An FM Tuner is Still a Vital
Audio Component
In spite of all the exotic digital componentry available
these days, most of us spend a lot of our time listening to the radio, usually analog FM
stations nowadays, and for that we still need something to pull in the signal.
In most situations, even a minimal FM tuner is all that's
required. And, in fact, tuners don't vary much in the sort of performance they offer. Most
tuners are built into a broader component, such as an audio receiver or a mini-system.
Still, difficult listening locations or peculiar requirements (like the need for dozens of
preset stations) might well lead you to a more ambitious stand-alone unit. Either way, the
considerations are basically the same.
Most FM tuners work well in most situations, but if you
live far away from your favorite station, or if what you want to hear is crowded up
against something you don't on the FM dial, differences in sensitivity and selectivity may
be important. Both factors often work together both to pull in distant stations
(sensitivity) and reduce interstation interference (selectivity). In the first case, low
numbers are best; in the second, go for higher values.
To a point, FM radio reception is insensitive to signal
levels: as long as there's enough reaching the antenna terminals, the signal-to-noise
(S/N) ratio will be good, and increasing level won't improve it. Below a certain level,
however, noise increases dramatically, especially in stereo, which is inherently noisier.
"Quieting" is an arbitrarily chosen S/N ratio, usually 50dB nowadays; tuner
manufacturers specify the minimum signal needed to achieve that level, the lower the
better. There are various ways to state this level, the most useful being "dBf."
Levels of about 12dBf in mono or 36dBf in stereo are excellent.
At the other end of the scale is a condition called
"front-end overload," where signals come in so strongly that they overwhelm the
tuner and cause gross distortion. One common symptom is that a particularly troublesome
station will pop up at a number of different places on the dial, usually badly distorted.
There's no one spec that will tell you whether a tuner is prone to this problem, but if
you get it home and experience this sort of overload, it's safe to assume the tuner is not
very well designed, and should be replaced.
There's another sort of overload that sometimes plagues
tuners. What we're talking about here is unnecessarily elaborate features. More than a
handful of preset stations, for instance, is probably too many -- how many stations do you
listen to regularly? And how difficult is it to tune in a new one now and then? Some tuner
makers seem to think it's a pain, and offer massive memory and various auto-tuning
schemes. They do work, and if you really need them, fine. But they also cost money, which
might well be better spent elsewhere in the system.
It's natural enough to drool over the massively expensive
equipment that holds a place of honor in the audio store, but basically gathers dust.
There are some truly awesome tuners out there, and if you can afford the really exotic
stuff, you can be assured that they perform superbly and will be a worthy part of a
high-quality sound system. But less-expensive equipment generally performs just as well;
what differences there are never have very much relation to the differences in cost. When
it comes to straightforward components like tuners, you should use your money to buy extra
features (if you need them), and take a very high level of performance for granted.
Central components like FM tuners tend to be fairly
self-sufficient, so add-ons and maintenance products are usually not required. It may be
necessary to provide some form of antenna other than the T-shaped dipole supplied with
most tuners, but you won't be able to tell that until you have taken the tuner home and
tried it out.
...Ian G. Masters
ian@mastersonaudio.com
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