Behringer 921B OSCILLATOR Quick Start Guide - Page 2

2 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. S et 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. M ake 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. R epeat 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. W ith 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. W ith 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 link inputs Input Impedance Maximum input level Frequency range Rectangular width link inputs Input Impedance Maximum input level Width range Sync input Sync input impedance Sync input lock range Sync input response Maximum input level AC / DC mod input AC / DC mod input impedance AC / DC mod response Maximum input level 2 x 3.5 mm jacks, 1 V/oct. 100 kΩ, unbalanced -6 V to +6 V < 1 Hz to > 40 kHz 2 x 3.5 mm parellel jacks, 1 V/16% 100 kΩ, unbalanced 0 V to +6 V < 10% to > 90% 1 x 3.5 mm jack, AC coupled 1.5 kΩ, unbalanced ± 6 semitones 10 Hz to 20 kHz, > -10 dBu +15 dBu 2 x 3.5 mm jacks, AC/DC coupled 100 kΩ, unbalanced 10 Hz to 10 kHz, > -10 dBu +4 dBu Waveform outputs Waveforms Output Impedance Output level Controls Frequency Range Sync selector Power Power supply Current draw Physical Dimensions Rack units Weight 4 x 3.5 mm jacks, mono Sine, triangular, sawtooth, rectangular < 800 Ω, unbalanced Typically -4 dBu 1 x rotary knob ±12 semitone, selectable 1 x rotary switch LO / 32' / 16' / 8' / 4' / 2', selectable 1 x 3-position toggle switch Weak / off / strong, selectable Quick Start Guide 3 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. Eurorack 45 mA (+12 V), 45 mA (-12 V) 58 x 40 x 129 mm (2.3 x 1.6 x 5.1") 8 HP 0.14 kg (0.31 lbs)