Have you ever used an exciter? Do you know when to use one? How do you use it? Do all users use them the same way? In this article, members of the Production Expert team try to bring a little clarity to the use of a highly subjective tool.

Exciters are funny, misunderstood ‘character boosters’ that have the potential to be unsubtly applied to just about any sort of recording in which the engineer might perceive a lack of ‘clarity’ or ‘sheen’. Exciters are most often used as a mid to top frequency range tool (3.5 kHz to 20 kHz), to help things stand out in a mix, without the need for riding faders or just to add a little sparkle to something in need of sparkle. This family of products can help a sound bully or slide its way into being heard in a mix whereas without this help, the sound might otherwise be obscured or lost. An exciter can also be used in place of an equalizer because adding clarity can be different than adding brightness. Exciters are really about injecting something new into a sound and equalizers are more about boosting or cutting existing frequency content.

How Does An Exciter Work?

Traditionally, hardware units had three main controls: Drive, Tune and Mix. The ‘Tune’ knob allows the user to select the frequency at which the exciter starts to work. Since exciters add harmonic distortion, this is sort of a ‘base frequency selector’ since the distortion carries on up through the spectrum. ‘Drive’ adjusts the density of the added distortion and ‘Mix’, the amount. Early exciter units were tube-based, using a triode tube type to hype the gain.

A Brief, Exciting History

Starting in the mid 1970’s with Aphex Electronics’ Aural Exciter, the technique of ‘exciting’ odd/even harmonics has been employed to overcome the dullness that could seep into analogue tape over multiple playbacks or just to add lustre for effect. Though originally discovered accidentally decades earlier in the 1950’s, it wasn’t until 1974 that originator Curt Knoppel brought the idea to Marvin Caesar of Aphex Electronics for commercial development.

 Initially tube-based hardware, the Aural Exciter model 402 was lauded for bringing clarity and air to analogue recordings by adding phase shift, some compression and most particularly, harmonic and intermodular distortion to the sounds it processed. Aphex’s Aural Exciter even garnered some album credits early on which is still rare for any piece of gear. If you want to read a little more about the early history, check out this article.  

So, this magic box was invented to add ‘air’ and ‘clarity’ to a mix and one might think this begs the question: Why wouldn’t we use an exciter on everything we mix? For one, the digital age has eliminated the need for any sort of clarity boost since the quality of our recordings doesn’t change over successive playbacks because the medium doesn’t physically degrade linearly. As a second point, our TV/web-based broadcast chains– another place exciters sometimes found a home- are almost completely all digital now too and again, there is no need to correct for analogue signal losses. The third and final point against using an exciter would be that exciters add artificial content and don’t actually bolster the original timbre of our audio so this can be considered a bit of technical fakery which doesn’t always go over well with the purists among us.

Modern digital noise floors being what they are (almost non-existent so far as human hearing is concerned), we can hear many simultaneously occurring elements distinctly and well, though each element might have been recorded, minutes, hours, months or even years apart. So it would seem in light of this that exciters might well have passed their prime.

But consider this: Aphex are still making their hardware– now more than a million units sold worldwide-, Waves has a very successful Aphex Vintage Aural Exciter plugin modelled after one of the nearly extinct original 402 units, iZotope’s Neutron 3 and Ozone 9 software have multi-band (and multi-option) integral exciters and many, many other software developers offer exciters as standalone plugins or as part of multi-use plugin/software offerings. SPL, for instance, has developed both hardware and software ‘Vitalizers’ which push the simple exciter up the audio evolutionary chain. For those of you who use the popular Waves Vitamin Sonic Enhancer, this again is a variation on the same theme. Very exciting and yes, has its place in many a healthy mix.

So, exciters are a very popular link in many signal processing chains across all audio disciplines so it stands to reason, there are multiple usage cases for them. The question is: Do we all use exciters for the same reasons?

Steve DeMott

When I started mixing in the ‘90s, the Aphex was one of those devices that bordered on ‘legendary’. I was lucky enough to have experience with the hardware units. Though, I’d say that I’m luckier now that we have moved to a place where we can have choices in exciters that are both less noisy and more configurable.

Exciters are a lot like seasoning food: Some spice is nice, but too much and you mask the flavor of the food itself. For me the Aphex comes with some overhead, in that it tends to take up a lot of the top end space in a mix, so it doesn’t work if you have sounds that already extend up in the mix to begin with. In those situations you have to add too much of it to really “feel” it and then it’s too much. For this reason I tend to avoid the original exciter in lieu of other options that suit me better.

There are 2 other exciters I really like for regular use, the SPL Twin Tube & McDSP’s Shine (part of the 6060 Ultimate Module Collection).

The SPL (SPL stands for Sound Performance Labs, in case you didn’t know) adds a gentler (and more focusable) top end sheen than the Aphex through the ‘Harmonics’ knob. What I like about the SPL is that it can add top end extension without taking up as much space, and I can leave the lows & lower mids unaffected by simply not dialling in any saturation. It’s sort of Pentode/Triode type controls, where one adds top end harmonics & the other knob adds girth and body.

McDSP’s Shine uses AI to add top end to sound sources. In some ways Shine straddles the fence and can have an almost ‘Pultec-y’ kind of phase thing happening as it adds top end harmonics. It claims the AI is based on a “transformer emulation algorithm”. I find it very useful on sources that may need a little top end to pop out or float above other sounds in the mix. It can be very subtle, but one of those things you notice something’s different when you bypass it, but it’s not in your face when engaged.

My favorite exciter trick is when you’re trying to get that ‘pick on strings’ sound on an acoustic guitar track and you just need a little more zing to make it bite while being pulled back in the mix. It often works better than straight EQ when you want it to expand “up” in the mix and not just out.

Mike Exeter

I don’t use exciters much in their original incarnation (as in the Aphex units) but the addition of higher harmonics seem to come nowadays from the plethora of saturation units and plugins available.

My favourite toolbox plugin for this is the Plugin Alliance Black Box HG-2 - total control over the saturation and ‘air’ process with the ability to balance the pentode and triode sat types against each other.  This goes from very subtle to brute force in a way that others don’t manage - they ‘try too hard’.

Cranesong Phoenix II is the one I reach for across the mix, or to enhance distorted guitars with a rich harmonic lift that ‘just works’. Think AVID’s HEAT but with so much more control and potential for subtle enhancement. 

Aphex do make one hardware unit that, if you’ve ever worked on a Rick Rubin project, you’ll come away scouring Ebay for.  A secret weapon on toms that enhances a well tuned drum to sit beautifully in a mix.  Record them through the Aphex 204 (with Big Bottom) and thank me later.

Mike Thornton

I take a different approach to using exciters, and my main application is improving intelligibility without resorting to EQ. That said, I was sceptical about this effect until a client brought over a hardware unit for a multi-site recording project back when I had my own mobile recording unit in a truck called the Omnibuss Mobile in the early 1990’s. Once I heard what this unit did for the sound, I was hooked. I have always preferred the sound of the BBE process to the Aphex process and so I have been using BBE hardware for live work as well as recording work since then.

As to how it works, like so many of these processes, it is shrouded in a degree of secrecy but we understand that the Aphex system works by synthesizing additional high-frequency harmonics related to the original signal. BBE chose a different solution, using a combination of dynamic equalisation and phase manipulation. In addition, there is also a ‘Lo Contour’ control, designed to add power to the bass end of the spectrum. Again, it’s not completely clear how this works but it appears to be another form of dynamic equalisation.

The phase manipulation side of the process is apparently a linear phase shift across the whole audio spectrum corresponding to a delay of under 2ms., intended to prevent the high-frequency detail from being smeared by the low-frequency components of the sound to increase definition without boosting the level.

For me, this makes it great for brightening the sound without pushing the EQ, so in a live sound setting it means I can improve the intelligibility of the rig without pushing the EQ and risking feedback. I also use it in my mastering chain for radio and podcast mixes to help with intelligibility when people are listening in difficult environments.

In my radio production or podcast mixes, other than a limiter this is the only other plug-in I use for basic speech programming content like the documentaries and dramas for broadcast on BBC Radio 4 or for podcasts like when I was editing and mixing our own weekly podcast.

If you want to use the BBE Sonic Maximizer in your DAW then there is a BBE Sonic Sweet v4 plugin bundle.

This bundle consists of four plug-ins all designed to bring the BBE Sound into your productions. This is what BBE say about the bundle…

1. Sonic Maximizer - Musicians and studio engineers for years have known that the D82 Sonic Maximizer is the best way to get that professional sound and extra sparkle that is so difficult to capture.

2. Harmonic Maximizer - The H82 Harmonic Maximizer increases presence and clarity. It restores natural brightness and adds deeper and extended low frequencies. It can be used in the studio on individual tracks or an entire mix, or live to enhance the sound of a P.A. system.

3. Loudness Maximizer - The L82 Loudness Maximizer is a mixing and mastering multi-band limiter plug-in. Its ultimate transparency allows the L82 Loudness Maximizer to dramatically increase the overall level of your mix without audible artefacts and pumping effects.

4. Mach 3 Bass - As a new addition to the “Sonic Sweet” lineup, Mach 3 Bass will take your low end to new sonic depths. Insert this plug-in on any type off bass instrument or signal where you need a big boost on the low end.

Damian Kearns

I first witnessed a re-recording mixer using an Aphex Aural Exciter in his regular dialogue processing chain in 1996, when I was a mix assistant at deluxe Toronto. I had already assisted a number of mixers by that point so I wasn’t all that sure I wanted to emulate this particular approach when I started mixing on my own for film and TV a year later. Like a lot of esoterica, this technique seemed un-magical and too scientific to find its way into my personal ‘audio wizard’s bag of tricks’. An exciter in my dialogue chain? Ridiculous! This seemed incongruous with my philosophy of keeping my work invisible to the naked ear. Thanks but… no thanks.

As with anything else I’ve ever learned about audio, there’s no such thing as a bad idea, as long as there’s proper context to support it. It wouldn’t be long before I found myself reaching for the Aphex Aural Exciter TYPE C in the racks in each studio at work when I was at the Canadian Broadcasting Corporation, and again, in various software forms over the years since.

Actually, there was a window in time in the late 90’s and early 2000’s when the TYPE C, complemented by the Aphex DOMINATOR II Precision Multiband Peak Limiter Model 723 was my voiceover processing solution for a singular very, very tricky voice. This voice suffered greatly every time I tried to EQ it even slightly but adding the Aural Exciter to it seemed to help the voice talent cut through the mix without losing any of his formidable vocal character.

While it was clear back then that exciters had a place in master control for various broadcasters to help ‘shine’ up the spectral content of analogue mixes, it was less clear when and how these devices ought to be used in post production audio. I mentioned earlier I used an exciter on a particular voice which, even on the best sounding mic, always sounded muddy. That was an easy place to apply this technique I’d been batting around in my brain for years. The real question was where and when else might I use an exciter?

As it turns out, exciters can sparkle up archival recordings, specifically older tape-based archives. Suck out a little top to reduce hiss and add back in clarity with an exciter. While this approach mightn’t be deemed restorative in a pure sense, it can really help to add definition to muddy recordings. Music mastering engineers employ exciters so why shouldn’t people working to restore audio archives? It makes sense to me. Exciters work well in audio restoration when they are used to undo the effects of tape wear.

Nowadays, what I mainly use Exciters for during my post mixes has nothing to do with restoration.

What I think Exciters do well is they allow audio elements to compete with each other so that dialogue or voiceover that’s not cutting through a TV/web/film mix because of a blaring heavy metal music track sitting behind it can now be pulled front and centre in the mix again by fighting distortion with distortion.

I tend to favour exciting just the upper mid and high frequency content in my dialogue for a bit of clarity, without drawing attention to the fact I’m using harmonic distortion to synthesize spectral content. To this end, I use iZotope’s Neutron 3, and before that, Neutron 2, then Neutron, back to Alloy 2. Try as I might, the ‘tape’ quadrant of Neutron 3’s seemingly infinitely selectable saturation model control (Retro, Tape, Warm and Tube are the options that can be dialled in to varying degrees) wins out virtually every time. Of the three Global modes, I tend to move between "‘Defined’ and ‘Clean’ most often during my mixes. I love the way this exciter makes dialogue sound and it’s so sneaky, I almost feel like I’m doing something naughty.

There are other cases where I’ve used exciters to liven up my music beds and sound effects and I’ve even used Waves Vitamin once or twice across a mix buss to add a little texture to a final mix. This isn’t canonical in post audio but I do like to borrow ideas from music mixers now and then.

As someone who mixes a lot of sports and advertising content, I can’t overstate my reliance on exciters in specific situations when audio elements are really competing to put my mixes ‘over the top’ for my clients and listeners.

William Wittman

I experimented with the early/original Aphex unit when it was still licensed (at I think $1,000 per minute of music??!!).So I go back with the concept a long time.

In my experience, I only feel I get a real benefit from the effect as opposed to more ‘standard’ top end eq, when there is enough space in the music to feel the difference.

So, apparently in contrast to Damian’s conclusion, I don’t find it satisfying in a dense or noisy mix.

But in a sparse record, like for example an acoustic guitar, a vocal and perhaps some strings, that little extra sparkle on the vocal sometimes adds that touch of ‘what IS that?’ magic.

It’s very rare for me to use one, but when I do it’s in those situations.

My MO is to push up the Aphex on an AUX return and when I can JUST hear it, back it down a dB and thats that.

Conclusion

Exciters have proliferated widely since their origins in the the high end pop music mixes of the mid 1970’s. Not just an effective tool, exciters can be restorative and corrective. They can punch, shine and slyly charm their way into any mix in need of a little lustre or sheen or a more nuanced timbre in the bottom end. Interestingly, none of us who contributed to this article mentioned favouring the same brand or tool, proving that indeed, excitement comes in many forms and there’s something out there to suit every individual.