A Guide to Choosing Monitoring Setups pt.3 – Headphones and Headphone Amps

In parts 1 & 2 of this guide we looked at the basics of selecting control room, live room and cue monitoring systems. In this final instalment we’re going to take a look at some considerations when choosing studio headphones and amplifiers to drive them. We’ll focus on studio (control & live room cue) stereo units rather than live venue or immersive options.

Since the introduction of the first successful pair of commercial headphones in 1910, numerous choices have evolved; each with their own strengths and weaknesses so, we’ll look at the basic differences and common applications of popular modern studio headphones. I’m going to group them into a few basic categories:

On Ear* Headphones – the vast majority of studio type headphones are “On Ear”, meaning they have some type of headband that allows them to be positioned over the whole of your ear; as opposed to “Ïn Ear” type headphones, which as the name implies fit into the ear (think buds for example), or “Conductive” headphones which basically attach to your body or skull and vibrate your bone structure to transmit audio to your brain!!!

*Also sometimes referred to as “Over Ear”

The term “closed back” refers to the casing design of the headphone. A closed back headphone casing is non – porous, i.e. it is designed to minimise audio leaking into or out of the headphone whilst it is being worn. This prevents, for example, the cue mix leaking out of a performer’s headphones, into a mic and onto the recording during tracking. Of course, the very nature of these designs and the laws of physics conspire to have a sonic impact, in many cases closed back headphones are prone to being quite bass heavy. The amount of air contained within the headphone cups is tiny in comparison to the air between a loudspeaker and listener so they don’t have the same ability to “breath”. Additionally some headphone users find them fatiguing as the better they isolate the wearer from ambient background noises the more the brain strains to hear those background noises – that’s a basic self-defence instinct that goes back to the age when humans weren’t the alpha predator on the planet.

Wired headphones (ie those that are connected to the headphone amp by an audio cable), are the standard choice for studio use as most studios prefer to isolate radio frequency interference caused by devices such as wireless headphones, mobile phones or walkie talkies from entering the recording chain.

In addition to the basic designs/suggested applications we’ve mentioned above, it is also necessary to consider impedance when selecting a pair of headphones. Impedance is, in very simplified terms, the degree of resistance one audio device presents to another when a signal is passed between them. The impedance of your headphones should be optimal to work with your headphone amp to get the best performance from them. That’s not the same as the headphone impedance being equal to the source impedance of your headphone amp though.

Most professional headphones have an impedance of around 100 Ohms or above which reduces distortion in the signal more effectively when compared to lower impedance or consumer models. They also require higher voltage than their lower impedance counterparts so both of these factors are important when it comes to choosing an appropriate headphone amp to pair them with. Ideally you need to pair your studio headphones with a headphone amplifier that has a source impedance roughly 2.5 to 8 times less than the headphone impedance. For example, for a pair of 300 Ohm headphones a good matching headphone amp would need to have a source impedance of between roughly 40 – 120 Ohms.

Depending on the “noisiness” of the studio environment these 300 Ohm headphones are operating in, their headphone amp would also need to supply a voltage of anywhere between 5 – 15 dBV to enable them to perform with optimal loudness/sensitivity and deliver their specified dynamic range. This level of voltage is not common in mobile or consumer headphone amps which typically only provide only 1-3 dBV so, a purpose designed studio headphone amp will invariably yield better results.

The final point to consider when it comes to matching is distance and cable quality. In general, the longer the length of the cable between headphone and headphone amp, the more getting impedance and voltage matching wrong will impact sound quality. The same is true of cable quality. So, if you’re driving professional headphones situated more than say 3 metres away from the headphone amp – get the impedance and voltage matching right and use high quality (low impedance shielded) cabling.

Assuming you’ve shortlisted a headphone amp that matches your headphones and working environment as described above, it’s time to consider what features you will need on it. But, before you rush to purchase a shiny new piece of kit, take a look at what you may already have. Most Consoles, Monitor Controllers & Audio Interfaces have at least 1-2 headphone amps built in which are suitable for mix engineers or a performer situated in the control room/very close to it. If you’re needs are that simple then perhaps this is sufficient. If you’re already running an integrated Cue Mix System such as those produced by Hear Technologies or Digital Audio Labs; then you have addressed your need to drive multiple headphones in more dispersed locations.

However, if none of the above quite deliver what you need, then you may want to consider a standalone studio headphone amp. There are many choices available today but to keep things simple let’s take a look at a few offerings which provide interesting additional features:

An audiophile dual output Headphone Amp with superb source analysing features. This suits a serious sound engineer providing, at the twist of a knob, the ability to listen in straightforward stereo, mono and also check left plus right, left, right, and even left minus right, for phase and digital artefacts. These diminutive boxes can be chained together to deliver multiples of 2 headphone outputs – useful if you need to scale up in the future.

British boutique manufacturers DACS have a long standing reputation for delivering crystal clear audio and this 4 channel headphone amp follows in that tradition. It’s a unit capable of driving multiple headphones over longer distances than most. Each headphone can select from 4 mono source inputs in 6 different configurations (2 stereo, 4 mono or 1 stereo/2 Mono) allowing more flexibility than a standard stereo in 4 headphone outs model. It can also be fitted with an upgrade Power Stage to drive multiple headphones from a single output.

That concludes part 3 and our series on Choosing Monitoring Set Ups. As with all things Funky it pays to seek advice and listen with your own ears before reaching for your wallet so please drop us a line if you’re looking for a new monitoring setup, whether that’s control room, live room, cue mix or cans and we’ll help find the right solution for you. Until the next guide….