SpectraFoo Rad 3 f17 Release Notes
This release is being made freely available to all registered
users of MLM, SpectraFoo and SpectraFoo Complete, just as all previous
updates to the SpectraFoo Range have been. This release contains two primary
enhancements. The first enhancement is a compatibility addition. The second
enhancement is a feature addition. We recommend that all customers update
to this version of the software.
The first enhancement is a compatibility addition: the TDM version of SpectraFoo now fully supports RTAS. This has two significant benefits for Pro Tools users:
The TDM updater will automatically replace the Plug-in with
the updated Universal/RTAS version of the SpectraFoo plug. This version
of the plug supports Merle ("Classic") DSPs, MIX DSPs, and RTAS.
You can now install MLM, SpectraFoo and SpectraFoo Complete for use with Pro Tools LE and Pro Tools Free.
You can now install or update MLM, SpectraFoo and SpectraFoo Complete for use with Pro Tools 5.1 and take advantage of RTAS instantiation in Pro Tools 5.1 to use SpectraFoo Metering without using any DSP. When used in this mode there may be signal routing limitations.
The second (and most significant) enhancement is the addition
of full, elegant support for the K-System metering system as defined by
Bob Katz. For a detailed description of the Metering System and its motivations,
please see Bob's Paper "An Integrated Approach to Metering, Monitoring,
and Leveling Practices" that appeared in the AES Journal. You may be able
to find other relevant (and not-so relevant to the K-System but interesting
and useful) information at his website <http://www.digido.com/>
While SpectraFoo provided all of the components to implement
the spirit of the K-System, it was not elegant. There are four issues that
needed to be addressed in order to implement support for the K-System:
All the issues have been resolved in cooperation with Bob
Katz. We have included K-20, K-14, and K-12 presets for the meters and
K-20, K-14, and K-12 signal generator presets for calibration. The K-meter
options may be used independently of each other to build other meters that
are not fully K-System compliant by may still be useful and interesting
in other contexts.
Native support for dbFS referenced K-20, K-14, and K-12 scales
needed to be added. This is required to allow consistent representation
of the 0 dB mark, which is important to the standard. In addition, the
standard sets out tick positions and labels. The K-scales implemented by
this version of 'Foo meet the specification.
The specification defines hard transitions in the color of
the RMS level bar. SpectraFoo only supported soft transitions. The color
transition mode is now a user selectable option in the Meter Options control
window. The K-System presets included with this release automatically set
the option to use hard transitions.
The specification is based upon the AES-17 standard for metering
practices. In this standard the reference level used for calibrating a
meter is directly related to the reading on the meter when the reference
signal placed into the meter. What this means is the specification defines
that a Peak Reading Meter will read 0dBFS when a 0dBFS amplitude sine wave
is placed upon its input. It also defines that an RMS reading meter will
also read 0 dBFS when it is fed the same sine wave signal. SpectraFoo has
always used the same scale for both Peak and RMS. This means that the RMS
level for the sine wave described above will be -3.01 dBFS. SpectraFoo's
RMS level reads 3.01 dB low when compared to AES-17 calibrated meters.
This is essentially a "po-tay-toe" vs. "po-tah-toe" issue, as long as the
definition is well understood by the user of the meter. However, this issue
has caused confusion in comparing studio calibrations and makes it impossible
to fully calibrate SpectraFoo to the K-System since the K-System simultaneously
specifies both peak and RMS calibration. In order to allow a full implementation
of the K-System (and, additionally, full support for AES-17 calibrated
RMS metering) we have added a user option to apply the 3.01 dB correction
to the RMS levels in the meter. This option is automatically selected by
the K-System presets.
The K-System specifies that the monitoring system must be
calibrated with pink noise so that 0 dB K is set to 83 dBC SPL. SpectraFoo
Complete provides a highly accurate wideband pink-noise source via the
integrated Signal Generator. This source may be used for monitor system
calibration. Previous versions of SpectraFoo Complete allowed the user
to set the output level of the Pink Noise via its peak amplitude. The K-System
specifies the level of the calibration signal in dBFS RMS. We have added
a RMS checkbox to the signal generator to allow you to set the pink noise
amplitude in dBFS RMS. We have also included 3 new signal generator parameter
files to allow easy monitoring system calibration for K-20, K-14 and K-12.
A configuration tip: In the meter options window: you
can click on the numerical readouts to "popup" a text-entry box. This allows
you set the parameter value precisely. We will be propagating this interface
feature (or a similar implementation) to all of the controls in the various
instruments in SpectraFoo in a future release of the Software. You can
use this feature to create derivative slow forms of the K-meters for calibration.
You would want to set the VU settling time from .600 s to 6 s for a slow,
long term average.
If you calibrate your monitor system according to the
K-System recommendations, you can configure SpectraFoo's global level calibration
to provide SPL readouts using the SpectraFoo scale. To do this use the
SPL reference offset, e.g. for K-20, -20dBFS RMS Pink = 83dB SPL, so 0dBFS
RMS Pink = 103dB SPL. In the global level calibration (Menu Path: Analyzer->Level
Calibration...) make 0 dBFS = 103 dBu and then ignore the dBu -- the reading
is SPL when you configure a meter with the SpectraFoo scale and select
the AES-17 compatibility mode (use the Meter Options).
NOTE: If you install this update using the updater your
signal generator parameter files get moved to the Metric Halo Moved Items
folder. Depending on your Mac system prefs, the Standard File dialog stays
"stuck" to the folder, even after it has moved. So, when you go to open
the file, it shows you the old files, which are, of course, the same as
the new files minus the K-System files. After you mess around enough, you
wind up resetting the Mac OS internal preference and you start seeing the
proper folder in the Standard File Dialog. Make sure you navigate to the
correct folder or open the file by double-clicking in the Finder.
Metric Halo would like to extend Special Thanks to
Bob Katz for reviewing this implementation of his specification.
Go to update download area
Copyright ©2001, Metric Halo Distribution, Inc. All
SpectraFoo is a trademark of Metric Halo Distribution.
Pro Tools, TDM and RTAS are trademarks of Digidesign, a division of Avid,