[PlanetCCRMA] ardour error

Steve Harris S.W.Harris@ecs.soton.ac.uk
Tue Jan 25 01:23:01 2005

On Tue, Jan 25, 2005 at 12:09:19 -0600, mike@banta.psyc.missouri.edu wrote:
> OK, sorry guys.  Every subsequent name I saved under worked fine??
> While I'm bothering you kind folk...Can someone tell me how much I should 
> trust the audio meters in Ardour?  Because, even when all individual 
> tracks stay under zero, and the master does as well, I still here what 
> sounds like clipping at the output.  This seems to be concurrent with 
> peaking of the sum of all tracks, rather than an individual one.  Also, my 
> preamp has a hard limiter on it at 0, which goes into a delta44..so input 
> should be ok, espically since ardour's input meters never go above -3.
> So, should I need to keep ardour's master well under "0"?  And when 
> mastering with jamin, can I trust those meters? Are there any meters I can 
> run through jack which can be trusted?  

Yes, you can trust the JAMin meters, I wrote the meter code and will vouch
for it. :) There is actually a small bug in the current version in the
planet, but it only bites between -50 and -60 dB.

If the output meters in JAMin are below 0 dB you should not have clipping.

You may well have a level mismatch, 0dB in analogue space should map to
-20dB on DA converters according to SMPTE. Most converters are set more
conserviativly than that, but still if you have an analogue limiter you
will need to set it well obove 0dBu or dBv to prevent clipping from a
0dBFS JACK sourced signal.

Other meters you can trust are in meterbridge, that also has a mode where
you can correct for SMPTE (or less) level conversions if you have them,
and you prefer working in non FS scales.

- Steve