Being a DJ myself I use headphones all the time to help me with my mix. There are a couple of reasons why DJs may use headphones and why some may not which I will explain in this post.
So, why do DJs wear headphones?
There are different ways DJs wear headphones and how they use them. A lot of technical terms come into play when learning the ins and outs of DJing. In the next paragraphs, more detail will follow.
In my opinion, the most important thing for a DJ to do when mixing is to choose 2 songs that will go well together in the mix. I value this more than beatmatching perfectly or having the most seamless transitions.
A headphone is necessary to preview the next song especially if you are not that familiar with the song you want to mix already. It often happens that you want to spice things up in your mix and you go a bit out of your comfort zone by choosing a different song than preselected before your mix at home.
Using a headphone as a DJ will make sure you are able to hear all the musical elements in the next song so you can decide in time if you need to pick another song or go with the currently selected song and mix it in.
Headphones also come in handy the other way around which means they are great tools when selecting a new song that you know but mixing it in with the current song which you are not familiar with. This could, for example, happen when you are performing B2B (Back to Back) with another DJ. Performing a live set with another DJ may mean you are not familiar with the latest song he is playing when it is your turn to tune in the next song.
Another import aspect of being a good DJ is to be able to manually synchronize your songs. You can do this by beatmatching and tempo matching. Beatmatching means you are synchronizing the beats of two songs.
Tempomatching means you are synchronizing the tempos between the two songs. Beatmatching and tempo matching often go hand in hand, by doing one it usually means doing the other. You can also hear your hot cues in your song which are adjustable time markers where the DJ can quickly jump to. When synced you can also check if you need to rewind the next song a bit so you have more time to mix it in before the next drop kicks in.
Headphones (when matched with the main speakers' output sound level to your ear) are able to provide you with information about the quality and loudness of the next song. This way you will know if you have to adjust the gain.
Gain is the amount of amplification the selected song has in relation to the master (main) sound output level. This way you will know if your next song will blend in smoothly or blends with a huge sound level difference with the current song played. Another way of knowing this is by looking at the sound level meter on your DJ controller which is displayed by a few LEDs in dBs.
Plugging in your headphones in your DJ controller is a crucial first step when using headphones with a DJ controller. The second thing that you want to do is to select the audio from which deck or decks need to route through the headphones. In my case, there are 2 LED buttons that I can press to select which deck needs to play on my headphones. This is independently from the main output and is demonstrated with an image.
The third thing that you want to do if fold your headphones (if they can) in such a way that they are comfortable to hold onto one ear. This way you can preview the next song by listening with one ear and listening to the other song through the main speakers.
You can then beatmatch the song using the tempo fader or the edge of the jog wheel which is visually explained in the image below. This way you will speed up the song or slow down the song precisely so they will match up in tempo and in beats.
With these techniques, you are able to preview your song, check the quality and loudness of the song and beatmatch them.
If you want to know more about what DJs hear while using a headphone you can check out the video below.
How do DJs perform without using their headphones? There are 2 main options why DJs may perform without headphones.
Be aware that a DJ who is using turntables needs headphones to beatmatch since turntables do not have the function to beatmatch or tempo match themselves. If you see a DJ mixing with headphones on a turntable you know something is not right. CDJs (Compact Disk Jockey) are essentially small DJ Controllers without the mixer part. Older CDJs are also not able to sync music which is a red flag if you see a DJ using an old CDJ without headphones.
What software should I use if I want to mix without headphones? In order to mix without headphones, you need to use the sync function. You can activate the sync function in the software or press the sync button on your DJ controller.
Almost all modern DJing software has some sort of sync function. It may be beatmatching or tempo matching that does not really matter since they are both able to replace the headphones for you. I have made a list of the most important DJing software in 2019 which include the sync function.
The second list I made is software that can be used to produce and to DJ as well.
I have made a page about recommended DJ software which you can check out if you want more detail about DJ Software.
Are open-back or closed-back headphones best for mixing?
The difference between open-back and closed-back headphones is mainly that open-back headphones leak a lot of the sound produced to the outside but also leak a lot of the environment sound from the outside. This creates an illusion that the sound if coming from further away which in audiophile terms is a good thing.
Closed-back headphones will barely leak environment noise inside and are also very good at keeping the produced sound inside. It's best to use closed-back headphones to hear the difference between the two songs. If you want to hear how to 2 songs sound together you can just use the headphone mix button on your DJ Controller. For a detailed explanation of open-back and closed-back headphones check out the article about open-back and closed-back headphones on Wikipedia.