Re: [LAD] [ANN] Invada Studio LV2 Plugins 1.2.0

From: Fraser <fraser@email-addr-hidden>
Date: Sun Aug 23 2009 - 18:38:37 EEST

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Hi Fons

Fons Adriaensen wrote:
> What's the point of using a meter if you adjust it to the signal ?

You are not changing the signal, you are changing the amount of headroom the VU
meter has. http://www.reference.com/browse/wiki/Headroom

To put it simply, 0dB on analogue equipment is indicating the optimal level.
There is an amount of headroom above that level before distortion will occur.

In the digital domain 0dB is the absolute maximum level and distortion occurs at
this point..

So whenever analogue equipment needs to work with digital equipment it is
configured so that 0dB in the analogue domain is at some (hopefully calibrated
and consistent) level below 0dB in the digital domain. The actual value is
arbitrary and depends part on preference and part on the quality of your
analogue gear. So if you elect to have 9dB of headroom on you analogue gear,
then you'd select -9dB on the plugin, and then VU metering 0dB will have the
peak metering -9dB.
- -18 to -9 is common, but I've seen all sorts of things.

> Anyway the meter plugin freezes my machine if the signal is muted
> or removed. Probably due to denormals.

I can't reproduce that.
A clue may help. (distro, arch, kernel, soundcard, host etc).

The plugins have been built on ubuntu studio (hardy) x64
and tested on ubuntu jaunty (x64), Arch linux (x64) & AV linux (x32).

> The VU is not a VU,

Correct since this plugin isn't in the analogue domain. It's a simulant.
It does convey the 'perceived volume' of a signal better than a peak meter and
does help if you are mixing to tape.

> the spectrum doesn't use valid 1/3 octave filters by any standard,

please advise where this standard is.
AFAIK there are just algorithms that simulate the behaviour of electronic RC
circuits with varying degrees of success, and yes I have a munge. Sorry if it
disturbs you.

> and the phase meter doesn't indicate anything useful.

Apart from the relative phase difference between the left and right channels.

With the demise of vinyl the importance of phase has been lost too to some
extent so it doesn't surprise me you don't what this meter is for or what it's
trying to tell you.

On vinyl out of phase signals make the needle go up and down instead of side to
side, this makes the needle bounce out of the groove. Worse still is what
happens when you have low frequency out of phase sounds. The wave length (on the
vinyl) is large enough for the cutter to go through the vinyl... => This is why
everything below 200Hz is mono'd for vinyl during mastering in case you were
wondering.

A quick guide to interpreting the phase meter:
* A mix that never goes +/- 20 is too mono. Pan something. Create some space
with reverb. etc
* A mix that spends all it's time between +/- 45 is as 'wide' as you want to
get. You should able to see some variety in there of course, ie a verse and a
chorus should be different widths.
* If the phase meter spends any time over +/- 55 then audible cancellation will
occur if the mix is mono'd or listened to from a distance.
* Any travel over +/- 60 is trouble, there is something out of phase in the mix.
although this may sound great with your head between the speakers it's going to
suck when heard anywhere else.
* If the meters stays at +/- 90 then the whole mix is out of phase :)

regards,
Fraser

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Received on Sun Aug 23 20:15:01 2009

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