Rane OPT 88 BB 44X Balance Buddy Data Sheet - Page 2

BB 44X BALANCE BUDDY Block Diagram T4 INPUT 1 3 2 1 9 +4 dBu 2 OUTPUT 1 -10 dBV 11 4 T3 INPUT 2 3 2 1 9 +4 dBu 2 OUTPUT 2 -10 dBV 11 4 T2 INPUT 3 2 -10 dBV 9 OUTPUT 3 +4 dBu 3 2 1 4 11 T1 INPUT 4 2 -10 dBV 9 OUTPUT 4 +4 dBu 3 2 1 4 11 OPTION 88 Rear Panel BALANCED WIRING: PIN 2 = POSITIVE PIN 3 = NEGATIVE PIN 1 = CHASSIS GROUND 12 +4 dBu INPUTS BALANCED 1 3 -10 dBV OUT -10 dBV IN 2 4 UNBALANCED 34 +4 dBu OUTPUTS BALANCED BB 44X MADE IN U.S.A. RANE CORP. ACN 001 345 482 OPTION 88 Accessory 56 +4 dBu INPUTS BALANCED 5 7 -10 dBV OUT -10 dBV IN 6 8 UNBALANCED 78 +4 dBu OUTPUTS BALANCED Application Information Conversion Ratio The casual observer would think to convert -10 dBV to +4 dBu, you would need 14 dB of gain. The casual observer would be wrong. You only need 12 dB of gain. The reason is not only do you change levels, you also change reference levels-from dBV to dBu. The first (dBV) references everything to 1.0 volt, while the second (dBu) references everything to 0.775 volts (this comes from the old power reference of 0 dBm, which equaled 1mW into 600 Ω, which equaled .775 volts). Driving Impedances Some people wrongly feel you cannot use a transformer to convert between -10 dBV and +4 dBu because of low impedances. This is not a problem as long as you use them to interconnect equipment with at least 15 kΩ input impedance. Since most professional products have input impedances of 20 kΩ or greater (50k and 100 kΩ are not uncommon), this should never be difficult. A 15 kΩ load winds up looking like 1 kΩ to the equipment with the -10 dBV output (due to transformer action). This may seem excessively low, but is not in practice. The maximum transformer output level of +24 dBu occurs with an input level of +10 dBV, which equals 3.16 volts. And 3.16 volts driving 1 kΩ only requires 3.16 milliamps, which is a very modest requirement for any -10 dBV equipment to deliver. Wiring The BB 44X follows AES/ANSI/IEC standards of pin 2 positive and pin 3 negative. Note the shields (commons) of the RCA jacks are tied for the Inputs and the Outputs but not to each other. This allows ground isolation of stereo Input and Output pairs. A positive signal applied to pin 2 of the XLR connectors causes a positive signal to appear on the tip of the associated RCA jacks, and vice-versa. Signal Direction Signal can be converted through the channels either direction. That means there is the possibility of having four channels -10 dBV unbalanced to +4 dBu balanced, or vice versa (in the standard unit). The only problem arises in the gender of the XLR connector. The solution requires same-sex XLR adaptors or special cables. Chassis Grounding A tapped hole and a #6-32 screw is provided for chassis grounding purposes. Good practice dictates earth-grounding the BB 44X. If the grounding integrity of the rack screws is in doubt, run a wire from this screw to a known earth ground. OPTION 88 The OPT 88 (Option-88) expands the BB 44X into an eight channel model. The OPT 88 consists of a printed circuit board with four additional transformers and jacks soldered in place. The OPT 88 installs easily in the blank side of the BB 44X. Assembly is simple: remove the cover, install the board in place, and secure with the supplied mounting screws. No soldering required; all you need are #1 and #2 Phillips screwdrivers. ©Rane Corporation 10802 47th Ave. W., Mukilteo WA 98275-5000 TEL 425-355-6000 FAX 425-347-7757 WEB rane.com Data Sheet-2 All features & specifications subject to change without notice 1-2014