]

Why would the qc20's have a dac built in? They only accept a signal through 3.5mm so the signal is analog by the time it even reaches the plug. They do have their own amp built in though the qc20s hiss much more than the qc25s so quality may be questionable. Doesn't hamper enjoyement though, i find the sound non fatiguing and plenty smooth for everyday listening, but forget about critical listening and lossless files, due to the hiss, there is much reduced dynamic range. But the bose qc series have always had unbeatable comfort for casual listening, i couldn't be happier with my purchase.

if you see the picture posted of the QC20 case opened up, you can see that there is no direct connection between the 3.5mm input and the earbuds
the analog signal is actually being converted back into digital , followed by processing for the noise cancellation and thats where the hiss and the reduced dynamic range is caused, before being converted into the final analog signal which is sent to the earbuds

 

[Brokkr]

headphone jack was accidentally ripped out of the main board (with the active noise canceling). The photos from this device can be found here: http://imgur.com/yy0gow6 I was able to open these quite easily. I had to peel off the ends which had a sticker type protection over them and then was able to pry the rest of the case open using a razer blade and another sharp straight edge. So, after opening this up I see that it appears to be some kind of black compound/glue on the connections and it appears to be 11 different wires that got ripped off the board.

The real question is, how can I tell where they should be reconnected and how should I go about doing it? Any advice, picture or schematic is welcome!
 
 

 

[Brokkr]

Also advice on how to remove that black glue would be welcome as well!