Behringer 921 VOLTAGE CONTROLLED OSCILLATOR Quick Start Guide - Page 2

2 921 VOLTAGE CONTROLLED OSCILLATOR 3. Insert the 10-pin connector into the socket on the back of the module. The connector has a tab that will align with the socket for correct orientation. 4. After both ends of the power cable have been securely attached, you may mount the module in a case and turn on the power supply. 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 921 VOLTAGE CONTROLLED OSCILLATOR module's "octave scaling" to an exact 1 V/oct. calibration to facilitate precise control. 1. Power up the 921 module and allow it to warm up for a few minutes. 2. Prepare the following control settings on the 921 module: a. Set the SCALE toggle switch to the ±12 SEMI position. b. Set the RANGE toggle switch to the AUDIO position. c. Set the RANGE rotary switch to 2'. d. S et the FREQUENCY control knob so that the sawtooth output is exactly 640 Hz as measured with an accurate frequency meter. e. M ake sure none of the FREQUENCY CONTROL INPUTS jacks are connected. Note: All adjustment trimmers are accessible from the 921 module's underside. Note the positions of the SCALE and HI ADJ multi-turn trimmers, and make sure you have suitable tools to adjust the trimmers if required. 3. Fine-tune the 921 oscillator's low-frequency scaling via the following steps: a. A pply exactly -2 V to a FREQUENCY CONTROL INPUTS input jack. (A 921A module can be used to supply the -2 V or use a similar low-impedance stable-voltage source.) b. Trim the SCALE trimmer to set 160 Hz, then remove the -2 V input and readjust the FREQUENCY knob to 640 Hz. c. 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 FREQUENCY CONTROL INPUTS jack. 4. Fine-tune the 921 oscillator's high-frequency scaling via the following steps: a. W ith no FREQUENCY CONTROL INPUTS jack connected, check the frequency is still set for 640 Hz output, then apply exactly +2 V to the FREQUENCY CONTROL INPUTS input. b. Trim the HI ADJ trimmer to set the 921 sawtooth output to exactly 2.560 kHz. c. Re-check that 640 Hz is still correct when the +2 V input is removed. d. Repeat as required. Specifications Signal Connections Frequency control inputs Rectangular width control inputs Input Impedance Maximum input level Clamping point trigger inputs V-trig input impedance S-trig input impedance Maximum input level Auxiliary outputs Output Impedance Maximum output level Waveform outputs Waveforms Output Impedance Output level Controls Scale Coarse range 3 x 3.5 mm jacks, summed, 1 V/oct. 2 x 3.5 mm jacks, summed, 1 V/15% 100 kΩ, unbalanced -6 to +6 V 2 x 3.5 mm jacks (1 x V-trig, 1 x S-trig) 10 kΩ, unbalanced 30 kΩ, unbalanced +12 V 1 x 3.5 mm jack, mono, +/- polarity 50 Ω, unbalanced +10 dBu 4 x 3.5 mm jacks, mono Sine, triangular, sawtooth, rectangular < 800 Ω, unbalanced Typically -4 dBu 1 x toggle switch ±6 octaves / ±12 semitone, selectable 1 x toggle switch Sub-audio range, typically 0.01 Hz to 800 Hz Audio range, typically 1 Hz to 80 kHz Frequency Range Rectangular width Clamping point Aux out waveform Aux out level Power Power supply Current draw Physical Dimensions Rack units Weight 1 x rotary knob ±6 octaves 1 x rotary switch 32' / 16' / 8' / 4' / 2' / 1', selectable 1 x rotary knob 10% to 90%, selectable 1 x rotary knob 10% to 90%, selectable 1 x rotary switch Sine / triangular / inverted sawtooth / sawtooth / rectangular / inverted rectangular, selectable 1 x rotary knob Off to +10 dBu, selectable Eurorack 50 mA (+12 V), 50 mA (-12 V) 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. 2020 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. Zhongshan Eurotec Electronics Limited No. 10 Wanmei Road, South China Modern Chinese Medicine Park, Nanlang Town, 528451, Zhongshan City, Guangdong Province, China 45 x 71 x 129 mm (1.8 x 2.8 x 5.1") 14 HP 0.18 kg (0.40 lbs)