Understanding Balanced Audio

hello everyone this is samir from audio science review i thought i'd do a video on a topic that was requested a while back on balanced audio it's one of those confusing topics uh somewhat technical and my goal in this video is actually to not get too technical but uh clarify what we mean by balanced audio and some of the misconceptions are that are out there turns out there are different things people calling balanced there is balanced input to an audio device there's balanced topology inside an audio device and there is balanced headphone connection there are three separate things um let me pull up this uh topping a90 which is a headphone amplifier because it has two out of three in here that we could talk about um if you look in here there are two sets of uh connectors on on this um headphone amplifier we have the traditional rca connections that we're all hopefully are familiar with but we also have a uh xlr connections and thus you can bring in xlr connections and these two female connectors and then two male connectors are passed through in this case if you use headphones you don't use these but if you use use it as a preamplifier you would so in this case we call this balance because the difference between that and the rca is that the rca uses this outside chassis as the reference so the signal varies relative to this outside chassis and as i explained in in previous videos when you do that the mains ground over here the safety ground can cause current leakage uh between two pieces of equipment the remains powered and they can actually travel over this this shield or the outside pin of the outside connection of rca and if it's loud enough it'll cause the classic hum and buzz that that you hear when you have what is called a ground loop the xlr connections on the other hand don't use the chassis as a reference they use two wires and those two wires um provide a signal and therefore no matter what is happening between you know as far as you know current flow between the equipment or voltage differential between the two pieces of equipment as safety ground and it won't make a difference to your signal so it provides great immunity to hum and buzz a lot of people talk about oh you only need these uh connections if you've got a studio or long connections and consumers never have long connections so you don't need this um that's not the reason i like to recommend them i like to recommend them because they completely eliminate this issue with with ground loops in uh i shouldn't say completely 99 of time it'll eliminate the issue with ground loops and in the old days we didn't have much of a problem with with ground loops you know we had them occasionally but not all the time today we have it for two reasons one is that when we use pcs then we wind up with this long chain of of ground that goes through a usb cable for example to a dac then to this one and there's so many different voltage differentials that you can get in ground loops and once you get hit with the ground loop boy i tell you is pain and neck to solve it after the fact so if you've got a device that doesn't have balanced input your options are very limited in solving your problem but if you start with balanced turns out you you basically you know have you know insurance policy against ground loop so even though your connection may be very short even a few inches i highly recommend if you can afford it these devices tend to be more expensive and have balanced interconnects because of connectors and the circuitry inside the circuits inside and uh but if you can you know get the balanced version of everything i think get balance tax now for 150 versus unbalanced or a hundred dollars so for extra fifty dollars on the dac you have both outputs and you can choose as you need it um these black balance signals uh they're called balance because the two inputs that uh the two pins that bring the signal usually put on twisted pair wire and come in and therefore because the the amplifier in there would only amplify the difference between these two is very immune to what we call common mode noise so if you know radiations or interference or something hit these two wires as long as the uh signal the interference couples to both of the pins equally it gets filtered out it only cares about what's different between these two pins um so as a convention the driving mechanism for uh uh for a balanced signal is also what is called differential meaning that these two pins they don't swing between zero and positive but they also swing negative to zero and then positive so and that usually means that you get double the voltage uh on a balanced interconnect versus unbalance so traditionally on a desktop product a dac that only has rca output puts out only two volts but if you use xlr it gives you four volts and that can be an advantage also as far as you know if you have longer lengths or you know you can also get better dynamic range on this thing so but just know that at high level balanced is a good thing to guard against into ground loops and if you have the option it's a good thing to use now some people then talk about okay is the circuitry inside that's also balanced or you know differential inside my advice to you is not to get wrapped around the axle on that one at all why do we care that the benefit of balance as i mentioned it comes in over the wiring and external world internally whether it has a benefit or not is up to the designer to choose it does make things more expensive uh it makes it insanely more expensive with things like tube amplifiers um and uh in general to me it's basically none of my business if it's balanced or not a lot of people complain so internal it is not balanced therefore it doesn't matter no it absolutely does because these receivers are balanced and that's all you want to avoid ground loop whether the circuits are inside a balance or not we're going to measure it and the measurements will tell us if they got better fidelity they didn't get better fidelity i don't care if they use balance or not i don't vice versa if the fidelity is superb what do i care about the internal topology of this thing it's like worrying about what the nuts and bolts are inside your engine you know you care about the horsepower and performance okay so those are the inputs on this thing and these inputs are available on preamplifiers power amplifiers in this case headphone amplifiers audio interfaces professional interfaces so remember this is an input benefit so just you know from point of view keeping it separate from other things i'm going to talk about so inputs are in here balanced you want balance if you can get them what's inside you don't care now in case of headphone amplifiers the industries really screwed things up in that they went out and invented so in here we have a quarter inch jack which is the classic headphone jack that you would have has got three pins on it now a headphone actually has two cups in it plus two little speakers in it so each one of these has two wires so total is four wires how did you get three wires well they take the negatives of the two drivers and time together to save on wiring and the pins on this and the two positives is what the other two pins are so you want that with three pins if you have that this is called unbalanced or traditional output then it comes in both quarter inch and three and a half millimeter uh versions that you know on portable device and and uh there's a mishmash out there of what headphones have what and so you wind up having adapters and all this stuff so from convenience point of view look at what you're buying as far as headphones and and uh and amplifiers and this side but this is the standard imp uh three pin up whenever you see three pin is what you call unbalanced now some people start inventing the notion of a balanced connection and i'll show you an example of that on this drop ether cx headphone and you can see it's a it's a form of a sort of xlr type of connector so very robust and that's good um it it comes with four pins however not three what have they done they simply brought out the two pins from each side independently they did not join the negatives together what that means is that you can drive both cups independent of each other importantly because the negatives are no longer attached together you can use differential signaling to pump twice as much voltage over this than you can with the three pin so instead of zero to two volts you can go from minus two to plus two so you have four volts differential let's say instead of two volts power is equal to voltage square times divided by the impedance so if you double the voltage you can actually get quadruple the power okay so in theory you could transmit more power if you're not limited by the three pin connection that in the older ones by decoupling the two channels independently now that is called differential signaling or differential drive it has nothing to do with the word balanced whoever coined that term the first time didn't understand what balance means headphones by definition are always balanced they're two pins for each one of these and they're floating in air they're not connected to the chassis they're not connected to ground so there never was an unbalanced connection so even the older ones were never unbalanced it just said they had one common pin so you couldn't drive them differentially if all this too complicated don't worry it nets out to the fact that if you have a balanced connection and i have an amplifier headphone amplifier oops headphone amplifier that has the mating connection in here the amplifier can choose to send twice as much power into twice much voltage really into the headphone as it can with quarter inch output now you should know that some headphone amplifiers small percentage of them have these kinds of connectors for convenience only they will put out the same voltage that they do on their quarter edge no difference in this case i'll show you the measurements in a second it actually is producing more voltage in here but just know that you can't automatically assume that if you see xlr connection on this thing or balance connection as it's called that you have double the voltage available now some people originally thought the benefit of that output was that by separating the negatives in the two cups that you get better crosstalk the better separation between the two cups it's a total total non-issue we don't need a ton of crosstalk to get channel separation um in in two cups three wires already plenty good we don't need the separation i've never seen anybody prove that you actually do get better separation i plan on testing that at some point but for now it it really get that out of your vocabulary that that you get better channel separation and better crosstalk it's just not an important thing at all the benefit if it exists means more power or convenience now many headphones can be converted to balance if they come unbalanced if they have a removable wire cable and in this case you're sort of stuck in this aka k371 because it only has one wire so you can unless this is four pin which i don't remember if it is you can't modify this but some other headphones you can actually like this one you can see that you can disconnect these and get aftermarket cables unfortunately for whatever reason you get gouged to death when you get balanced cables they can be 40 60 80 100 for those cables and when they come with specialized connectors usually you can't sometimes you can't make your own either um so it's a bit of an annoyance it's a complete mess it's more of a mess than even i talked about because it's not just xlr but they come in multiple connectors this is a 4.4 millimeter and it's actually also balanced uh again typically is balanced it also comes in two and a half millimeter very skinny skinnier than three and a half millimeter uh it's even skinnier than this uh which is suitable for portable devices although very fragile uh connector and uh that also provides you know for balanced uh output if if the uh amplifier can produce so with that why don't we switch to a a a review of of this product so maybe you can see the pictures better than uh that i was showing you here so again this is the device in here the excuse me topping a90 you see the four pin xlr um differential output although everybody calls it balance and i've started calling it balance because i got tired of just calling it differential and people wouldn't know what i'm talking about so you can see the word balance written over here so both of these are balanced outputs and then you have it's a single lender osce as a traditional quarter inch and if you have 3.5 millimeter then you need one of these adapters to go from three and a half to a quarter of an inch and this is the back as i mentioned these are the input side xlrs which have nothing to do with the output side you could have rca inputs over here and have balanced output for headphones there is no nothing tying these two together each one of them you have to look at independently whether you have that or don't have it so this one is a state-of-the-art uh device that's why i use it for all my headphone testing it has tremendous amount of power uh its distortion is less than 140 db which is like 25 db below threshold of hearing just incredibly good i'm not going to get into the how good it is but you could read the review you see his noise floor is just amazing it's instrument class noise 4. better than 21 bits it's just it's hard to get anything better than 21 and and we have it here uh it ranked at the time i was testing and i think it's still so it as far as noise floor is so low that even if you use a sensitive iem it still uh you know has basically that silent background and it's it's the best i've measured but the reason i wanted to bring you here was to look at balance versus unbalance so if you look at 33 ohm load it puts out two watts of power using its quarter inch unbalanced output but when i switched to the uh balanced output the impedance changed to 50 ohm so the number is not going to be four to one but but notice that it actually produces almost five watts of power why big because again in a differential output mode for a headphone is able to use plus or minus swings so you double the voltage and therefore it can potentially get quadruple amount of power and that's what you see in here now do you need this you may not um if you look at the headphone measurements i do and i can quickly go up here and show you a focal utopia that i just reviewed if you go in here i produce this graph in here it tells you how inefficient or efficient your headphone is case of this for cal utopia is extreme extremely it's very efficient so for this one you don't need balanced output is plenty loud but if you have this high five manage e6 or you know the bear dynamic dt 990 um these are bits headphones this head headphone these things most definitely require balanced input to pump out enough voltage now there are some crazy output single-ended uh headphones topping actually has one i forget the model number that they recently released and it puts a tremendous amount of power using single ended if that's the case then you don't need balanced output remember that's all that is used for when it comes to headphone amplifiers it's just more power if you don't need it because your headphones already efficient or because the single-ended output is just so powerful anyway like in this case i'm getting uh you know over 2 watts at 33 ohms on about 0.2 watts 300 ohm um if you don't need it more than this then great you already have what you want so it doesn't mean that you should rush out and get something with balance output a lot of people say can should i upgrade the balance i'm like is your iphone loud enough and like yeah i guess pretty pretty loud if it's not if it's getting loud and it's not getting distorted you're all set now from longevity point of view if you got the money go buy a headphone amplifier that is like this basically yeah balance input so you know you have noise immunity for ground loops and you have balance output which means that any kind of headphone you buy is going to be efficient enough so because you never know if you're operating down here and all of a sudden you really review of a headphone you jump at it and buy it and bring it home and connect it and all of a sudden it's like oh i gotta crank it all the way to the max and when i do that it's getting distorted or just doesn't get loud enough then you know you're sort of stuck so best of all worlds is balanced input balance output but you know this will cost you unfortunately so let's look at what the a90 cost 500 now these prices have gone up because of covid and shipping restrictions between us and and uh asia um and so hopefully over time you know your two will see these go back down a little bit but for now yeah it does cost money on portable devices and phones and otherwise uh this when you get to 300 ohms with a high impedance load voltage is everything to increase this number you need voltage and current is not that important and differential output like i said it doubles this voltage so it's very much needed on many devices that are anemic otherwise i've tested little dongles that oh most angles most phones only put on one volt good dongles put out two volts but the ones that do balance actually put out four volts so again that enables them to have four times the power of the voltage and in theory four times the power coming out of them so it's a good thing to have um you know if you got power hungry headphones if you have efficient headphones and forever you're going to stick with them then single ended is fine so remember to summarize there's two different concepts in here we have inputs and excuse me which is only needed for noise immunity and then the output is needed for power and then sometimes with just compatibility because your headphone vendor assume that you know they're going to ship you balanced ones and if you don't have that you can get adapters by the way they're 20 30 dollars i've got the adapters from everything to everything because you're going to need it so you can take a balanced headphone by the way plug in an adapter or go unbalanced and connect to this so don't worry if your headphone comes balanced excuse me with balance you could just short out the two pins the two negatives and get three pins out of it the inverse you can't do with an adapter you have to get all new chords because the wires already shorted out at the beginning and you can't separate them back out okay so hopefully you found this useful and practical i know it's a little bit theoretical but uh you know if you're into headphones and everything you need to know this and if you're into uh audio in general i recommend that you do look at getting balanced uh inputs and outputs on your devices if you can okay thanks for watching and see you in a future video bye-bye

Channel: Audio Science Review

Views: 68,067

Keywords: Stereo, Audiophile, Audio

Id: N1lJCL5OCxM

Length: 20min 51sec (1251 seconds)

Published: Mon Apr 05 2021