Adding Harmonic Content..How Can It Work For You?

When recording or mixing tracks there are many instances when certain elements sonically just ‘work’ better than others, this could be due to many different reasons. The type of mic, the design and speed of the mic preamp, the way the artist performed, the compression or EQ chosen or even the Key of the track can all work together to make something sound perfect through sympathetic cohesion of these elements.

With the development of In The Box (ITB) recording and mixing there have been many tracks I’ve worked on where the arrangement sounds good, everything is working, but it’s lacking some sonic depth. Usually I’ve found this is due to lack of Harmonic Content on the parts or sounds used.

Distortion And Saturation Types

Harmonic content I feel tends to break down into Distortion and Saturation, and usually I find one at least can be just what is required to add some extra ‘life’ or character to tracks. Likewise, if the individual tracks aren’t available there is a a lot that can be achieved by applying the same ideas to Stems or the Mix Buss only.

Clipping Distortion

Clipping distortion is the type of distortion achieved by clipping your Digital audio signal, or driving the levels into the Red in your DAW Software. This arises because we’re trying to achieve an output level that the system or device cannot handle, it doesn’t have the headroom.

CLIPPED waveform

The waveform basically gets chopped off and whilst technically it is ‘distortion’ -as anything where the wave shape is changed from input to output is classed as distortion- it doesn’t actually sound very good and I would always refer to this as Clipping to avoid confusion. I do know some producers and mixers though who use Digital Clipping to achieve a certain type of sound.

Impedance miss-match distortion

Distortion from pedals or plug-ins can sound harsh, brittle and fizzy, sometimes due to incorrect matching of impedance from a guitar pedal to an Audio convertor. This can be solved by using a Re-Amp box (the Radial Reamp JCR for example) making sure the pedal and the Audio interface (or Tape) play nicely together and are seeing the correct impedance signal in the chain.

One tip here if you still think the distortion is too fizzy is to roll off some high end with a Low Pass Filter or send it through an Amp Sim if you’re in the box. Re-amp it if a guitar amp is handy, as by the very nature of sending the audio through a guitar speaker (virtual or real) is automatically rolling off some brightness due to the non-full range speaker cone in the cabinet (or simulation).

Reamping technique


If you were to drive your signal like you would in the example Digitally Clipping but with analoghardware, usually through the use of transformers on the output, your hardware would gently flatten the waveform rather than abruptly cut it off. All transformers will Saturate their Core at some point, and it is the variety of transformer designs by the likes of Jensen, Lundahl, Sowter and Cinemag that equipment manufacturers choose (or have custom made like AMS Neve) to do so in a way we think of as more pleasing to the ear. Some transformer designs can do Even-order in the mid and high end, with 3rd Order in the low end.

Saturation though, is most talked about during the art of recording to analog Tape. When recording hotter signals the tape saturates in a very musical way (providing the Tape Machine is set up well) and this has become a ‘Holy Grail’ of reference for many hardware and software designs, trying to recreate the perfect Tape Saturation sound, if a real Tape Machine isn’t available.


 Odd-Order and Even-Order Distortion

This is the type of distortion we’re after…Musically related harmonic distortion can work wonders on elements that sound a bit ‘flat’. Harmonic distortion can improve the sound by adding extra musically related Odd-order or Even-order harmonics to the original signal. This can be achieved in many ways and combinations through Valves/Tubes or Tape and Transformers.


What Are Odd-Order And Even-Order Harmonics?

Harmonics above the original note (called the fundamental) are whole number multiples of this frequency, so Even harmonics are 2 times, 4 times, 6 times, 8 times etc etc and Odd harmonics are 3 times, 5 times, 7 times etc etc. Odd and Even harmonics do sound different, but they’re both extremely useful when we use them in different ways to make them appealing to the human ear.

Even-order harmonic distortion tends to sound weighty in the low end with smooth sympathetic musicality in use, but they can also sound muddy and warm. But these are sometimes tricky to hear, and obviously when the signal changes so does the harmonic sound. But when they’re not there, and taken out, we do tend to notice something is missing.

Odd-order Harmonic distortion, which is the kind tended to be produced by analogue tape tends to sound more edgy, and can add richness and depth.

Combining Harmonic distortion and Saturation in some way can give sterile digital tracks some depth and lovely character similar to the way Tape used to saturate and distort. Whether you do this on the individual elements or over the mix just make sure that the tracks aren’t just LOUDER. It’s easy to be fooled into liking louder (and brighter) sounds especially if we’ve been up all night mixing…

So How Does It Sound?

I’ve taken 4 different designs and recorded how they all add harmonic distortion/saturation in one way or another. The settings on each unit I chose based upon what I felt sounded right, rather than trying to emulate each other, as they’re all different designs.

There is no use of any EQ or compression so hopefully this will give an idea of what each unit could offer to your sessions. The files are a variety of :

  • Original Stereo Mix with no Harmonic Content
  • Harmonic Content applied just to the Stereo Mix Buss
  • Harmonic Content applied to each individual track and then bounced as a Blended Mix
  • Extreme settings or Creative Use on certain tracks

So…the weapons of choice :

Rupert Neve Designs 542 Tape Emulator – £629 inc vat

Rupert Neve Designs 542

First up is the Rupert Neve Designs 542 Tape Emulator (well actually a pair of them). Designed purely for adding Saturation, colour and including a real Tape head inside the unit **, this is an updated version of the original 5042 which was available in a half rack design. The 542 has adopted the popular 500-series  format, and it has the excellent Silk Texture circuit providing three types of Transformer tones alongside the 3rd order harmonics and soft clip circuit.

Thermionic Culture The Culture Vulture – £1518 inc vat

Thermionic Culture Vulture

Thermionic Culture are no stranger to Valve Harmonic sonics, and the Culture Vulture is described as ” the original and only all valve rack-mountable distortion / enhancer”. Featuring 3 types of distortion : T = the Triode Valve effect, suitable for warming up signals, P1 = Pentode distortion to add extra harmonics and more aggression but still remain valve sounding, P2 = much more aggressive distortion, even providing an extra octave at higher bias settings. There is an Overdrive switch that can be activated at any point on any of the settings, and with Bias Control, High Pass Filter and Drive settings, the Culture Vulture is one of the most flexible valve units since it’s arrival in 1998.

Dave Hill Designs EUROPA1 – £1159 inc vat

Dave Hill Designs EUROPA1

Dave Hill is no stranger to Harmonic Content, as many of his Crane Song products like theHEDD192, Flamingo and IBIS EQ, all have various ways of creating and manipulating Harmonics. The EUROPA1 is from his new spin off company Dave Hill Designs and is actually a very clever, flexible pre-amp.

Inclusion here is because when the micPre is set to 0db it then works as a Line-Level processor, and this is where is gets really interesting. Not content with just adding Odd and Even harmonics there is a Slew Speed control which dictates the way the PreAmp allows signal through so you can make it sound vintage or very clean. The controls all work in series and along with a quality HPF and Phase switch provide another unique twist on adding Harmonic Content, Dave Hill style.

Looptrotter SA2RATE – £429 inc vat

Loop trotter Sa2rate

The last example is from a very recent company, Looptrotter Audio Engineeering from Poland. Their first product was the Looptrotter Monster compressor which had saturation based on Tubes, however the SA2RATE has the character of Valves but has been achieved using semiconductor technology. The amount of harmonic distortion is controlled by the Drive and Output with the LED’s showing up at 4% and 8% THD (Total Harmonic Distortion). A modern twist on harmonic content with the ability to work like a ‘soft limiter’ as well as adding character.

Take Your Pick…

The RND 542 I think gives the most natural Tape and Saturation sound, with the flexibility of control and how much Tape Drive you can choose. This alongside the Rupert Neve Red/Blue Silk transformer circuit works excellently on all sources, and could take you back to a ‘sound of the 70’s’ easily or add some modern weight to anything really.

The Culture Vulture is a Beast, and just awesome at creating sonic diversity with the different Valve options available giving more depth of sound, with the extra bite of distortion should you need it to smash into the gates of hell…

Dave Hill’s Europas are far more subtle in their approach, but they have a ‘poshness’ and sonic character that is Crane Song familiar, but experimenting with the EVEN harmonics and how they route into the ODD harmonics can help sculpt your sound from the recording start point, through to your mix, and it can be pushed a little too. This tracks and stacks up really well.

The SA2RATE was a real surprise, as I felt it to be actually quite fizzy on the overall mix and drums even at lower drive settings (which you can hear in the examples) but it totally nailed it on the Acoustic Gtr and Bass. There isn’t too much control available other than Drive and Output, but at the price point I could see this sitting across the right elements in a mix really easily, and on SoftSynths / Hardware Synths I think it would add just the right amount of bite.

Software OR Hardware?

It goes without saying that you don’t have to wait until the end of a track to add harmonic content. The most natural way of working is to add elements of Saturation and Distortion as you’re tracking and recording, working with different pieces of equipment and seeing how they react with each other and experimenting with sound. There are also many software designs that have been created with harmonic content in mind, and there are MANY Tape Saturation plug-ins that may also work for you should hardware not be available.

Some of my favourites in software are the Dave Hill Designs RA, Crane Song Pheonix II andCrane Song Peacock (a Vinyl Emulation). If software is the preferred way to go, this is where I would start.

CraneSong PhoenixII

Dave Hill Designs RA

CraneSong Peacock

Slate Digital also has the extremely flexible VCC (Virtual Console Collection) plug-in which has Drive control and console saturation…

Slate Digital VCC

As do many examples by Universal Audio in their popular UAD-2 format. The Studer A800, the ATR-102 and the Vertigo VSM-3 are all examples where harmonic content can be added in tracking and/or mix down and stay ITB.

UAD2 Tape Machines

Vertigo VSM-3 UAD2

Adding Harmonic Content..How It Can Work For You

No matter how good the software emulations and plug-in designs are, running sources through high quality analog hardware I always feel is more satisfying and rewarding, and usually ‘gets you to that place in your mix’ quicker.

Many software emulations do work well on their own, but I find as soon as you start stacking them up, or layering intensively, there tends to be a ‘2D’ effect happening. Things tend to flatten out, and before long you can find yourself chasing your tail with plug-in after plug-in before you go back to taking them all off again! This could be due to a number of reasons, lack of phase cohesion, plug-in latency not being measured accurately or just the general type of Code used within a plug-in design.

With hardware, not only is it tactile, it immediately becomes more ‘3D’ and the depth is far more tangible. Obviously we all work these days with hybrid systems, due to recalls and the need for running multiple sessions and of course some plug-ins make the impossible, possible. But if the budget and situation allows, try the harmonic content in hardware as you can drive and push things much further to the edge than you can with software, and you get happy accidents that may be what you’re looking for.

Before reaching for EQ or Compression to make something sit better or work with other instrumentation, have a go with adding harmonic content, or at least try and pass the tracks through something. You possibly won’t have to EQ or compress as drastically afterwards, and it may provide the excitement and inspiration to enhance your mixing.

** After posting this review I was contact by Rupert Neve Designs where they explained that their original literature for the 5042 Tape Emulation did say that a ‘real tape head’ was inside, however on the RND 542 unit there is no tape head inside. It consists of a custom transformer that mimics the performance of a tape head, this is one of 3 transformers inside that look after the Saturation and Silk controls.**

By Nick Mitchell