Digital has been rewriting our world for a few decades now. Who remembers their first digital camera or set-top TV box? Anyone remember analog mobile phones? The revolution has affected music and audio just as much as any other field. So what’s the big deal when it comes to guitars and amps?

To get to grips with analog (or analogue) think of the air that moves when a string is plucked or a speaker vibrates. That movement of air causes our eardrums to vibrate sympathetically and we process and interpret this information as sound. These are continuously variable transfers of energy, real-world physical transactions.

An analog waveform is a graphical representation of this, a wave alternating above and below a centre line, from node to antinode, and describing accurately the minutest details of an audio signal. It is analogous to the movements of the diaphragm in the microphone, the needle on the vinyl or the driver in a speaker cabinet.

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In the land of digital this waveform is sampled, many times, and described in code in such as way as can be understood and reconstructed at the other end of a signal path and turned back into analog for our listening pleasure.

Slice the waveform vertically and those are your ‘samples’, then slice it horizontally to quantise the results (each sample is allocated to the nearest slot – like rounding-up or down in maths). Early digital was capable of comparatively few samples and had low quantise values – imagine a smooth curve turned into a crude staircase – and some musicians, engineers and audiophiles claimed they could ‘hear the gaps’.

Today’s digital is far better, with 96kHz sample rate commonplace (i.e. sampling the waveform 96,000 times per second) typically allied to 24bit quantising (over 16.7 million possible values per sample) however there are still those who consider analog warmer and more satisfying to listen to. The recent vinyl resurgence is testimony to this.

Back in the day, recordings would sport a three-letter code such as AAD, ADA, DDD etc., showing which of the recording, mixing and mastering processes were analog and which digital. At no point in a AAA recording process was the signal digitised. Today, of course, it’s nearly impossible to listen to music which has not been chopped-up and reconstituted, however well. Nowadays most commercial recordings are DDD and only the instruments and microphones at the start, and the loudspeakers or headphones at the end of a song’s existence are truly analog.

Guitarists, however, still have control when it comes to their own signal path. The analog-to-digital-and-back conversion all takes place, for example, in a digital delay pedal or effects processor. Basically any digital device with audio in and out contains both AD and DA convertors so, for the purist, the signal is no longer 100% ‘authentic’ – although today’s level of accuracy would make a blindfold test nigh-on impossible.

Still there are players and artists who prefer to retain the analog signal path for as long as possible, hence the continued popularity of vintage studio equipment, valves, transistors and ‘boutique’ analog effects pedals. The arguments still continue around guitar amplifiers too, with the versatility and feature-sets of digital-modeling amps competing for the guitarist’s affections against the perceived responsiveness and tonal qualities of analog, especially tube (or ‘valve’), amplifiers.

guitarcongress-analog2The two sides of the debate tend to go like this: tube amplifiers sound better cranked-up, but become less enticing at lower volumes, where the tubes are not being driven to anywhere near their capabilities, whereas modelling technology allows for a wide range of usable tones at lower volumes but may sound a little unforgiving at higher volume. However, like all-things digital, the technology has improved at a rate, and A/B comparisons over time may become tougher and tougher to call. At the same time, the comparatively recent craze for small wattage valve amps has gone some way to addressing the former issue, allowing advocates to achieve full tube tone at lower volumes.

For a look at some current mid-wattage modeling amps, see our post here.

Or, if tubes are for you, here are some of the current mini heads on the market.