In my experience as a mix engineer, I've heard many tracks mixed by artists, either before I mix them, or giving feedback. I've noticed that there are three stand out problems that make a mix feel small, stunted or unbalanced. In this post I'm going to talk about each problem, potential causes, and what you can do to rectify them.
1. Too Much Bass
An issue I often find in EDM mixes, but it happens in many other genres too. Sub bass frequencies (we're talking from about 30-80Hz) will cause compressors to work harder, leading to a squashed sound. You'll also lose out on a lot of loudness, as these frequencies have more energy than higher frequencies, eating up your headroom.
Causes
Speakers/headphones not reproducing sub frequencies
Poor room acoustics (more on this further down)
Overdoing the 808s!
Fixes
Reduce the low end on your kicks and bases (a simple shelf will do a lot)
Add a side-chain high pass filter to your bus compressor(s)
Boost low end after mix compressor to avoid pumping
2. Overcompression
Compression is best used sparingly, or it can very quickly squish your tracks into the dirt. On the mix bus, fast attack, feed forward compressors can be a pain in the neck, giving you 'lovely' pumpy sound that hinders rather than helps. You're looking to add a little bit of glue, not squish everything together. On drums, the same applies - those transients help the drums cut through, compressing them too much will keep them behind your other tracks and take away the punch they need.
Causes
Too much gain reduction
Attack is too fast
Too much low end (see mistake 1!)
Fixes
Increase attack time and use feed back compressors - on a mix bus, I rarely use attack times below 30ms, and I avoid 'feed forward' compressors as they tend to squish more quickly/obviously
Compress in parallel instead - If you still want the aggressive sound of heavy compression, mixing it in with the uncompressed signal adds the squish but maintains the transients and clarity
Less gain reduction - increase the threshold or lower the ratio to lessen the amount of gain reduction. When I use compression, I'm mostly looking at 2-4dB of gain reduction (vocals and parallel comps are exceptions).
Reduce low end - as low end effects compressors more, using a side-chain high pass filter, or boosting the low end after the compressor (while cutting before) can help reduce how squashed it sounds. My favourite tool for this is the API 2500's "Tone" control, which adds a tilt EQ favouring the high end into the detection circuit.
Use alternatives for 'glue' or loudness - In my experience, compression only gets you so far. My mix bus chain includes a saturation or tape plugin for extra 'glue', and a hard clipper for loudness (reducing transient levels stop the limiter from overworking)
Stack different compressors for 'cleaner' heavy compression - The classic vocal stack includes both an 1176 and an LA2a. They both have different characteristics, and lightly compressing with both of them will sound less 'squashed' than heavily compressing with just one.
3. Lack of Low Mids
I get it, mixing low mids is hard! There are often lots of instruments competing for space in this area, and this can get us into 'muddy' territory really easily. A lot of artist mixes I come across can sound very thin and a little lifeless, and it's normally because of excessive cuts to the 100-400Hz region, or really aggressive high passing of non-bass instruments.
Causes
Excessive high passing
Difficult production/arrangement decisions
Poor listening environment
A little more on the listening environment - If you're working in a square/rectangular room, sound waves are going to reflect back and forth between the walls. The result, when the dimensions of the room are relative to the wavelength of a sound, is points around the room where that particular frequency is louder than it should be, or completely absent! The common frequencies for these 'standing waves' sit right in that low/low mid frequency range, so you should be aware of this while you work.
Fixes
High pass less! - ask yourself if you can really hear what's going on in that low end. FabFilter Pro-Q will show you sub frequencies that look like they're enough to cause problems, but really they're at -80dB! My rule on high passing is "only do it if you can hear the track needs it"
Acoustic Treatment - it's very hard to mix in a room that isn't ideal. Different tracks can come out completely different if they are in different keys, as different notes will 'activate' different parts of the room. The tiny foam squares are useless for this. You need rockwool/fibreglass acoustic panels. They are cheap and pretty easy to make yourself - mine worked out at around £35 per 120x60cm panel
Mix on headphones if your room can't be fixed - Personally, I'm terrible at mixing on headphones. I need speakers and a good room. But I know many people doing amazing work on headphones only, so don't let that discourage you! Sometimes, if your listening environment isn't ideal, it's probably safer to work with a pair of good quality, open backed headphones that you know really well.
Work on the Arrangement First - If you're finding you have to suck the low-mid life out of everything, it's likely you've got an arrangement build up in that area. Try shifting the voicing of some of your chords, or shifting the tone of a synth out of that area. Less conflict in the low mids will allow you to keep more body!
So there we are, my top three mix killers, and some solutions to try! Do you struggle with any of these points? Have these techniques helped? Let me know!