Mixing Synth Pop: Synths
In part three of this series about mixing Synth Pop, mixer/engineer Tristan Hoogland describes his processes for mixing synths.
22 April 2020
In the first two parts of this series we went through my processes for mixing drums and bass for synth pop. Now let’s look at introducing the more atmospheric element: the synths! Of course, the word ‘synth’ could refer to any number of keyboard sounds – it could be a warm pad from a Juno 60, a stabby chord from a Prophet, an aggressive MS20 lead line or even just an electro piano sound. Whatever the case, the various techniques described here can be applied in all sorts of scenarios. Let’s get stuck in to it!
EVERYTHING IN ITS PLACE
I request wet and dry copies of all mix stems, but I almost always use the wet stems and treat the dry stems as an insurance policy. There’s no use trying to recreate what they’ve worked on and lived with for so long! I’ll request them to print any filter sweeps they’ve applied, but I may break out the filtered sections to new tracks so I can have finer control during those passages.
I spend my initial prep time working out if a synth sound is truly stereo, or if it’s just a mono synth with some kind of inverted phase effect that makes it sound wide but might cancel out in mono. It’s usually easy to spot this; it will sound disorientingly wide in stereo, but will thin out considerably when heard in mono. My solution here is to monitor in mono (or center the pans) and, if there’s a problem, I’ll invert the phase on one side to see if that rectifies the issue. If that fails to improve matters, I’ll ditch one side altogether, go mono and recreate a stereo effect with something like a microshift.
Artists and producers tend to be allergic to synths being panned out, especially if the rough mix doesn’t illustrate it. I believe this happens because when synths are layered in a particular way the relationship creates a block of sound – a unity that comes undone when you pan them off or try to break them away from each other. Don’t let this discourage you from experimenting, but, unless what you’ve panned out feels better and there’s a part that can balance it panned to the opposite side, you’re exposing yourself to an onslaught of “narrow that back in!” feedback from the artist or producer.
What I sometimes do is pan two lines that balance each other out, or in this example play a ‘call and response’ role. To make it less shocking, I’ve also sent these to a reverb with the pans inverted to retain some sense of stereo. This can be an effective solution if you’re wanting to achieve a bit more width and space. (1)
NOISE
Sometimes I’ll receive sounds with a lot of noise. This can be a result of poor gain-staging, noise induced from effects, or even just the patch of the keyboard. I’ll usually leave the noise in and assume it’s part of the vibe. If it’s having a negative impact, or the client requests for noise reduction, I’ll attempt to rein it in. If I’m unable to tame it effectively with low and high pass filters, I’ll resort to iZotope RX’s Spectral De-Noise. Put it first in the chain, then select a small area of the track where the noise is present but there is no musical audio (a millisecond or two will do). Click ‘Learn’ and hit play so Spectral De-Noise captures the selected noise as a reference. Before proceeding further, set the Threshold to +6.0dB and Reduction to 0.0dB – this will act as our starting point. Now, with the music passage playing right through, we can begin adjusting the Threshold and Reduction in real time to find the sweet spot for removal. Start by bringing up the Reduction slider until the noise is completely removed from the signal. Next, bring down the Threshold until the noise begins to reappear. Having found the area to tweak from, finely adjust each slider in tandem until the desired amount of reduction is achieved. The relationship between these two parameters is integral and takes a bit of massaging to get it right. Once I’m happy, I’ll usually process this at a higher quality in AudioSuite. (2)
MAKING SPACE
I rely on carving with EQ – and particularly using high and low pass filters – when attempting to make synths work together in a mix. Using the bass track as my reference point, I’ll turn up the synth parts one at a time and focus on anything that’s blurring the low end. I find this happens because artists will often record synths full-range despite being used to only fill a certain part of the spectrum. This means they can have a lot of unnecessary low end when heard in the context of the mix.
I’ll start by using a high pass filter and set it quite high, usually between 400Hz to 1kHz depending on the material, and then drag it down until I get back the integrity of the sound and leave out everything below it. It’s not unusual to be parking this around 200Hz to 400Hz, but sometimes even as high as 1kHz! Naturally, context and source is the variable here. Once I’ve done this I might need to focus my attention further up the spectrum and rein in some mids or upper mids to steer the sound back closer to the original tone. At this point it can become a bit like a game of whack-a-mole as you continue to alter the tone, but you get the picture.
Conversely, there may be an excessive amount of high end. It can sometimes be difficult to hear this and/or the masking it might be creating, but a spectrum analyser like the one in FabFilter’s Pro-Q3 can display any unwanted top end. I’ll either resort to Avid’s Lo-Fi – reducing the sample rate down to somewhere between 16000 to 36000 cycles – or use a steep low pass filter to remove it. In the example shown here, from the song ‘Tonight’ by Golden Vessel, the pad track from the DX7 had no real musical content above 2.5kHz and yet it had an insane amount of noise – presumably from some kind of onboard chorus effect, which is often the culprit for this type of noise. (3)
Beyond this I’m usually quite conservative, preferring to make space by using a few subtractive moves with EQ; cutting rather than boosting. With this approach there are some areas where you need to focus your attention, depending on the sound. If it’s a thick pad or piano sound, you might need to look somewhere around 100Hz to 400Hz. If it’s a buzzy synth, look around 2kHz to 5kHz. For something furry and fuzzy it’s more likely to be around 400Hz to 1000Hz. Of course, these areas I’m removing could be in the sound itself, or in the elements surrounding it. If subtractive measures haven’t taken me all the way I’ll find some areas to boost, usually in the midrange between 500Hz to 1kHz and between 3kHz to 6kHz – anything that will highlight a part or create some contrast against the surrounding elements.
HARMONICS & SATURATION
I generally don’t reach for compressors unless a synth part is wildly dynamic; I find volume and corrective EQ gets the job done most of the time. If, however, I have a track full of synths that are tonally similar I will experiment with distortion to achieve contrast. If a part is stabby or has a lot of transient, I’ll drive the signal with something like Lo-Fi, Culture Vulture, iZotope Neutron or similar. I prefer using distortion over compression in these situations because it rounds out the sound in a musical way and juices more out of the tone, as opposed to squashing it.
Lo-Fi is great at quickly focusing a signal in a single move. I’ll grab the distortion knob, wind it up until it starts brick-walling during the loudest passages, and adjust from there (typically settling somewhere between three and six on the dial). Doing this might bring forward some unpleasant qualities that weren’t obvious before the processing, so I’ll have an EQ ready to address that. (4)
The Culture Vulture is great for fattening the tone and adding dimension to a sound; it drives and interacts with the signal in a way that’s akin to a guitar amp. It feels very musical with a broad range of tonal options. The ‘T’ setting is the warmest and most gentle of the bunch. I’ll usually start with this if I just want to take a sound up another 10%. The ‘P1’ setting on the other hand is great at adding aggression and fuzz to a sound; it’s good for brass pads and buzzy lead lines. With either the ‘T’ or ‘P1’ setting, I’ll usually set the bias between four and six on the dial and engage the 9kHz low pass filter because the resulting top end is generally unremarkable. On the track ‘Unconditional’ by Touch Sensitive I used it as shown here to bring more focus to the mid range. Decent alternatives include Radiator and Decapitator. (5)
On the more extreme end of harmonic generation we have guitar amps (simulators or otherwise). I’ll resort to these in the rare cases where I’m feeling a sound is unremarkable or in dire need of a makeover. In the example shown here I had a dull sounding Prophet playing a repetitive three-note chord stab. In the mix I felt like the song had way too much of the same tones going on, so I used Softube Amp Room to add some harshness higher up and bring out the harmonics of the passage. There’s also SansAmp’s PSA1; it’s an oldie, but it works great too. (6)
DELAYS & REVERB
I’m a huge fan of expanding the dimension of a mix. Even in events where synths come in entirely wet, I’ll push them even further out into the ether. I like effects that aren’t noticeable or cheesy, and the best way to achieve that is to focus on the immersive qualities of the space rather than the tempo or sound of it.
For pad sounds I’ll use carefully timed delays, and my favourite tool for this is Soundtoys’ Primal Tap. Despite being a digital delay, it’s quite dull and murky which is perfect for this application. I’ll start with something like a 1/16th or 1/8th division (maybe even dotted) and set the feedback to taste depending on the desired effect (for a long reverb-like effect I’ll go for 80% to 99%, while for a short room I’ll use 20% or less). To make it sound even more diffused I’ll unlink the two channels and offset each side, something like 10ms to 15ms in opposing directions. Place an EQ after it and roll off a ton of the high end until you can barely make out the delay, then back it up a bit (2kHz to 5kHz). I’ll also put a high pass filter (around 400Hz to 600Hz) on the return of the delay to keep the repeats from muddying up the low end. The modulation knob is also worth experimenting with. Another favourite delay for achieving this effect is Soundtoys’ Echo Boy when using its Space Echo or DM2 settings. (7)
Conversely to delay, if I’m using reverb it’s because I want to hear it. My go-to for this is the UAD AKG BX20. Despite being a spring reverb it’s incredibly deep and dark sounding, which is perfect for placing synths further back into the mix. I’ll set the reverb time to taste and maybe include a short pre-delay if I want a little more separation between the wet and dry signal.
I want to hear the reverb in the mix, but because the BX20 is quite dark in tone it needs a little help to translate. So I’ll usually send quite hot off the source, and I’ll run an EQ on the send into the reverb and another on the return from the reverb – both quite drastically! I’ll apply a high pass filter and a low pass filter over the send going into it (400Hz and 6kHz respectively) and then further EQ the return in a flavourful way with the Neve 88RS to remove a lot of low end along with some liberal boosting around 500Hz to 600Hz, and also something higher up between 3kHz and 6kHz to really highlight the tone of the synths. My other favourites for synth reverb include Lexicon 480L’s Hall setting, and Valhalla Vintageverb’s Concert Hall setting. (8) + (9) + (10)
Tip: When using delays and reverb it’s always worth experimenting with inverted panning to achieve even stranger stereo effects, particularly if the dry signal is panned to one side!
DON’T HESITATE, MODULATE!
Chorusing and modulation effects are great at keeping a signal audibly dry, but smear them into the mix so they feel less stark and upfront; this is perfect for synths that intentionally have no ambience effects applied. In my toolkit I’ll default to either the Brainworx ADA Flanger, Soundtoys MicroShift or the UAD CE-1.
The ADA Flanger is incredibly versatile; it can be a way over-the-top warbling flanger, or a gentle and soft wavering chorus. I’ll usually insert this on the track itself, rather than via a send. I start by leaving the threshold full, turn the range quite high so I can exaggerate the effect, and then find the rate I want by adjusting the speed. I’m using this for tone just as much as I am using it for a chorusing effect, so I tend to go for something medium-slow and wavy (less than 3.00 on the alphanumeric display) that softens the sound and takes the edge away. Then I’ll dial back the range considerably and set the overall wet/dry mix to taste, generally arriving somewhere around 15%. (11)
UNTIL NEXT TIME…
That about wraps things up for this instalment. I also use sidechaining techniques when mixing synths, but I discussed those in detail in the previous instalment about mixing bass and the techniques remain the same. Next issue: mixing the vocals!
This was a really great tutorial! I’ve been working on a lot of synth pop lately so this is perfect mentality to add to my toolkit. I’d love to read the part about bass!