RHYTHM R3710
www.onsemi.com
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the last band, and each one provides up to 24 dB of gain
adjustment in 1 dB increments.
Biquad Filters
Additional frequency shaping can be achieved by
configuring generic biquad filters. The transfer function for
each of the biquad filters is as follows:
H(z) +
b0 ) b1 z
−1
) b2 z
−2
1 ) a1 z
−1
) a2 z
−2
Note that the a0 coefficient is hard−wired to always be ‘1’.
The coefficients are each 16 bits in length and include one
sign bit, one bit to the left of the decimal point, and 14 bits
to the right of the decimal point. Thus, before quantization,
the floating−point coefficients must be in the range −2.0 ≤ x
< 2.0 and quantized with the function:
round
ǒ
x 2
14
Ǔ
After designing a filter, the quantized coefficients can be
entered into the PreBiquads or PostBiquads tab in the
Interactive Data Sheet. The coefficients b0, b1, b2, a1, and
a2 are as defined in the transfer function above. The
parameters meta0 and meta1 do not have any effect on the
signal processing, but can be used to store additional
information related to the associated biquad.
The underlying code in the product components
automatically checks all of the filters in the system for
stability (i.e., the poles have to be within the unit circle)
before updating the graphs on the screen or programming
the coefficients into the hybrid. If the Interactive Data Sheet
receives an exception from the underlying stability checking
code, it automatically disables the biquad being modified
and display a warning message. When the filter is made
stable again, it can be re−enabled.
Also note that in some configurations, some of these
filters may be used by the product component for
microphone/telecoil compensation, low−frequency EQ, etc.
If this is the case, the coefficients entered by the user into
IDS are ignored and the filter designed by the software is
programmed instead. For more information on filter design
refer to the Biquad Filters In Paragon
®
Digital Hybrid
information note.
Volume Control and Switches
External Volume Control
The volume of the device can either be set statically via
software or controlled externally via a physical interface.
R3710 supports both analog and digital volume control
functionality, although only one can be enabled at a time.
Digital control is supported with either a momentary switch
or a rocker switch. In the latter case, the rocker switch can
also be used to control memory selects.
Analog Volume Control
The external volume control works with a three−terminal
100 kW – 360 kW variable resistor. The volume control can
have either a log or linear taper, which is selectable via
software. It is possible to use a VC with up to 1 MW of
resistance, but this could result in a slight decrease in the
resolution of the taper.
Digital Volume Control
The digital volume control makes use of two pins for
volume control adjustment, VC and D_VC, with
momentary switches connected to each. Closure of the
switch to the VC pin indicates a gain increase while closure
to the D_VC pin indicates a gain decrease. Figure 7 shows
how to wire the digital volume control to R3710. The digital
volume control can be setup to adjust both volume levels and
memory configurations depending on the length of time the
momentary switch is depressed.
It is also possible to read and write the digital volume
control with the ARK software. Using these software
functions will lock out the digital volume control until the
next time the hybrid is powered on.
Figure 7. Wiring for Digital Volume Control
D_VC
VC
GND
Memory Select Switches
One or two, two−pole Memory Select (MS) switches can
be used with R3710. This enables user’s tremendous
flexibility in switching between configurations. Up to four
memories can be configured and selected by the MS
switches on R3710. Memory A must always be valid. The
MS switches are either momentary or static and are fully
configurable through IDS in the IDS setting tab.
