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Exploraudio designs and builds products to simplify and/or improve the capture and reproduction of music [...]

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Live performance

move with the music

There are as many techniques for creating the perfect sound on stage as there are performers and technicians [...]

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lock onto perfect tone

Despite the relatively controlled (and controllable) environment of the recording studio, capturing just the right sound [...]

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Live Performance

There are as many techniques for creating the perfect sound on stage as there are performers and technicians. The individuality this creates is part of the beauty of the live performance but the quest for the perfect sound, whatever techniques are employed, can be a frustrating business. Some are more successful than others but everyone struggles with the limitations imposed by the venue and the technology needed to fill it with the right sound.

Please click one of the following titles to jump to the relevant section:

 

Exploraudio's products:

  • make the quest for the perfect sound easier
  • allow performers to redefine what is considered the perfect sound
  • free musicians from some of the constraints that restrict their expressiveness on stage

 

It's impossible in a few paragraphs to cover all realms of live performance, from impromptu social gatherings to global events beamed worldwide by satellite. Equally, it's a nonsense to generalise about the techniques for filling a space with sound when the venues may be as diverse as an intimate bar and a sports stadium.

Nevertheless, these applications notes are intended to give an indication of how Exploraudio products can overcome some of the most common and difficult challenges faced by artists and their technical crew on stage in a variety of different situations.

 

Getting the best acoustic sound

What is the best acoustic sound? On the face of it this seems like a stupid question but it depends both on your view of what makes an acoustic instrument sound good and on the circumstances in which it is being played. For example, in an intimate recital the best acoustic sound might be defined as the sound a listener would hear if listening to the instrument being played without amplification. As we’ll consider in more detail later, that’s not entirely straightforward either but sounding exactly the same as an unamplified instrument, just louder, is often considered the ‘Holy Grail’. While not a bad starting point, there are also times when a fuller, more strident, heavier or thinner feel than the ‘true’ unamplified sound might actually be more desirable.

At one end of the spectrum, this ‘enhancement’ may mean little more than making the instrument sound larger than life, adding drama or enhancing the texture of more delicate passages of music. At the other end of the spectrum the sound is more of a caricature of an acoustic instrument and reproducing the nuances of a particular instrument’s natural tone is less important than simply giving a credible impression of a particular type of acoustic instrument within a diverse and/or dense soundstage.

Despite their various sonic issues, this is where electronic pickups come in. When the best acoustic sound is actually a bigger, punchier, more raw, edgy or piercing sound than the unamplified instrument could deliver, one or other (or a combination) of the different types of pickup may be the answer.

From their earliest days, pickups have also had advocates who enjoy the alteration of tone they generate, as demonstrated by the success of the Ovation guitar and ‘semi-electric’ instruments. With the former the sound is distinctly coloured but is still very recognisably acoustic in nature, whilst the latter’s primary character is electric but is tempered by the subtle resonances of a hollow chamber.

 

So the acoustic sound that might be considered ideal will vary depending on:

  • solo vs collective performance
  • style of music
  • type and quality of instrument
  • auditorium size and acoustics
  • personal preference.

The last, personal preference, is perhaps the most important but all contribute to the decision about where the perfect sound lies on the scale from transparently natural to heavily coloured or synthetic.

The tools available for producing the ideal amplified sound fall broadly into two categories:

 A)   ‘Sensors’ to capture the sound

 B)   ‘Processors” to manipulate it

 

In simple terms, the ‘Sensors’ can be divided into two basic types:

  • Microphones that ‘hear’ sound waves in air
  • Pickups that ‘feel’ vibrations in steel strings or wooden bodies

 

The ‘Processors’ include devices, such as effects pedals, that deliberately shape tone and equipment such as mixers and amplifiers that influence tone largely as a by-product of their primary function. Essentially all may be either analogue or digital, are extremely diverse and are often used in combination. The focus of this guidance is on the ‘Sensors’ but the techniques, such as EQ (equalisation), used most commonly to shape their sonic output will also be discussed.

In the past, the demarcation between the applications of the two categories of ‘Sensor’ was fairly clear. For faithful reproduction of ‘true’ acoustic tone, the only realistic option was a microphone and a pickup would only be used as a last resort. Now, pickup technology has advanced to the point where the tone produced by higher quality pickup systems can be remarkably good, though still no substitute for a good microphone at the end of the acoustic sound spectrum striving for transparency and natural tone.

There are strong proponents of microphones who would be very reluctant to accept that pickups are capable of capturing a good approximation of a guitar’s true tone and equally, there are fans of pickups who would be difficult to persuade that the improvement in tone possible with a microphone was sufficient to warrant accepting the limitations inherent in the use of microphones for amplification. In truth, the choice of ‘Sensor’ depends on a number of factors and often, a combination of both may be the optimum solution. It’s also worth remembering that just as each model of pickup has it’s own individual sound, so do different models of microphone. Whilst it is true that almost any microphone will sound more natural than a pickup, there is certainly some cross-over at the very ‘low end’ of microphone ranges. However, the pickups that may rival lower quality microphones are likely to be much more expensive.

Equalisation can be used to improve the sound of ‘low-end’ microphones and mics designed for one type of instrument can sometimes also work well with others but there are limits and budget permitting, pickups should always be considered as a potential complement or even an alternative. Microphones have also traditionally been much more limiting ‘physically’ than pickups, partly because of problems with feedback but also because they forced performers to remain pretty much motionless in front of them, while pickups allowed musicians to move with their instrument largely unhindered. This aspect was one of the first we addressed, in order to allow musicians and technicians to be less influenced by the ergonomics of alternative amplification methods and to concentrate instead on producing the best acoustic tone.

Our products are designed to aid the reproduction of the sound of an extremely wide variety of instruments, including the human voice, but for simplicity and brevity their application to capturing the ‘best acoustic sound’ will be described here with reference primarily to the acoustic guitar.

 

Guitar amplification

LiveGuitar, with and without pick-ups

So you have an acoustic guitar and it sounds great. But when you play to more than a handful of people you have to use amplification. That’s where the trouble starts.

If you own a high-end electro-acoustic guitar or have had a very sophisticated pick-up fitted, you may be happy with the sound but may still suspect it doesn’t really do your instrument justice. An acoustic guitar’s perceived ‘true’ tone is affected by many things, including the space in which it is being played and the position of the listener in relation to it (the player hears a very different sound to someone sitting directly in front of them). But in the end, the only way to capture a tone that is truly representative of the acoustic guitar’s natural sound is to use a microphone suspended somewhere in front of the instrument.

The character of the sound reproduced by the microphone is influenced heavily by the same major factors that affect a listener’s perception of the sound of an acoustic instrument (the space and the listening position). Unsurprisingly, the type of microphone employed also has a strong influence on the sound produced.

Understanding the reasons for unsatisfactory reproduction of an acoustic guitar’s sound is one thing, doing something practical about it is another. On a comparable cost basis, a microphone suspended externally will always sound better than a pick-up. Yet, in practical terms, unless you have a very sophisticated sound system and access to the services of an experienced sound engineer, there are always occasions when relying entirely on microphones for acoustic guitar amplification is not feasible. When speaker placement is difficult or you’re playing in a band with other amplified instruments and/or drums, feedback can be a major frustration. What’s more, if you’re going to use an external microphone for your guitar, even very small movements can change the sound considerably. But standing or sitting absolutely motionless while performing may limit your expressiveness or deny the audience some of the visual energy that sets apart live music from recorded.

The question is, how do you make the best of the situation. Exploraudio’s developers pondered this problem for over 10 years but finally came up with a solution that does just that, whether you’re an acoustic purist or simply want your piezo or magnetic pick-up to sound more natural – the LiveGuitar H-clamp.
 

The Purist’s solution


The last thing you would want to do to a beautiful classical or any other high quality acoustic guitar is fill it with electronics and wires and make a hole to attach an audio jack. They may not themselves resonate or affect the resonation of the instrument and may not cause significant damage but equally, it may not be worth the risk. Particularly since the sound from piezo or magnetic pick-ups or inboard microphones, however expensive, may do no more than make your unique instrument sound no better than any number of mass produced instruments with similar electronics built-in.

So instead, you stand or sit motionless in front of your favourite microphone, trying to keep it pointing directly at the right spot to capture the perfect tone. Depending on the room or open space acoustics, you may want to place the microphone very close to a particular square centimetre of the instrument or further away but still pointing precisely to the right part of the guitar. Getting it right with a microphone mounted on a stand is no mean achievement but keeping it perfect throughout the performance may be more of a challenge than the performance itself. The LiveGuitar H-clamp gives you the best of all worlds, the convenience and relative simplicity of piezo, magnetic or other pick-ups, with the sound quality of a decent microphone:

 

  • No permanent modifications to the guitar
  • No damage to the instrument of any kind
  • Select the best microphone(s) for the occasion
  • Limitless flexibility of microphone positioning
  • Minimal or no impact on playing action
  • Use multiple microphones at the same time
  • No restriction of movement during a performance
  • Repositioning at any time for different tonalities
  • Simple and quick to fit and remove
  • Can be swapped at will between different guitars
  • Light and easy to transport
  • Strong and durable

 

Basic set-up

Unlike built-in or retro-fitted pick-ups, using the LiveGuitar H-clamp allows you to select whichever microphone best suits the situation. Very sophisticated pick-up systems combining multiple pick-up types and/or locations and perhaps also including an on-board microphone, may offer a wide range of adjustment to assist in optimising the sound for the venue. While helpful, it cannot rival the range of tonalities achievable with different microphones and different positions around the guitar. You may have a microphone that sounds wonderfully airy and detailed in a room that is dull acoustically but sounds thin or even harsh in more lively or open spaces. Equally, a microphone that sounds full and rich in spaces with hard, clear acoustics may sound muddy or ill-defined in warm or dead acoustic environments. Choosing a microphone with a different polar patter can also have a considerable effect on the sound – a cardioid or hypercardioid pattern will help to isolate the sound from the room acoustics and/or extraneous noises (for example, other instruments) but may not deliver the airy ambience possible with a unidirectional (omni) pattern.

 

In an ideal world, having two or more different microphones in your kit bag should allow you to either make the most of excellent room acoustics or compensate for less flattering audio environments.

Fortunately, even if you only have one microphone for all occasions, the colouration imparted by the space in which you are performing can be exploited or counteracted to a large extent by experimenting with different positioning of the microphone.

In general terms, for a lighter, more open sound, the microphone should be focused on the fret board. The more the sound emanating from the sound hole is excluded, the brighter the sound should be. Conversely, focusing the microphone on the soundboard and/or sound hole should give a richer, fuller sound. The sound hole is a very strong sound source and generally best avoided as a direct focus of the microphone – it tends to impart a ‘boomy’ quality to the sound. However, experimenting with off-axis directional effects using cardioid microphones or placing unidirectional microphones nearer or further away from the sound hole can add richness to otherwise over-bright tones. Microphones can also be placed to emphasise percussive sounds from finger picking or finger movements on the fret board.

In general, mic positions towards the longer side of the H-clamp's adjustment range with its standard boom (ie. holding the microphone several inches in front of the guitar) are best for capturing the most natural tone as the mic 'hears' more of an overall 'summary' of the instrument's sound. However, the futher away the microphone is placed, the greater the contribution made to the captured sound by the acoustics of the space in which the instrument is being played. This can be highly desirable for recording but for live amplification it may create excessive reverberation effects if the acoustics are particularly lively in the venue. There are also positioning options, such as close proximity to neck or body, that would be all but impossible with microphones mounted on stands. Not all microphones work well when positioned very close (less than 50mm from the surface of the instrument) but it can be a useful technique for improving isolation from other instruments and creating different tonal effects.

In summary, using the H-clamp, not only can microphone choice be used to tailor the sound to the occasion but also the mic's positioning on the instrument can be varied according to the circumstances and the desired tone to deliver the right sound for the performance.

 

Need more tone shaping? - try EQ

As mentioned in Getting the best acoustic sound one common and very useful form of sonic 'processing' is equalisation (EQ).

Modifying the characteristics of the sound 'sensed' by the microphone by trying different positions / orientations (or using different microphones) may be the least 'artificial' way of shaping the amplified sound but EQ offers additional flexibility. When used carefully, in combination with appropriate mic positioning, can still preserve the impression of truly uncoloured, transparent sound. In general, the more sophisticated the EQ device, the easier it should be to achieve the perfect tone for any given instrument, auditorium and music / performance. However, even the simplest EQ can help considerably, as long as the electronics are not so poor that they add noise, degrade the audio signal or limit the frequency or dynamic range unduly.

As discussed earlier, disappointing tone may not be anything to do with either the instrument or the microphone. It may be caused by the acoustics of the space in which the performance is being given or the characteristics of the amplification system. Equalisation can be used to counteract these influences and help to create a closer representation of the instrument’s ‘true’ tone. It can also be used to deliberately alter the character of the instrument's sound.

When applied carefully, it can give body to an otherwise thin sound or add energy to a dull or subdued tone, whether or not these are characteristics of the instrument being amplified. The result may not therefore be accurate reproduction of the instrument’s inherent tone but may instead create an ‘alter-ego’ that perhaps fits the occasion better.

Equalisation is a huge subject in its own right but there are basically two types of system:

  • Preset frequency bands
  • Parametric

Both approaches rely on frequency specific filters that alter the level of signal across a range of frequencies, called a frequency ‘band’. The filter can be adjusted to have the effect of increasing or decreasing the volume of all sound within this band relative to other bands. The difference between the two types of EQ is that the central frequency and width of the band is fixed in the preset band equaliser but both can be adjusted in parametric EQ equipment.

Preset frequency bands are more common and graphic equaliser based equipment with 10 or more bands can offer quite fine control over the profile of the sound shaping. These systems can also seem more intuitive or easier to operate. However, parametric EQ is much more powerful and once mastered, allows much more effective shaping of the amplified tone of an instrument.

Whatever the EQ available, a constant concern when using microphones for amplification is feedback. Judicious application of EQ, notch filters (to surgically suppress troublesome resonant frequencies) and phase switching can help to control feedback but there are circumstances (eg. in groups with loud electric or percussive instruments) in which this may not be effective enough. Main and monitor speaker placement (or the use of in-ear monitoring) may prevent feedback problems but where these options are not feasible, an alternative solution may be required. Where a more powerful, driving, edgy or piercing tone is needed to sit in or cut through a crowded or dense mix, the only practical option may be to blend the microphone with a pickup or even to rely solely on a pickup system – see Making the most of electro-acoustics.

 

Using vocal microphones


Vocal microphones can be used with the LiveGuitar H-clamp as instrument microphones, vocal microphones or both. Although vocal microphones are normally optimised to flatter or strengthen a vocalist’s voice, they can also be used as an instrument microphone. With the directional and positioning flexibility of the LiveGuitar H-clamp, the vocal microphone can be suspended in the best spot and orientation to capture the sound you’re looking for.


Only one microphone? – no problem

For anyone who uses their guitar as an accompaniment to vocals, using the LiveGuitar H-clamp can make live performances simplicity itself. One microphone, a guitar and a PA or acoustic amp is all you need – no bulky microphone stands, no need for separate instrument and vocal microphones and no need to be rooted to the microphone stand during the performance.

When used to capture both the guitar’s sound and the guitarist’s voice, the best results are normally obtained by pointing a cardioid microphone directly at the performer’s head. The balance between the guitar’s sound and the voice can be controlled by changing the position of the microphone relative to the guitar. Typically, the closer the microphone is held to the guitar, the louder the guitar sound will be in the blend of sound with the voice. No great surprise there. What is perhaps more surprising is that, with a cardioid or hypercardioid microphone, the combination of ‘off-axis’ pick-up of the guitar sound with a ‘centre of pattern’ capture of vocals can make an excellent blend. With the correct positioning, a good cardioid pattern vocal microphone can capture a very natural acoustic guitar tone, while at the same time doing exactly what it was designed for with the vocals.

The opportunities for vocal micing using the H-clamp are described in more detail in the Vocals applications pages but there are two basic options:

1. use of a single microphone to pick up both the guitar and the guitarist’s vocals
2. placement of a microphone solely for vocal pick up


Any vocal microphone can be used with the LiveGuitar H-clamp. The major limitations for live performance are the practicalities of performing with large, heavy and potentially very expensive pieces of equipment attached to the guitar. These considerations are dealt with in a later section (Practicalities) but they really only become an issue for live performance in relation to the large diaphragm condenser microphones used more typically in recording studios. For the typical vocal microphone used in live performance, the only cautionary note is to ensure the H-clamp is attached securely and the boom holding the microphone is locked tightly to hold the microphone in position if more energetic movements occur during the performance.

 

Making the most of electro-acoustics



Many acoustic guitarists do not have the luxury of being able to optimise the stage sound system for acoustic instruments. The result is that, to all intents and purposes, pure acoustic performance is not a practical proposition. What’s more, some music may sound better with the semi-electric sound generated by pickups.

A natural acoustic guitar sound can add wonderful textures to some of the most fiercely electric music but only if it can be heard. Without serious sound engineering, this is never going to happen in most ‘rock’ bands and adverse room acoustics can even make it a challenge for purely acoustic bands. The electro-acoustic has therefore become something of a must for even some of the most committed acoustic guitar players. This necessity probably explains the electro-acoustic’s incredible popularity but how can you turn a necessary evil into an instrument that also sounds great? That’s where the H-clamp comes into its own. Using the LiveGuitar H-clamp can transform a mediocre electro-acoustic guitar’s piezo or magnetic pick-up into a high-end blender system.

Pickups have come a very long way in recent years and some can sound pretty good with careful equalisation, at least in live performances. It’s undeniable though that many electro-acoustics can also sound awful, especially when turned up loud enough to be heard over drums and electric instruments. Blenders (pick-ups that incorporate multiple transducers, usually including a small microphone) do a better job tonally but are expensive and don’t offer a great deal of flexibility in the tonal contribution made by the microphone. With the LiveGuitar H-clamp, an external microphone of almost any kind can added into the equation, creating a whole new palette of sounds.

Best results will be achieved by selecting a microphone with tonal characteristics that complement the pick-up well but almost any microphone should improve the sound dramatically. Depending on the type of sound you’re after and the most prominent limitations of your pick-up, the microphone can be used to add a lighter, more airy ‘top end’ or a warmer, more natural mid range / bass.

 

 

By experimenting with the positioning of the microphone (and/or different microphones) and different equalisation settings for the pick-up (and microphone), it is possible to transform the sound. The more microphone level used in the blend, the more natural the sound will be but the price is greater sensitivity to feedback. It is impossible to be prescriptive about the ideal set-up for maximising both sound quality and level because it varies with the instrument, the pickup(s), the microphone (and its position relative to the guitar and other sound sources), the acoustics of the venue and the type and proximity of other instruments / monitor speakers. In general terms, the higher the microphone level you can achieve before feedback becomes a problem, the better.

There may be many occasions when the blend can be set during the sound check and remain unchanged throughout the performance. Equally, the ability to mix the pick-up DI and microphone signals differently for different songs or passages of music may add a new dimension to your performances.


The right blend at the right time

Most live performances contain contrasts. A guitar set up to slice through the barrage of sound in a loud, driving song / passage is unlikely to sound great in delicate, lyrical music. To switch between the robust sound of an electro-acoustic and the natural, deft sound of an acoustic might mean swapping guitars and/or playing in front of specially positioned microphone on a stand. With LiveGuitar H-clamp, this transition can be achieved with the same or better results, using a single guitar and without having to become anchored in front of a stand-mounted instrument microphone. The pick-up’s DI and the microphone can be blended at will to create the best sound for each piece of music.

When the atmosphere changes from frenetic, loud rhythm to delicate, lyrical picking, the pickup’s contribution to the sound can be cut back, allowing the natural tone of the guitar to shine through. The process can then be reversed to return to the cruder, more punchy sound required to penetrate a dense mix.

 

Recording live performances

An unconvincing acoustic sound may be acceptable in the charged atmosphere of a live performance but it’s a different story when you take a live recording back to the studio. If the pickup’s output is all you have to work with, you could be in trouble. When played back in the sterile atmosphere of the studio, home or car, what seemed to be a fairly innocuous guitar sound on stage can be very disappointing indeed. A highly polished live performance can be made to sound amateurish and there’s little the studio can do to help matters if there’s no other sound source to work with.

Even if the venue’s acoustics or the nature of the music, make using an instrument microphone for amplification impractical on stage, there’s nothing to prevent one being used solely for recording purposes. Using a LiveGuitar H-clamp allows you or the sound engineer to set up a microphone on the guitar in the ideal position to capture it’s sound (and exclude extraneous noise). You can still perform as freely as you would have done without the microphone fitted and there will be no concerns over feedback but wherever you go with the guitar, the microphone will capture it’s sound in all it’s glory. Back in the studio, the recording can be used on it’s own or blended subtly with the pick-up’s output to give a more faithful representation of the live sound.

For the more adventurous, experimentation with ultra-close micing and multi-micing can open a whole new world of possibilities in live recording. Some of the possibilities are outlined here in the section “Only with LiveGuitar H-clamp”.


Only with LiveGuitar H-clamp

Ultra-close micing:

With the LiveGuitar H-clamp, microphones can be positioned millimetres from the strings or the surface of the guitar. Microphone placement of this kind necessarily emphasises a particular aspect of the guitar’s tonality and may not therefore on its own deliver the kind of well-rounded, highly natural sound you might seek normally. It is, though, worthwhile experimenting with very close micing to explore the possibilities, particularly if more than one microphone / H-clamp is being used.

In a live situation, even if the microphone is only being used for recording, close micing (not necessarily ‘ultra-close’) is a good means of improving isolation of the guitar sound from any other sound sources, musical or other. However close the microphone needs to be to achieve the desired result, the LiveGuitar H-clamp is the only convenient way of ensuring good, consistent results for live performances.

Multi-micing:

Mounting two or more H-clamps on the same guitar may begin to get a little cumbersome but expands the opportunity for experimentation still more. Using unmatched pairs of microphones, positioned deliberately to capture different tonal characters can have unexpected results due to phasing and other effects. These can be undesirable but there appear to be no hard and fast rules for avoiding such problems. There are tried and tested techniques for stereo recording (eg. using matched pairs of microphones, mounted close together and orientated in the same plane) but the interaction between dissimilar microphones, separated widely or orientated differently can be very unpredictable. Using multiple microphones to capture a particular tonality or atmosphere is therefore something of a black art but experimentation can be rewarded with almost magical results.

A sound engineer’s palette can be constructed using microphones placed all round the performer and the performance space. In the studio, it is feasible (if inconvenient for the performer) to close mic with multiple microphones but on stage, the restrictions this can impose on the performer are likely to be pretty undesirable. Adding more H-clamps and microphones to a guitar becomes increasingly cumbersome but it should be possible to fit at least two without unacceptable impact on the player’s performance. Close micing using a matched pair for stereo recording introduces interesting possibilities for stereo imagery. While possible in the studio, even the slightest movement could cause unwanted disturbances in the panning / imagery. Achieving acceptable results for a live performance is therefore somewhat problematic. Using a pair of LiveGuitar H-clamps overcomes these problems, opening a range of new possibilities.

 

BlueStrings



Imagine being able to use any Bluetooth headset as a wireless microphone for any impromptu guitar performance. With BlueStrings in your guitar bag / case, that’s exactly what you can do. The unique Bluetooth audio adapter we have developed will plug into any audio amplifier or powered speakers with RCA (phono), 1/4” or 3.5mm connections and the H-clamp holds the Bluetooth headset.

BlueStrings is a package containing everything you need to perform wirelessly. The individual components can also be bought separately, so if you already have a Bluetooth headset, all you need is the BlueAir Bluetooth Audio Adapter (BA-01) and a LiveGuitar H-clamp with the optional multi-purpose shockmount. For vocal and guitar performance together, it may be possible to use a Bluetooth headset on your ear and dispense with the H-clamp. With an existing Bluetooth headset, all you would then need to go wireless is the BlueAir Bluetooth Audio Adapter.

The Bluetooth wireless link has a range of 10m and the adapter can be connected to long audio cables or extension to allow the guitar to be played a long way away from the audio system amplifier. This may be particularly useful for performances in venues with odd shaped rooms or difficult layouts and logistics. For example, no amplification may be necessary for the immediate area around where you are performing but beyond that, background noise or obstructions may make your music difficult to hear. Placing your amplifier in the best location to reach those who are not in immediate earshot will mean they can still hear you perfectly, without having to play so loud that people close to you are deafened.

 

 

Being able to place an amplifier up to 10m away from where you are playing is also very helpful if the main room is sufficiently intimate to allow performance without amplification but there is a large ‘off-shoot’ tucked behind a corner. Alternatively, the main performance may be in one room but the sound needs to be relayed to another, perhaps for background music. A welcome by-product of placing amplifiers remotely from the performer is the relative immunity to feedback – if the amplifier is necessary for the more distant members of the audience to hear your performance, placing it where it is needed should mean that little, if any sound from the Amplifier’s speaker will make it back to the performer, where it could be picked up by the microphone. Hence, the risk of feedback should be low.

Nevertheless, like all microphone based systems, BlueStrings is more susceptible to feedback than many piezo, magnetic or other pick-ups and while the omni-directional pattern of a typical Bluetooth headset microphone is beneficial for guitar and vocal together, it increases the sensitivity to feedback.

The sound quality achievable using BlueStrings with a good acoustic amplifier / PA is excellent, vastly superior to the DI from many electro-acoustic guitars or acoustic guitars retrofitted with anything but high budget piezo, magnetic or contact pick-ups. It does not suffer from the harsh edge / quack that plagues piezo pickups or the ‘quasi-electric’ character of magnetic and contact pickups. Reproduction of vocals is also surprisingly good, as you might hope from a headset designed originally to optimise audio quality for phone conversations. Although the sound can not be expected to rival that of a studio quality instrument or vocal microphone, for many live applications, it is ideal, combining a great sound with total freedom of movement and the ability to place the amplification where it is needed, not right in front of you, where the audience can hear perfectly well without it.

One of the beauties of BlueStrings is that you are not restricted to using only the headset included in the package. Any standard Bluetooth headset should work equally well, although sound quality can vary considerably.

Personal monitoring

On stage there are many options for personal monitoring using earpieces but few can be as convenient as using your own Bluetooth headset. The headset supplied with BlueStrings is well suited to this application because its ear speaker makes a seal with the ear and therefore helps to exclude extraneous sounds. If the Bluetooth Audio Adapter (BA-01) supplied with BlueStrings is plugged into a feed from the PA / mixing desk that isolates your own instrument and / or vocals, the extra reinforcement can be very welcome for personal monitoring, even if other sound is not excluded entirely. The more tightly the headset fits into the ear canal, the better it should be but as with all ear speakers, great care must be taken to ensure the volume does not reach damaging levels.

Other uses for BlueStrings

The BlueStrings package includes the BA-01 Bluetooth Audio Adapter. This adapter can be paired with most Bluetooth headsets and can be plugged into almost any audio equipment, including the audio in/out sockets of computers. The list of possible uses is practically endless but in additional to ‘professional’ applications, others include:



  • Public address (conferences, fetes, speeches, commentary, etc.)
  • Karaoke (see the e-acoustics karaoke systems)
  • Internet telephony (using normal computer audio in/out sockets)
  • Dictation (recording on cassette, minidisk, etc.)
  • Amateur ‘fun’ recording
  • Eavesdropping / one-way call intercom


 

Some practicalities


 

The “F” word (feedback)

A useful tool in the hands of a talented electric lead guitarist, feedback is nothing but a pain for almost everyone else, not least acoustic guitarists.

In essence, feedback is a simple phenomenon. When a microphone ‘hears’ enough of one or more frequencies produced by a speaker to which it is connected (via amplification), an audio spiral begins. The microphone feeds the sound it ‘hears’ to the amplifier and it comes out of the speakers. But if the same sound coming from the speaker is ‘heard’ by the microphone (ie. it is fed back to the microphone), it reinforces the original sound, which is then fed back louder still by the speaker. The resulting loop amplifies the particular sound (frequency) being fed back rapidly to create the characteristic howls and squeals that we know all too well.

Although electronic cures (feedback destroyers) are available and have their uses, prevention is usually better than cure. As with the quality of sound produced by an amplified instrument, feedback is influenced by both the instrument / microphone combination and the acoustics of the venue. But whatever the instrument / microphone or venue, the easiest way to create feedback is to position speakers carelessly. Equally, in some rooms may not be physically possible to place speakers in the optimum position to prevent feedback. And even the most careful placement is unlikely to eliminate the possibility of feedback completely.

Using a high quality lavalier (button / tie) microphones clipped to or inside the sound hole can give good results sonically (though some colouration is inevitable due to the proximity to the sound hole) but any feedback problems may be exacerbated. By design, the sound hole / board are very ‘live’ acoustic environments. Resonation of the kind that generates feedback is therefore very easy to create when a microphone is attached directly to the vibrating surface and / or is suspended in the air within or immediately around, the sound hole. Microphones suspended within the sound box can be shielded from feedback to an extent by ‘capping’ the sound hole but it is not a complete solution and the sound ‘heard’ by the microphone within the sound box is only part of the sound that makes up the tone of the instrument as heard by a listener.

Cardioid or hypercardioid pattern microphones can be very helpful. However, the guitar can also act as a sound reflector. So even though sound from main or monitor speakers in front of the performer may be in the microphones ‘deaf’ zone, it may be reflected back off the guitar directly into the microphone’s most sensitive spot. The practicality of using microphones with other polar patterns will depend on the circumstances but omni-directional and bi-directional (figure-of-eight) microphones are likely to be more difficult to work with than cardioid. Nevertheless, a cardioid pattern is not, in itself, a guarantee of good feedback rejection. The degree of rejection of off-axis sound is frequency dependent, with some microphones becoming almost omni-directional at certain frequencies. Also, while the forward facing sensitivity pattern of a hypercardioid microphone is narrower than for cardioid microphones, they are more sensitive in the supposedly ‘deaf’ zone in the opposite direction. Sadly, the result is that no single microphone is likely to be optimal for feedback rejection under all circumstances, though some will be better all-rounders than others.

Whatever the microphone used, it may not be your own playing that is the problem, the acoustic guitar will resonate to sounds generated externally as well as to your own playing and even cardioid microphones pick up sound from elsewhere when it’s loud enough. Deliberately ‘folding back’ microphone amplified acoustic guitar for monitoring purposes may be just asking for trouble, particularly where the venue’s acoustics exacerbate the problem. Although not an ideal solution, in these circumstances the electro-acoustic guitar’s pick-up may be able to come to the rescue. By sending only the pick-up’s signal to the monitor speaker(s), the monitoring volume can be set much higher than by folding back the microphone’s signal.

 

Admittedly, the guitar player will not hear the same sound as the audience but as an aid to the performance, it may be considerably better than relying on weak monitoring, particularly when singing at the same time. Trying to sing in tune with a guitar that is barely audible can be something of a challenge. The tone may leave something to be desired but at least with a monitor driven by the pick-up, volume should not be an issue.

 

Trip wires


 

Unless the LiveGuitar H-clamp is being used with a Bluetooth headset (as in the BlueStrings Guitar package), there will always be at least one wire to contend with. As with any wires attached to a guitar, this creates a potential tripping / treading hazard. It is therefore important to minimise the potential for damage to the instrument or microphone in the event you (or anyone else) treads on or trips over the wire. If the trip is sufficiently violent to cause you to take a tumble with the guitar, there is little the H-clamp and its cable restraints / tidies can do to prevent potentially serious damage to you or your instrument and microphone(s).

The LiveGuitar H-clamp package is designed however to cope with the less catastrophic treading and tripping incidents that are much more common on stage. All LiveGuitar H-clamps are supplied with flexible loops and straps to tidy and provide strain relief on microphone wires / cables.

Velcro ties are provided for use primarily as strain relievers. Full details of how to fit these to prevent tugs on the trailing microphone cable from pulling at the H-clamp or microphone are provided in the LiveGuitar H-clamp User Manual in the Support pages. This simple but effective strain relief measure transfers any tug on the trailing cable to the guitar’s body, not to the H-clamp. The risk of the clamp being dislodged by a tug on the microphone cable is therefore reduced drastically.

The H-clamp can be fitted to the edge of the guitar very securely so it is unlikely that a casual tug would dislodge it, even with no strain relief. However, the behaviour of the H-clamp boom, microphone and to some extent, the clamp itself may be unpredictable if there is no strain relief and the microphone cable is tugged sharply.

Fine and highly stretchy translucent loops are provided to hold the microphone wire close to the clamp in normal use. These hold the wire gently in normal use but are deliberately fine and only weakly elastic so that if all strain relief fails, the ‘tug’ will tend to pull the microphone at the end of the boom away from the guitar. While this provides a degree of last line of defence, it must not be relied upon to protect either microphone or guitar from damage.

The Velcro ties supplied with all H-clamps can also be used to bind the microphone cable to the guitar strap (if in use) and keep it well out of the way during the performance.

The LiveGuitar H-clamp fits very securely to the edge of the guitar’s sound box without causing any damage because it’s design is based on the cramps used traditionally by luthiers to hold the edges of the case together tightly when they are being glued. The H-clamp is very easy to fit for the same reason (a luthier needs to fit cramps all round the edges of case quickly and without having to ensure they are all the right way round – they have to automatically be in the right orientation to be tightened).

Every effort has been made in its design to ensure the LiveGuitar H-clamp fits easily and securely and stays firmly in place until released. In normal use, it would therefore be difficult to damage either guitar or microphone inadvertently, though there are some boom positioning options that would bring it (or a microphone) into close proximity to the instrument. Clearly, under these circumstances care must be taken to ensure that the weight of whatever is attached to the boom is not sufficient to cause the boom grip to move towards the guitar if the position of the guitar is changed. For example, in the playing position, for most LiveGuitar H-clamp fitting options the tendency would be for gravity to pull the boom and microphone away from the guitar but if it were then laid down on its back, gravity may tend to pull the boom down towards the guitar. As long as the boom grip is tightened securely and the clamp is fitted properly, this should not be a problem. Alternatively, if the boom grip had been tightened only sufficiently to hold the microphone in position when it was in an orientation that was fairly immune to gravity, this may not be sufficiently secure when the guitar is moved.

 

Weight lifting


 

Even the most solid of the LiveGuitar H-clamps is too light to have, on its own, a significant impact on the feel of the guitar. However, the size, shape and orientation of the microphone attached to it can make an appreciable difference. Size and weight are obvious factors but it is also worth remembering that the effect of the weight will be affected by the positioning. For instance, a heavy microphone held on a boom extended to its maximum length perpendicular to the face of the guitar in the playing position will feel much more ungainly than one held closer to it.

For live performances, the range of suitable microphones is limited more by factors such as comfort or ease of use than by any functional limitation of the LiveGuitar H-clamp. Using BlueStrings gives the maximum freedom of movement and convenience but apart from the issue of trailing wires, lavalier (button / tie clip) microphones are also well suited to live performance. Being as light as possible may seem an important factor and the added weight of a LiveGuitar H-clamp fitted with a lavalier microphones is imperceptible. And yet, it is surprising how large the microphone can get before it begins to have a noticeable effect on the feel of the guitar. The degree to which this causes any real difficulty depends on the size of the guitar, the playing position (eg. standing or sitting) and the style of music. For delicate classical music played on a light classical guitar cradled gently in the musician’s lap, the lighter the microphone the better and even some of the smaller instrument microphones may be considered unacceptably bulky. In contrast, playing folk / country or rock music played on a dreadnought or similar guitar held on a strap should not be affected noticeably by even the heaviest of vocal microphones designed for live performance.

For practical purposes, large diaphragm studio condenser microphones are not normally a good option for live performances. It is questionable whether the subtlety of the audible improvement in sound quality would be perceptible in most live performances. Hence, unless the performance is also being recorded, the sonic benefit may be negligible. Perhaps more important, large condenser microphones are cumbersome pieces of equipment and strapping them to a guitar makes an appreciable difference to the weight and feel of the instrument.

 

 

Unless the LiveGuitar H-clamp is tightened very firmly indeed, any energetic gyrations during the performance would be likely to cause the microphone’s positioning to slip or potentially, the H-clamp itself to become dislodged. For more sedentary performances, this should not be a problem but these large microphones can make the guitar feel quite ungainly. For most purposes therefore, a lavalier style microphone should be almost as unobtrusive as a pick-up and large capsule studio condenser microphones are unlikely to be a practical proposition. Between these extremes, the choice is really a matter of personal preference and whether or not the LiveGuitar H-clamp is being used for guitar or vocal amplification (or both).
 

Need a new pickup?

- maybe not...


If you like the sound of pickups in general but yours just doesn't sound right, a new one may be the answer. But it may not. If you really want a more natural acoustic sound, an H-clamp may be the ideal solution.

Microphones will always sound more natural than pickups - a pickup detects vibrations in wood or wire; a microphone detects pressure waves in air, just like your ears. In other words, pickups feel the sound, microphones hear it.

Sadly, microphones also hear other sounds very well too, including the ones coming from the speakers they're connected to. Pickups also feel this sound but to a lesser extent. The result is that all microphones are more susceptible to feedback than pickups.

For soloists or all-acoustic groups, it should be possible to position microphones and speakers to avoid feedback in most situations. For groups including electric or other very loud instruments, things get more complicated. Using a pickup is the simplest solution but changes the character of your instrument completely. It may change the sound in a way you like but if it doesn't, an excellent compromise is to blend the pickup with a microphone.

Before the H-clamp, that meant sacrificing your freedom of movement and remaining motionless in front of a microphone stand. But with an H-clamp, your microphone moves with you in the same way your pickup can. So now you don't have to compromise your freedom of expression but you do have to balance the pick-up and microphone levels and/or equalisation to get the best possible tone at a given volume. The louder the sound necessary to compete with other instruments, the further towards the pickup the balance must go to avoid feedback. The key to the best sound is usually to keep the microphone level as high as possible without risking feedback and set the pickup level to deliver the necessary overall volume.

The first time you try this technique it may seem a bit of a fiddle but if you have your own small mixer to hand, it soon becomes second nature and is no more more demanding than tuning your instrument.

So, do you really need a better pickup? well, perhaps not after all. The solution may instead be to add a microphone. With an H-clamp mounted microphone, you don't sacrifice any freedom of movement but you do get a whole new world of tonality:

  • Use a microphone alone for the most natural sound possible (you can even experiment with different timbres by changing the position of the microphone on the instrument)
  • Blend the microphone with the pickup to get a whole new range of sounds and solve tricky feedback problems. While not entirely natural, the sound of a pickup blended with a microphone can be extremely impressive. Blended well, the pickup can add solidity and drive without overwhelming the microphone's airy quality. The result can pure theatre, a larger than life, rather than true to life, sound perhaps but one that can deliver both power and lightness of touch while still sounding like a real acoustic instrument. For a sound that has the extra presence needed to punch through a dense soundstage, blending has a great deal to offer.


There may still be occasions when a pickup on its own is the only practical solution and you may in the end conclude that a better pickup is after all the only realistic option. But just imagine how amazing a better pickup might sound when blended with an H-clamp mounted microphone...

 

A pickup's natural partner 

Use a pickup when you have to and a microphone when you can - for most acoustic guitarists, that's probably the best summary of how to decide on the right kind of amplification.
A pickup has its own particular sound. Love it or hate it, there are times when there's no practical alternative. Equally, there are times when a pickup is not necessary to achieve the required levels of amplification. Using an H-clamp mounted microphone brings the ultimate in versatility to electro-acoustic guitars. It can be used on it's own when pure acoustic sound is the primary requirement, it can be blended with the guitar's pickup when more volume is required and when there is no way of achieving the volume necessary without causing feedback through the microphone, it can be taken off entirely.
With the right combination of guitar and pickup, the result is a single guitar that can perform brilliantly in the widest possible range of circumstances.