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921B OSCILLATOR
Installation
The necessary screws are included with the module for mounting
in a Eurorack case. Connect the power cable before mounting.
Depending on the rack case, there may be a series of fixed holes
spaced 2 HP apart along the length of the case, or a track that
allows individual threaded plates to slide along the length
of the case. The free-moving threaded plates allow precise
positioning of the module, but each plate should be positioned in
the approximate relation to the mounting holes in your module
before attaching the screws.
Hold the module against the Eurorack rails so that each of the
mounting holes are aligned with a threaded rail or threaded
plate. Attach the screws part way to start, which will allow small
adjustments to the positioning while you get them all aligned.
After the final position has been established, tighten the
screws down.
Tuning Procedure
This procedure tunes the 921B OSCILLATOR module's
"octave scaling" to an exact 1 V/oct. calibration to facilitate
precise control.
1.
Power up the 921B module and allow it to warm up for a
few minutes.
2.
Prepare the following control settings on 921B:
a. Set the SYNC toggle switch to the center
OFF position.
b. Set the RANGE switch to 2'.
c. Set the FREQUENCY control knob to exactly 0
on the scale.
d. Make sure no 921AB LINK FREQ jacks are connected.
Note: All adjustment trimmers are accessible from the 921B
module's underside. Note the positions of the FREQ ADJ, SCALE,
HI ADJ multi-turn trimmers and the OCT ADJ single-turn trimmer.
Make sure you have suitable tools to adjust the trimmers
if required.
3.
Carry out an initial FREQUENCY control calibration by
adjusting the FREQ ADJ trimmer so that the 921B sawtooth
output shows exactly 640 Hz when checked with an
accurate frequency meter.
4.
Fine-tune the 921B oscillator's low-frequency scaling via
the following steps:
a. Make sure the FREQUENCY control knob remains at 0
on the scale during this procedure.
b. Apply exactly -2 V to a 921AB LINK FREQ input jack.
(A 921A module can be used to supply the -2 V or use
a similar low-impedance stable-voltage source.)
c. Trim the SCALE trimmer to set 160 Hz, then remove
the -2 V input and readjust the FREQ ADJ trimmer
to 640 Hz.
d. Repeat this cycle until both 160 Hz and 640 Hz are
accurate to ±1 Hz when the -2 V is plugged in and
out of the 921AB LINK FREQ input jack.
5.
Fine-tune the 921B oscillator's high-frequency scaling via
the following steps:
a. With no 921AB LINK FREQ jack connected, check the
frequency is still set for 640 Hz output, then apply
exactly +5 V to the 921AB LINK FREQ input.
b. Trim the HI ADJ trimmer to set the 921B sawtooth
output to exactly 20.48 kHz.
c. Re-check that 640 Hz is still correct when the +5 V
input is removed.
d. Repeat as required.
6.
Make a final fine-tune of the RANGE rotary switch scaling,
if required, via the following steps:
a. With no 921AB LINK FREQ jack connected, check the
frequency is still set to 640 Hz on the RANGE knob
2' setting.
b. Set the RANGE switch to 32' and adjust the OCT ADJ
trimmer for 40 Hz at the 921B sawtooth output.
c. Re-check to make sure that 2' = 640 Hz and
adjust the FREQ ADJ trimmer if required.
d. Repeat as required.
Specifications
Signal Connections
Frequency control
2 x 3.5 mm jacks, 1 V/oct.
link inputs
Input Impedance
100 kΩ, unbalanced
Maximum input level
-6 V to +6 V
Frequency range
< 1 Hz to > 40 kHz
Rectangular width
2 x 3.5 mm parellel jacks,
link inputs
1 V/16%
Input Impedance
100 kΩ, unbalanced
Maximum input level
0 V to +6 V
Width range
< 10% to > 90%
Sync input
1 x 3.5 mm jack, AC coupled
Sync input impedance
1.5 kΩ, unbalanced
Sync input lock range
± 6 semitones
Sync input response
10 Hz to 20 kHz, > -10 dBu
Maximum input level
+15 dBu
AC / DC mod input
2 x 3.5 mm jacks,
AC/DC coupled
AC / DC mod
100 kΩ, unbalanced
input impedance
AC / DC mod response
10 Hz to 10 kHz, > -10 dBu
Maximum input level
+4 dBu
Waveform outputs
4 x 3.5 mm jacks, mono
Waveforms
Sine, triangular,
sawtooth, rectangular
Output Impedance
< 800 Ω, unbalanced
Output level
Typically -4 dBu
Controls
Frequency
1 x rotary knob
±12 semitone, selectable
Range
1 x rotary switch
LO / 32' / 16' / 8' / 4' / 2',
selectable
Sync selector
1 x 3-position toggle switch
Weak / off /
strong, selectable
Power
Power supply
Eurorack
Current draw
45 mA (+12 V),
45 mA (-12 V)
Physical
Dimensions
58 x 40 x 129 mm
(2.3 x 1.6 x 5.1")
Rack units
8 HP
Weight
0.14 kg (0.31 lbs)
Quick Start Guide
LEGAL DISCLAIMER
Music Tribe accepts no liability for any loss which may be suffered by any
person who relies either wholly or in part upon any description, photograph,
or statement contained herein. Technical specifications, appearances and
other information are subject to change without notice. All trademarks are the
property of their respective owners. Midas, Klark Teknik, Lab Gruppen, Lake,
Tannoy, Turbosound, TC Electronic, TC Helicon, Behringer, Bugera, Auratone
and Coolaudio are trademarks or registered trademarks of Music Tribe
Global Brands Ltd. © Music Tribe Global Brands Ltd. 2019 All rights reserved.
LIMITED WARRANTY
For the applicable warranty terms and conditions and additional information
regarding Music Tribe's Limited Warranty, please see complete details online at
musictribe.com/warranty.
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