Audio, hi-fi and car audio - Another sub-bass option

In article , Stewart Pinkerton
wrote:
On Fri, 10 Oct 2003 14:26:48 GMT, "Wally" wrote:

To give you some idea, I use some 11dB of bass equalisation in the
20-30Hz range on a pair of Tannoy 633s that I use for TV sound. These
are 90dB/w/m speakers which take about 3-5 watts of average drive on
action movies with the equaliser out of circuit. When it's in circuit on
a good 'blockbuster' like T2 or U-571, then my Audiolab 8000P, which
puts out a measured 195 watts/channel continuous into 4 ohms, sometimes
clips on the loud stuff...........

Are you sure it is the amp clipping as distinct from the speakers reaching
the end of their travel or becoming nonlinear? - i.e. have you measured the
waveforms when this is happening?

I ask because when I was testing amps at high powers many years ago I often
heard 'clipping' at LF, but tests showed that in many cases the amp output
waveform was fine. It was often the speaker that was running into trouble.
In some cases moderate signal nonlinearity was causing the cones to 'creep'
and this reduced the level at which LF would cause the speakers to 'clip'.
A visual sign was the cones seeming to 'suck in' or 'push out' of the
cabinet as this happened. I have never tried the Tannoys you're using,
though, so the speakers I was using may have been rather more limited in
terms of the cone displacements they could handle.

Slainte,

Jim

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