A common question we get is from people asking how to choose the right headphones for their application. Even if you have the luxury of trying out some headphones it is still difficult to know how they will really perform under demand, which is certainly a concern for studio owners. But it’s not all that hard to narrow the choices if you know what to look for. There are two major things to consider when choosing headphones:
The first is how isolated do you need them to be from the outside world? The answer to this question will go a long way toward helping you decide between three main categories of phones: open air, semi-open air, and closed ear. The circumstances that tend to dictate using more of a closed air design are basically situations where you don’t want the headphone sound leaking out, as in the case of something like a vocalist cutting a vocal track: you don’t want the headphone sound leaking into the track. Or, when you don’t want outside sounds leaking into the headphone mix making it harder to hear, such as working with a drummer. Drums are loud enough to make even loud open air headphones hard to hear.
Generally recording studios employ closed ear headphone designs because of their better isolation. In situations where isolation isn’t as critical most people prefer open air or semi-open designs. These types of headphones tend to be a little more comfortable when word for long periods of time, and many listeners say that, all other things being equal, they usually sound better and are less fatiguing to listen to. About the only time open air headphones are used in most studios is for the engineer to listen to and check a mix (even then many still used closed ear phones), however, for casual listening quite a few folks prefer open or semi-open designs.
The second major criteria is how loud the headphones need to get. Clearly when strapping headphones on most drummers they are going to need to be capable of getting loud. In fact, most musicians expect a good amount of volume when performing. The bass player really needs to hear the bass over the other sounds in the room and over the sounds of his bass resonating through his body. The same can be said for singers, though there are some that prefer the headphone volume low so they can monitor the sound of their voice resonating in their head. Closed ear headphones are generally easier to get loud because less energy is lost to the outside, but there’s an even more important factor that determines how easy they are to get loud: impedance.
Many headphones have historically been designed with relatively high input impedances (100 to 600 ohms are common). This has a lot to do with making sure headphone amps that are less than ideal (as is quite often the case with the headphone amps built in to a lot of equipment we use) don’t have to deliver very much current to make sound. This scheme actually works pretty well when loud volumes aren’t needed. But in a demanding studio or stage application it can be difficult to get enough power to high impedance headphones to really get the volume up where it needs to be. This is where lower impedance headphones have become popular. To put it simply, it’s much easier to get them loud enough, even if you don’t have a dedicated headphone amplification system. Headphones that are considered low impedance range from about 4 ohms to 100 ohms, and these days there are a large number of makes and models in that range that do an excellent job.
Be careful taking this too far, however. Lower is not necessarily better, especially when it is very low (under 8 ohms). Many power (and headphone) amps don’t like very low impedance loads. If you’re in an environment where you may be driving many pair of headphones off of one power amp you should be aware of the overall net impedance load you are presenting to the amp. You may want to consider one of the breakout boxes made for headphone distribution. They help present a more consistent load to the amp and many of them also provide individual level controls for each set of headphones.
If you’re considering putting a headphone system in to your studio you’d be best served by discussing your plans with your Sweetwater Sales Engineer. He or she can bring other issues to the table that will help you put together the best overall system for your needs.