The best acoustic guitar amplifier money can buy is the one you think you can’t actually hear – because its prime job is to make your instrument imperceptibly louder, while preserving your pure acoustic tone. If it’s really good, your audience might not even notice that there’s an amp there at all! But this total tonal transparency is not simple to achieve. In fact, it’s something only the elite acoustic amp designers – like Michael Eisenmann – are achieving…
Apart from the human voice, nothing in music is as honest, pure, and natural as an acoustic instrument.
Straight from the musician’s hands to the listener’s ears, it’s a signal that’s vibrantly alive, multi-layered, and very direct. It can also a bit chaotic and unpredictable, which is all part of the beauty!
The acoustic guitar merits special mention here because of its ubiquity – it’s the acoustic instrument almost everyone knows well, more so than the recorder, piano, drums and trumpet.
Anyone can play guitar
Our brains know the acoustic guitar sound.
The instrument has the power to delight us almost instantly – just a few notes are all it takes to capture our attention, because the acoustic guitar is such a powerful and delightful musical magnet.
It’s the people’s instrument, and so versatile it excels in practically every tradition and genre.
The varieties of artistic expression, styles and playing techniques you can achieve with an acoustic guitar are almost endless.
Unlike the electric guitar, an acoustic six-string’s power to fascinate and delight is totally pure; it has no need for accessories such as amplifiers, effects, and the like.
If an acoustic guitarist needs any sound reinforcement at all – for example, at concerts of a size where even the loudest dreadnought will be too quiet – it is an amp that, ideally, renders the guitar’s unique dynamics and tone as faithfully as possible.
The amplification has to be neutral and transparent, adding nothing but volume – and taking away nothing at all.
Every nuance, even the most subtle personal idiosyncrasy, must be increased only in volume, and not tonally altered.
Acoustic amplification is not easy
That might sound simple enough, but neutral sound reinforcement is anything but.
Many people can’t even agree on what ‘neutral’ actually means, but for our purposes, we’ll take it to mean uncolored, or as transparent as possible.
Basically, the acoustic amplification Holy Grail is a sound as close to the original instrument’s sound as possible.
Engineering the perfect tone
Technically speaking, an engineer looking to design an amp for acoustic instruments – Michael Eisenmann, for example – is better guided by the idea behind a perfect studio monitor than the rationale for a high-fidelity stereo system.
The former is to render acoustical realities; the latter is to polish sound to perfection. In this video, Eisenmann tells us about his journey towards designing the best acoustic guitar amplifier he can:
An electric guitar amp is certainly no template for its acoustic cousin. On the contrary, it’s more instructional as a lesson in how NOT to do it.
Digital beats analog?
Given these specifications, the right answer to the question of faithful rendering can only be found in the digital world.
For the moment, let us turn a blind eye to the great analog-versus-digital debate to see if we can’t agree on this: personal preferences aside, digital technology is unmatched when it comes to efficient, effective and clean signal processing.
Most of the day-to-day work in studios these days gets done with digital tools in hand. Few producers or sound engineers opt for anything else when the task calls for 1:1 reproduction of signals.
Modern methods of capturing acoustic guitar sounds – piezo systems, on-board microphones or a combination of both – can deliver superb authenticity and sound quality.
Once that sound is properly captured, transforming this weak signal into a clear and neutral yet vivid sonic image of the instrument is mostly down to engineering.
But mostly is not all.
Some emotional experience has to be somehow added to the mix. It’s a soul thing – you’ve got to have empathy for the acoustic axe.
I’d say that it would be very difficult to design an amp that sounds as warm, as natural and as ‘analog’ as the original instrument without having spent many years listening to and appreciating the real thing.
And I believe it’s impossible for an engineer to find the sweet spot between cold digital neutrality and woody analog warmth unless he or she knows both sides of that equation inside and out.
Recreating the sonic sweet spot
The complexity of it all; the challenges of tweaking each part to strike the right balance for the greater whole are enormous.
And, unless you’ve got the skills, experience and knowledge of how all these components interact, you’re going to fall short of greatness.
The tone is not enough
Of course, today’s acoustic player also expects more than just great sound.
Simply boosting the instrument’s volume on stage while retaining its characteristic tone won’t always do. These days, we all want extra goodies: multiple channels for instruments and vocals, an effective voicing section, a direct out, a notch filter for suppressing feedback, studio-quality FX, and more.
But the more extra stuff you build into an amp, the more there is that can negatively affect the sound it makes – so you’ve got to strike a winning balance between the power of engineering and the musical emotions of the players.
The quest for perfect acoustic tone, only louder
Ultimately, he search for true tonal transparency is not simply a naval-gazing quest for great sound for its own sake.
It is a search for truth, if you will, and the only ‘true’ sound here is the original sound of the instrument.
The design brief for an acoustic amplifier is as complex as that for an electric guitar amp, but the objectives are very different.
An electric guitar amp is not just an amp. It has a personality of its own and a formative hand in shaping the guitar’s sound.
That makes it an instrument in its own right.
An acoustic amp’s purpose is make the instrument’s personal tone imperceptibly louder, and nothing more – or less.
That may sound harsh, but it’s the outcome that matters. We’re talking about a chain of high-quality components – the guitar, the pickup system, the acoustic amp – that connects the guitarist with the audience.
It’s all about what you get at the end of that chain – sweet acoustic bliss at larger-than-life volume levels.
First published: July 14 2017. Most recent update: July 14 2017.