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I was hanging out with my brother-in-law the other weekend (hey I kind of have to – he made my website! ;0) and he was having trouble getting a guitar track to fit in the mix. There wasn’t a lot going on in the song – mainly drums, bass and guitars with a few vocals – but he was having some real trouble getting all the elements to be heard clearly in the mix, especially when it came to the chorus which sounded kind of wimpy.

This is when I gave him some tips on using an HPF – High Pass Filter and this should be the first bit of EQ’ing that you master before you start cutting and boosting all over the place.

The theory is that there will be an awful lot of bass information recorded on a track when you don’t need it. For example – if you record a high frequency part like a shaker, the mic will still have picked up a load of bass information that you don’t need – stuff like air conditioner hum, foot tapping etc etc. This is where you should use an HPF because although you might not hear the bass per track it will all add up to some serious mud when you get to 50+ tracks!

The picture below illustrates what I mean by High Pass Filter. It’s an EQ that lets the higher frequencies through unchanged while cutting or removing the bass or lower frequencies. Here I am using the stock EQ plugin from Apple Logic Studio 9 but any EQ will do although some might not have a GUI – kind of better in my opinion as it gets you to use your ears rather than your eyes!

Threecircles Recording Studio Logic HPF

So why did I advise my brother-in-law to use this type of EQ? Well the problem was that he was trying to compress the sound to give it more energy but because the guitar track had lots of bass, the track was actually getting smaller rather than bigger because the compressor was working overtime on all the bass! I inserted an HPF on the track to get rid of the unwanted bass in the track so the remainder of the sound that was actually wanted in the song could be treated more efficiently by the compressor and actually put much higher in the mix without overpowering the bass end of the frequency spectrum.

Sometimes I look back over mixes and find that I have hardly used any EQ at all except for HPFs on most tracks. A great feature of Apple Logic Studio is that there is an EQ thumbnail above each track in the mixer – only the Logic EQ though.

I tend to put an HPF on everything EXCEPT where you want all the low end – Kick and Bass Guitar. But even then this isn’t a hard-and-fast rule. Sometimes (especially with Heavy Metal production) you need to filter out some of the bass on the kick and bass as well to give the clout required – sometimes filtering them up to 60Hz really makes it sound like there is MORE bass (counterintuitive I know!).

The way I use HPFs is simple: Roll the HPF frequency up until it sounds like you’re taking too much out of the sound and then just roll it back down a little. This ideally should be done whilst listen to the track in the mix – remember you won’t hear things in solo during the mix! You might find that the tracks sound a little weak when solo’d but don’t worry – it’s what they sound like in the track that matters most after all right?

Threecircles Recording Studio HPF Mixer Closeup

In the above shot you can see a mix from a band I recorded and at no point are there any EQ boosts – I have simply use a load of HPFs which you can see in the green EQ thumbnails. On some tracks you can see that the filter frequency is set really high, especially on the percussion tracks, coloured pink in the left of the picture. It doesn’t matter what the frequency is as long as the track is doing what it’s supposed to in the mix.