Using a reference track when mastering is a kind of standard practice, but it can be done much better with the wonderful EQ matching functions found on so many equalizer plugins. Here’s what I’ve tried and how it’s worked out for me.
Equalizers That Match
I use both the Tokyo Dawn EQs and Fabfilter’s Pro-Q (version 3 at this time), but other manufacturers are including an EQ Match function in their plugins. What the EQ Match function does is match the equalization of your track to a reference. The reference can be either side-chained (most matching EQs) or a stored spectrum (Fabfilter Pro-Q and Tokyo Dawn EQs) or a music file like mp3 or wave (Tokyo Dawn EQs). If you apply the required equalization from the analysis, what you end up with is your track sounding remarkably similar in tone to the reference track.
Here is a good article by Sage Audio comparing a couple of EQ matching plugins (Fabfilter Pro-Q and Izotope Ozone): https://www.sageaudio.com/blog/audio-plugins/what-is-the-best-plugin-for-eq-matching.php
Here are some videos of the Fabfilter Pro-Q EQ showing how the matching function works.
Tokyo Dawn’s Slick EQ, Slick EQ M, and Nova EQ
This is the EQ that I prefer for numerous reasons and below are some videos of how it works.
The EQ match on this set of EQs is a part of “smart operations” and each has even more than just an EQ match capability. Check it out. I think these are far superior to Fabfilter or Ozone in both matching capability and EQ sound in general, in my opinion:
Newfangled Audio’s EQuivocate
I like the idea of EQuivocate and how it matches. In my workflow, I tried to incorporate it, but it just does not show me enough about what I am doing. I need to both hear and see the spectrum, and it is more based on hearing so it doesn’t work well for me. Also, the bands are not always appropriate for my music. Of course, you can change these bands, but that is an extra step and time-consuming, so I favor the Tokyo Dawn EQs for the speed of workflow. Below are some videos showing how EQuivocate works.
Where to Use EQ Match
Reproducing a particular sound or duplicating a song:
I have done this on whole songs such as when I was trying to replicate the sound of Biosphere’s Shenzhou and I have done this when trying to replicate a certain noise or sound found within a song such as when I did this with Susumu Yokota’s Saku noise. I used Fabfilter Pro-Q for those instances because it is very surgical and precise in the number of filters it suggests, and it gets it right on the money for reproducing sounds.
Use: Fabfilter Pro-Q
For replicating Shenzhou, my EQ curves looked like this one below and made it sound exactly the same as the original source material. Exactly the same. Incredible.
Replicating the background noise in a track also was easy using just pink noise and Pro-Q. Here is how the EQ curve looked for replication of the background noise in Susumu Yokota’s Saku track:
Mastering my own tracks using references:
When mastering my own tracks, I want to get the right “flavor” of sound but not necessarily reproduce another exactly. Creating my own tracks, after all, is a creative process and I want full creative control over them. But I also like a good suggestion. And, I don’t want to contact actual people or rely on anyone else’s opinion, so I rely on a suggestion from my favorite equalizer plugins and tweak them to suit my ears.
Use: Tokyo Dawn EQs (Nova for dynamics processing on my master. SlickEQ Mastering for my final master EQ just before the TDR Limiter GE.)
The Tokyo Dawn (TDR) products are consistently the best and I highly recommend them.
I sometimes (not always) like to use Nova to give me some dynamics earlier in my master chain.
- I downward expand (gate) the low frequencies and adjust the threshold so that the low volume-level lows are being taken down even farther into the inaudible range. This decreases rumble and helps to define the low end.
- I use standard downward compression for the mids. This is kind of to glue things in the middle. I use a really low Q so it is spread wide and not too noticable.
- I use upward compression for the high frequencies and adjust the threshold so that I get a sweet but not harsh amount of the low volume-level highs being brought up and amplified.
Then I use SlickEQ Mastering Edition for the suggested levels against either pink noise, grey noise, or a reference track of a similar type and genre. I make sure that up to this point in my master chain I have all the effects of saturation, compression, equalization, etc., all included before I make the SlickEQ Mastering Edition EQ do that matching.
Next, I choose a reference source for the matching. I either use pink noise, grey noise, or a track.
Pink Noise Reference
Why use pink noise as a reference? It has a human-friendly response where it loses energy as the frequency goes upward (as opposed to white noise that does not). It is a good starting point for any set of tracks and can help bind them all together in an album release. There are several articles out there about it.
I use this as my default mode of reference matching on my master bus and for most of my tracks. It is o.k. if used properly and that means not going too low or too high with the reference. These are relative, but the Special Ops section of Slick EQ-M usually does not pick something too low or high of a range.
A lot of times I make single tracks that sound completely different from one another when combined in an album. This is not what I want, so I use the EQ Match function with a pink noise reference to give them all the same kind of tone while retaining their individual unique sounds.
Pink noise has a downward slope when you look at the frequencies from low to high, and this approximates the Fletcher Munson curves of hearing.
But, know your EQ and its tilt because this distorts the view. Maybe pink noise does not show a downward slope and that could be because, as is the case in Fabfilter Pro-Q, the default tilt is 4.5 dB/octave. Or, in TDR EQs, pink noise appears as a straight line not tilting downward or upward, and that is because the TDR EQs have a 3dB/octave equal energy weighting applied to the curves shown. Here is a video showing how the different types of noise look in these EQs. Read the description of the video on YouTube to know more:
With the Tokyo Dawn EQs (and SlickEQ Mastering Edition in particular), I often use pink noise as my reference source because it is not genre-specific. I have not found other matching EQ products that provide the pink noise as a reference, so I would recommend the Tokyo Dawn (TDR) EQs for this type of matching. While you can do it with others, it saves a step and saves time when using the Tokyo Dawn EQs.
In the SlickEQ Mastering Edition, I set the match percentage parameter from around ten to twenty percent because if there is more then it gets out of hand as far as the low end is really loud and the high end gets really tinny-sounding. The default for the program is thirty percent but I find this is usually too much.
Check out the great explanation of the Fletcher Munson Curves and EQ in the video below.
But, again, keep in mind to know your EQ and how the curves are weighted or tilted.
Below is the section of SmartOps in TDR EQs that deals with reference matching to pink noise:
Grey Noise Reference
Another reference source can be “grey noise” which is a noise that more closely matches the equal loudness, Fletcher-Munson curves. If I use grey noise as a reference, I can extend down into the lower frequencies and up to the highest. I think grey noise as a reference can be very valuable if done right, but I have better luck with using the pink noise internal reference of SlickEQ-M and set the range to 15% with the lower and upper frequencies wherever
I am usually in the ten to twenty percent range for the range setting.
I get my grey noise reference signal at -12 dB from wavtones.com.
I find that I can do just as good with the internal pink noise reference if I just watch my low end.
Comparison of Noise References
Boulez’s DeBussy performance is well-made. I used this as a subject for my mixing to noise references and tried it against the pink noise and grey noise references.
First, the original:
Next, I used TDR Slick EQ-M to generate an adjustment EQ curve for it using pink noise as a reference:
Then, I used a grey noise reference:
Gregory Scott from Kush Audio has a good video about reference mixing, which is essentially what you are doing when EQ matching, in my opinion:
If I want to get the tone of a certain type of music, I will choose a track from that genre and use it as my matching EQ reference.
I try to choose the reference to be similar to my track. I want to use a classical reference for classical music, an electronic reference for electronic music, and so on. But a lot can be done by breaking these rules such as using a hip-hop reference to equalize classical music, and you can end up with a whole new and creative sound.
I tend to have better luck with pink noise as a reference because it is rare that I have a genre reference that closely matches what my music sounds like. More effort is required with the genre references because of this. I find myself tweaking the sound afterward much more when I use genre reference material. But, it also opens some creative doors for me as well because I often get sounds that are unexpected.
In Fabfilter Pro-Q, I have recorded the spectrum of some of my favorite reference tracks and have saved them for future use when EQ-matching tracks. In the Tokyo Dawn EQs I don’t need to do this but instead can import the music files (wave, mp3, etc.) at the time of matching and this saves incredible amounts of time. So, for this reason, I would recommend the Tokyo Dawn (TDR) EQs.
How I Choose Reference Tracks
I choose reference tracks that sound best to my ears. It is that simple and will be different for everybody.
I like a good low end with crystal clear highs for most of my classical music or orchestral work. I find this range of tones in Pierre Boulez’s recording where he conducts the Cleveland orchestra in DeBussy’s works. It sounds airy and clear but with good bass.
Another is Tord Gustavsen’s music from his album, The Other Side.
Here are some more:
Each of these is for a different type of music, but they all have qualities that I like.
You can also search Spotify or other streaming services for “Reference Tracks” and find playlists of audiophile-quality mastered tracks. This could suit your needs as well. In any case, it is interesting to do.
Phase and EQs
Always keep an eye on the phase. It can mess up the sound and the perceived equalization. The key word here is “can” and not “will.” Dan Worrall has good videos about it:
Signals in parallel can cancel each other out so it is something to watch out for.
Tokyo Dawn’s Nova and Slick EQ M EQs are parallel EQs. These two work well on the master bus and do not introduce issues for me. The creator of these EQs has discussed how they are made and it is worth checking out.
Clariphonic is a parallel EQ and it works so well it is stunning. I often use it on the master bus but also on instrument tracks as well because it can pull out the great tone from lifeless instruments.
You can always use a linear type of equalization (available in Fabfilter Pro-Q and others), but you run the risk of pre-ringing.
The phase response is responsible for the tone of an EQ and this is primarily why each EQ will sound a bit different from another. Linear phase equalization ruins transients because it causes phase shift but then cancels the shift by applying the same process earlier in time, combining the two in the end. This combination restores the phase shift, but in the process, you get pre-ringing or pre-echo. This pre-ring/echo stuff messes up the transients. You end up with a worse tone, in my opinion.
I favor the parallel type of equalizer found in the Tokyo Dawn equalizer products and the Kush Audio Clariphonic. Once you’ve tried these, you may never go back to any of the others.
So to summarize, there are a few instances I can think of, in general, where you could use EQ-match:
- Make exactly the same sound by using a reference track that is exactly what you are trying to duplicate. Check my Biosphere example, and my Susumu Yokoto example. Fabfilter Pro-Q[x] is good for this.
- Make your music sound similar to a reference track of the same type or genre. For example, if you are making a classical piano piece, then the reference would be from a classical piano performance that you think sounds good and would like to emulate. Fabfilter Pro-Q[x] works for this, but it takes longer using Fabfilter than it does the Tokyo Dawn EQ products.
- Make your track sound similar to the rest of your tracks or another of your tracks. This would be for album continuity for example where you want all of the tracks to have a similar tonal character. You would select one as your reference and match the rest to it – preferably pink noise. Tokyo Dawn (TDR) EQs are good for this.
- Creatively use EQ matching to make a track of one genre sound like another. For example, use a hip hop reference track while making a classical piano track, so the classical piano takes on the character of the hip hop genre reference. Either Fabfilter or Tokyo Dawn products can be used here.
- Match the reference spectrum of pink or grey noise as a generic way of making well-balanced mixes.
Of course, there’s way more to make a track sound good outside of the equalization. There’s a whole host of things including balance, width, reverb, delay, compression, saturation, and the list goes on and on. But, you can get a surprisingly long way by using just equalization (EQ).