Transducers 101: The Yin and Yang of the Recording chain

Whether you are aware of it or not, microphones and monitors share a common genetic lineage in that they are both prime examples of what we commonly refer to as transducers.

Whether you are aware of it or not, microphones and monitors share a common genetic lineage in that they are both prime examples of what we commonly refer to as transducers. Put simply, a transducer is a device that converts air pressure (or sound as we hear it) into an electrical signal and vice-a-versa. If you have ever witnessed a DJ scream into their headphones and have it pick up like a microphone, you would have witnessed how this relationship can be reversed to interesting effect. When digging into the fundamental concepts and principles of capturing and reproducing sound, it’s actually pretty crazy the similarities that these principles, designs and thus, pieces of equipment share. When placed at the opposing end of this signal chain, these seemingly diverse pieces of equipment essentially act in the reverse of one other. Fascinating.

This is a pretty heady topic, so we are probably best to take it back to basics and start by defining what mics and monitors actually do.

At its core, a microphone is a device which takes acoustical sound pressure in the open air and converts it into a small electrical signal, which can then be routed through the system to whatever ends we see fit.

In the case of large diaphragm dynamic like Shure’s iconic

SM7b, this is achieved via electromagnetic induction, or rather sound waves causing a diaphragm to vibrate which inturn triggers the moving coil of wire to push and pull against its magnetised core, in turn creating an electromagnetic pulse and a variance in signal between positive and negative. This variance is essentially an electrical representation of the sound pressure, as captured in the open air.

So what happens at the other end? The exact inverse. With the electrical signal produced by the microphone now in our system, we are free to amplify and process it as we see fit before we need to convert it back into acoustical analogue energy in the open air. This is exactly the role of the studio monitor (like the awesome KRK V8 S4 midfield).

Both of the above devices are still transducers. Both deal in converting acoustical energy to electrical signal and vice-a-versa and yet both sit at completely opposite ends of the recording chain. One deals in diaphragms, one deals in drivers. One deals with sound going in, the other deals with sound going out.

Now, in the above example we have specifically gone with the SM7b and KRK V8 S4 for a number of reasons. Firstly, they are both examples of transducers that are prized for their robust low end and low distortion properties, characteristics that have made them favourites across a whole host of studio and content applications. Secondly, they are both examples of a sophisticated moving coil topography-one that expertly straddles the line between clean detail in the upper mids and exceptional low end performance, a direct result of the slightly larger diaphragms and drivers employed in their designs. This serves as a perfect way to introduce the obvious correlation between physical size and low frequency response in relation to transducer design.

Just like with mics, monitors come in all kinds of varieties and designs, usually with specific applications in mind.

Because of their larger size and heavier mass, large diaphragm microphones tend to have slower recoil properties and a slightly more delayed transient response than their small diaphragm brethren, and require more air to be moved at the acoustic level. but are generally able to produce a bolder, deeper capture, with a more extended low end reproduction. Because of the sheer amount of energy involved in moving a component of this size, this will generally require more gain at the amplification stage, to bring our analog signal up to nominal level, which is why you often see people employing signal boosting devices like cloudlifters etc into their signal chain for mics like the SM7b. As studio monitors tend to be dealing in full mixes as opposed to isolated sound sources, they require multiple transducer circuits to tackle the broad range of frequencies required as accurately as possible. The high frequencies are usually taken care of by a monitor’s tweeter (typically a 1” diameter HF driver). Which makes total sense when thinking back to how Small Diaphragm mics are more sensitive to and are better at capturing high frequency information. Whilst this takes care of the high frequency content, the woofer is where all the low end information is being reproduced –and in this case, the shoe needs to fit the foot.

As mentioned, the energy required to accurately reproduce these much larger sound waves is pretty substantial. The driver or woofer of a monitor needs to be of adequate size and design to achieve this properly – hence why typical midfield and far-field monitors will have larger woofers sizes. This not only allows for more precise reproduction of bass frequency content, but also gives monitors the required throw to get this information to the listener positioned at a distance from the monitor. Even in smaller studio spaces, to accurately reproduce bass frequencies and give that real impact when tracking and mixing, a woofer of 6” – 8” will be required. Monitors like the KRK V6 and V8 have become synonymous with low-end punch for just this reason and of course their fundamental design more than does the low end justice.

Although posit, both the humble microphone and trustworthy studio monitor are well and truly branches of the same audio tree. While they both share a common design ethos, each are tailored and tuned with their specific application in mind as a means to give us, as engineers, the maximum amount of creative control.

To bring in the new year with a punch, any pair of KRK V6 and V8 studio monitors come with a free Shure SM7B studio microphone. Head to your nearest KRK dealer today and get yourself a bargain!

BY ANDY LLOYD-RUSSELL