JAMO C 803 IW Opuscolo - Pagina 16

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Compared to the conventional conductive rings in a magnet system AIC has the

advantage that it is signiﬁ cantly better at higher frequencies i.e. in the midrange

(on voices) where distortion is most audible to the human ear.

Even though they are visually identical with the mid/woofers, there is a small but

signiﬁ cant difference in the designated woofers for the C 80 ﬂ oorstanders.

Designed to work only at the lowest frequencies, these use a heavy 4-layer voice-

coil, sensitivity at high and mid frequencies is reduced while efﬁ ciency at low fre-

quencies is increased.

This works in two ways: A high B*L product** will increase port output and reduce

bandwidth around port resonance. The increased weight will counteract the in-

creased B*L at higher frequencies. The result is a gain of about 3 dB at low frequen-

cies - or put very simply – a more authentic and powerful bass.

The 6in drivers feature 33mm diameter voice coils while the 7in drivers feature

40mm examples. These oversized voice coils ensure optimum heat dissipation/

power handling as well as full control over the cones.

The combination of magnet size/force and length of the voice coil wire results in the so-called B*L Product.

In popular you could call this the size of the "engine" in a loudspeaker.

(Sub)Woofer

The 10in woofer features a vented magnet system and a 50mm/2in aluminium

voice-coil former. The long 4-layer voice-coil allows linear excursions up to +/-

10mm/0.4in while still retaining more than 80% of the B*L product available! The

maximum excursion possible is more than +/- 15mm/0.6in!

The double magnet system features a vented pole-piece in order to avoid over/

under pressure building up behind the dust cap (mechanical damping) when the

cone is moving.

The cone is made from aluminium making it incredibly stiff and airtight. Try to

imagine the air pressure generated inside a cabinet where the woofers are fed with

1800W... the importance of being airtight becomes rather obvious.

Also, the huge rubber surround allows fast and free movement at its low frequency

working range.

The basket is made of magnesium giving several beneﬁ ts:

First of all it makes it possible to create a very 'open' basket – even behind the spider

– thus ensuring high airﬂ ow at low frequencies, and preventing under-/overpres-

sure causing mechanical losses.

Secondly, as magnesium is a non-magnetic material, the magnetic force from the

magnet does not spread out in the basket, but stays concentrated where it is need-

ed... around the voice coil.