Half the battle in capturing a great electric guitar sound lies in understanding problems with the instrument itself — and solving them quickly.
During the 1950s and '60s, the electric guitar took centre stage in popular music and, despite ebbs and flows in its popularity, it seems as ubiquitous as ever. In some cases the instrument defines the sound of a genre, but it also has a habit of cropping up in unexpected places across the whole spectrum of modern music. Given this prevalence, it's perhaps a little surprising that the guitar can be at all problematic in a recording situation.
Yet many producers and engineers at the start of their careers, as well as guitarists going under microscope of the studio for the first time, are taken aback at quite how difficult guitars can be to work with. Apparently impossible intonation issues, rattles, choking strings, hums and interference can all put spanners in the works at just the wrong moment. In fact, in my sessions, it's common for guitarists to abandon their own instruments in favour of one of mine, simply due to setup or maintenance issues.
With the help of luthier Matt Gleeson of Monty's Guitars, I'm going to explain what sort of problems we face when recording guitar, what causes them, and what, if anything, can be done during a session to improve matters. Where possible, the best approach is to have your guitar professionally set up, because an experienced guitar tech will be able to spot all the problems, and know just how much correction each requires. What follows is not a guide to setting up guitars, although Matt will explain how to address certain basic problems which could make all the difference in getting through the day. A lot of the issues I'll discuss result from an interacting series of problems across the whole instrument, and in many cases it's a question of a number of subtle changes being required to fully correct a symptom.
The way guitars are strung, and what they're strung with, has a significant bearing on the way the instrument performs. We need to choose strings that are appropriate both to the player and to the instrument. If a guitarist plays hard or tunes down below concert pitch, a thinner, 'lighter' string is going to be unstable — it's going to swing sharp as it's hit. That's always the case to some extent, but there comes a point at which the swing is too great to work with. A player used to a thicker, 'heavier' gauge may find the lack of tension difficult to adjust to. On the other hand, as strings increase in diameter, so their tone changes, and we can lose some desirable 'springiness' or 'twang' in the sound. A heavier string can be physically more difficult to play, and it can behave differently with respect to the changes in pitch mentioned above — it can seem to stay sharp for longer at any given tension, which becomes a factor when you down‑tune.
I can't tell you what specific gauges to use (that's a decision for the player) but whatever those gauges are, the guitar needs to be correctly set up for them. When you choose a different string gauge, the saddles, nut, truss rod and bridge may all need adjustment. I'll look at some of those things in more detail later on, but it's fair to say that if you change from one gauge of string to another, you're going to introduce some sort of setup issue. Note that there are many brands of string, but rather fewer choices of material, by far the most common being nickel‑wound steel. There are subtle differences in feel and sound between them. The most widely used brands are D'Addario and Ernie Ball.
The scale length — the distance from the nut (the slotted channel in which the strings sit, at the point where the fingerboard meets the headstock) to the bridge — will almost always be 25.5 inches or 24.75 inches. The shorter scale length will have less tension at any given string gauge and pitch, and this can affect both how the guitar feels to play and how prone it will be to pulling sharp when hit hard. A player with both a Fender Strat or Telecaster (25.5 inches) and a Gibson Les Paul (24.75 inches) will sometimes use a slightly heavier gauge on the Gibson to compensate for this. This isn't something we can easily change at a session, of course, but if the bottom string is going noticeably sharp on the attack of the note, you might find that you have more luck with a guitar which has a 25.5‑inch scale length.
While we're on the subject of strings, I asked guitar tech Matt to offer a few words of advice. He suggests that before putting a string on the guitar, you should check that it's neither bent nor kinked. Remove the coiled string from its packaging and gently let it unwind, taking care not to force it. Hold it by the 'ball' end and let it hang towards to floor. It should form a smooth, even curve with no kinks, not an 'S' shape or a spiral. If it doesn't, use a different string, as this one is liable to cause problems with intonation and buzzing.
You also need to think about how the strings are actually seated on the guitar. A lot of tuning stability issues arise when the string isn't neatly wound onto the machine head: any messy overlaps can cause problems, as the windings move against each other. A video accompanying this article (see 'Audio & Video' box) demonstrates a good, basic technique for stringing.
Once fitted, a new string will stretch with use, continually drifting flat as it loses tension. To stabilise it quickly, gently stretch and retune the string until it stops moving: just lift the string up directly away from the fingerboard at some point about half way between the nut and the bridge. Don't go mad and pull it past its point of elasticity, as that will cause problems, and do be aware that the string will continue to give a little bit in the first few hours of playing. This stretching process will also help to eliminate any slack at the bridge or machine head.
One of the first things a player notices when picking up a guitar is the age of the strings. When I was playing in bands, I preferred strings to be as new as possible, and changed them regularly, both to safeguard against breakages and because I liked the bright character. But in the studio there's a problem with brand-new strings: they can create a messy, shimmering buzz over the note, which gradually lessens as the string wears in. I've included a comparison in the accompanying sound files which illustrates the difference between old strings and new on the same instrument.
So what's going on here — and is there a way to artificially age new strings to avoid this problem? I've thought about this a lot over the years, and tried all sorts of ways to address it. For a long time I believed that the strings just needed to oxidise a little — to lose that fresh, polished shine — in order to sound clear and defined. I tried unwrapping strings and leaving them exposed to the air for a few weeks before putting them on, and pulling them through the palms of my hands to speed up that oxidisation process, but none of that ever really worked. I have an additional theory, which is that the surface of a string increasingly deforms as it makes contact with the fret. The windings gradually flatten out, increasing the contact area, and effectively 'mating' the string with the fret. It feels as if a brand-new string isn't 'bedding' itself into the fret properly. Examine a used set of strings, and run them between your fingertips, and you'll see and feel that at the fret positions there are flattened sections of string. It's common to find bass guitars with very old sets of round‑wound strings that sound as if they're flat‑wounds. And, in a way, they are!
I've tried going up and down the fretboard, pressing new strings firmly into the fret at every position. I'm not sure it really speeds things up, though, and if you press too hard, you risk deforming the core of the string as it bends towards the fingerboard behind the fret. Matt and I even tried using a small hammer and a piece of leather to gently tap new strings into the frets and create a flat spot immediately, but we found that we just ended up kinking the string around the fret. Neither of us felt that this was the sort of thing that would be good for the frets if done repeatedly over a long time. So, take care if you plan to experiment with ways to speed up this process, and ensure that strings are properly stretched and tuned in advance, or you'll be bedding the wrong part of the string against the fret!
While I still feel that this deformation of the underside of the string accounts for some positive change in tone, I don't think that's the whole 'new string' story. I'm sure that the oxidisation does contribute to the effect, and I suspect that — as horrible as it sounds — the dead skin and oils that come off our hands as we play end up coating or reacting with the string in some way.
What happens when a string is too old? Typically, the intonation goes haywire and the string sounds dull and lifeless. In some cases that 'old string' sound can be quite useful, particularly on basses and acoustic guitars, and I know producers who keep old sets going as long as they possibly can, regardless of the loss of intonation. You may come across guitars where strings are clearly rusted, though, and that's not good.
If strings can be both too new and too old, you need to try to catch them within their window of useful operation. Luckily this is usually quite a long period of time, but exactly how long and, crucially, how long it takes to arrive in the first place, depends on the particular strings, who plays the guitar, and how often they play. During the pre‑production phase of a project, I'll usually advise people to change their strings a few days before the session itself. A 'studio' guitar that sees less frequent action may need longer.
Pre-production is a useful opportunity to identify setup problems in general, and suggest professional attention if it's required. I also like to take some of my own guitars for players to try, and introduce the idea of them using some of my gear.
So... what if a player shows up at a session with strings which are not sounding good, and there are no other guitars available? You can't easily speed up that natural bedding‑in process, so you need to decide which is the lesser of two evils for that particular session. Sometimes, tuning stability and intonation are everything, sometimes tone takes precedence. You may have to choose. Just be aware that a new string will need to stretch, and the re-string will take a little time. If that's something you don't have in ready abundance, it may be better to press on with the old set.
Imagine a string breaks and can only be replaced with a brand-new string. What should you do? One new string in among a used set usually sounds odd. If the part can be reworked so that string is not required, put a new one on so that the tension on the neck is as it should be, and then continue with the modified part. If it can't be reworked, give it a go with the new string and make a decision on whether it would be less distracting to change the whole set or not. It might be possible to move on to other parts which don't require that string, and come back to the affected part another day.
It's always a good idea to have an alternative instrument available if at all possible. While the issue of string age might be difficult to overcome during a session, it's easily and cheaply prevented by changing the set and playing them in beforehand. Ultimately, if there's no choice but to move forward with brand new strings then go for it. There's no point in worrying about something that you can't change.
Some people advocate keeping 'played in' sets of strings to hand; they put new strings on, play them for a few days, and then take them off, ready to be used in times of need. On the face of it, this sounds like a great plan, but my experience of this approach is mixed. Firstly, with most designs of bridge, the whole string needs to pass through a narrow hole, into which the ball end eventually seats itself. That's very easily done when the string is new, because it's straight. Once you've wound it around the machine head a few times you end up with permanent coils in the string, which can result in some pushing and pulling to get it off the guitar and then back on again. Remembering that we upset our intonation if we deform the string's core, this procedure can create intonation problems, or buzzing. Secondly, it can be tricky to get the string back on with those 'flat spots' I mentioned earlier facing the frets. You can end up with some rattles if those dents in the windings don't fit the frets exactly as they did before. I'm not saying that putting old strings on will never work — sometimes it's fine, and it's worth a try if you already have such a set — but do be aware of the potential problems.
Tuning stability and poor intonation are the most obvious symptoms of many problems, and can be a huge source of frustration. It's important to understand that even a perfectly set-up guitar can not be in tune for every key at once. This physical limitation is explained elsewhere, but the long and the short of it is that guitar tuning is a compromise: you can tune one chord perfectly, and leave another sounding slightly wonky. The accompanying sound files include an example of this, in which I've tuned a guitar to a 'G' chord in the open position, and compared that with open 'A' and 'E' chords.
There's no special knowledge or approach required to deal with this: you just have to be prepared to retune and drop in if you feel that the result you're getting is unacceptable. Some players will instinctively avoid playing certain chord shapes that highlight this problem, and there's nothing wrong with asking a player to try a different inversion of a chord to see if it's more pleasing to the ear. Distortion will exacerbate this, and all tuning problems, as the increased harmonics make discrepancies more apparent. Furthermore, a full chord complete with thirds will be more troublesome than a power chord of just root, fifth and octave.
I should mention that it's also possible to modify a guitar to 'compensate' for the tuning, which, when combined with a specific matching of certain fretted and open positions when tuning, allows you to average out some of the discrepancies. In other words, you can find a less jarring middle ground — but note that all you're really doing is swapping one compromise for another. Besides, that sort of modification is not something you can carry out at the drop of a hat.
Some bands prefer to tune to each other by ear. Don't let them. It's very awkward when the time comes for the keyboard overdubs, and they've collectively tuned themselves half a semitone up. Everyone should share the same tuner, and they should tune often. It's important to use a high‑quality tuner, and that means one with a fast enough response that you can clearly see the pitch on the attack of the note as well as the sustain. This used to be costly, but these days, the Peterson Strobe app on the iPhone is an example of an excellent tuner for very little outlay.
It's crucial to tune up to the note, rather than down onto it. This is because as you reduce tension at the machine head, the string may stick slightly as it slips back through the nut, leading to an imbalance in tension either side of the nut, dropping the string flat when it subsequently evens out. Always tune down below the pitch required and then gradually up to pitch — half a turn back on the machine head is a good place to start.
As I mentioned earlier, when the player strikes the string, it will not attack and decay with an even pitch. The attack will be higher in pitch, followed a second or so later by a stable period of sustain, and finally a gradual drop in pitch as the string vibration reduces. As a general rule it's best to ignore the brief pitch increase on the transient, and tune so that you're 'green' as soon as the string stabilises. But that's not always going to give you the result you want: if the player hits the low 'E' string hard, it could end up being very noticeably sharp on the attack. It's possible that you'll need to tune to the attack, especially if it's a faster riff with no longer sustained notes. This is where a tuner that tracks the note quickly is an invaluable asset. As the player moves up the fingerboard, shortening the string, that effect may become less pronounced, and you may need to retune.
Sometimes it can be hard to find the right point at which to tune a slightly wild bottom string. If you find that you're still getting some unwanted 'beating' on a particular chord, tune everything to the tuner first, and then tweak only the bottom string by ear, as the player hits the chord. Just don't be tempted to then adjust other strings in the same way, or you risk moving away from concert pitch. You may well find that if that chord needs to sustain for any length of time the bottom string will then drift flat. That's the joy of guitars! You'll need either to accept a middle ground, or to encourage the player not to hit that string so hard!
It's often best to tune at a specific position if that's where the guitarist is playing. For example, if the part is based around a fifth‑fret power chord, I'll generally tune the guitar by fretting each string at the fifth. If a player has a style which results in a string being inadvertedly bent, for example the bottom 'E' string in a barre chord, I'll have the player hold that chord and then tune those notes in place. Sometimes you're going to get problems in the open position if the guitar is tuned that way, but all you can do about that is prioritise. My advice is to make sure that whatever else happens, the main downbeat of the chorus is right. And remember that as this is a recording, you can retune and drop in to correct certain chords if you wish, time-consuming though that approach can become. Note that when you add distortion to a sound, the added harmonics highlight issues which don't usually bother us, so tuning problems tend to be more obvious with distorted guitar parts than clean ones.
Capos present a challenge in relation to tuning. If you tune a guitar in the open position, and then apply the capo, there will almost always be some tuning issues. It's best to tune with the capo in place, but be aware that changes at the machine head can result in a sluggish response at the tuner readout as the capo 'clings' to the string. If you stretch a string with the capo in place, you can end up with higher tension behind the capo. This will gradually equalise and you'll drift sharp. Some capos use a spring to clamp the strings. That spring can sometimes apply enough pressure to the string that it bows up away from the fingerboard just above the fret, resulting in intonation problems. Use a capo with adjustable tension, and set the tension just tight enough to fret the note without buzzing. A capo that matches your neck profile will allow you to get the optimum performance.
Some tremolos and floating bridges present a challenge. As you play the instrument, the bridge moves, thus the strings move through the nut, and their tension at the machine head changes. These movements can make a poorly set-up guitar very frustrating from a tuning point of view. The Floyd Rose bridges with locking nuts address this problem by having the string clamped both at the bridge and the nut, making the machine heads redundant during use, and eliminating any movement across the nut. These systems give much greater stability than the typical tremolo you might find on a Fender Strat for example. If you are tuning a guitar with one of the more classic tremolo designs, I suggest that you gently dip the tremolo each time you adjust the machine head. This helps to equalise the tension across the guitar. You may find that after you 'dip' the tremolo the string you were tuning has slightly changed in pitch. Just keep working through the process. Obviously, these systems rely on the tension of the strings being balanced by springs at the bridge. If there's an imbalance between the two — for example if you change the gauge of string — the bridge will change in angle, affecting the action and intonation. By tightening or loosening the springs, you can realign the bridge angle, but be aware that this is not always a quick process — mid‑session is not a good time to tackle this issue.
Sometimes, tuning and tuning stability can be affected by nut slots that are too tight for the string gauge used, or a string tree (see glossary) that's improperly positioned or inhibiting the movement of the string. If you turn the machine head and hear little creaks or sudden shifts in pitch, these possible causes are worth investigating. There's not a lot you can do about the nut in the middle of a session, but you could remove a string tree that's causing a problem. Be aware that the purpose of the string tree is to increase the break angle across the nut. Removing it could potentially cause buzzing on the relevant strings, and they might conceivably pop out of the nut slots if hit hard. Both nuts and string trees can be lubricated with a little graphite or oil. Commercial products like Big Bends Nut Sauce are available, but at a push you can try rolling a pencil lead across the edge of the nut slot so that some graphite shaves off and drops into the slot.
If tuning is becoming an issue in your session, have a look at the way musicians are going about it. Offer some advice and help if needs be. You may have to be prepared to either accept some tuning problems, typically 'beating' manifesting itself in overdriven chords, or retune and drop in some problematic chords. What's acceptable really depends on the genre and your client's expectations of the result — there are many great records with quite obvious tuning problems, but also a lot of modern records with not a note out of place. You just have to juggle the resources available against the type of record the client wants to make.
Also, remember that changes in temperature and humidity can affect tuning stability — so leave the guitars in the room in which they will be played for as long as possible to minimise this.
Given what I've said about tuning, it's important to do everything possible to help ourselves with respect to intonation. With most electric guitars, checking and adjusting intonation is usually a quick and simple procedure. First, locate the screws used to move your bridge saddles backwards and forwards, and then using a high quality, accurate tuner like the Peterson app mentioned earlier, compare the 12th-fret harmonic with the fretted note at the same position. If the fretted note is sharp, move the saddle backwards, if it's flat, move the saddle forwards. A good way to remember this is that the F's go together: "sharp back, flat forward”. Make sure that you check your intonation every time you change your strings: this procedure is really easy to do once you know how, and is demonstrated by Matt in an accompanying video clip.
Further factors are liable to skew your intonation, many of which stem from the playing action being too high at certain positions: while some areas of the neck are fine, when you move to a position with a high action and fret a note, you're actually bending the string sharp. There are a few things to look out for when troubleshooting this issue.
Almost all electric guitars have a truss rod running down the centre of the neck, underneath the fingerboard, which will be adjustable at one end or other. The truss rod dictates the curve of the neck, or the 'relief', as it's known. If the neck is bowing too far forward, you tend to get a playable section at either end of the neck, with a high action in the middle. Tightening the truss rod can straighten the neck slightly and help to correct this problem. The inverse problem is a truss rod that's too tight, giving a totally straight or slightly back‑bowed neck. This results in a low action through the middle of the neck, and often choking in that position, but a high action at the top. If the nut or bridge saddles are too high, you can end up with an action that's too high in general. If the nut is a little high, the first-fret position can be sharp.
The neck relief, neck angle, nut, bridge and saddle height all interact to affect the playing action. If you adjust the truss rod, it's quite possible that you'll then also need to make adjustments at the bridge. It's always best to get an experienced tech involved as soon as is practical, but if you can see an obvious problem that's making a guitar unusable, you have nothing to lose by making careful adjustments.
Again, I invited Matt to offer some further words of advice. "To see what is going on with the neck, have the guitar in the playing position and hold down the first fret of the high 'E' string with first finger of your left hand. At the same time hold down the 13th fret with the thumb of your right, and tap over the fifth with the first finger of your right hand. You want the gap to be about the same as a .010-gauge string. Do the same on the low 'E' string. You will more than likely find that there is more relief on one side, usually the treble. This can be due to the neck being slightly twisted, the wood not giving evenly, or simply that you've been playing a lot in a particular area and the frets are unevenly worn. The amount of relief needed can vary depending on string gauge, playing style and player preference. Adjust the truss rod a 16th or eighth of a turn at a time — and always remember your starting point, so that you can go back if things get worse. Remember 'righty tighty, lefty loosey', and never force the truss rod if it won't turn freely.”
The frets themselves wear over time in the most commonly used positions, flattening out and losing height. When that happens it's possible that the intonation point of the fret can move. Frustratingly, the nature of this problem is that it tends to happen at the position you use the most! Pulling the strings aside can reveal the extent of any fret wear. This is not a problem you can correct on the day. If the frets are that bad, change guitars, or find a different position. Excessively high pickups can also affect your intonation — more about that later.
If a high action causes problems with intonation, the opposite problem — that of a low action — results in notes choking out, buzzing and rattling as the string comes into contact with frets above. Adjustments to neck, nut and bridge are appropriate in the same way as with a high action, but there are a couple of other issues to be aware of. Sometimes the frets themselves are set at uneven heights, which can affect performance even if the neck is perfectly adjusted. There's not much you can do about it immediately, other than to raise the action further than you'd otherwise wish to: that's one for a guitar tech to look at.
The neck profile of an electric guitar is rarely flat from the bottom string to the top string. Most fingerboards curve up towards the 'D' and 'G' strings to some extent, with radii typically varying between around seven and 16 inches. The flatter the fingerboard, the lower the action can be set while still allowing the player to bend the strings. On a fretboard with very curved radius, like on an old Fender guitar, bending the top two strings can cause them to choke out as the string moves towards the centre of the neck, where the frets are higher. The solution to this is a higher action on those strings, or in general. The player's preference will dictate which is more important out of playing action and the ability to bend at those positions. Some guitars have a compound radius, with greater degree of curve at the lower end of the fingerboard, flattening out as it gets towards the higher registers. Be aware of this issue: if you adjust the action to avoid choking, you also need to check what happens when the player bends the top two strings. They won't necessarily ring freely, especially if the radius is tight.
Sometimes guitars generate buzzing, rattles and unwanted mechanical noises for reasons other than the height of the action. The nut can be too tight for the strings to sit properly in their slots, for example. This can cause buzzing on open strings, tuning problems and can even result in the nut cracking. A nut slot that's too wide can cause 'sitaring' and/or dulling of the open string. Some guitars are made in such a way that there's not much of a break angle across the nut for the treble strings. This problem typically affects guitars with straight headstocks, for example Fender Strats and Telecasters, and results in the string buzzing in the nut as it's not being pushed down firmly into its slot. The solution to this problem is the use of a string tree to pull the string down towards the surface of the headstock after it has passed through the nut. These are commonly fitted as standard to guitars which need them, but sometimes they have been removed. If possible, you could refit the string tree to remedy this problem.
In the same way, some bridges don't have enough break angle, and strings can be prone to buzzing where they make contact with the saddle. The solution might be to raise the bridge, but of course you then open a can of worms further back down the neck. There's no instant fix.
The truss rod can sometimes cause a rattle or knocking sound if it's slightly loose. Tapping the back of the neck can reveal this problem. It usually happens when there's little to no tension on the truss rod, and a very slight turn to the right can be the remedy.
Bridges and saddles of all types tend to have small screws which can work loose and rattle. This presents itself as an unpleasant buzz in the decay of the note. If you can see something that's obviously loose it can be tightened, but be careful not to inadvertently change the saddle height or intonation setting in the process. I find that a little blob of Blu‑tak stuck on the head of a rattling screw can be a good, instant way to solve the problem.
On a guitar fitted with a tremolo system, the springs that balance the string tension and make the bridge 'float' can sometimes buzz or cause other mechanical noises. Take the plate off the back of the guitar and see if a little fiddling around cures it. You can try holding a piece of cloth or towel against the springs to dampen vibrations, but be aware that if you put pressure on them, you will affect the pitch as the bridge moves. Just do whatever you need to do to control the noise while you get that part down.
In a similar way, the springs that are fitted to pickup height adjustment screws can also vibrate, causing a rattle. This can often happen if the springs are not being compressed because the pickups are too low. Fiddle, and if necessary, adjust the pickup height.
Sometimes, in search of more output, players raise their pickups up too high and if pickups are too close to the strings, the magnetic pull of the pickup can result in some strange effects. As well as this causing the note to decay in a quick and unnatural way as the string's vibration is inhibited, for example, strange dissonant overtones known as 'wolf tones' can often be heard. Luckily, the fix is simple: lower the pickup until the wolf tones disappear.
It may seem likely that powerful humbuckers would be more prone to this problem, but the humbucker actually has a magnetic base, rather than the magnetic pole pieces of a single‑coil pickup —and that extra distance between the magnet and the string makes the humbucker less prone to causing wolf tones (though you will still notice some tonal changes as it gets too close). Another sound file is included to demonstrate the 'wolf tone' effect.
While we're on the subject of pickups, here's a quick tip: a high output from your guitar may seem like a good thing, but some pickups are so hot that they make it impossible to get a clean tone from the amp. Rather than chasing the highest possible output from your pickups, consider using a clean boost pedal to hit the amp harder when required.
So far we've spoken mainly about mechanical issues, but obviously the electronics have the potential for problems too. Sockets, pots, switches and wiring can become dirty or damaged, leading to intermittent (or permanent!) loss of signal. It's well worth investing in a can of switch cleaner and, if you're so inclined, a basic soldering iron.
One very common problem relates to the wiring of the jack socket. Over time, the nut which holds the barrel of the socket in place can come loose, and the natural reaction is to tighten it up. But in doing so, it's easy to rotate the barrel of the socket to some degree. Eventually one of the two wires that connect to the back of the socket comes loose, and signal is lost. It's a simple matter to re‑solder that wire and tighten the nut properly, getting the guitar back into service. This problem can be prevented by always exposing the whole socket and holding the barrel still while you tighten the securing nut. On most guitars the socket is accessed via a small plate on which it's mounted, or by unscrewing a rear panel.
Matt suggests that a great way to clean the contacts in a jack socket is to tightly roll up some wet-and-dry paper, insert it into the socket, twist and remove. This gets rid of oxidisation and any grime that may have built up on the contacts.
If there are problems with pots, dry joints, wiring, screening or damaged switches, they're generally going to be difficult to tackle mid‑session unless you have prior experience with this sort of work. You can try rotating a pot a few times, applying switch cleaner to a pot or selector switch, or melting the solder on what you suspect may be a dry joint, but detailed descriptions of these sorts of repairs are beyond our scope here.
You can't work with electric guitars for long without discovering that they're often prone to external interference in the form of electrical hum and buzzing. This particularly affects single‑coil pickups, which was why the humbucking pickup was developed. The last few years have seem the emergence of 'noiseless' single-coil designs, and other noise‑cancelling devices such as the Ilitch Plate. The guitar's electronics should ideally be shielded, the best way being to completely line the cavity with copper foil, but even if a guitar is well shielded, the whole signal path is vulnerable: cables, pedals and amplifier can all be susceptible. When you start introducing multiple amps, splitters, pedalboards and pedal power supplies, the potential for interference and hum increases. These matters have been discussed in past issues and we won't go over old ground in detail, but there are a few things to try if you're plagued with these sorts of noises during your session...
Keep well away from obvious sources of interference, like old CRT screens and low‑voltage lighting. Try rotating the player — and thus the instrument — to find a 'quiet' angle. You may well find a position in which the noise all but vanishes, as demonstrated in the sound files that accompany the article. Maintain the shortest signal path you can using the best cables available to you. Remove any pedals that you're not using for any given part. Some components of your chain may be noisier than others. It's worth seeing if you can optimise your noise floor by changing the relative gain structure between your guitar, pedals and amp. For example, some fuzz pedals are really noisy, and it might be that the chain is quieter if they're given a little less gain, or output, and the amp a little more. Effects-pedal power supply units are a common source of noise. I've tried pretty much all of them, and I've yet to find one that's better in this respect than using batteries. Obviously some units can't run on batteries, but where you can, I personally would. It's always worth having a stash of them.
Some pedals seem to sound better with batteries, whether or not they lower the noise floor. I asked AudioKitchen's Steve Crow to shed a bit of light on this:
"Neither mains-powered DC supplies or 9V batteries are 'black boxes' containing a perfect DC supply. Nine Volt batteries are made up of six 1.5V cells, each of which will have its own internal resistance, capacitance and inductance. Add into the mix the contacts between each cell and the next with the impedance (resistance + capacitance + inductance) they entail. Battery connectors add some more. I'm not saying these factors are huge, but they will exist, and vary with the brand and 'flavour' of batteries you use. What you won't have with a battery are any remnants of 100Hz (rectified 50Hz) AC ripple or potential for multiple ground/earth connections causing 50Hz hum, both of which become pertinent when considering mains-powered DC supplies. The internal impedances associated with mains-powered DC supplies will be different to those of a battery and the delivery of the power may be affected by AC ripple, ground/earth loops and so on. Deliver it through a long bit of non‑shielded wire via connectors and you have some more variables. The upshot of all this is that very simple circuits (old fuzz circuits, for example) will rely pretty heavily on the quality of their DC supply to perform well, as they do not have much (any) capability to reject power-supply noise. Pedals with lots of gain (fuzz) will obviously multiply any power-supply junk a great deal so it will show up more — believe what you hear, not what you're told.”
You can clean the socket of your amp and its pots and switches in the same way as those of your guitar, but beyond that it's quite difficult to suggest quick and simple remedies to electrical problems in an amp. Hum and wind noise that crops up is often to do with valves, and if you don't have replacements, there's not a great deal you can do other than to re-seat the dodgy ones and hope for the best. Where output valves are arranged in two pairs, for example in an AC30, you can try swapping one of each pair and see if the hum is reduced — a potential cause of hum is a mismatch between the pair of output valves. If you can achieve a better match with the valve from the opposite pair, you might reduce the hum a bit. It's not going to go away, and really you need to replace the valves with a matched set. Often this then requires a re‑biasing. It's been said many times, but be extremely careful when messing about with the internal parts of a valve amp. They can give you a potentially fatal electric shock, and store enough juice in their caps to do so even after the amp has been disconnected from the mains. Don't take risks, especially with older amps.
A loud amp vibrates a lot, and sometimes we end up with all manner of vibrations and mechanical rattles both within the amp itself and nearby. If you're being driven mad by some sort of vibration, check that the cabinet itself is solid, and that it's not causing, for example, catches on a flightcase wheel base to vibrate. Some amps are quite prone to this: to take the example of an AC30 again, the amplifier portion of the combo slides out of the main cabinet, in which it sits as a sort of shelf. This whole assembly can be noisy if the screws aren't tight.
Every time I do a guitar session, I arrive with enough time to set up one solid combo, or cab that I know sounds good, mic it and get it ready to record before the band arrives. That way, whatever they bring with them, and whatever the problems we may later encounter, I know that I've got this one rig ready to go at all times.
Reading this, it may seem like guitars are plagued with problems at every turn, and in fact that's not a million miles from the truth. But we have to keep some perspective on how serious these problems really are in the context of a recording. Does it matter if your part is a little noisy? Does it matter if it's out of tune? Does it matter if your amp sounds like it's slowly but surely breaking? Well, that's up to you and your client. Sometimes it will, sometimes it won't. What this piece aims to do is to help you get a handle on what might be wrong, and decide whether a simple solution is worth pursuing in the time available. Always remember that the perfect is the enemy of the good: don't be paralysed by a problem if it won't really matter in the end.
Jack Ruston is a record producer and mixer, working primarily with rock bands. He usually ends up playing guitar in some shape, size or form on most of the records he makes.
Matt Gleeson is a luthier, who has done work for the likes of David Gilmour, Kasabian and Biffy Clyro. He builds and repairs guitars from his Monty's Guitars workshop, based at State Of The Ark Studios in Richmond, and also designs and hand‑winds his own range of custom pickups.
We've created a number of audio examples to illustrate several of the points discussed in this article. You can also find a couple of videos in which Matt Gleeson demonstrates good practice in restringing, and how to check for and correct intonation issues.
These sound files accompany the Optimising Electric Guitars For The Studio article which appeared in SOS April 2014. The files can be download as 24‑bit 44.1kHz WAV files.
Old strings on a Fender Telecaster recorded with a DI
New strings on the same guitar a few minutes later.
Typical guitar tuning discrepancies. Tuning for a G chord and comparing to open A and E. Recorded via a DI box.
Finding the null point to combat interference. Recorded with a DI box.
Here's a quick practical tip for you. Most of us find it difficult to tell when low frequencies played in isolation are slightly out of tune. For that reason, if there are limitations that affect how many musicians you can track at the same time, I'd always try to get the drums together with a guitar, and then overdub the bass, rather than track the bass alone with the drums. Alternatively, a guide keyboard part following the chords provides a handy anchor for our sense of pitch — and this can be binned once you're happy with the rhythm-section tracking.