Sonic Varnish July 19, 2022 11:22

Editors note: the following is an article written by Allen Farmelo. This article made a big impact on me when I first read it about 10 years ago, and it certainly played a role in inspiring the Colour Format. It's since disappeared from the internet, so I'm very happy to be able to re-post it here with the author's permission. - Peterson

When I was about ten years old my father drove an old-school Mercedes with a wooden dashboard that I thought was one of the most beautiful things in the world. Its glassy finish fascinated me because I could see every detail of the wood grain. I asked my father how it got like that and he explained varnishing to me, claiming that “Mercedes probably put at least twenty coats on.” Not long after that I bought an old skateboard that was horribly beat up, and I told my father that I wanted to varnish it to look like the Mercedes dashboard. Down in the basement we stripped the nasty paint off that wooden skateboard and started applying thin layer after thin layer of varnish with careful wet sanding and cleaning between each one. It was taking forever, and after twelve coats I proclaimed that the skateboard was done. It was glossy – not quite glassy – and I’d certainly learned about varnishing. It’s a lot of subtle work, and no one layer really seems to do all that much.

Harmonic Distortion is Sonic Varnish

Today when people ask me how I achieved certain sounds in the records I work on, I struggle to answer the question because it’s such a multi-faceted thing. Then it occurred to me that you could think of it like applying many small layers of varnish, except that instead of applying clear-coats of lacquer I apply layers of very subtle harmonic distortion. The word ‘distortion’ here is nothing like the overdrive and fuzz we talk about when discussing guitar pedals and amps. In fact, most people with untrained ears can’t hear a single layer of truly subtle harmonic distortion because it only gently changes the sound, and sometimes it’s so subtle that it’s basically inaudible.

All audio equipment (including most plug-ins) imparts a small percentage of harmonic distortion, and this percentage is called total harmonic distortion, or THD. THD can be understood as the amount of extra sound generated by the electronics in the piece of equipment itself. Some audio gear is sought solely for the character of its harmonic distortion and is said to be very “musical,’ meaning that we humans tend to like how thing sound when it goes through these circuits. Equipment famous for harmonic distortion includes Neve preamps, Fairchild compressors and Pultec EQs. These are units that people will run sounds through just to pick up harmonic distortion that the circuit generates even when it’s not particularly doing anything to the signal. We call it tone, vibe, mojo, fairy dust, goodness, sweetness, fatness, warmth, size, girth, a sonic halo and all kinds of other names, but what we’re basically describing is that subtle percentage of extra sound that the circuit adds to the signal. For this article I’m calling it sonic varnish.

It’s important to remember that most undeveloped ears wont be able to tell the difference between a sound going through a Pultec EQ set at neutral and a sound that isn’t. Over and over again I’ve inserted pieces of gear in and out of signal chains to show people the difference. If their ear is untrained, or still developing, they squint intently at the speakers for a bit then open their eyes, lean back in their chair and say, “I can’t really tell the difference.” Could I tell the difference between a Mercedes dashboard that had twenty-one coats of varnish as opposed to twenty? I’d probably squint at them and give up as well, but a professional wood worker might be able to see the difference. And – far more importantly – a pro will know which varnish to use, how to apply each coat, and which of those coats should be the last in order to achieve the desired result. It’s the same with sonic varnish. One layer doesn’t do all that much, but many layers add up to a finished sound that anyone can hear and say, “Yeah, that sounds really cool.”

Applying the Layers

I believe that one of the reasons we love the sound of records from the 60s and 70s so much is that the sounds were achieved by the (often unintentional) application of many subtle layers of harmonic distortion. Take a Beatles record like Sgt. Peppers recorded on 4-track – a classic example. I’m not sure of the historical accuracy of this explanation, but lets assume that Ringo’s drums were tracked early on. Then those drums were bounced back and forth between the four tracks of tape as they made room for further overdubs. For the sake of argument, let’s guess that Ringo’s drums made two bounces after they were tracked. Each time they bounced, they picked up the sound of the console’s electronics, the tape machine’s electronics and the sonic character of the tape itself. If you count each stage as a layer of varnish, that’s roughly seven layers (preamp, compressor, tape, preamp, tape, preamp, tape). Then you mix the record, which adds another layer, then master it, then play it on your home system (which will have a THD rating, too), and we’re somewhere in the realm of twelve layers of sonic varnish before you hear Ringo’s drums.


  • Layer 1: mic
  • Layer 2: console preamp
  • Layer 3: compressor
  • Layer 4: tape machine
  • Layer 5 & 6: bounce 1 (console and tape)
  • Layer 7 & 8: bounce 2 (console and tape)
  • Layer 9 & 10: mix to mono tape (console and tape)
  • Layer 11: mastering
  • Layer 12: your home system

Now compare that to a modern home recording. Typically the signal is recorded into a consumer grade preamp, processed with a compressor plug-in and bounced to disc.


  • Layer 1: mic
  • Layer 2: preamp
  • Layer 3: plug-in compressor
  • bounce
  • Layer 4: your iPod

The way I see it, this signal has had two chances to receive a coat of sonic varnish. During the recording it hit the preamp and then the compressor plug-in to achieve a second layer. Someone with only two layers of consumer grade varnish will still want to make the most of the recorded sound, so she or he is likely going to try to make each of those two layers as thick as possible. I see this all the time, and a slew of common amateur techniques have evolved. What I see most of is way too much compression, double and triple tracking of parts to add dimension, and the use of distortion plug-ins for a lo-fi sound that is more often a final ditch effort at sounding interesting than an aesthetic choice. People will try anything to make those two or three layers as thick as possible.

The temptation to overuse any one of these stages is strong because the sound just isn’t going to pop out of the speakers if you’re doing subtle work. This lack of sonic excitement is confounded by the lower quality components in consumer grade equipment, too. When you start to overuse any of these layers you acquire obvious sonic artifacts that will change the nature of the source sound to such a degree that the characteristics of the processing itself can overtake the characteristics of the original sound. A kind of haze emerges between the sound and the listener, and when you multiply that by however many tracks you have in the mix, things can get downright foggy. I hear it all the time and the result is simply unremarkable. As my father will still tell you, thick layers of low-quality varnish look horrible. They don’t dry evenly, bubbles get trapped in the varnish, and brush strokes are often visible. Rather than showing off and accentuating the amazing colors, details and depth of the original wood, you end up seeing the varnish and the artifacts of its application. The exact same thing happens with thick layers of consumer grade sonic varnish. There’s no short cut. You want your skateboard to look like a Mercedes? Start layering. You want your mix to sound like a great classic album? Start layering.

Modern Varnish Mixtures

I use a combination of digital and analog gear to achieve my layers of sonic varnish, and I chose each layer very carefully to emphasize a particular quality in the sound that I think serves the artistic vision of the project. And I always have my eye on the final mix. For example, if I know I’m going to mix to tape, I have that in mind as I compress the vocal because I know the vocal will “sit down” a bit more once the mix has hit tape. As I apply each coat of sonic varnish, I have the next layers in mind so that I don’t apply any one layer too thickly. I’m interested in the cumulative result of many subtle layers. Let’s take a look at a particular vocal sound to get a sense of what I mean. This is from a very sparse record of which I’m particularly proud of the vocal sound:

    • Layer 1: Vintage Telefunken U47 (tube microphone)
    • Layer 2: Chandler TG2 mic preamp
    • Layer 3: Tube Tech CL-1B Compressor
    • Layer 4: Cranesong HEDD converter (a touch of its Pentode processing)
    • Layer 5: API 550a EQ
    • Layer 6: Tube Tech CL-1B hardware compressor
    • Layer 7: API 2500 stereo bus compressor
    • Layer 8: Dangerous Audio BAX EQ
    • Layer 9: Studer A-80 1/2″ tape recorder
    • Layer 10: Studer output stage
    • Layer 11: Cranesong HEDD A-D conversion (with a touch of Pentode processing)

Each and every one of these eleven layers is doing something so subtle that very few people can really hear the difference. But, each and every one is just as important to the overall sound as the one before it or the one after it. Use a different mic and the sound will change. Use a different preamp and the sound will change. Use a different converter into the DAW and the sound will change. Use a different bus compressor or tape machine and the sound will change. Each and every layer is equally important, while no single layer is all that important on its own.

My personal theory about why this technique works is that you’re never letting a single piece of gear overtake the original sound. Instead, you’re letting each piece of gear impart just a little bit of harmonic distortion – a little mojo, a small halo, a bit of warmth, a little extra size – and then moving on to the next piece of gear that’s going to impart another kind of harmonic distortion. Maybe the preamp warms up the mic a bit, and maybe the compressor puts a little halo around things, and maybe the tape machine adds a certain depth, and maybe the converter adds a little something-something. Layer by layer the varnish becomes thicker while each layer remains relatively transparent. The original sound is still in tact, but it has acquired all of these wonderful, subtle qualities along the way.

Gain Staging – The Craft of Varnishing

With wood, layers of varnish go on rather simply, one at a time, but there is still a craft to it. My coats of varnish on that skateboard weren’t nearly as well applied as my fathers because he had years and years of experience with a brush in his hand. He had the craft that told him how far to dip the brush, how hard to push that brush against the edge of the can to remove excess varnish, where to begin and end his strokes and how hard to push as he made them, and he knew when enough was enough. He knew how to varnish.

In audio, how you varnish is called gain staging. Gain staging refers to the rather complex craft of knowing where the optimal (or intentionally not optimal) operating levels are for any piece of gear in the signal path. How much signal you feed into a piece of equipment will elicit a certain amount and kind of harmonic distortion out of that circuit. Whether it’s tubes, tape, solid state or even a digital plug-in, the way you set the gain will determine the sound. To make matters more complicated, the way one gain stage is behaving will effect how the next one behaves in real time. Add to this that many pieces of gear can be calibrated to different levels, and that every sound you record is going to change how the gear is going to react, and you start to see the endless complexity. Gain staging is not trying to hit a moving target; it’s trying to hit a moving target from a rotating platform on the back of a speeding pickup truck on a hilly, winding road.

Developing Your Brush Stroke

So how do you learn how to gain stage properly? Practice, practice, practice and get great teachers who can guide you. It took me years to know how to get a good, solid signal happening with just a pre amp, more years to learn how to send that signal to a compressor properly, and more to learn how to get a tape machine to react the way I wanted it to. And I’m still learning all the time. My aim in writing this essay isn’t to pretend to be able to teach you how to do gain staging – how do I know which target you’re shooting from which pickup truck on which road? My aim is to stress that as you apply sonic varnish you need to really be aware of how you’re applying the layers.

My best suggestion is that you begin by simply considering the concept of sonic varnish when you’re making a recording and start to train your ear to hear subtler and subtler layers of harmonic distortion. And if you’re using a DAW to do recording, you can try to emulate more and more stages of sonic varnish using plug-ins. Believe me, it’s not a great idea to stack up a bunch of the same plug-in and expect them to do what a vast combination of great hardware and software can do together. Nor can you expect too much out of consumer grade gear. (Yes, the signal path I describe above costs thousands of dollars, and I don’t expect everyone to have access to that kind of gear). But, you can learn a lot by trying different things in the box. Here are some ideas:

  • Use a plug-in that emulates analog gear (a compressor, an eq or other will be fine) to try to put a tiny halo on a guitar sound, or a little girth into a bass sound, or a bit of sweetness into a vocal. Don’t try to engage much of the processing – only enough to apply the smallest amount of harmonic distortion you can hear. Work in very very small increments and see what you can hear.
  • Try using a few different plug-ins to achieve subtle harmonic changes in the sound without changing the essential nature of the original sound. See if you can get the sound to come to life while sounding just the same.
  • Try to get 3db of compression out of two compressors doing 1.5db each. Then try three doing 1db each.
  • Try remixing something you know you’ve put a few big layers of varnish on and see if you can achieve a less hazy result with more sonic impact by using more subtle layers.

In other words, take the concept of sonic varnish and experiment with it. There are really no hard and fast rules to follow, but hopefully the concept of sonic varnish will help you have a general guiding principle to follow. I’m sure you’ll come up with all kinds of ways to play with the concept.

What About Sonic Paint? – I need to recognize that there are many times when one is going to want to slam the hell out of something with a compressor, or distort something to the point where you can’t tell what it is, or eq something so drastically that its very nature is transformed. That’s not varnish – that’s paint. However, remember that most paints also need to be applied with great skill and are typically finished with a few very thin layers of clear varnish in order to add depth and brilliance to the color beneath. So, even if you’re going to slam a sound against a wall until it bleeds, those gaping, bloody wounds will be all the more gory if you can get a few coats of varnish on there to show it all off.

What About Lo-Fi? – Everything I’m saying would apply to achieving lo-fi sounds. If you’re interested in making a lo-fi recording, one of the most important things you can take away from this essay is that multiple layers of distortion will get you better results than one single lo-fi distortion layer. Some of my favorite lo-fi recordings are by Guided by Voices on four track recorders that imparted a lot of THD, but they also bounced their tracks back and forth quite a bit, layering the sounds and slowly degenerating the original sound. Compare that approach to sticking a distortion plug-in on a single digital track and most people will agree that the vibe is with the layered approach. Also, no matter how distorted a lo-fi record is, the layered approach will allow the original signal to acquire its new vibe and sound in lighter layers that will allow the original sound to maintain its character.

What about Genre Specific Sounds? – Absolutely work toward the aesthetics of the genre you’re working in, but keep in mind that in any genre the concept of sonic varnish will help to achieve great sounds. Techno may be a genre where digital sources never leave the computer, but even the sampled sounds will go through multiple manipulations to come to their finished luster, and many subtle layers will often serve that goal well. Black Metal may want to achieve an endlessly muddy distortion, but any guitar player will tell you that the pickup, the amp, the speaker, the mic, the preamp and the rest of the recording chain all go into making those sounds. Again, trying to achieve that sound in one or two small stages isn’t going to get the pro results. Extend the logic to any genre and I think the concept of sonic varnish will still prove a useful guiding principle.

What about Honest Recordings? – Classical and jazz recordists often talk of transparency and of “honest recording,” but the very fact that THD is present in every piece of gear makes “honest recording” a myth. Perhaps using fewer layers of sonic varnish will help keep the original recorded signal less tainted, but I think its important to keep in mind that the original recorded signal just passed through a rather tiny diaphragm or ribbon and became wiggling electron waves in a long thin piece of metal called a cable. To think of a recorded sound the way we think of a live sound isn’t going to help one grapple with what it takes to make a recording appear natural when it comes out of two speakers. More often than not, subtle harmonic distortion has helped me render sounds more honestly because the recorded sound can take on an added complexity, richness and 3D quality that got lost in the act of capturing it. The tendency in making these “honest recordings” is often to try to apply as little varnish as possible, but the counter-intuitive move of adding more harmonic complexity might bring the sounds of the instruments to life in ways that the thinner layers might not be capable of. As always, experiment and see what works for you.

It’s a Concept – Sonic varnish is a concept, a guiding principle, an idea. It’s something to have in mind when you’re recording and mixing that can help keep the bigger picture in focus. There are so many stages to recording, and no single one of them is any more or less important than another. As technology changes faster and faster our tools are going to change as well, yet our methods for recording seem to stay more or less the same. We still have to put a mic somewhere near a source, amplify it, get it onto a medium of some kind, then take that recorded sound and process it in some way in preparation for it’s final format. No matter how careful you are, you’ll be introducing some level of harmonic distortion at every stage, so it’s good to be aware of it. Even better to really know how to apply that harmonic distortion in a way that’ll get you the sounds your after.