Following my post on what size amp you need for gigs I received a very valid question on Twitter: Why amp->microphone at all? Why not just guitar->sound desk. This wasn’t a question I could answer in 140 characters, so I promised to write a blog post on it.
Here’s an overview of the answer which I will expand on below –
- Electric guitar pickups don’t sound very good on their own.
- Guitar amplifiers significantly alter the raw tone of the guitar to make it sound better.
- A sound engineer could attempt to recreate this, but it’s not really his job to ‘fix’ your sound.
- There are various devices which emulate amplifiers and do allow you to plug directly into the desk.
- There are some downsides to emulators to do with hearing yourself on stage but that doesn’t mean they’re not good.
- There are some ways round the downsides to emulators.
Electric guitar pickups don’t sound very good without an amplifier
If you plug your electric guitar straight into the aux input on your Hi-Fi system it doesn’t sound very good. I know because I tried it today to research this article. This is partly because the signal from an electric guitar is very weak. The Hi-Fi isn’t designed to amplify signals that small so it doesn’t do it well.
Professional sound desks don’t have this problem. As long as they have the right pre-amps built in they can amplify weak signals to a level they can work with. However, it still won’t sound great if you plug your guitar direct to the PA. As far as I can tell this is for two reasons:
- An electric guitar pickup does not detect all the vibrations occurring on the plucked string. It has to be positioned at a specific point along the string. At any given point some of the strings harmonics will be particularly prominent and others will be undetectable. You only have to swap between the various pickups on your guitar to hear the effect of this. Furthermore, some of the smaller harmonics detected by a pickup will cancel themselves out. This is more prevalent on a humbucker because it is wider, so more of the smaller harmonics will cancel. These smaller harmonics are the higher frequencies so this is one of the reasons humbuckers sound ‘warmer’ and less trebley than a single coil. This Sound-on-Sound page explains this effect and lots more about passive pickups. (Note: Unfortunately the page seems to be formatted badly but I managed to read it by copy-pasting the contents into a word document)
- The nature of the electrical circuit formed by the guitar pickup, controls, cable and whatever it is plugged in to creates a mid-range boost at a certain frequency (called the resonant frequency) followed by a fairly sharp drop in higher frequency detection after that point.
Combined, these factors mean that the ‘raw’ guitar sound is mid-heavy with very little treble, making it sound mushy and indistinct. It’s a bit like listening to it from underneath a duvet. It’s not terrible, but it’s not great either.
Guitar amplifiers correct the deficiencies in the raw guitar tone
It probably won’t come as a surprise that guitar amplifiers have developed to correct the problems with the raw guitar sound. The two were developed hand in hand so it’s natural that the amp counterbalances the tone issues. Specifically, amplifiers cut the mid-range allowing the bass and particularly the treble to be heard more clearly. This makes the sound more distinct and more like an electric guitar as we know it.
To be completely clear, when you have all your amp tone controls set to 5 it will be applying a mid-range cut to your sound. The exact frequency and amount of cut will depend on the particular amp and manufacturer. It is a significant part of what gives different amps their particular sound.
There is a little programme which gives a visual display of amplifier frequency responses at different tone control settings for those of you who want to delve deeply in to the nuances of amplifier tone.
I guess you could but I wouldn’t recommend it. Firstly, I don’t think the Engineer will take kindly to it. He (or she) is not there to fix your guitar tone, he’s there to get your sound out to the audience. That’s what you want him concentrating on. You should be providing a good quality sound to make this as easy as possible.
Secondly, even if you could talk the Engineer into doing it for you, it means you are no longer in control of your sound. You can’t make adjustments without attracting the Engineer’s attention and asking him / her to do it for you. If you’ve ever been in the situation where you’ve had to try to do that mid-gig you’ll know how hard it is. It also looks unprofessional if you’re waving and gesturing at the engineer, or worse, having to ask for changes over the mic between songs.
An amplifier is not just the way you make your guitar louder. It is 50% of your instrument. You should know it as well as you know your guitar. Understand how it works, how the different controls interact with each other and with the controls on your guitar. It is fundamental to creating the tone and sound you want to create. I wouldn’t want to hand that over to someone else.
(I should mention that there’s a limit to how much control you have over the sound the audience hears because the Engineer may apply some EQ before it comes out of the PA. However, if you at least start with the sound you want you’ve got more chance of it being realised than if you rely on the Engineer to EQ your direct guitar sound.
Also, on the point about control over your sound during the gig, I would caution against making big changes to the settings on your amp mid-gig because that may upset the Engineer’s front of house sound. However, you can make small tweaks if you need to).
Devices that allow you to plug your guitar direct to the PA
These days there are a number of devices that emulate amplifiers and allow you to plug directly into the desk. The most well known of the analogue ones is the Sansamp range which have been around since 1989. More recently with the rise of digital sound processing there are digital amp modelling units to suit any budget. You can get them in all sorts of configurations – stompbox pedals, rack units, standalone boxes or applications that run on a laptop or iPad.
Amp emulation is incredibly useful for a number of reasons. Often you can get a much wider range of sounds than you can from one amp. They make it easy to switch between these sounds giving you more flexibility than one amp can (unless it has built in modelling itself).
They’re also smaller than an amp so they’re much more convenient to carry. That’s especially handy for gigs abroad. Pop it in your hand luggage, check your instrument in the hold and you can fly out to any location knowing that you’ve got ‘your sound’ with you. I do this when I play abroad and for some gigs in the UK.
One thing to be aware of is that these devices usually have a switch or setting to tell them whether you are plugging them into an amplifier or straight into a desk. This is because if you are going in to an amplifier you don’t want the mids cut by the emulator and also the amp – this would double up the cut unnecessarily. However, if you are plugging straight into a sound desk you definitely do want the emulator to apply the amp-like mid-cut. Make sure you know how to set this on whatever piece of kit you are using, but also try out all the options because sometimes I’ve found that the ‘recommended’ setting doesn’t actually sound best. Always choose the option that sounds best to your ears even if it’s not the ‘right’ one according to the manual.
Problems with amp emulators
There are a few drawbacks to amp emulators. I’m not talking about whether they sound as ‘good’ as traditional amps. That’s very subjective and not something I want to go in to here. I’ve said before that I think the majority of your tone comes from you, not your gear. I don’t think the small differences in tone between emulated and ‘real’ amps (if any) has a significant impact on whether you should use one.
However, amp emulators do create the problem of how you hear yourself on stage. Hearing yourself is vital for giving a good performance.
If you have an amp pointing at your head then you know you will be able to hear yourself. If you use an emulator you will need the Engineer to put your guitar sound in the on-stage monitors so that you can hear what you are doing.
The problem with this is that you may end up competing with other members of the band who also need to hear themselves in the monitors. In smaller venues there might only be 1, 2 or 3 monitor mixes available. If you have to share a monitor with a singer or maybe a keyboard player or violin it may be difficult for one of you to make out your own sound. If you turn that sound up it might drown out the other one.
On stage it’s important to have separation between the instruments. This allows everyone to hear themselves clearly and concentrate on their own performance. If people have their own amps this separation happens naturally. The monitors can be reserved for vocals and backing and a little bit of the other instruments but not too much. Everyone has their own sound source.
If everyone goes direct to the PA then ideally everyone should have their own monitor. That way they can ask for the specific level of their own sound compared to all the others. However, smaller sound desks can’t provide many monitor feeds. Smaller venues may not have that many physical monitors available. If you end up having to share a sound source (i.e. a monitor) with someone then you may have problems separating the sounds and thus hearing yourself. That’s why many guitarists will bring an amplifier even if they are using some kind of amp emulator.
Getting around the separation issue
There are a couple of ways to try to get the ‘best of both worlds’. You could take two outputs from your amp emulator (most of them provide this), one to the desk and one to an amp. That way the desk gets the pure signal direct from the emulator and you just use the amp for monitoring, giving you separation. No need for a microphone in front of the amplifier. A violin player I work with does this.
Another solution would be to buy some kind of personal monitoring device such as an in-ear monitor (IEM). Most professionals playing big gigs use these. They mean you can move about the stage, you’re not tied to a sound source. You can also control the levels to your exact specification without affecting anyone else on the stage. They’re not cheap, although they are comparable in price to a good guitar amp and they are more portable. They can be a good option if you really want to ditch the amp.
There you have it. The reason we don’t plug guitars straight into the desk is due to the limitations of guitar pickups which amps correct. It is possible to go direct to the desk using an amp emulator as long as you are aware of the potential issue of sound separation on stage and have thought about how you will address it.
I’ve learned a lot researching this question and it’s been good fun. If anyone has any further questions fire them at me in the comments or on twitter (@matthelmguitar) or however you like.