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FM-531HD / May 2013
F M - 5 3 1 H D P R O G U I
When in the Off position the Multipath Controller is completely out of the circuit.
When the control is at the 100% position the L-R may be permitted to achieve 100% of
the instantaneous L+R audio level. At lesser percentages the amount of L-R energy is
constrained to that percentage of the L+R level at that instant.
A good starting point for this control is 70% which constrains the L-R to about 3dB
below the L+R.
With the Multipath Controller at this setting it will almost never touch “normal” ste-
reo program material – even when stereo enhancement is used. This is in contrast to a
control in another audio processor that has Stereo, -3dB, -6dB, and Mono settings within
its stereo generator control menu. In that product, setting the control to -3dB causes a
static 3dB reduction in stereo separation regardless of the incoming program material!
The Wheatstone approach is more intelligent in how it works; it does not decrease stereo
separation on program material that does not need it.
BS412 MPX Power Controller
The Wheatstone BS412 MPX Pwr Controller has 15 possible
settings, plus OFF: +8dB, +7dB, +6dB, +5dB, +4dB, +3dB, +2dB,
+1.5dB, +1.0dB, +0.5dB, 0, -0.5dB, -1.0dB, -1.5dB, and -2.0dB.
The 0.5dB resolution near the control’s zero setting is to al-
low small adjustments in the MPX Power’s reference level to
compensate for unusual things a user might do to create his on
air sound. Though the MPX Power Controller is not easily fooled
we provided a small amount of tweaking near the “0dB” reference level “just in case.”
To prevent accidental activation of the BS 412 Power Controller, one must Enable
the controller first even before making adjustments from the OFF position.
TURNING ON THE BS412 MPX POWER CONTROLLER
IMPORTANT!
The BS412 MPX Power Controller’s sole purpose is to reduce loudness
and program density. If you are not required to use the BS412 Controller it should
be left in the OFF position because turning it on can cause up to a 5dB loudness loss
when the control is set to its “0dB” position.
When the BS412 control is moved away from its OFF position the MPX Power con-
troller is engaged and the algorithm begins measuring and controlling the processor’s
total MPX power according to the ITU-R BS.412-7 standard. Because the measurement
is essentially an average value integrated over a very long time the MPX Power controller
will not make quick adjustments to the MPX Power when first engaged.
As the controller integrates the MPX energy the drive to the clippers will be modified
until the measured MPX power satisfies the reference level as set by the Stereo Encoder
menu’s BS412 control. The control’s “0dB” setting conforms to the current ITU-R
BS.412-7 Multiplex Power standard.
TURNING OFF THE BS412 MPX POWER CONTROLLER
If the BS412 Controller has been on for more than a few minutes and the BS412
control is set back to the OFF position it will take some time for the MPX Power to re-
turn to an unregulated state. This is because the BS412 controller is not turned OFF by
bypassing it (which could cause abrupt changes in output level!), but is instead defeated
Summary of Contents for FM-531 HD
Page 2: ...Technical Manual Wheatstone Corporation May 2013 FM HD Digital Audio Processor FM 531hd...
Page 122: ...page A 2 FM 531HD May 2013 A P P E N D I C E S Appendix A General Specifications A 3 Contents...
Page 128: ...page A 8 FM 531HD May 2013 A P P E N D I C E S Appendix B FM 531HD GPI Interface A 9 Contents...