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Tighten the Low End of Your Mix with a Frequency Analyzer

For an updated version of this article and video demonstration, see: Make Space for Tight Bass

Most mix engineers don’t hear the bottom octave (20-40 Hz) because their monitors can’t produce it. Unless your room is 300 square feet or larger, and professionally tuned, adding a subwoofer will probably do more harm than good. Whether or not you can hear it, it’s important to balance the sub bass with the rest of the mix. You want deep full tone from the bass and a healthy “chest thump” from the kick without blowing out any speakers.

A common DIY solution is to simply roll off the whole mix with a highpass filter (HPF, also known as a low cut or LC), but that’s ugly and imprecise. Even if the frequency and slope of the filter leave an appropriate amount of sub, the EQ will color the mix, usually in an undesirable way. Instead, we want to sculpt the low end on a track-by-track basis, balancing out the sub bass and shaping competing elements to produce a clear and powerful foundation for your mix.

We can’t always hear what’s down there, but with the right tools, we can see it.

Voxengo SPAN

TIP 2: Use a frequency analysis plug-in to cut unnecessary bass

My personal favorite is Voxengo SPAN, which you can download for free. A newer version than what you see here is available for both Mac and Windows.

Configure the plug-in as follows:

  1. Set the block size to 8192. The higher the block size, the better the accuracy at the lowest frequencies, but the slower the refresh rate. If you want to see the transient attack of a hi-hat, a small block size is better, but for our purposes, 8192 is perfect if your CPU can handle it.
  2. Set the Low Freq to 5 Hz in order to detect DC offset and other subsonic garbage.
  3. Set the dB Scale to -20. This setting adjusts the frequency display on the y axis. -20 is probably right for an unmastered mix, but let your eyes be the judge.
  4. Click on Preset, then Set as default so you won’t have to go through steps 1-3 again the next time you launch the plug-in.

The screenshot above was taken during playback of my song “We’re Not Getting Any Younger,” which many of you are all too familiar with from the OurStage competition. It’s a good example of how a healthy mix should look (if I do say so myself). There’s no extra garbage below 20 Hz, and the lows carry most of the energy, with a gently falling slope all the way to 20 KHz. It didn’t start that way though! Check out the synth bass before EQ:

WNGAY Bass

See all the extra energy below 20 Hz? Without getting into a technical discussion of DC offset (which nobody I know, myself included, seems to fully understand), we don’t want that. I call it “the snake” because of the way it undulates during playback. We want to cut off the head of the snake (the subsonic peak) with a HPF.

Without further ado, here is my four-step method for sculpting the low end of a mix:

  1. Insert SPAN on the master bus. Place it somewhere on the screen where it won’t get covered up, or set it to “always on top.”
  2. Solo the bass. If you see more than a hint of energy below 20 Hz, insert a HPF into the first slot (or use your software’s built-in EQ if you don’t have anything better). Set the frequency and slope to tame the frequencies below 20 Hz while altering the tone as little as possible. Lower and sharper is better, assuming it gets the job done. If you set the frequency too high, the low notes will be quieter than the high notes. Experiment with a variety of EQs to see which one colors the sound in the most desirable way. My personal favorite is the Neve 1081 on my UAD-2 Quad, though I’ll sometimes use the Waves LinEQ for transparency.
  3. Solo the kick. Repeat the process. If the bass and kick are fighting each other, you might choose to accentuate the sub bass in one and the mid bass in the other. For example, you might roll off the kick at 80 Hz and boost the “snap” in the 1-2 KHz region, while letting the bass dominate the sub. Taking it a step further, you might try complimentary EQ by cutting the bass at 100 Hz by a couple dB, and boosting the kick at the same frequency by the same amount at the same bandwidth.
  4. Solo the other tracks one at a time. If there’s not much going on below 150 Hz, leave it. If there is, insert a HPF into the first slot. We want the bass and kick to utterly dominate the lowest frequencies. Use your ears to set the frequency and slope of the cutoff while the track you’re adjusting plays with the bass and kick. It’s okay if it sounds thin by itself, as long as it plays nice with the bass and kick. I usually roll off my vocals around 150 Hz, but sometimes I’ll roll off pads or guitars as high as 300 Hz. For meaty snares, I might go as low as 80 Hz. You don’t want to clutter the bass, but you don’t want to leave a hole either.

On synthesizer tracks, you might be able to address the issue at the patch level. The Access Virus is the worst offender, but it’s easy to balance the sub bass by turning down the suboscillator (Osc3). On the other end of the spectrum, Native Instruments FM7 and FM8 have a habit of producing nasty spikes in the 17-18 KHz region, which can be tamed with a LPF.

The result is a mix with tight, clean, punchy bass. Best of all, if you clear the subsonic clutter from just the offending elements of your mix, your mastering engineer won’t need to roll off the whole thing. I’ve got a $1,500 EQ (the Algorithmix PEQ Red) that I bought just for its low cut filter. It does a remarkable job, but it’s still a compromise.

Below are unmastered clips of three songs from my new album, first with low cuts on individual tracks, then without. While you may initially prefer the “no low cut” versions simply because they have more bass, listen for the clarity of the individual elements in each mix.

For more mixing advice, see my other articles:
A Mastering Engineer’s Guide to Final Mixdown
Spectral Management

Keep Your Mixes Consistent by Using a Reference

30 thoughts on “Tighten the Low End of Your Mix with a Frequency Analyzer”

  1. I recently began applying this technique to my mixes and it has really brought out the definition I had been missing. Great to come across your post and hear the results confirmed in other examples. I look forward to trying your technique out as well, great advice here.

  2. Man! Love the nitty-gritty! Really want to give this a try but can’t get the vst into my host…got it in the right vst pref location, just wont load it. running sony acid 6…hmm
    any other plugs with these abilities/features that you’d recommend?
    I don’t usually have this problem…downloaded three copies and still nada…some great insight though!

  3. Is there an option to make Acid re-scan the VST plug-ins folder? If that doesn’t work, I’d check the Voxengo forums. If there’s nothing there, create a new thread and Aleksey (the author of the plug-ins) should respond promptly.

    I’ve got a couple other analyzer plugs, but I don’t trust them in the lowest frequencies. WaveLab also has an internal meter, but I strongly prefer SPAN.

  4. Yeah, rescanning, restarting…it does look like a nice plug. I’ll check out the forums next and see whats what and what not…Thanks!

  5. OK. I knew this. I’ve been mainly working with midi soft synth devices lately and just forgot this would be loaded as an ‘effect’…moving on.
    Now to reread your post!

  6. This isn’t a mixing question but back to promotion, if I may, concerning CDBaby and there process of getting metadata out. I’d like to get into Pandora and they say they get album art and info from Amazon…does CDBaby send that out to Amazon? I’ve noticed Color Theory can be found there and just wondered how you did it?

  7. Actually, if you click on the “about pandora” link on their home page and search for a band, it says on the bottom of the page that they get their info from AMG. I explain how to get your CDs to AMG here, and how to get on Pandora here. CD Baby certainly provides Amazon with at least track titles and album artwork, and of course the audio, for CDs enrolled in their digital distribution program.

  8. Great. I had already saved your post about AMG and Muze but forgot or missed the one about Pandora…guess I’ll send to AMG first then wait a few to send it to Pandora so they can find the info when there ready.

  9. I’d just send to both ASAP. I don’t think being on AMG is a prerequisite for inclusion on Pandora. In fact, Pandora is showing my album cover but AMG’s site isn’t, so maybe Pandora is filling in the gaps in AMG’s database.

  10. Great advice! You may also want to mention that you want to leave these settings flexible so if you work with a great Mastering Engineer that will give feedback on the mix, per song, you can quickly tweak these at the mastering engineers request. I find mixing bass to be difficult yet important since I don’t have a tuned or treated room. I won’t be printing any HPF to my mixes because of this. I have an older DAW though. Those with newer DAWs probably don’t have to worry about bouncing tracks with plugs on them due to lack of power. ;)

  11. Great post; handy product from a great company!

    I have very sensitive ears, especially my left ear. And I can hear a radical difference between with and without on this. The without is muddy and fatiguing compare to with. Thanks!

  12. Just to add a dissenting voice – I’d say this idea is a matter of taste rather than an essential technique for use on every mix. In the examples posted above I prefer the versions with the bass left on them. The versions with the sub removed do sound clearer and more defined but I think that that is a bad thing. The parts sound too separate, too clean and to my ears that doesn’t flatter the music. Although it’s obviously a matter of taste this sort of precise, clear sound is characteristic of digital sound and processing generally and many people prefer the warmth that’s associated with tape and vinyl recording which both have a tendency to glue the separate sounds in a mix together.

    It’s a good technique to know but use it only if it serves the spirit of your music…

    1. I suppose it is a matter of taste, and you’ll want to trust your ears, but you bring up an interesting point with vinyl. If your low end isn’t clean and in mono, the needle will jump out of the groove. So it probably makes sense to not only follow this technique (at least to some degree), but to download MSED from Voxengo (another free plug-in), mute the mid channel, and make sure the side doesn’t have too much low end information.

  13. Hi Brian, I’ve been enjoying all your output for the last few weeks since finding a link to one of your mixing posts on twitter… anyhow, i’m mixing my album and am having trouble killing “the snake” with EQ8 or any other HPF plug I’ve tried. They seem to taper off and the 10Hz and below freqs seem to come up again. Do I not have the Db scale set right in SPAN? I couldn’t find the setting to change it to -20 in the newer version of that plug. Thanks much and keep up the great work! Hope to be needing your mastering services in the near future…

  14. Thank you Brian,

    I Absolutely Loved this article and will definately reference in my blog’s next post. I Love and grew up in the 70s/80s with synth pop and you drew my attention to this article the other day after uploading an old cd to mixcloud.The same day i thought Remaster!

    While waiting to renew my plate at the SOS… I had a look on twitter and started reading your article and looking at the wave image,it was clear how the bass bottoms out.

    I continued to read on and started to question just how hard it would be to produce top quality edm with “Freeware”. Cakewalk was such a versatile and easy to use platform and is now available for download and other Free DAW’s for your computer.
    I’m Having Real “issues” with a Korgs’ connectivity and the only way seems to be using Cakewalk!

    I might have to take the Brian Hazzard “Freeware challenge”!

    Working In a studio on a budget, it seem strange to me that probably the best musical fidelity available to me is my Chevy Suburban! I am going to be finding myself listening to alot of my own work in the car before i can say if the SUB BASS is right! Oh i miss my B&W”s i left behind in England.

    Thank’s again Brian for your contributions to the #edm community and your words of advice. And please continue to follow ;)

    @joncoopermusic

    1. Thanks for the kind words Jon!

      Let me know if you take the “freeware challenge”! I don’t think I use any freeware at all, but I know there’s some great stuff out there. The FabFilter stuff (not free) is my bread and butter when it comes to mixing.

      Actually, checking sub bass in the car isn’t a bad idea if you’ve got a good subwoofer and a well-tuned system. That’s because the door panels are thin enough to allow the low frequencies to travel through them, rather than bouncing back to create nodes and modes.

      1. With today’s engineering in cars, sound “insulation” is a crucial factor in car design and innovation. Which benefits us all in the fact that the same works in reverse!

        With a good ear and a good idea of what a “balanced” sound is your car or truck, “the SUBurban” in my case, can be a great testing place for you mix downs. It only takes a 1k amp and a nice box and speakers and a little tweaking but when you get the balance right it’s perfect. Anything over that is Overkill! Unless you do enjoy a little Booming fun occasionally ;)

        I have even considered recording vocal in the truck with a reflection filter behind the mic, for its ‘Deadness’ of reflections and acoustic qualities. Unfortunately it won’t fit in my garage so it isn’t an option, but I would be interested to know if anyone ever used a car as a sound booth? Probably not but if could record the songs my 3 yr old daughter makes up when the music is off in the truck and I’m driving, well I would have no shortage of edm greats!

        1. I’ve got a pimped out system in my Prius, but it’s nowhere near as good as the studio. While cars are good for judging bass, there are many problems inherent with car audio. For one, you don’t sit dead center between the left and right speakers, so you need to adjust the timing. Just don’t move your head! ;)

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