In the second part of his series on guitar recording, Brian O'Shaugnessy looks at the multiple amplification and equalisation options confronting the recording engineer

In the introductory piece in last month's issue we covered a lot of general ground, but we didn't go into technical detail about actually recording anything. We looked instead at the hardware. This month, we're going to get down to individual instruments and the recording techniques they require. There are lots of different classic guitar types with their own characteristic sounds. I'll mention a few of them in no particular order.

The Gibson Les Paul has double coil pickups and a thick, warm sound, giving smooth, creamy distortion and lots of sustain. Its sound is better clean for jazzy stuff, distorted for rock. The Fender Telecaster has a wirey, twangy sound that has made it a favourite with country-rock guitarists. Possibly the most famous electric guitar is the Stratocaster — with three single coil pickups that can be selected out of phase, and a tremelo arm or 'whammy bar'. The Strat first appeared in the late 50s, and remains very popular to this day.

Honourable mention must also be made of the Rickenbacker 6 and 12 strings with their unique bright, chiming sound, and Gretsch guitars which are very popular at the moment. If you want a guitar to sound like one of these, then hire, borrow or beg the genuine item — trying to make a Strat sound like a Ricky is a waste of time. There are lots of less common classic makes that you may encounter, like Framus, Burns, Mosrite, Epiphone, Vox, Guild and so on, which all have their own sound.

Then there are Japanese & Korean guitars — originals such as Aria, Yamaha, Ibanez, and copies such as Tokai which are excellent. Guitars designed specifically for heavy metal are generally Strat style: three pickups (normally one double coil Humbucker, two single coil), with the out of phase option, locking nut, fine tuners at the bridge, and one of those astonishing heavy metal whammy bars. They often have active circuitry (a battery powered pre-amp built into the guitar) which boosts the signal, and provides a wide variety of tone.

Regardless of which guitar and amp you're using, always do your best to get a good source sound. Make sure the guitar is properly set up, with new strings and check the tuning frequently. Beware tuning and response problems, particularly with old guitars.

DI Recording

'Direct Injecting' is the simplest way of recording electric instruments. Typically, the output from an electric guitar is a few millivolts, whereas the line input on a mixer is likely to be 10-100 times greater; so if you plug a guitar straight into a line input, either the level will be too low, or you'll have to boost the desk gain so much you'll end up with a very noisy signal. What you need is a DI box: This is a little pre-amp (either battery or 48 volt phantom powered, and costing from £30) which boosts the guitar signal to the right level for a mixing desk mic input.

The basic DI guitar sound is very clean, and may be a bit thin and weedy (but if you want a Chic-type funky rhythm sound, then a Di'ed Strat or Tele is ideal), so let's try some EQ: a boost of a few dbs at about 100Hz will give the sound more body, at about 500 hz you'll get warmth: 1.5 - 2Khz will give it bite, and around 10Khz will make it sparkle. Remember to check your EQing by comparing it with the original signal, and don't be fooled by the fact that the EQed signal is going to be louder (don't confuse louder with better).

Next, we're going to compress the signal. Always patch the compressor across the input channel you're using, set the threshold so all but the lowest levels are above it, then adjust the compression ratio so the gain reduction is about 5 dbs — this will give you a punchier sound, with more sustain. Again, don't forget to compare the new sound with the original. Beware of over-compressing, as it will make the guitar sound too clicky. Remember the golden rule; you can't undo compression at a later stage in the mix, but you can compress later.

Effects

You may at this stage want to add some effects. I always get the guitarist to set up with whatever effects they normally use, and start from that basis. Most guitar pedals are sonically perfectly acceptable, although they may sound a bit 'digital'. Make sure batteries are new, and take care the signal doesn't get too noisy. Never record reverb or echo (unless it's integral to the musical part, like an in-time repeat). Remember you can't take effects off later, and dropping in on a track with reverb can be tricky. However, feel free to add some monitor reverb or echo (monitor reverb means reverb that is heard but not recorded on tape), both to help the guitar to sit in the track and to help the player get a better feel.

This brings us to another general point that is most important: the musician must feel comfortable to give of his/her best; if the guitar being recorded is too loud in the mix, the playing is likely to sound tentative, and if it's too quiet it may be untidy. Don't spend ages fiddling around trying to get a sound; the player will get sick and tired of playing the same thing, become bored and stale, and you won't get such a good performance. But do make sure to ask if they're happy with the sound.

Amplifiers

Generally, I think electric guitars sound much better recorded through amplifiers. There's something about the (mostly) low and mid-range frequencies, and the air currents of an amp that gives a guitar sound a character that a Di'ed guitar cannot match. Try to use valve amps if you can. Valve circuitry, when overdriven generates 'odd order' harmonics, which sound warm, rich, and pleasing; whereas solid state (transistorised) circuitry generates 'even order' harmonics which usually sound harsh and tinny. Without going into detail, I'll mention a few of my favourites: Marshall JCM 800, Fender Twin Reverb, Vox AC 30, Mesa Boogie, Gallien & Krueger.

Basic Technique

So, let's get set up. Put the amp in the sound room and get the guitarist to plug in and get a sound. Put a dynamic mic, facing slightly off axis, about six inches in front of one of the speaker cones, and patch if through to the desk. Get the guitarist to play along with the track, and set approximate tape and monitor levels. Then have a listen — it should sound okay — if it doesn't, then try adjusting the amp settings accordingly. Remember, however, that a guitar amp is designed to project low and midrange frequencies, and when really cranked up it will move the air in a way that your standard studio monitors will struggle to represent. Also, try to get your sounds in context (with the track running). In isolation, the right guitar sound for the track may sound dreadful, and what sounds ideal on its own might get lost in the track.

Assuming we've now got a reasonable sound, it's time to apply some EQ. I usually boost a few dBs at about 600Hz for warmth, and about 2kHz for brightness. If you've got low frequency shelving filters on your mixer, try rolling off some bottom end, else it can muddy up the track. Next, patch your best compressor across the channel, and set it as described above; you can afford to experiment here. Set the ratio as high as possible, and the threshold low (this is known as limiting) and you'll get loads of sustain and an almost backwards sound. Beware, however, of increasing the amp noise to an unacceptable level: the way to prevent it is by patching an expander or noise gate before the compressor.

Mic-U-like

All the advice so far has been for an 'in your face' guitar sound which you can sit in the mix using (not too much) monitor reverb. But you may decide you need a bigger, more ambient sound. Don't be afraid to experiment with different miking techniques — here are some suggestions:

(1) Using an open backed combo: put another mic close up to the back of the combo, reverse the phase of this mic using the phase reverse switch on the desk input channel, and route its signal to the same group as the mic in front. Take the compressor off the mic channel, and put it across the group, so you're compressing the two signals together. This should give you a thicker sound, and help convey the movement of air.

(2) Reflected sound: put a mic about six feet from the combo or speaker cab, about two feet from the ground, pointing at 30 degrees to the ground, and back towards the amp. If your floor is carpeted, lay a sheet of board between the mic and the amp. for the sound to bounce off. Then mix the signal from this mic, with the close mic as above, and adjust the blend till you like what you hear.

(3) Ambient miking: a whole article could be devoted to this, but briefly, here's what you do. Put the amp in a live room (one that hasn't been acoustically deadened) and put a few mics up at varying distances from the amp. Try two PZMs at opposite ends of the wall at the far end of the room from the amp. Now set up a stereo group on your desk, and route the PZMs hard left & right, and then blend in varying amounts of the closer mics, panned more centrally. With a little bit of adjustment, you should be able to get a massive stereo sound like this.

That's probably enough for this month — you've got a few things to try out. Remember, always try and use your ears, and don't be afraid to experiment (there's no substitute for experience), but make sure the band isn't getting impatient. After all, getting good music on tape is what they're paying you for, and bored, restless musicians don't give of their best.

That's all for now folks! Happy twanging, and see you next month.