(How Not To Hang Yourself By Mixing With Headphones)
It can be easily demonstrated that doing your final mixes with headphones can produce stellar mixes when the mixing engineer is familiar with the practices of mixing with headphones. But how is this possible? I have heard from so many mixing engineers that you can not mix with headphones for many reasons. The one that most frequently is that things sound too good in headphones to get an accurate mix. How can this be true? If you can hear things better in headphones, then why not mix with them? The answer lies in the familiarity of the environment. Most likely the mixer has always mixed using loudspeakers, and can be rather confident that the mixes produced will sound correct on the largest variety of playback devices.
Then why mix with headphones? For one thing, the loudspeakers react with the room so that you hear the room effects while you are mixing. Sure, most of the best recording engineers can mentally ignore the room sound so that they can create a mix what is not befuddled by room acoustics. For the home studio person, we usually do not have a professionally designed control room to work in. We also do not have luxury of using the best sounding room in ones residence. So we are relegated to a little room that is virtually impossible to mix in. What sounded great when you were mixing it, now sounds anemic when played elsewhere. What happened? All that bass that piles up in such a small room, the inaccuracies if the “monitors”, and the total collapse of any likeness of a realistic soundstage. Wow!
Slip on a correctly calibrated pair of high quality headphones, and listen to your favorite CDs for a while. Then listen to your mixes that you made using speakers. Do you notice the difference? Are you mixes lacking clarity and life? Do not start blaming this piece of gear or that piece of gear. Most likely it is the result of mixing with loudspeakers in a bad room. Why not eliminate the room altogether? So lets use the headphones!
Another advantage of mixing with headphones is the clarity of the sonic picture due to perfect time alignment inherent in headphones. You do not have to deal with the room resonances and phase cancellations due to reflections off the walls and the console. The time smear caused by the typical nearfield monitor situation can gloss over things you will want to hear clearly when you are mixing. This is where you can lose control of your mix and run into trouble using speakers.
Mixing with headphones will take some getting used to. You should make a copy of your mix, and play it through various playback systems such as boom boxes and car stereos. Try listening in a variety of environments,and not the same little room. This will keep things in perspective, as a “reality check”. If your headphone mix does not sound good in these situations, then you are doing something wrong. But what are you doing wrong? Like any new skill, you must gradually familiarize yourself with different acoustic space that headphones create. This takes some time and practice. You will know when you have it down when your mixes sound correct on a variety of systems.
Good stereo placement in headphones requires that the mikes be placed in such a manner as to facilitate the sonic illusion you desire. There are ways to use stereo reverb to do this. This can be divided into two distinct arenas. One is how to create a convincing stereo image from a signal source that does not occur in real acoustic space, and the other is how to utilize stereo miking techniques to obtain a real stereo image that does not sound annoying in headphones. You would never be able to tell if a particular stereo field sounded really distressing in headphones if you only used the speakers in the control room.
Using a stereo miking technique during your tracking process:
There are several common stereo miking techniques used. some of which are: m-s, spaced pair, ortf, coincident pair and dummy head. For the purpose of this article, I will discuss a binaural “roving mike” method I have used, and have had quite good results. I can record an entire song using only the roving mike system. Each instrument will be recorded separately using two tracks. When mixing this song, I will use no panning or reverb, just the levels of each stereo pair.
I built a special microphone stand that has the bottom of an office chair and a top with a mike tee with two short goosenecks (figure 1). This is quite easy to make for yourself. The mikes can be easily moved around while maintaining the exact distance between the mikes. This “Mike Tree” can be rolled around, and the height and spacing can be adjusted. With this method, you only adjust the spacing if it is required, not every time as you would using two conventional mike stands.
Now for the fun part. Start with a spacing of six inches between the mikes. Connect the mikes to stereo monitoring amp with a pair of closed-back headphones. I use the Beyer DT990 open-back phones. However, with these headphones, you will be able to hear what is going on in the room in addition to what is coming from the mikes. I am quite used to this effect and can easily differentiate the mike sound from the room sound. There is less of this effect with a pair of closed headphones. Move the roving mike stand around so that you get the sonic image you desire in the headphones. (Remember that rolling the mikes around while listening in the headphones at even reasonable volumes can damage your headphones due to loud bass transients caused by the movement.) The way to do this is to turn your headphones down and move the mike tree to a location you think may sound good. Give it a listen, and try to zone in on that sweet spot that sounds best to you.
You can place an instrument anywhere from left to right naturally, without resorting to the panpots on your mixing console. Vary the distance between the instrument and the mike stand to change the perspective. The easiest analogy is to think of the mike tree as an aural camera. Use it as you would use a camera. You can get close-ups. You can place your subject anywhere in the sonic picture. Each sonic picture will take up two tracks. You can have several instruments playing together at the same time to save on tracks. Just get the balance you desire in the headphones.
Enhancing Mono Signals
So, what do you do with a mono signal source such as a keyboard, a close miked vocal, a bass guitar plugged in direct and so on? A stereo reverb box can fool the ear into thinking the signal source was actually recorded in stereo. You may desire the mono source to stay mono, but also create a sense of reality of acoustic space surrounding the mono source. This is commonly done with the lead vocals on most pop albums.
For this purpose, I use the Alesis Nanoverb at the current price of $99. Of course you can use a better and more expensive reverb. But I found the Nanoverb to do just fine if used judiciously. You certainly don’t want your vocals swimming in reverb. Remember, reverb is like certain spices. A little goes a long way. Should you put reverb on the bass guitar? Think of this. When you listen to a real band playing in a real room, do you think the room has absolutely no effect on the bass guitar? Just use a little, so that the bass is playing in the same room as the rest of the band, and not in some sound-proofed room somewhere. The same goes for anything other mono source.
Placing Sources Too Low In The Mix And Mixing For Deep Bass
One of the minor pitfalls with headphone mixing is placing things too low in the mix. This is because the clarity of the headphones allows you to hear things easier than you would in speakers. You must learn to mentally compensate for this. Another pitfall is in the area of deep bass. Headphones will never give the visceral impact of good speakers in a good room. If you are not careful, you will tend to equalize the deep bass far too loud in your mix. You must develop an intuitive sense as to how the bottom end will ultimately sound with a variety of playback systems. You could add substantial amounts of the deepest bass, but you will never hear it on a those little portable systems. Experience will tell what is the correct low end characteristic is desirable.
Tuning The Bass
The subject of “Tuning” the low end of the bass and the kick drum is a sticky one indeed. Many engineers have their individual ways to make the two fit together and sound correct in the mix. This can be done when miking the bass drum. Or it can be done after the fact with tools like equalization, compression, etc. The same holds true for the bass guitar. This is why many engineers mike the bass amp in addition to the direct sound. Experience works to your advantage here.
I have developed a circuit (figure 2) that tailors the low end of particular items such as the bass drum and bass guitar to be used for individual tracks during mixdown, not across the entire mix. With the circuit, I can set the low end rolloff characteristic and stored energy of each of these items separately. There is stored energy in the speaker/cabinet combination that adds body to the bass guitar that you can not get with typical equalizers. The tuning device allows you to get the bass drum to sit well with the bass guitar. There is little point in boosting the area below the cutoff of most speakers. As strange as it may seem, rolling off the bass content with a 12 db per octave, tunable high-pass filter can actually give you a fatter and more defined bottom end than you would have if you let the response stay flat to 15hz. Of course you do not need to use any highpass filters to get a great sounding mix. They are just one of many tools that are handy to have around.
You can build this circuit for each instrument that contains significant low frequency content. Of course it is far better to get these to sound correct by mike placement and actual tuning of the kick drum. It is also better to use the miked bass amp to get that punch you desire, if the room you are recording in allows. If your recording room is small and has the typical standing waves that most small bedrooms have, you are better off going direct with the bass. But you cannot go direct with the kick drum, drum machines notwithstanding.
The closer the mike is to the sound source in a given room, the less the room will have an effect on it. The tuning circuit applied to each of these low frequency signals can allow you to improve your bottom end. It is beyond the scope of this article to provide a primer on drum miking. Let’s just say, record it as best you can. It takes experience to get it right.
Using the tuning circuit:
There are two controls on the tuning circuit: Frequency and “Q”. The tuning circuit is a variable frequency, low cut filter with a resonance control, which is referred to as “Q”. Set the Q to minimum, and set the frequency to minimum. Things will sound pretty much as they did without the circuit.
Then increase the frequency of the filter. Notice how the sound gets thinner. Then increase the Q control until you hear an audible ringing at the frequency you selected. Now decrease the frequency control slowly until the desired tuning is achieved. Vary the Q control for the desired amount of resonance. Do this separately for the kick drum and the bass guitar. You will find settings that make them compliment each other without stepping on each other sonically. In other words, the tunings should not be the same for both. You just have to fiddle around until it sounds best to you. Make a tape of this and listen to it on different systems, such as the car, the boom box, other peoples stereos. Make a mental note of what tunings sound best in most places, and get used to how this sounds on your headphones!
The advantages of mixing with headphones are the clarity of the sonic picture, the total lack of those annoying room resonances, and the portability of your mixes. But you must be sure to use only the highest quality headphones, free of tonal colorations. Otherwise mixing errors can occur.
Your brain is correctly calibrated to the particular headphones by listening to many of your favorite CDs on them. As with any skill you develop, practice is essential. Learn to calibrate your ears to how a familiar CD sounds in the headphones as compared to speakers in various places. This is how you can learn to get correct sounding mixes using headphones. But you must use really good headphones. Go back to your reference CD often at first so that you can strengthen your aural memory. After a while you will not need to use your reference CD as often.
Mixing with headphones will take some getting used to. One must refer back to speakers at times to keep things in perspective, as a “reality check”. If your headphone mix does not sound good in speakers, then you are doing something wrong.
Here are some mixing guidelines:
- Keep bass frequencies in the middle and in mono. Be sure bass frequencies are not applied to the two channels out of phase, or else an unpleasant “pulling” sensation will occur.
- Try to record things in true stereo, using two mikes to maintain accurate sonic images. Use reverb judiciously to balance items placed to one side in the mix. Example: When putting tambourine in the left channel, create real stereo space using a stereo reverb. Be sure to have a sufficient amount of reverb to create a convincing sonic image.
- When using reverb on vocals, it is important to create a stereo reverb space around the vocals and not dead center. Real reverb does not occur dead center and in mono. Things should sound as they actually do in real space unless you are trying to create an effect.
- Be wary of boosting lower bass. Headphones will not deliver bass to the entire body so the usually pleasant sensation of bass is lacking. Excessive bass will have an annoying effect. Such excessive bass is also not good in mixes that will be played through speakers in the future, since most speakers will either be pushed into distortion or will poorly reproduce this bass and ampl[ifier power will be wasted. It is a good idea to check the mix with speakers to be sure that the bass tonal balance is correct.
- If the bass tonal balance sounds good with speakers but has an annoying character with known high quality headphones, then the lowest bass frequencies should be cut in the mix. Such lower bass frequencies are usually wasted with speakers.
Of course, these are very general guidelines, and you should experiment and hear how what you do works. It will take some time, but you will have the benefit of being able to get consistently good sounding mixes in a variety of control rooms without ever having to worry about the particular “sound” of their control room.
c. 1999, LXH2.
Author’s site: The Official LXH2 Website.