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What Mic Should I Buy First?

Sound Advice
Published July 2003
By Paul White

We answer one of the most common queries from those just starting out with home recording.

What Mic Should I Buy First?Photo: Mark EwingWhen it comes to setting up a home-based project studio, deciding which microphone to buy first can be pretty daunting, not least because of the huge number of models and types available. The good news is that today we have a choice of some extremely good, low-cost microphones, many imported from China or the former Eastern Block, all of which perform significantly better than anything we could afford when home recording first took hold in the late '70s. This strong competition has also resulted in European and US manufacturers launching budget mics, something made possible by the higher volumes of sales generated by the growing project studio market.

Dynamic Or Condenser?

Before trying to pin down what to buy, it pays to be aware of the main differences between dynamic mics and capacitor mics. Dynamic mics work on the moving-coil principle, rather like a loudspeaker in reverse, and have in their favour mechanical durability, cost-effectiveness and a solid, punchy sound that works well for guitar, bass and drums, as well as other loud instruments such as brass. They also need no phantom power to work (see the 'Phantom Power' box for details), which makes them very popular for live use, but working against them is the fact that their high-end response isn't so good as a typical capacitor mic and they are also relatively insensitive. In practical terms, this means that sounds relying on a lot of high-end detail, such as cymbals, acoustic guitars, pianos and even some voices can sound restricted in the upper frequency ranges if recorded via a typical dynamic mic, though there are exceptions which have a more extended frequency response. Typically, though, dynamic mics are good up to around 15-16kHz, above which their sensitivity tends to drop off quite drastically. The overall sensitivity of the mic determines how much gain you have to add on the mixer or mic preamp to bring the output up to the required level and, while dynamic mics are adequately sensitive for close-miked vocals and fairly loud instruments, they struggle with more distant sounds or quieter acoustic instruments. In these situations you have to add more gain at the mixer and more gain invariably equates to more background hiss.

Although a condenser mic will usually be the best first buy for the home studio, if you decide to go for a dynamic mic then the Shure SM57 and Sennheiser MD421 are both industry-standard microphones with good all-round performance.Although a condenser mic will usually be the best first buy for the home studio, if you decide to go for a dynamic mic then the Shure SM57 and Sennheiser MD421 are both industry-standard microphones with good all-round performance.Photo: Mark EwingCapacitor mics (or at least those used in studios) fall into two categories — true capacitor mics and back-electrets. A true capacitor mic uses a very thin film to form the diaphragm, coated with a conductive metal such as gold, and, because there is no heavy voice coil attached to the diaphragm, it puts up less resistance to being moved at high frequencies. The diaphragm forms part of an electrical capacitor and is charged via a polarising voltage enabling it to convert movement to a change in voltage. Phantom power is needed to drive the on-board preamp electronics and to polarise the capsule.

A back-electret mic may use a similarly constructed diaphragm and can produce the same level of performance as a conventional capacitor microphone, though models designed for use with batteries are usually less sensitive than their 'phantom power only' counterparts, especially if they are designed for live use. The principle of operation is similar to that of a conventional capacitor mic, except that, instead of needing an external polarising voltage, the capsule's back-plate is covered with a material that carries a permanent electrical charge within a highly insulating film (the electret material). A voltage is still required to run the onboard preamp, though, so power may come from phantom power and/or batteries depending on the model. An example of a popular back-electret mic that offers the same performance as a regular studio capacitor model is the Audio Technica 4033. Dual battery/phantom models, such as the well-established AKG C1000, are often less sensitive, so that they are able to match the requirements of live sound close-miking. Capacitor mics are used in the studio for most vocal and acoustic instrument recording as well as for drum overheads. They may also be used for recording electric guitar, where they deliver a useful alternative to the dynamic-mic sound.

 Peaks & Presence 
 A microphone can be engineered to produce a very flat frequency response extending from below 20Hz to over 20kHz, though this isn't always desirable other than for measurement applications. Most models have either an in-built low-end roll-off to keep unwanted deep bass out of the signal chain or a switchable low-cut filter. At the high end, the response curve may be shaped to produce a particular sound. A boost at 3-4kHz provides presence, while boost above 10kHz gives more of an airy high end. Some capacitor models may also be rolled off gently at the high end to give them a warmer sound. For general-purpose use, a mic with a fairly flat response is the most flexible, though a gentle peak at 8kHz or above is usually pretty benign. I'd only recommend choosing a mic with more extreme coloration if you intend to use it mainly with one voice and you've found a particular model to suit that voice. 

Polar Patterns & Diaphragm Size

Although mics can be bought with omni, cardioid or figure-of-eight pickup patterns (and every stage in between), the cardioid response is the most useful in a project studio, as it excludes more of the room sound and spill from off-axis sources. Omni mics have a more natural, open sound than cardioids, but pick up equally in all directions and so tend to be used only when the room has a particularly supportive sound or where there is little risk of spill from other sources. Cardioid and figure-of-eight mics both exhibit a bass tip-up when used close to the recorded source, called the proximity effect, but omni mics don't suffer from this and so may be used very close to the sound source without the tone becoming more bass heavy.

Here you can see the relative sizes of typical large-diaphragm and small-diaphragm mic capsules.Here you can see the relative sizes of typical large-diaphragm and small-diaphragm mic capsules.Photo: Mark EwingMuch is made of the way a mic's diaphragm diameter affects its tonal attributes, but this is more subtle than you might expect. As a rule, large-diaphragm mics have a slightly fuller sound, but are less accurate when picking up off-axis sounds. For example, in omni mode, a large-diaphragm mic may suffer noticeable high-end loss when used 90 degrees off axis. Conventional wisdom has it that large diaphragm mics (around one inch in diameter) are best for close-miked sounds, such as studio vocals and guitar amps, whereas smaller diaphragm mics (typically 0.5 inches or less in diameter) are the preferred choice for recording ensembles at a distance or for recording acoustic instruments. Having said that, either type of mic can produce perfectly acceptable results in either situation, so where you can only afford one mic, large-diaphragm cardioid models are a safe bet, as they should give good results most of the time.

 Phantom Power 
 Capacitor microphones require a power supply to polarise the capsule and to drive the preamplifier which is normally located inside the microphone body close to the capsule. Back-electret mics and active DI boxes need power to run their onboard preamps. To avoid the need for a separate power supply, the majority of capacitor microphones (other than tube mics, almost all of which need a separate power supply anyway) and most studio-quality back-electret models use the universally standard 48V phantom powering system, though some models will operate at lower phantom power voltages at the expense of some loss of headroom.

The AKG C1000 back-electret mic can be powered either from a normal phantom supply, or from a 9V battery fitted inside the mic casing. The option of battery power could be very useful if your mixer or recording channel has no phantom powering option.The AKG C1000 back-electret mic can be powered either from a normal phantom supply, or from a 9V battery fitted inside the mic casing. The option of battery power could be very useful if your mixer or recording channel has no phantom powering option.Photo: Mark EwingThe term 'phantom' was coined because no additional wiring is needed to carry the power from the power source to the microphone — it is passed along the microphone cable using the same wires that carry the audio signal. Phantom powering is only possible with balanced wiring systems (the cables have two cores and one outer screen) and most studio mixing consoles have their own internal phantom power supplies that feed their microphone inputs. Depending on the mixer, the phantom power may be globally switched or switched per channel. Separate phantom power supplies are available (some running from multiple batteries for mobile use), and all serious microphone preamplifiers also have integral phantom powering.

Dynamic microphones do not require phantom power, though where the phantom power on a mixer can only be switched globally it is safe to connect balanced dynamic mics provided that balanced cables are used. This is because the same phantom voltage is present on both the hot and cold pins of the mic cable and so no current flows. However, those mics not wired for balanced operation could be damaged if phantom power is applied.

 

Tubular Balls?

So, what about tube mics — they cost more, but is it worth it for that magical tube warmth? That depends on what you expect tube warmth to sound like, because the tube's contribution to the sound is subtle in a well-designed tube mic. To my ears, a well-designed tube mic has a slightly denser sound than a conventional solid-state model, almost as though subtle compression has been added, while the high end can be more open and detailed but without harshness. If the sound is audibly distorted or dull, someone has tried to design in a particular sound rather than rely on the natural mechanism of a good tube circuit to do the job. This is quite an acceptable thing to do on an artistic level, but be aware it may sound quite different to the classic tube mics so revered by those engineers privileged enough to use them on a regular basis.

The valve 'sound' used to be out of the reach of the home studio owner, but now there are several cost-effective valve mics, such as the Groove Tubes GT66, within reach of the first-time buyer.The valve 'sound' used to be out of the reach of the home studio owner, but now there are several cost-effective valve mics, such as the Groove Tubes GT66, within reach of the first-time buyer.Photo: Mark EwingThe same is true of some tube circuits that run high-voltage tubes from a low voltage. There are special tubes designed for low-voltage use, such as some military devices or those developed for use in hearing aids, but most tubes are designed to run with a plate voltage of between 250V and 300V, which is why the vast majority of tube mics include their own power supply. In fact the only exception I know to this is the new Audio Technica 3060, which uses a low-current, low-voltage hearing aid tube and works from regular phantom power. It is worth noting that some mics also include transformer output stages and these often influence the sound in a positive manner, but simply buying a mic with a transformer output is no guarantee in itself of a warmer or more musical sound. With both tubes and transformers, you have to listen to the specific model you're interested in and make up your own mind.

You Pays Your Money...

Having set out the background, how do you set about choosing that first mic? My first observation would be that, while most studio gear seems to become obsolete shortly after the credit card statement arrives, a good mic will last you a lifetime, so buying the best you can afford for your particular application, then looking after it, is a good investment.

There's little to be gained from buying a dynamic mic as your first choice for recording these days, as a good one will cost as much as a budget capacitor model and will usually deliver a lower-quality vocal sound. Its lower sensitivity may also show up noise problems in budget mic preamps. The exception is when you find a model that suits a particular voice — for hard rock vocals, a dynamic can work well, as it often delivers a more focused, punchy sound than a capacitor model. Naturally it still pays to buy a good dynamic mic rather than a cheap one as it will always remain useful, no matter how many other mics you buy afterwards. Although there are lots of good dynamic mics to choose from, the Shure SM57 is still a great all-rounder. That said, the Sennheiser MD421 is probably the model I'd choose if I had to pick one dynamic mic that would work acceptably well on everything, from vocals and guitar to brass and kick drums. If I was ever stuck on a desert island with no phantom power, the MD421 is the mic I'd choose!

Because large-diaphragm mics will give acceptable results on just about everything aside from a kick drum (I can't bring myself to subject a capacitor mic to those kinds of SPLs!), there's little point in buying a small-diaphragm mic as your first choice unless you intend to specialise in some sort of acoustic instrument recording, such as solo acoustic guitar. In such situations, there may be an advantage in a small-diaphragm model, and in most instances the same mic will still produce perfectly acceptable vocal recordings if used with a pop shield. It's just that large-diaphragm models are often more flattering to vocals than the relative honesty of a small-diaphragm model.

Pop Shield.Pop Shield.Photo: Mark EwingIf you're only going to buy one mic, then a cardioid pattern is the clear choice. Figure-of-eight mics are most useful when you're recording two sounds at once and need to separate them as much as possible — and for this you'd obviously be working with two mics. Nevertheless, if you feel this may be a mic technique that you'll need to explore in the future, it could be worth spending a little more on a mic with switchable pickup patterns.

...But How Much Should You Spend?

If, like many SOS readers, you're doing vocals in a bedroom studio, then pretty much any of the budget large-diaphragm cardioid capacitor models (typically under £150 in the UK) will do a good job — you're likely to run into the limitations of your acoustic environment long before those of the mic itself. Most of these mics are sensitive enough that they'll give good results even with relatively inexpensive mixers or preamps, but always use a pop shield and try to ensure that the space you use to record your vocals is free from excessive room reflections. If used reasonably close to the source, the mic will turn in a good noise performance, even with budget mixer preamps, provided that you take care not to choose a low-sensitivity back-electret model designed for live use. Also, it's worth paying the extra for a proper shockmount and pop shield (though many mics now come bundled with a shockmount) as these make a big difference to the quality of vocal recordings.

Shockmount.Shockmount.Photo: Mark EwingThe same large-diaphragm cardioid condenser mic will serve you well for recording acoustic guitar, electric guitar and percussion. If you're recording a complete drum kit, a single capacitor may give you good results if you have a nice kit in a good-sounding room, but in most situations you'll need multiple drum mics, so if you can buy two of the same model, at least they'll double as stereo overheads. Similarly, identical pairs may also be used to record acoustic piano and I've made a lot of really nice-sounding recordings at my daughter's school, where all they have are four budget Superlux capacitor mics, a Behringer mixer and a Minidisc recorder. Better mics undoubtedly turn in a better performance, but the difference is often less than you imagine unless you happen to be working in a very good acoustic space — the law of diminishing returns applies as much here as anywhere else.

We get lots of enquiries about upgrading microphones to get a better vocal sound, but in most of the cases that we've investigated the most serious limitations to the sound quality are imposed by the recording environment rather than by the mic. You really can make pristine vocal recordings using capacitor mics costing as little as £100 and, in my view, the introduction of affordable capacitor mics must rank alongside cheap digital reverb as the most important factors in enabling project studio owners to make professional-quality recordings on a budget.

If your studio is a step up from the basic bedroom setup and you have a good space for recording vocals, then it's probably worth comparing these lower-cost mics with the mid-priced solid-state models or lower-cost tube mics such as the Rode NTK, Audio Technica AT3060, Groove Tubes GT66 or SE Electronics Z5600 to see if there's a noticeable benefit. Furthermore, if you're choosing a mic for yourself or for a particular vocalist, try to borrow or hire a small selection of mics within your price range so that you can try them in your own surroundings and then pick the one that works best for you. Once you start working with this class of microphone or above, it's probably worth considering getting a good-quality preamp to go with it, as you'll eventually reach a point where the benefits of a better mic are partially negated by the limitations of your mixer's mic preamps.

To be honest, I'd only recommend buying a mic worth £1000 or more in the UK if you are running a commercial studio or if you are preparing vocal tracks in a very well-designed home studio that will be used to complete a commercial release. Having said that, the fact that a good mic can last for several decades if looked after might be reason enough to buy something a little bit special, in exactly the same way as a weekend guitarist might buy a top-of-the-range Les Paul or Fender guitar.

Published July 2003