Can budget radio mics really deliver reliable performance in a gigging environment? PAUL WHITE finds out.

If you're a newcomer to radio mics, the choice and range of products can be very confusing. At one end of the scale, you can buy a complete system for a couple of hundred pounds, whereas at the top end, you can pay well in excess of £1,000 per channel, and still have to pay extra for the mic. You're only trying to do away with a £10 mic lead, so what's the difference?

Leaving aside the question of quality for the moment, you can buy radio mics that work on the VHF (Very High Frequency) band and on the UHF (Ultra High Frequency) band. Budget systems invariably employ VHF technology, because it is cheaper to build. The weakness of VHF, however, is that there is always a possibility of interference from the likes of taxi radio transmitters, CB enthusiasts, and so on. This doesn't happen too often — unless you happen to be working in an unfortunate location — but if you're running a top West End musical, you can't afford to have it happen at all, which is where UHF scores. A well-designed UHF system is significantly less prone to interference, but it is expensive.

A radio mic system comprises a transmitter (usually built into the mic body) and a remote receiver, but the receiver doesn't just pick up signals directly from the transmitter, it also picks up signals reflected from dense solid walls or metal structures. Depending on the position and distance of the reflecting surface, the reflected signal may be in or out of phase with the direct signal, and as you move around the stage, the phase changes. If the reflection is out of phase and is strong enough, it can almost entirely cancel out the direct signal, resulting in loss of signal. In practical terms, this means that you may find certain dead spots in the venue that you have to avoid. If you're not planning to move too far from the receiver, then a little experimentation with the receiver position may be all that's needed to avoid problems. If you have a proclivity for wandering out into the audience, however, it may be as well to check for dead spots during the sound check, and avoid them during the performance.

The usual way to minimise the dead-spot problem is to use a 'diversity' system, an approach which utilises two antennae that automatically switch so the strongest signal is always the one used. The idea is that if the signal strength at one antenna falls, the signal at the other should be OK. By electronically switching to the strongest signal, reliability is increased and the switching process is quite inaudible.

Professional diversity systems tend to use separate antennae that can be positioned in optimum locations, often out of sight, and a good deal of expertise is required in order to set them up for optimum performance — large musicals would use such a system. Low cost diversity systems are available, but to make these usable by non-technical musicians, they tend to come as a single receiver box with two antennae sprouting from it. This takes away the ability to modify the spacing between the antennae, but it is still more effective than a basic non-diversity system and just as easy to use.

Finally, how many mics do you want to use at once? All radio mics interact with each other to some extent, and with budget systems, you probably have a choice of around five operating frequencies. Using more than three at once, however, may lead to problems. For a pub gig where only the lead vocalist and guitarist use radio, this presents no problems, but for a major musical or theatre production with perhaps a dozen or more mics in use at once, the only option is an expensive UHF system. With really big systems, a computer has to be used to calculate the operating frequencies of the various mics so as to avoid interference.

DIVERSIFYING

Having got the basics out of the way, it's time to take a look at the Scanner I and Scanner II systems. Both are DTI approved budget systems, which means they can be used quite legally in the UK with no licence, and they have CE compliance. Scanner I is a non-diversity system whereas Scanner II uses an integrated diversity receiver, and both systems may be ordered with either a hand-held mic or a Lavalier transmitter pack for use with a miniature microphone. The Lavalier pack is also said to be compatible with electric guitars, but a special adaptor lead is required. The technical department at JHS are happy to provide further details in this area.

As you'd expect from the price, the Scanners are VHF systems. They are available with a choice of five operating frequencies: 173.8, 174.1, 174.5, 174.8, and 175MHz. The upper audio frequency range is limited to 15kHz, which is still perfectly adequate for the vast majority of live sound applications, and the built-in compander noise reduction system (something all VHF systems rely on) gives a signal-to-noise ratio of better than 100dB. In addition to transmitting the signal, the microphone (or Lavalier pack) also transmits two pilot signal tones so that the receiver can always tell if the transmitter is in range. The technical term for this kind of system is Pilot Tone Squelch! Normally, when a VHF signal becomes very weak, the sound breaks up into a noisy mess, but with tone squelch, the receiver quietly mutes itself before this happens. You still lose your signal if you go out of range or into a dead spot, but at least you do it gracefully!

SCANNER I

Outwardly similar, the main difference between the two receivers is that Scanner I has blue trim, the Scanner II red. Both are packed in a tough carry case along with the mic, a jack lead, antennae, and receiver power supply.

Scanner I is the simplest of the two systems. After fitting the telescopic antennae's BNC connector, it's just a matter of plugging the unbalanced jack lead between the receiver and your mixer, then switching everything on. A level control on the rear panel allows the signal level to be matched to the mixer. A red LED on the front panel confirms that a suitably healthy RF signal level is being received, while a green LED flickers when an audio signal is present. When the 9V battery in the mic starts to run low, a red LED on the mic body flashes to warn you.

The mic itself uses an Audio Technica dynamic, cardioid capsule and compares favourably with other high quality dynamic vocal mics in the £100 to £150 range. Installing the battery is easy, but it is essential to remember to switch the mic off after use as the battery life is only a few hours. Alkaline batteries are preferable as they give the longest life — rechargeables are generally considered unsuitable for radio mic applications. Unlike earlier radio mics, there is no protruding antennae or wire tail.

SCANNER II

Scanner II is a little more expensive than the Scanner I because of its diversity mode of operation. It also has a few more operational features, including both unbalanced jack and balanced XLR outputs. Additionally, there is an audio-in link allowing you to mix in the output from another radio mic (or other line source), on those occasions where you find yourself one mixer channel short. A similar link provides DC power to a second unit.

A tiny rear panel control sets the audio output level, and unlike its cheaper relative, Scanner II can also be switched between mic and line output levels — good news for those using multicores which are only connected to the mixer mic ins. A second control adjusts the squelch level, although in normal use, there seemed to be no reason to change this setting.

Front panel metering is rather better than on the Scanner 1, with a 5-LED signal strength meter and a 5-LED audio level meter. However, on the review sample, the audio level meter didn't work at all — presumably due to an electrical fault. Two further LEDs monitor the active channel of the diversity system so that you can observe the signal switching as it occurs when you move into potential trouble spots.

TESTING TESTING

Both systems were trouble free in operation. I was rather surprised that there were no proper operating instructions provided, all you get is a single sheet of paper which is little more than a spec sheet. Usually you'll just be able to plug in and go, but advice on things like receiver positioning, checking for dead spots, and what to do with the squelch knob would be helpful.

The receiver remains dead until you switch on the mic, after which the mic's red LED flashes once, then you're in business. A compander circuit keeps the background noise during pauses to a very low level, but just like compander tape noise reduction systems, you can sometimes hear a little noise coming up underneath the sound you're miking. This effect, known as noise breathing, is only a problem if the sound source is unusually quiet. In a typical gig situation where the mic is being used fairly close to the mouth, it shouldn't present a problem.

As to overall sound quality, the mic sounds pretty much like a direct wired dynamic model, having a nice combination of warmth and projection, with reasonable top end detail. Overloading the system is unlikely unless you put your lips right on the mic and bellow as hard as you can. I was also surprised by how far I had to move from the transmitter to get out of range. The budget Scanner I worked reliably at well over 20 metres, even with a couple of walls in the way. Dead spots didn't start to appear until the mic was close to the extremes of its range. Scanner II was predictably more resistant to dead spots, and the improved metering gave a good clue as to the quality of reception at all times. In terms of tonality and noise breathing, both models sounded identical to my ears.

"... the performance of both systems is really very solid..."

SUMMARY

Competition is really hotting up in the budget radio mic market, and the standard of performance is very much better than in previous years. The days of dodgy, illegal radio mics are over. Although the new budget systems don't perform to the same standard as top-end pro radio systems, they do deliver 'near-cable' quality, with surprising reliability providing you respect their range limitations and don't try to finish the last waltz from the far side of the pub car park!

Any criticisms of the Scanner systems must be viewed in the light of price. Personally, I have to admit to disliking external mains adaptors on any equipment intended for live use — it's too easy to pull out the non-locking connectors and the cables are too fragile. It's probably also fair to point out that these receivers are very small and light, so you have to be careful to put them somewhere that they're not likely to get knocked off or dragged away by the weight of the output cable.

As for the Lavalier system (see box), this is equally functional. It does include a respectable tieclip mic, but given the number of guitar players desperate to escape their leads, it seems crazy that the range doesn't include either a dedicated guitar transmitter or, at the very least, an off-the-shelf adaptor cable. Other than that, the performance of both systems is really very solid; there's plenty of range with only the merest hint of 'noise breathing' sneaking in occasionally.

If you want to escape from the limitations of your lead without sacrificing your sound, this is a very cost-effective way of doing it. If your budget will stretch to it, go for the Scanner II — not least because of the improved metering and greater tolerance of difficult environments — but if not, the Scanner I is a solid little performer for use in less demanding situations.

We'll be looking at a number of similarly priced systems over the next few months.

As an option, the Scanner systems are available with a compact transmitter pack and a miniature tie-clip mic — the L1. These so-called Lavalier systems (named after the Frenchman who thought that hanging a mic around his neck on a piece of string was sufficiently original to earn him a place in the audio history books!) are more often used in theatres or by stand-up comics and suchlike, where the mic is required to be unobtrusive. Such a system may also be a guitarist using a radio link on the guitar, although the mic would need to be fixed to a headset to keep it close to the mouth or, ideally replaced by a dedicated headset mic.

Like the mics, the transmitter pad has no 'rat's tail' and is operated from a 9V battery.