[sdiy] "Time Winding" in Audio Cables ???

[Richard Wentk]

At 20:22 11/07/2005, Magnus Danielson wrote:

>You loose alot of dynamics that way. You need larger amplitude for the same
>effect etc. If you would run two-way or three-way active crossover with
>suitable amplifiers you would have less total amplifier effect for the same
>overall soundlevel than a single amp with passive filter. There are many
>benefits for going this path, at the cost of spending money on several amps
>rather than a single amp.

And... triamping will always sound better for other reasons too.

> > But it's interesting that there are so few active designs around, with -
> > say - the speaker/filter in a feedback loop to try to minimise distortions.
>
>????
>
>An active filter sits before the amp, dealing with signal-level signals.

I didn't mean that kind of active. The Philips idea was based on some kind 
of servo control concept. Now, this was 30-odd years ago so I'm not clear 
on the details, but it was either based on fairly simple feedback (more 
likely...) or some kind of active measurement of cone position (less likely).

In fact the latter couldn't possibly work because cones are never perfectly 
stiff and you'd have to work out some kind of monster transfer function 
that mapped cone position to actual pressure dynamics under different 
loading and transient conditions.

You could probably do this today with some hefty DSP power, but it's - at 
the very least, I'd guess - a three year PhD project, just to characterise 
the details of the problem, never mind solve it.

>Actually, I've designed two-way and three-way systems with ampracks well
>separated from the speakers. Cables included! ;O)

I'd have been a lot more impressed if you'd made a system that eliminated 
cables altogether. Now *that* would be cool. :)

Richard