[sdiy] Re: crystal clear

[Magnus Danielson]

From: "Czech Martin" <Martin.Czech at Micronas.com>
Subject: RE: [sdiy] Re: crystal clear
Date: Mon, 12 May 2003 17:44:30 +0200

> don't forget that the average power spectra of 
> classical music look different from
> electric instruments music, and certainly different
> for "academic" electronic music, where perhaps
> sine waves bounce arround, causing unusually high
> power at 1kHz and above.

Well, first of all I wanted this part of the discussion just to establish how
things hook together without confusing them up with power-spectra aspects.
For the discussion of why you loose in the dynamics (need of unnecessarilly
large amp) you don't need the argument of relative power between frequency
ranges.

Those would reflect themselfs in how much power we think we need for bas, mid
and top (and possibly also subbas), and this is then even further becomes more
complex when we consider the cross-over points if we want to be very scientific
about things.

Normal rock music and classical music isn't that far of each other actually.

> Some PA systems can not really deal with sine
> wave compositions, because of power and
> distortion, well , at least those that I had
> for my stuff.

Actually, quite many PA systems are crap, that's true. When you learn for
instance how you should have dimensioned the passive filter setup, you directly
start to understand why you so easilly run into distorsion with them, *easier*
than if you had used smaller amps totalling with the same power as the single
big amp. Now, toss in that people tries to save in on amplifier costs and you
don't even have to start breathing before your started. Then, on top of that,
the system is not very "clean" in responce, so you have big resonances and
zeros (swallowing of energy) in the range where the music moves around (which
is an area of the s-plane, just to help confuse the hell out of people).

This is why it is important to establish a set of ground rules so that people
understand it well and is able to make correct judgement of existing systems.
Good PA systems comes from a line of painfull insights followed by a long line
of experimentations. The field is actually more complex than the competence of
most people in the field. PA systems can even be more complex from a systems
design viewpoint than many other systems. You have large powers, big dynamics
(about 110-130 dB), large range of frequencies (9-10 octaves), impulse-signals
(and not steady state), fairly uncontrolled environment (you move the system
around, temperature-effects like the Haas effect, damping of amount of people),
3 dimensional impulse responce problems and usually a very tight budget. It's
just very complex and takes time to grasp it all.

Cheers,
Magnus