The Problem

At some point, working on music, most people are in need of mixing in headphones while they work on new material. No, this is not an ideal solution, but one born out of necessity. When working in the studio with others in the studio, sometimes I do not want to subject them to three hundred passes of the same measure that I am hand tweaking notes, velocities and automation. In addition, I always like to test my mixes on a multitude of output devices to ensure good levels. Let’s also not forget that if you are recording your own vocals, chances are you are listening through headphones as well. While most of this information could pertain to mastering in headphones as well, this is not something that I do. Also, before we get into discussing the different areas of concern for headphone mixing, I am a firm believer that final mixing should be done through monitors in a neutral room to maximize the quality of your mix.

For headphone mixing there are three general things I concentrated on when doing my research; headphones, headphone distribution and live space modeling. Let’s look at each of these.

Headphones

Without question there are a ton of different headphone options to chose from. I’ve had my share of headphones and can certainly say that headphone choices come down to certain preferences. I currently use three sets of headphones for different reasons. The one thing I will say I find most important across all headphones I use is a flat response, just as with studio monitors. If you aren’t getting a flat response then what you are mixing is biased. Also, taking into consideration the Fletcher-Munsen curve which shows ears do not hear linearly, the further the coloring of the headphones can be, resulting in making your mix even further off.

Our concern for headphones in this article is relative to stereo source material. Note that there exists some amazing surround sound capable headphones, however, that is not the focus of this discussion. In looking at headphones I split up the features on two main criteria; how the headphone interfaces with the ears and how the driver functions with respect to the ear canal. I then broke my needs into three additional categories; headphones to use in the studio working on mixing, headphones to use in the vocal booth for tracking, and headphones that I could take with me for use with my laptop if I am not in the studio.

In looking at headphones for the studio, initially I wanted these to use in the vocal booth as well. This meant I couldn’t use an open back headphone. Open back allows sound waves to travel away from you ear as they are reflected and out into the surrounding room. This causes the material you are working with to be heard by others and allows sounds in the room to be heard by the listener as well. The claim is that these headphones reduce the amount of distortion that you can find in closed back headphone which block sound from being transferred into and out of the headphones. Using headphones in a vocal booth requires no sound escaping from the headphones so open ear headphones were out for this reason alone. I have used a few different open ear headphones to just hear how they sound, including expensive models from Graco and Ultrasone. These headphones do sound amazing, although a bit weird if you are used to using closed back headphones. If you are just mixing, it might be good to at least try out a few open back headphones if you mix at louder levels to reduce distortion. However, these headphones are going to be a lot louder to your surroundings if that is what you are dealing with in the first place by the necessity to use headphones.

In addition to the type of cup the transducer sits in, one thing I had noticed early on is using headphones can lead to ear fatigue much sooner than if using typical monitors. This was the problem I was having with the headphones I had at the time when I starting researching headphones further, which were the Sennheiser HD 280 Pros. These headphones had been heralded for their bass response and comfort. For my taste, the springiness was too tight around the head and the bass response was too pronounced. Things mixed in the headphones always lacked bass when played through regular monitors. They had definitely been a step up from what I had been using before, but just weren’t going to cut it for studio use. This is when I discovered circumaural headphones. The transducers do not fire directly into your ear and based on some manufacturers descriptions, require as much as 40% less output for the same perceived loudness. This seriously reduces ear fatigue and was noticeable immediately when I started using this type of headphone. I settled on the Ultrasone HFI.700 headphones. These worked great in the studio for mixing. They did not, however, work as well for me in the vocal booth.

Ultrasone HFI.700

One of the problems of using very sensitive microphones is that they can pick up electrical interference quite well. The Ultrasone HFI.700s are not listed as electronically shielded. This means that energy from the headphone transducers is free to propagate to whatever is around them that amplifies such information. There are other models of headphones that provide higher levels of electromagnetic protection. However, I was very happy with the HFI.700’s in the studio so I did not want to replace them again. I started thinking about the problem further and figured if I could reduce the energy needed to drive the transducer, I could probably cut down on the interference with the microphones I was using. I started looking at in ear monitors and settled on the super.fi 5 pros.

Super.fi 5 Pro In-Ear Monitors

They fit in my ear well and had good sound. There are tons of different manufacturers of in ear monitors with the addition of having custom ear molds made. I am sure many of them for this application would work well, as they did for me. The interference caused from the headphone situation in the vocal booth was seriously reduced.

Even with all this criteria I had for selecting headphones, there are many other considerations as well, if not even cost alone. You can quickly go up the scale and still be very unhappy. Most local music stores have headphones out for listening. I took with me a few tracks on a CD that I had spent a lot of time mixing so I was very familiar with their sound. At the stores I visited, they allowed me to put the CDs on repeat and listen to all of their headphones. I would seriously recommend doing this because most headphones sound very different.

Now that I’ve got you thinking about headphones, let’s talk a bit about headphone distribution and what kind of options there are.

Headphone Distribution

Many audio interface units have headphone outs on them already, like the Motu 896HD and the like. This is what I used for a long time because it was simple. However, my audio interfaces now are much further away so it is harder for me to get to my volume knob, so, I started looking elsewhere. Since in the studio I use two different sets of headphones, I like them to be setup independent so I don’t always have to change the settings. In addition, I do have other people in the studio, so I wanted to have more than two so I could accommodate others. There are quite a few different varieties of headphone amps that also cater to a wide range of uses as well. First, be sure to get something with a decent level of quality. I’ve used some older DOD headphone amps that just sounded horrible. I was amazed what they were doing to the sound. I also personally did not get that great of sound from a Nady 4 channel micro headphone amp I used, but to be fair, I never contacted the company so I am not sure if the unit I had just had technical problems. In my studio, I use a Presonus Central Station which has two headphone outs. (I use this as a glorified volume knob and monitor selector since I use multiple monitor sets for testing mixes). This, however, wasn’t enough, so I also hooked up a Behringer HA4800 to use in the main studio and a Behringer Miniamp AMP800 to use in the actual vocal both. I went with Behringer because I was able to use each of these pieces first and felt they were satisfactory for the job. I know that Behringer products get a bad rap many times for their quality and durability, but in all my testing I was satisfied with the quality. It also didn’t hurt that they were priced right. The nice thing about the HA4800 is that I can also bring in an additional source on each headphone channel through an aux input and then mix the main input and the aux.

HA4800 Headphone section with Aux Input

With the multitude of outputs in my studio that I do not use on my audio interfaces, this allows me to feed in using busing in my DAW specific sounds at louder levels for different people. In addition, for vocals or guitar, I can bring in the analog signal for monitoring with zero latency and avoid having to monitor through the DAW in applications where zero latency really matters. As a side note, I also use the monitoring system in my Focusrite VoiceMaster Plus pre-amp for zero latency monitoring of vocals and a Lexicon MPX550 effects unit in the effects loop for a little reverb for the singer. This signal is only for the singer and is not recoreded.

While the headphone distribution is more a matter of preference and need, I wanted to bring it up as a point of configuration. Here, I’ve described many methods that I have utilized is maximizing my ability to control the mix and its components to both myself and others. If you are working with bigger groups, or want more options or control, you might want to look into the likes of the Hear Back system from Hear Technologies. There are certainly many others as well. What you hear while you are mixing or monitoring is just as important as what a client or collaborator hears that you are working with. Having more flexibility just means you will be able to accommodate a wider variety of needs.

Just remember, most audio interfaces have an equal number of inputs and outputs and using those extra outputs is a great way for monitor routing flexibility for systems that allow additional inputs to be mixed in.

The last piece to this puzzle can be just as important as selecting the right headphones, and that is compensation for the fact headphones direct sound into one ear only which is unlike what happens in a room with monitors.

Live Room Compensation

The biggest issue with using headphones is that unlike monitors in a room, headphones output the left and right channels directly into each ear. There is no crosstalk between the ears or even any room reflections that you’d get with actual loudspeaker monitors. If you’ve ever spent time mixing or listening to music in headphones, you know how different it can sound. Even worse, how something you thought sounded great in headphones sounds poor and uninspiring when you listen to it out loud. For the longest time I wasn’t sure what to do until someone introduced me to the concept of the HRTF or Head Related Transfer Function. In simple terms, HRTFs are used to model the effects of sound entering your ear from different angles and different distances. Having something that would allow the use of HRTFs is the first half of simulating the effects of loudspeakers on your ears. The second is the response of the room itself. Most sound rooms are not anechoic chambers so there is still reflections happening in the room which makes it sound right, this is a desirable characteristic to a certain degree. Therefore the second thing we need is a decent reverb that doesn’t overdo it by coloring the sound unrealistically.

WaveArts Panorama5 Plugin

While there are a few companies that sell plugins that can do both of these, I am going to discuss Panorama5 from WaveArts, as this is the plugin that I found handled both of these very well and was reasonable priced. Please note that this plugin does a lot more than just what I am using it for. It can be used to widen tracks or generate motion based audio effects like Doppler for both headphone and loudspeaker use. In addition, you can download this plugin for a free trial run to experiment with it and see if you get the results you want. Regardless, other plugins providing similar functionality can be used as well using the techniques described here.

To use this plugin, I place it as the last plugin on the Master Fader track in my DAW. Then, as I switch between headphones and live monitors I switch the bypass of the plugin on and off. Just don’t forget the bypass or you’ll be scratching your head sometimes wondering why it sounds strange.

Left Side of Panorama Interface

Now, when the plugin is active, start by selecting the preset ‘Live room, headphones’ as a starting point. With these default settings, play some audio that you are familiar with. It will sound a lot different than what you are used to. There are many settings you can tweak to get a modeling closer to your sound room. First, you can adjust the distance between where your head is and where your monitor speakers are located. In the ‘DIRECT’ section of the plugin, set the DISTANCE parameter to the distance to the center of one of your monitor speakers. Next, you need to measure the angle of the speakers from your head which you can approximate. The angle is between the line a point directly in front of you between the speakers to the line from you that ends at the speakers themselves. If you are so inclined, you could use some trigonometry to solve the angle mathematically.

At the bottom of the left side of the plugin do not change MODE as this should stay as Headphones. The other modes are used for modeling other speaker widths to your speaker widths. Next to that the HRTF used can be changed, there are many provided. The Panorama5 3D Tutorial covers many of the provided HRTFs and where they come from. The default for this patch has worked best for me however, not all ears are created even remotely equal so your milage may vary.

Right Side of Panorama Interface

Next, the REFLECTION settings can be used to approximate how far your walls are from where you normally sit in the studio. Finally, you can tailor the reverb settings for what sounds more realistic. Since different rooms have different acoustical treatments and structures, you will probably need to spend a little time adjusting these values. Don’t forget to save your preset once you find something you are happy with.

Conclusion

Now you are on your way to perfect mixing in headphones. Well, maybe not perfect but a lot better than just using raw audio in headphones. After using this technique for over a year and a half now I find it to be a invaluable resource for when I am forced to use headphones for a time. I especially find it powerful for working with vocals which I find translated the worst between headphones and monitors in the past. However, this system is not perfect so always check your material in your room monitors before you’ve finished with it. I hope this information can help you as much as it has helped me.