Line-out ≠ Headphone-out 

I think the whole "line out can be used for headphones" comes mainly from PCs, where line out and headphones were often coming off the same audio amplifier chipset, and were both volume controlled in software.

as a musician and audio engineer, this video is hilariously necessary for the music consuming public

I think another thing that is confusing in this discussion is that many modern devices either combine line out and headphone out, or have line out that is “amplified”, but have no volume control

As an audio engineer for the better part of 30 years (and an all-round nerd for much longer) I often find myself explaining the finer points of interconnect standards to normal folk with glazed eyes who couldn't care less and just want the thing to make the sound. I have to remind myself that there are far more walks in life about which I'm ignorant than there are in which I am expert.

Funny thing, I once had a CD player in the military that I left at the squadron one day. My buddy took it apart and soldered the headphones and Line Out wrong. When I got it the next day I couldn't figure out why it was so quiet, so I plugged it into the Line Out and it worked great. A few days later he told me what he did. Started telling people that it was a rare CD player because they mislabeled it. A lot of the new guys actually believed it.

Desktop pc sound cards have a socket labeled line out and you can plug in headphones into that, sound card detects the impedance of what’s been connected and adjusts levels appropriately. This may be the source of confusion.

This is a great video, I've always wondered this myself! A lot of the confusion comes from PC because the audio volume is always controlled manually on windows.

This is such a great channel. Always such interesting stuff and the production is top notch. Keep up the awesome work.

As you stated, a main source of confusion is that in practice, headphone outputs are often used as line outputs. Many a laptop or phone has been connected to an amplifier or powered speaker system by using the headphone output to feed the line input of the amplifier. Judicious use of the source device's volume control can give an appropriate signal level at the headphone output. Output impedance is really the issue here. Headphone outputs are low source impedance outputs while a line out is typically a high source impedance output (and as you say, line outs don't typically have a volume/level control). So a headphone output can do a passable job of providing a line output function, but a line output cannot drive most headphones.

I like that the headphone amplifier looks like a little whiskey flask.

After doing some restoration research and finding mostly useless videos with no editing, coming back to techmoan to relax is a welcome change of pace. Your videos are so well recorded, edited, and informative, thank you for your efforts

Thanks so much for taking the time to clear this up! For those of you who want to jump to why line out is not the same thing as a headphone jack - Purpose of line out 4:18 How to use a headphone amplifier to amplify the line out 8:15 Love the 8-Bit Guy Retro Grooves crossover btw.

Until now, I really thought Line Out was the same as Headphone out. Very informative. Thank you as always, Techmoan!

You are the first person that has managed to finally, at long bloody last, explain to me the whole concept of Line Level in clear and simple way. Many, many thanks for that. You may want to look into explaining other similar equipment intricacies, you are pretty satisfyingly good at it.

I have had some headphones that can be used in Line-out (according to their packaging), they have volume control on their cord. But I am thankful you explained this because now it makes a lot of sense!

Great video! More technical: Impedance mismatching between the line out and the headphones itself is causing low volume. Most of the modern headphones do have an impedance below 50 Ohms (typical 32 Ohms, but it slightly varies). To drive a 32 Ohm device, you'll need an amplifier that is at least 32 Ohms, but for a stable and predictable coupling, it's better to go way below that. In fact, a good designed headphones amplifier will have an output impedance that is 8 times lower, around 4 Ohms. And that's the issue with line level outputs. They have an output impedance of about 600 Ohms. You're literally overloading the output with headphones. It will cause a voltage drop. Line inputs tend to have a fairly high impedance of around 10kOhms. They're not able to overload a headphones output.

I think the concept is slightly blurred for a lot of people due to quite a few devices out there which have an output labelled as a shared headphone and line out socket, which is of course usually just a normal headphone output. Also nice to know someone else is enjoying Philips Fidelios!

I worked at Radio Shack in the late 70's, and I must have explained all this a hundred times to people in the store! Good video and explanation on it.

Nice Video. As "IT- Guy" I always get into the same problem with USB C. Most people think USB C is automaticly USB 3.0 or higher but that not the case. The one thing is the way it is build: TRS (Tip Ring Socket) or TRRS (second Ring often used for Microfon) known as Audio Jack and "Line In" or "Headphone" Jack is the technic behind it on the other Side. I mean USB C is the same connector like Thunderbold but it is almost never compatible flawless with USB 3.2 Gen 2 and so on...

The "gain Lo/Hi" is for either coming directly out of a record player at "Phono" level (Lo) or "Line" level (Hi) after it's gone through a mixer or some other piece of equipment that brings it up to Line level. Some record players may boost it to Line level now days, and this could account for the difference in levels you've experienced with different Vinyl players, however usually the vinyl player's Phono output will be some 20dbmV-30bdmV quieter than Line at a bare minimum being that Phono is normally around 0.15mV-5mV only (5mV is super high compared to the average), and Line runs at a level of up to around 300mV!. ;)

Another difference to consider is that the circuitry for creating a line output is designed to only provide just enough power to convey the signal from one device to another. They aren't meant to provide the power required to physically move a speaker/headphone diaphragm. And doing so could potentially damage or destroy the line output of a device, as it is being asked to provide a lot more power than it was designed for. Related to that is the impedance mismatch. Consumer line outputs are meant to drive a load of roughly 10,000 ohms. Headphones are typically less than 100 ohms. Not only does this mean that it takes more power to drive the headphones than a line input, it also means that the frequency response is going to be all wrong. When headphones are plugged into a line output, not only will it be quiet, and you could be damaging the circuitry, it's also going to sound bad -- usually seriously lacking in bass, overemphasizing higher frequencies. You can usually get away with going the other way (headphone output into line output) because it's easier to drive a higher impedance load than a lower impedance load, so headphone amplifiers can easily output the power required by a line input. Sort of like asking a sports car to idle down the street. But the impedance mismatch is still there, and it could result (depending on how the circuitry is designed) in bass frequencies being over emphasized. The other issue there is that headphone amplifiers, because they are primarily designed to provide more power rather than a cleaner signal, are often rather noisy (mostly in the form of hiss) compared to a true line output. The best thing to do is make sure that whatever load (headphones, line input, whatever) you're driving matches what the circuitry in the output is designed to handle. Anything else can result in poor quality sound at best, and damage or destruction at worst.

When I was at college, and poor, I bought a pair of ear phones from Poundland (back when everything was £1) and used to use them as a microphone for talking to friends on MSN. Wasn’t great quality, but it worked.

OMG I loved that stylish Walkman cassette player! Imagine those back in the day haha. I already knew all this but I was just interested in your equipment as I always loved EQ's, VU meters, plugs and wires and having the option to literally fine tune your music from any frequency or amplification! I used to install sound systems in cars and the odd home theater but, it's not the same as everything is wireless and hidden. Car stereo setups are exactly the same. Hook up a sub to the dedicated RCA line out and there is nothing. It was quite amazing how many people asked the same question that you are answering now. Great video and very detailed! Thanks.

Thank you for this video. I work in IT and dabble in audio a bit - the amount of times I have had to try to explain this difference to others has been an exercise in frustration. I'll be sending them your video from here on out :D

Like you said, the misconception comes from the fact that it’s the other way around. Before Bluetooth was so widespread there were car radios and small home hifis which had an input at the front labeled line in or aux in. Those were made to connect MP3 players or other small devices instead of other hifi equipment. Especially in the case of the car radio.

I love that Techmoan takes the time to educate us on stuff like this, especially when there's no guarantee a video about line-out vs headphone jack will be popular/bring in a lot of ad views.

You have a shockingly good mic! I swear I could hear the percussion engraved on that vinyl even before you turned on the amp.

I did not know that! Thank you for showing it. This does explain some of the issues I've had in the past! Most PCs have a line out-headphone hybrid though

Thanks for taking the time to set the record straight properly Techmoan. The problem with the information age is that as information has become more accessible, so has disinformation. Wise men talk because they have something to say; fools, because they have to say something.

The amplification on a Headphones output is Current based (amps) rather than the Voltage based level for Line Out. The circuitry is 'high impedance' for line out (can be thought of as having the volume pot set to low) therefore does not supply enough current to drive magnetic headphones. You would probably find old piezo headphones would work much better because of their low current demand. This would still not resolve the need for variable volume of course unless the headphones had an integrated pot. EDIT - For clarification, Headphone Output = Low impedance ( eg 8 or 16 ohms), Line Out = High Impedance ( could be 1000s of Ohms).

have designed a lot of professional gear in my time. I would sometimes be asked to put an 1/8" mini stereo jack in so a tech can check for output with headphones. The line output would be 1/4" Phone XLR. Often to save space I used the same op-amps for the line and headphone outputs. As all of these outputs have a resistor in series, to eliminate the capacitive loading of the cable making the op-amp oscillate. I tried to make this as small as possible, usually 100 ohms. This worked fine as an unbalanced line out. For headphones, whether this world work depends on the impedance of the headphones. With 8 ohm or even 32 ohm ones the level would be quite low. But with ear buds with an impedance over 100 ohms then the line outs could also drive those. My point being that whether the line out could drive headphones depends on both the series resistor the designer selects, which is not standardized, and the impedance and efficiency of the headphones/ear buds. My point is that there is no standard. Sometimes a line out will drive headphones and sometimes it will not. The same is true for the other way. Sometimes a headphone output can serve as a line out and sometimes not. But unless the designer was incredible stupid, using the line out for headphones or vice versa will not hurt anything.

The gain selector on the headphone amplifier is intended as an easy way to accommodate both output levels as inputs: line out, high gain is needed and headphone out, low gain is adequate.

The other issue with headphones these days that might have influenced the decision to not have headphone out is back in the day headphones were often used to plug in to home audio systems and had quite a generous length of cable. Modern headphones generally have much shorter cables as they are usually designed for personal audio equipment. The impact of this is you would struggle to use modern headphones on the burger without tugging the machine every time you move or having to keep your face really close to the player.

The headphones/line-out confusion seems like it is a case of "not all rectangles are squares but all squares are rectangles". Although, this is one of the things I have wondered on older items, I figured they had to be different in SOMEway or else they'd just all "headphones/line-out" or the like.

Line out gives you a line level output, which is exactly +4dBu (0dBu being 0.775V and +4dBu being 1.736V) Line level is a very important standard when professionally working with audio. Mic level is 60dB below the line level and its usually what dynamic microphones put out. -60DB is btw the same as saying 1/1000. So the output voltage will be amplified to 1000 times as much as it came in when you plug anything into the mic port (Condenser mics usually give off a much higher level and you will amplify them by something like 40dB or sometimes even less). Professional mixers usually let you set the exact gain because you rarely need the full +60dB of gain unless you are using a microphone not suited for the situation you are using it in. But you could theoretically use a preamp before the preamp. Something like a cloudlifter, which adds +20dB of gain (which is a 10 times amplification). After amplyfying the microphone the 0dB on your mixer means exactly +4dBu of level. And if you send this signal out it will peak at exactly 1.736V, which is very important as said for other devices because all devices expect 0dB to be at exactly this voltage once the input was processed. So the line out is intended to be sent to a device, which expects a standardized signal, which could be the amp for your speakers. What exactly your amps do isnt specified - every model is capable of different things. From there on the signal gets either reduced for lower loudness or increased for greater loudness. The Headphone out has exactly this amp built in already. It takes the line level signal and increases it further. But if you dont like the built in amp, or want to plug the player into a mixer for whatever purpose you need to do that, you should use the Line out and then wont need to apply neither gain nor attenuation in the next device in the processing, chain since its already at line level - provided the music you play is normalized and the output is working, as it should.

It’s a useful point about using a headphone out as a line out! I use a Vox Amplug2 through a splitter to get enough signal into an iPad to be able to use the software amplifiers; the vox also works well when I want a highly portable guitar amp for practice - plugged in the back of a 20W powered speaker. It even sounds nice - nothing like an AC30 or a good Fender amp - but enough noise for a small jam session with friends, or a singaround!

2:05 "The fact that something plugs in to something else doesn't mean that it's designed to go in to there." 🤔🤔🤔

Something to bear in mind with headphone out vs line is is that, in a device with built-in speakers plugging something into the headphone socket will defeat the speakers, but plugging something into the line out will not. Once needed to amplify a portable keyboard and it only had a headphone socket so with the PA speakers in front of me, no foldback and a guitarist behind with his own amp it was very hard to hear yourself playing.

As a DJ, if we ever forgot a mic during a gig we would plug our headphones into the mic input and just use our headphones as microphones. It always blew my mind how that would work at all

Short version: headphones is amplified while line-out is only the signal.

One possible reason for the confusion is PCs. On mine the line out is the headphone jack, and it has amplification built in. All the motherboards with built in sound cards I've used for more than a decade have labelled it as line out, even though it's also meant for headphones.

This also reminds me of a separate record deck. Some people think their deck is faulty when they plug their deck right into a line in…. But what you need is something called a pre-amp. So it would go… Deck -> Pre-Amp -> Line-In - AMP … which brings the audio from the stylus up to the correct level. Some audiophiles go as far as using tube pre-amps because it gives a warm sound. Yeah, sometimes old is better than new.

We could boil this down to: Line out is an output set to a standard output level, where a headphone out is intended for a variable output level. You could reduce the headphone out to the same level as a line out and at that point they are effectively producing the same signal. One thing about professional DJ mixers such as a Rane is that their headphone preamps are substantially more powerful to allow DJs to queue in loud clubs. In that sense, not all headphone outputs are the same, but all line outputs will have far less variability.

Stuff like this is exactly why I subscribed years ago. Good to hear a good techmoan moan

This takes me back. My first headphone amp was a Radio Shack kit built into one of their project boxes the size of a brick. It required two 9V batteries which it ate Pretty quickly. Sounded great though.

Going into this I was wondering why this merited a video. Love why you made this video, the structure and how you seemed to hit all the points that anyone would wonder about. I legitimately think this video literally made the world a better place.

The first time I got in contact with line in/out vs mic/headphone was a few years ago when I had to get some audio from seperate devices recorded. Not knowing anything it was hard to search for but in the end I was able to do what I wanted. Thanks for now providing me an answer for the why on all of this. Scratched a knowledge itch I didn't knew I had! 😄

Good video - thanks for sharing! Perhaps you should also cover impedance mismatch... using a headphone output into a line-in (on anything) can potentially affect frequency response.

thanks for explanation! I've had (recently) a belief, that Line-Out was too loud for most headphones... but as I'm now reaching old memories from my childhood, I remember that this socket was always useless for using with most headphones.

The lack of a volume control was almost all you needed to point out, but I think this was still an interesting video and worth making. You are good at taking a fairly unpromising topic and fleshing it out into something worth watching.

I got that difference as a kid, I can't even remember the device, but curiosity taught me that line out was super quiet and, more importantly, did not respond to the volume control at all. I never consciuosly came into much contact with Hi-Fi equipment, amplifiers and the like, but I'm regularly driving my speakers from headhone outs, so over the years I kinda unlearned that.. thanks for the brush-up!

Thank you for answering a question I have wondered about every time I've plugged in an audio device but never bothered to look up.

It all boils down to output impedance. Line out is typically kiloohms, headphone output is meant to handle 32...600 ohm phones. If you connect these to the line output, you not only get a very silent sound, but it'll lack in low frequencies as the output coupling capacitors combined with headphones will form a high-pass filter.

Actually, it´s pretty simple: the signals sent by the line-out outputs are not amplified, but the signals sent by the headphones are. That´s because you have always a volume knob for the headphones and none for line-out...

Great commitment with the channel! Love it

Good thing the Sound Burger has a built in phono pre-amp or this would be a MUCH longer video (; Great video, as usual!

my fellow humans, you should always keep this in your mind "the fact that something plugs into something else, doesn't mean that it is designed to go into there"

Sir, I've been watching your videos for about 10 years & really gain the knowledge you share. It's my humble request to make videos of car Audio systems like cassette players, CD players/changers, ESP's, Ampl;ifiers, Woofers etc.

Those little headphone amps are awesome, I have the one you showed and several others. Perfect for audio odd jobs like impedance matching, signal boosting and, er, amplifying for headphones 😂

Thank you for educating people on this. I feel like I’ve spent decades trying to explain this yet people still don’t seem to get it.

Similarly, line in != mic in. But I use my computer as a free mixer for my handheld gaming sometimes and either works fine. That's because you can easily change the mic gain to offset the difference in expected line level. I wouldn't try to use headphones from line out since there's no additional amplifier

Thank you for that explanation. Understanding this would have saved me a lot of hassle a while back when I couldn't figure out why my laptop's "headphone" jack was so terrible.

Thanks for taking the time to clarify this for me. You mentioned a Bluetooth standard, but said it was lower quality. Can you discuss some of the BT standards for audio? I bought some very cheap BT headphones, and can’t get the volume down to where I want it. At that end of the range, it is either too loud, or off. I’d like to understand where I went wrong, other than just being cheap. Thanks

Now we need a video explaining Mic vs Line-In! 😂

As always: nicely demonstrated! 👍 In technical terms the problem boils down to input-impedance and output-impedance (remember: impedance is the relation of voltage to current). The rule of thumb is that your output-impedance should be an order of magnitude lower that the input-impedance, so it is strong enough (voltage does not collapse due to too high current drawn) to drive it. In this case the headphones have the input-impedance (typically 16 or 32 Ohms for consumer gear and up to 600 Ohms for professional ones). Sadly, very often the output-impedance is not specified on the device or in the manual. But for RCA jacks (line level), they are roughly standardized (output: 200 to 2000 Ohms, input: 10000 to 1000000 Ohms). So you can match all kinds of Hifi components without any problems.

thank you for setting the record straight, mat!!

So many people fall in the trap of thinking if it fits it should work! As a qualified electrician I have seen some very worrying things because people think it fit so its ok. Love your videos, thanks for sharing.

Line out will have intrinsic impedance in series with whatever you plug into it, so a headphone will see only a small fraction of the output voltage. Basically it's not designed to output very much current or power. It's meant to go into the high impedance input of an amplifier.

Thank you very much for this video! I appreciate that you know not everyone is as much of an audiophile as the majority of this channel's viewers and that basic things like this are actually not known to the average person.

Great video! Never understood the difference and this is literally the first time I have ever found anyone explaining it

Excellent explanation, gentleman, thx for it 👍 Love ur videos 💖

@Techmoan - Mat, while I'd never use bluetooth for vinyl at home, I think for the intended use of a soundburger it makes sense. The big problem for me is Audio Technica only specified the SBC codec. SBC really does not sound good. If they had specified AAC, APTX and (ideally) LDAC, it would have been a perfect device for its intended purpose. As it is, bit of a letdown.

You tell them Techmoan! Setting straight the 'know it alls'

I've learned this from old PC sound cards, when they had separate jack outputs and inputs for line out, line in, mic, and headphones... And also had a volume wheel!

This cleared up all misconception up that I had about line and headphone levels. I was always worried about blowing up somethin when using headphone outs into line-level devices. Just turn down the gain and I should be fine. Thanks.

Very well done Video Matt. 40 some years ago in My early Years I had some one give Me an RCA to 3.5mm patch cord they said was no good and was just gonna toss it. Me being the inquisitive person I still am with trouble shooting, Found it to have Resisters in the 3.5 Plug body. It was used for connecting to an "Headphone" out to a Line in. I still have it and use it occasionally . Mike M.

Furthering confusion, sometimes line-in jacks on things are more designed to be used with headphone output rather than a line signal. For example, I have one of those Pure radios where there's no volume control on the line input - only DAB/FM has volume control (and bass/treble, for that matter). So if you use it with a line-level signal, which I have done, you end up with something louder than the volume at which I'd normally listen yet still quieter than the hardware is capable of.

running a bar, I have to explain and fix this with so many people; various staff, party organisers, rubbish DJs etc. this is gonna help me teach em, thanks

The difference is also that any tone control is in the headphone amplifier stage, so in the situation where a piece of equipment has both headphone and line out, as well as some form of tone control, the line-out is unaffected by that tone control. (YMMV for specific bits of kit, of course)

with Vinyl you get even more fun with line out. does the record player have an RIAA circuit or not. if not it needs to be put into a proper phono input on the other end, if yes it can to into a generic line in or powered speakers or a headphone amp.

I have a Sony MZR-50 where the line out was about the mid-level of the headphone out. So it worked in a pinch with the headphones I had at the time when a couple people wanted to listen at the same time.

It's all in what's called an output impedance. Line-out has high output impedance(~1K Ohms) to be the source of audio amplifier's input, while headphone-out has low output impedance(32 Ohms are common) to drive a small speakers. There is amplitude difference as well as impedance difference which degrade audio volume and quality.

OHHH thanks I was trying to find out the difference between line out and headphones on my computer, and I found this recommended video... NOW it all makes sense, thanks!

To further muddy the waters some devices can switch between the two either automatically add did here by impedance detection or old school switches that bypass the amp. The real problem is that we have made these connectors so ubiquitous that they are cheap and used for everything from audio to video to data, heck some have fiber optics built in. But there are standards for most of that too some degree, but because the connectors are so cheap they are used for all sorts of things like i2c, I think void star labs used them at one point to connect halves of a keyboard using i2c in fact. Cheap and abundant makes them great for all sorts of things up to around in think four conductors. I think makers should utilize proper connectors but sometimes it's easier and faster and then cheaper to produce this way than use a less common connector.... It's an issue

Fiio headphone amplifiers are great I had one when I used to rock my ipod with audio technica headphones that needed amplification. Great stuff Matt. I could tell you were a bit annoyed at those silly people misinforming others.

Line-out is a signal voltage source (not a power source for a low impedance speaker), and it likes to see a high impedance load. It isn't designed to drive appreciable current into its load. Headphone-out has to deliver power into a reasonably low impedance load (the speaker) and is designed to be able to deliver higher signal currents.

The older people of us knows the difference, growing up with audio equipment in the 70's and 80's. I heard many people who also doesn't understand why you can't connect a turntable or an electric guitar to a line in jack (the newer ones made nowadays usually have a built-in preamp though).

The line out and headphone jacks have a very simple difference coming down to the fact that the "line out" is supposed to supply a fixed output volume/impedance etc that normal device inputs should expect while the headphone jack is just a variable output that can work for both cases but is not optimal for feeding line level inputs and better reserved for direct to speaker/headphone connections to correctly power them and help avoid mismatched impedance and therefore drive the headphones properly (for the most part). At least that's my sorta educated guess...

Amps and DJ mixers have separate inputs for Line In and Phono In because the line output from analog records is lower than other line level (like CD players). Since this is a record player, I wonder if it's really "plain" Line level or the quieter Phono level.

There’s also some impedance matching issues with respect to head phone ams verses line inputs. Great video

Came here through recommended and learned something new. I always (for as long as I can remember) knew that the line-out and headphone outputs had the same data on them, but now I know why line-out isn't a replacement for a headphone output.

I quite often find myself amplifying music thru a headphone out, and I've always wondered how to best optimize sound quality in that instance. I had thought that generally it was good to lower the volume on the output device, and I'm glad to see that I was more or less right, but it would be interesting to know if there are any generalizable rules to this, in the many instances where consumer electronics come without any way to measure levels. I usually do aim for about the same as you seemed to, roughly 1/4 volume on the headphone out device. Was that pure coincidence, or is it a fairly safe bet? I bet people would watch a video about this.

Given how often it comes up, and the fact it's technically audio equipment, I'm surprised you haven't acquired one of those headphone testing rigs, with the manequin head, yet ;D

I had no idea. Thanks for this clarification!

Always knew that "Line-Out" and "Headphone-Out" were different and you should use each accordingly. Before the video I thought it may have something to do with total volume but now I'm informed. Thanks for the concise but in depth video :)

Ironically, i think this is a scenario where my old kitsound headphones would come in handy. They were intended as BT headphones, but you could take a line in as well, and they did have built in amplifiers to facilitate it. Sadly, they just weren't all that durable.

3.5mm sockets get used for a *lot* of things. Additional example: a couple of music instrument companies (Korg and Arturia, but there are others) have started using them for MIDI connections.

Thanks very much for the interesting explanation and demo 😊

Info that most of us amateur audiophiles don't know we need but is essential! Thank you

Thank you for educating another generations about the subtle nuances of audio electronics!