[Meanstreak]

Hi all,
I have an LG V20 which has a quad DAC built in. I am looking for headphones that are high impedance. The DAC handles between 50 and 300 ohms but would prefer to stay around 80 ohms, maybe up to 250 but the higher the impedence the faster it will drain the battery. I would like something with removable cable so I can add mic and remote capabilities for Android.

 

[MindsMirror]

the higher the impedence the faster it will drain the battery.

This is not correct. It is the sensitivity that will determine how much power it will use and how fast it will drain the battery.
 
I don't think it is wise to shop for headphones based on their impedance. First make a list of headphones that have the sound, comfort, style, price, etc. that you're after. Then you can rule out the ones who's impedance and sensitivity is not suitable for your source.

 

[Meanstreak]

I want high impedance to take advantage of the Quad DAC that is built into the phone. I need 50 ohms to trigger the high output of the DAC

 

[Meanstreak]

I'm looking at Beyerdynamics custom studio which are rated at 80 ohms

 

[ProtegeManiac]

Quote:

the higher the impedence the faster it will drain the battery

 

There is no direct correlation between power output level and power consumption and impedance. A 52ohm headphone with 93dB sensitivity will still require more power than a 300ohm headphone with 97dB at the same dB level of actual sound output.

 

That said, for mobile devices, one concern is how much clean power you can pump out at 300ohms when you're starting with a chip that does maybe 15mW at 32ohms with inaudible distortion. This is where high impedance has an indirect effect on the power consumption since you'll probably have to run the chip near full tilt just short of really obvious distortion.

 

 

 

Quote:

The DAC handles between 50 and 300 ohms but would prefer to stay around 80 ohms

 

AFAIK the LG V20 has a low enough output impedance that even 32ohms isn't going to be a problem. However as tempting as Grados might be, the non-existent isolation could still mean you'd still need to crank it up, so a closed headphone would be your best bet. Look into the Focal Spirit Classic and Spirit Pro.

 

[obobskivich]

That said, for mobile devices, one concern is how much clean power you can pump out at 300ohms when you're starting with a chip that does maybe 15mW at 32ohms with inaudible distortion. This is where high impedance has an indirect effect on the power consumption since you'll probably have to run the chip near full tilt just short of really obvious distortion.

There is no rule that says "if you can only do 15 mW into 32 ohms you will do less into 320 ohms" however - there are plenty of OTLs that can provide a lot more power at 300 ohms than at 30, because they have significantly more output voltage on tap. Mobile devices are basically the inverse of this, as they are generally output voltage limited due to being battery powered and the compromises made for their size/battery life/cost/etc. That said, 15 mW is absolutely earsplitting into a lot of headphones, especially ones designed with some portability/mobility in mind. If you need to run something fairly power demanding, it'd be better/easier to just get a mobile amp.

Higher impedance headphones will not improve battery life unless you're eliminating power consumption questions, for example an ANC headphone that provides its own amplifier and looks like a line sink to the phone (so the phone's output behaves more as a voltage source) may somewhat extend battery life because the actual output power requirements are almost nil (but you're going to run the batteries on the ANC headphone down to run the amplifier there). Of course remember: absolutely everything on the device represents a drain on the battery, so even running the media player and handling all the storage accesses and decoding is going to drain on the battery too.

I don't know anything about the specific model of phone in question here, but I get the sense there's some (potentially misleading) marketing material being misappropriated in the discussion.

To add: I absolutely agree with the broader sentiment of the replies thus far - high impedance won't magically extend battery life (and actually be a worse choice as it will probably be harder for the phone to drive), and it's not a good variable to base a headphone purchase on.

 

[ProtegeManiac]

There is no rule that says "if you can only do 15 mW into 32 ohms you will do less into 320 ohms" however - there are plenty of OTLs that can provide a lot more power at 300 ohms than at 30, because they have significantly more output voltage on tap.

 
I normally mention OTLs but they're the exception to the rule and are not the type of circuit that the OP will be using, which in this case is a smartphone, and as you've discussed is very limited in voltage output.
 
Just to add though, even if the source device is used to output a line output signal to another amp (stand alone amp, wired ANC, etc), there are exceptions, as when for example even on the same earphone some phones can get them loud enough at 50% setting, but then adding an amp with insufficient gain will then end up not getting the same earphone louder and still require higher volume settings. That said, the same smartphone would be distorting if a headphone was hooked up to it at that setting, so in such a case, the amp makes it possible to drive that headphone properly, just without extending the source device battery life.
 
 
 
 

 

[Meanstreak]

I was thinking of running the Beyerdynamics custom studios. I think I should be fine with the built in Quad DAC

 

[Meanstreak]

There is no rule that says "if you can only do 15 mW into 32 ohms you will do less into 320 ohms" however - there are plenty of OTLs that can provide a lot more power at 300 ohms than at 30, because they have significantly more output voltage on tap. Mobile devices are basically the inverse of this, as they are generally output voltage limited due to being battery powered and the compromises made for their size/battery life/cost/etc. That said, 15 mW is absolutely earsplitting into a lot of headphones, especially ones designed with some portability/mobility in mind. If you need to run something fairly power demanding, it'd be better/easier to just get a mobile amp.

Higher impedance headphones will not improve battery life unless you're eliminating power consumption questions, for example an ANC headphone that provides its own amplifier and looks like a line sink to the phone (so the phone's output behaves more as a voltage source) may somewhat extend battery life because the actual output power requirements are almost nil (but you're going to run the batteries on the ANC headphone down to run the amplifier there). Of course remember: absolutely everything on the device represents a drain on the battery, so even running the media player and handling all the storage accesses and decoding is going to drain on the battery too.

I don't know anything about the specific model of phone in question here, but I get the sense there's some (potentially misleading) marketing material being misappropriated in the discussion.

To add: I absolutely agree with the broader sentiment of the replies thus far - high impedance won't magically extend battery life (and actually be a worse choice as it will probably be harder for the phone to drive), and it's not a good variable to base a headphone purchase on.

I guess I wasn't very clear but my phone has a 32 Bit Quad DAC which automatically adjusts its output to the device its connected to. It will kick into high output mode if it senses 50 to 300 ohms being connected to it. I want use high impendance headphones because in general based on what I'm reading they provide better sound as long as you have the output to drive them. My only concern was if high impendance uses more power. I wasn't looking for high impedance to extend battery life.

 

[obobskivich]

I normally mention OTLs but they're the exception to the rule and are not the type of circuit that the OP will be using, which in this case is a smartphone, and as you've discussed is very limited in voltage output.

There's not really any "rule" here - it depends on the device what kind of loads it will or won't be more efficient with. That's my whole point.

Just to add though, even if the source device is used to output a line output signal to another amp (stand alone amp, wired ANC, etc), there are exceptions, as when for example even on the same earphone some phones can get them loud enough at 50% setting, but then adding an amp with insufficient gain will then end up not getting the same earphone louder and still require higher volume settings. That said, the same smartphone would be distorting if a headphone was hooked up to it at that setting, so in such a case, the amp makes it possible to drive that headphone properly, just without extending the source device battery life.

Hooking up multiple devices will always be a ballet of gain and sensitivity, and different settings don't necessarily mean "less power" or similar (e.g. you can never directly compare volume control settings of different devices or devices into/with different loads because its a relatively arbitrary value - think of it as a unitless number). As to whether or not it helps or hurts the phone's battery, that's why I said "may" but most likely we aren't talking significant changes one way or another because *everything* is a drain on that poor battery.

I guess I wasn't very clear but my phone has a 32 Bit Quad DAC which automatically adjusts its output to the device its connected to. It will kick into high output mode if it senses 50 to 300 ohms being connected to it. I want use high impendance headphones because in general based on what I'm reading they provide better sound as long as you have the output to drive them. My only concern was if high impendance uses more power. I wasn't looking for high impedance to extend battery life.

Can you provide a link to more in-depth information on this device? Or a more complete model # so I can go find it myself?

 

[Meanstreak]

I did include the complete model number
It's made by LG and its the V20

 

[obobskivich]

I did include the complete model number
It's made by LG and its the V20

Must've missed or misunderstood.

Took a bit of digging (all in about 15 minutes), and we can cut through the marketing schtick:

- It has an ESS Sabre 9218 2ch DAC ("QuadDAC" is marketing nonsense, if you were wondering)

- The 9218 advertises a built-in headphone amplifier (which I'm assuming the LG uses), which touts its ability "to drive high impedance headphones." I have found absolutely nothing (in probably half a dozen reviews, the LG website, etc) that mentions anything about "needing a higher impedance load to 'engage' this feature" however.

- Very much of this device and its actual specifications are shrouded behind marketing double-speak, but some sources have tried to unravel the whole thing: http://www.androidauthority.com/lg-v20-quad-dac-explained-713587/

- It appears that ESS specifies it with "up to" 2Vrms output, which would comport with the ability to drive higher impedance (and thus higher voltage requirement) loads. However they don't specify anything useful like current, or more practical like power output, but again, I've seen nothing, anywhere, that says "it must use high impedance loads to activate" or anything of the sort.

- There is a HUGE V20 thread that I turned up: http://www.head-fi.org/t/816024/lg-v20-sound-quality It does mention the prior version, the V10, at launch trying to automatically "read" the headphones' load, but that post-update this has been removed because the feature is somewhat inaccurate/misapplied (e.g. high impedance != high quality, it just means high impedance). A reddit thread seems to indicate this carries over for the V20, and that the user should be able to select "hifi mode" - https://www.reddit.com/r/headphones/comments/58yr2w/headphone_test_with_the_new_lg_v20_in_hifi_mode/

- The device tries to engage a higher voltage output mode (high gain) for high impedance loads, which is unnecessary for low impedance loads. More here: https://forum.xda-developers.com/v20/help/impedance-device-dac-t3494760 Basically what the device is trying to do is be too smart for its own good, by automatically detecting if it needs to be in high or low gain mode based on whats plugged in. Too many assumptions are made for that feature to work though, like MindsMirror pointed out - sensitivity is a big part of this discussion too, and the phone cannot "poll" that.

Ultimately this is kind of what I had projected: stupid marketing features run amok, leading to significant confusion and a device that's obnoxious to live with. There's a lot of really atrocious "reviews" or "articles" about this that erroneously claim that "high impedance" somehow equates to "studio headphones" or some other faff. Just ignore it all - its wrong and exists within its own little walled garden of reality distortion. For the absolute last time: impedance is NOT A METRIC OF SOUND QUALITY, IS NOT A METRIC OF "hard to drive-ness," AND IS NOT A METRIC OF PERFORMANCE.

Get whatever headphones you actually want/like and get on with life. The V20 should be competent to drive many things out there, at least by phone/tablet standards, and that's that.

 

[Meanstreak]

I found that thread and I'm still reading. The quad DAC is not all marketing but I do agree a part of it is The amp is only triggered by high impedance headphones so that's what I'm getting.

Thanks

 

[Meanstreak]

I forgot to mention that I have an inexpensive Sony Noise Cancelling headphones that are high impedance due to the NC circuit. They trigger the amp and you can really hear the difference on output. There are 3 levels of output.
Normal for low impedance devices.
Aux level for external devices
High impedance level for headphones that range from 50 TO 300ohm.

I'm not going to the higher end of things. I am looking at a Beyerdynamics Custom Studio headphones which seem to review well and are 80 ohms and can be found for 199us

 

[obobskivich]

I found that thread and I'm still reading. The quad DAC is not all marketing but I do agree a part of it is The amp is only triggered by high impedance headphones so that's what I'm getting.

Thanks

What I mean by "is all marketing" is how they're presenting it. It's confusing and misleading. Historically there have been higher-end devices that really do have multiple DACs, whereas what ESS is providing here is a 2ch DAC with some other features built-in to the SoC, and probably a new/clever filter design, which they're outing as a "QuadDAC" largely because they can. It's like how nowadays any feature put into an SoC becomes a "core" and you get these n-core devices where things like MMUs, I/O controllers, etc become "cores" too. It's like megapixel marketing for the new generation. This doesn't mean it isn't a high quality device.

From everything I could find on this device (and there is also a bit of logic here which I hope becomes apparent) the amplifier output, and the DAC's output, are ALWAYS active (by necessity - it isn't dumping over to some "other" signal path because it simply doesn't have another signal path to drop over to), all that it is doing is trying to adjust gain settings relative to the load (and this is problematic because the information it can actually measure isn't sufficient for it to make these guesses). It's a neat, if gimmicky, feature. You're welcome to dismiss this and believe what you want (and it seems like you had your mind made up well before even posting this thread), but that isn't changing reality.

I forgot to mention that I have an inexpensive Sony Noise Cancelling headphones that are high impedance due to the NC circuit. They trigger the amp and you can really hear the difference on output. There are 3 levels of output.
Normal for low impedance devices.
Aux level for external devices
High impedance level for headphones that range from 50 TO 300ohm.

Of course you can hear the difference - if it needs higher voltage swing/higher gain to drive it, and it provides that voltage swing/gain, its being properly driven and is thus better (or the old standby - the louder sound in any sighted comparison usually wins, and this is actually a thing). But you're unable to actually test your claim here (because its contextually weighted), nor would it produce anything but the same outcome, because again - its simply changing its output to better accommodate the load at hand. It's a gain switch. They took a gain switch and turned it into a "new and advanced feature." That's marketing schlock in my book. Like I said, get whatever headphone you want that you actually like and be happy. If you're seriously going to lose sleep over this "high output" nonsense, go buy something with high impedance, but there's not a good rationale behind it. I don't like Beyerdynamic cans personally, but Koss makes some good cans that still run 250R (like the PRO4/AA), and there's some new-ish ATs and AKGs that still present 250R or 600R loads that are designed for studio use.