[linux-audio-user] Linux music editor, greater than 32-bit ?

[Paul Winkler]

On Tue, Feb 27, 2007 at 10:43:39AM +0100, Arnold Krille wrote:
> You have amps and speakers doing 120dB? Show them to me.

Are you talking sound pressure level, or dynamic range?

It's really not hard to reach 120 dB SPL at close range.  I own a bass
cabinet and an amplifier that I could, if I chose, drive to 130 dB SPL
at 1 meter, and be well within the system's limits.

The cabinet is rated at 103 dB at 1 watt / 1 meter, and has impedance
of 4 ohms, and maximum continuous power handling of 1000 watts.  My
amplifier can deliver 800 watts at 4 ohms. You get roughly 3 dB per
doubling of wattage, so let's see: 1 watt << 9 = 512 watts is well
within the system's limits, and that puts the SPL at 103 + 9 * 3 = 130
dB at 1 meter. You could back away to 3 meters and still be at roughly
120.

Dynamic range, though... highly doubtful :-) I do not know what the
noise floor of my system is, but at those settings I'd guess it to be
at least 20 dB SPL with no input connected, and this is a very good
"quiet" system.  With a bass guitar connected (humbucking pickups),
forget it... the noise floor skyrockets, I would guess it to be well
over 40 dB. These are just guesses. The manufacturer rates the
amplifier's noise at "-85 dB or better".  A popular brand of
professional power amps rates their noise level at -107 dB, but that's
just a power amp... add a complete system and you'll get a lot more
noise (mine includes a preamp with equalizer).

> Most time when I try to reach that dynamic range (with my home
> stereo or with a professional) PA I get several problems:

Your comments below again seem to mix up dynamic range with sound
pressure level.

> - Neighbors banging on the door because of the loud passages in the
> music.

agreed :) but that's purely SPL.

> - Listeners complaining about not hearing anything in a silent
> passage after 2 minutes of 100dB.

agreed :)

> - To small mainlines to get the current for powering 120dB(A).

Again, that's just SPL.  And it depends on the amplifier. Mine is a
class D system that draws about 1000 watts at maximum rated output, or
roughly 8 amps at 120 volts AC. A standard 20-amp household circuit
can easily handle that, unless it is already pretty heavily loaded.

> - To small budget to be anywhere near 120dB dynamic range.

agreed :) The noise floor is going to be high.

120 dB dynamic range is an incredible amount, it corresponds roughly
to the difference between whispering and a rifle fired at 1 meter.
Even the humble CD can capture the difference between whispering and a
chainsaw.

And please remember folks, even 85 dB SPL can be enough to damage your
ears with long-term exposure.

-- 

Paul Winkler
http://www.slinkp.com