Observing Polarity; Power Amplifiers - Tannoy Reveal User Manual

damping factor, generally a cable with a cross-sectional area of 2.5 mm², or greater is
recommended.
The lower the resistance of the cable between the amplifier and the speakers, the better the
damping factor acting on the speaker. This has been covered in every audio magazine that has
ever been written about speakers, so we won't beat it to death here. You don't need to buy
speaker wire that costs as much as your speakers to get some benefit from wire size, select a
finely stranded speaker cable, and dress the cable ends to prevent "hairs" or stray conductors
from shorting across the terminals. If your amplifier will not directly accept that size of cable, you
can trim down the cable size at the amplifier end. Ensure that the binding post retaining nuts are
screwed down firmly without stripping or over tightening them.

2.4 Observing polarity

You already know about connecting the positive terminal on the amplifier to the positive terminal
on the speakers, and ensuring that both channels are "in phase" by checking to ensure that
there's more bass with both speakers on and not less bass. Absolute polarity is a bit trickier to
confirm. Absolute polarity is the maintenance of a positive pressure wave from the microphone
capsule to the listening room. A kick drum, for instance, has the drum skin whacked by the foot
pedal, and it pushes the air, which pushes the microphone diaphragm, which goes through the
electronics and should eventually come out of the speakers as a positive pressure wave, which
should have the speaker cones moving towards you, just like the drum skin. It turns out that you
can't trust a conventional recorded source to test this because there is no way to confirm that
absolute polarity was maintained, it can even change from track to track. This isn't a trivial thing,
especially when you're using a true stereo microphone setup, or trying to accurately place things
in your mix. This is something that should be rigorously checked with every microphone and
every signal line in a studio, but the first step would be to use the kickdrum test described above
with a few microphones. If you don't believe it can make a difference, set up a little test using a
mix you know and flip the polarity of both channels at the same time, while listening to the same
program...imaging, vague imaging, imaging, vague imaging. Believe it.

2.5 Power Amplifiers

The power amplifier should be reasonably well matched in power to the power rating of the
speakers (see specifications). The use of a powerful amplifier (i.e. in excess of the recommended
figure) provides headroom, which is useful especially for highly dynamic programme materials.
Due of the high peak power handling of Tannoy monitors, responsible use of even more powerful
amplifiers should not represent a danger to the speakers if the amplifiers are not overdriven. Now,
just because you have a Ferrari, it doesn't mean to say you can drive it at the red line all of the
time, it will eventually blow up. Same thing goes here, just because the speakers will handle a
large amplifier, it doesn't mean that you can run them flat out constantly without eventually
blowing something up.