How To Use: Frequency Analysers

Frequency analysers, spectrum analysers, visualisers – call them what you like, these can be essential tools in a producer’s arsenal when it comes to tweaking and fine-tuning a mixdown. But they can also provide any number of red herrings and other things to distract you from the most important thing of getting your track sounding right! So how should you use them? And perhaps more importantly, when should you use them?

Any modern DAW will come with a decent frequency analyser – possibly several. Logic, for instance, has two very solid analysers built in; the Multimeter, which comes as a standalone plugin, and the ‘analyser’ button built into the Channel EQ. If you can’t get on with the one that comes bundled with your software however, try Voxengo’s ‘Scan’ – it’s a free download from a very credible plugin company, and is so feature-packed that many engineers swear by it.

So, step one when it comes to using a frequency analyser – stop us if you’ve heard this one before – always has to be Use Your Ears. We say that a lot on this blog but it’s possibly the single most important mixdown tip there is. Most engineers will be reminding themselves of it daily, and in this context it means that although an analyser should be giving you an accurate interpretation of what you’re hearing, you shouldn’t be trying to mix through it. Make your decisions based on what you can hear, and briefly refer to the analyser if you need to. It can still get things wrong!

The most common way of using analysers is as an aid to help you isolate problem areas in the mix. If you’re struggling with a resonant frequency that you can’t seem to find, then open the plugin on the channel in question and see if there’s a frequency that really jumps up above the others. This could be resonance on a synth, sibilance on a vocal, or even an earth hum on one of your vinyl samples, but a good analyser should be able to spot it. If it’s not obvious, try changing the scale at the side of the plugin – you can effectively ‘zoom in’ on a certain dB range which will give you a much finer reading.

Another use – and this one is really essential amongst bedroom producers and people working in small, untreated studios – is to make sure your low end is really in check. Small studios, especially those in box rooms which for some reason often tend to be almost square, are terribly prone to rampant low-end resonances. This makes mixing the sub-bass and kick very difficult, as it’s hard to tell if they’re of comparable volumes. Frequency analysers are incredibly useful in this situation – solo the sub and the kick (even consider low-pass filtering the kick at about 120Hz while you’re checking the analyser) and have a look at the levels. If one is dramatically louder than the other, it suggests you’ve been over compensating for the sound of the room, and you should probably reassess the mixdown, making frequent use of other tunes you know sound good, and a decent pair of headphones for good measure!

While working at the low end, it can be instructive to try a little experiment – get a tone generator, make it create a pure sine wave at 50Hz, and then put a frequency analyser on the channel. Ideally, the analyser should show you a single very thin spike at 50Hz. Invariably though, it will actually suggest that there are frequencies present either side of 50Hz, and in some many cases will imply that there are frequencies all the way down to 0Hz. But you can’t hear them, and if you used a tone generator, you’ll know they’re not actually there! It just happens because of the way they work. But this is a good example of why you should only be using a frequency analyser for reference and to help solve problems you’re stuck with. Rely on it too much and you could find yourself solving problems that don’t exist and trying to filter out frequencies that aren’t really there. And that’s never productive.

Having said that, however, it’s often useful to have a glance at your whole mix through an analyser before you finally bounce down. If you think you’re finished, have a quick check of the analyser and see if there isn’t anything that really jumps up above anything else. Obviously, some things will be louder than others, and in general the low end will be the loudest, with a gradual decline as you move up the frequency spectrum, but if there’s a particular frequency that seems to be louder than all the others it may be worth going back to the mixdown to see if there’s something you missed. It could be that something slipped through the net and is now eating up all your headroom – if so, it may be worth going back to fix. But again, if it really sounds right to you after you’ve listened again, then never mind what the frequency analyser says. Don’t let them dictate your sound!

Ultimately, frequency analysers can be an invaluable tool for helping you get your mix on track. But too many people use them too early in a mix, with the result that they change their creative decisions based on what they’re being told by a plugin. Which is putting the cart before the horse somewhat. So get things sounding as close as you can first, then use an analyser to root out any issues, and don’t get caught up trying to solve problems that aren’t really there!