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Overview I/O Connections

 

 

· MIC In

Accepts low impedance balanced signals between -70 and +14 Nominal level. Phantom power is

provided via the front panel +48V switch. Internal provisions are available for phantom voltages up

to +300 VDC. Shield is carried to Pin 1 via the power ground internally for phantom purposes.

The shield connection of the XLR is made via the chassis connection internally.

· Line In

Nominal level is between -10 and +14. No provisions are made for phantom power and

system will accept balanced or single ended signals. Shield is expected to be served by the driving source, and is internally lifted. If desired, there is a

jumper available to provide shield connection to Pin 1.

 

· Insert Send

The nominal signal level is -10. The signal is balanced, but may be used as single ended. A TRS plug should always be used. Tip is hot, Ring is minus and the shield is served on the sleeve.

· Insert Return

Nominal signal level of +4. Located at the input of the gain cell, this is the input of the limiter, bypassing the mic preamp and associated circuitry. Input is balanced. See above note regarding headroom. This signal is normalled to the side chain input

· Chassis Gnd (Green)

The chassis ground connection provides the ohmic contact to the enclosure of the BA-660. This signal is also the conductor present at pin 1 of both the line in and the line out. Inside, this line is tied directly to the 3rd pin of the IEC Power entry connector. When the unit is operated with the 3rd pin of the AC cord connected, The link that is supplied should be used to connect the signal ground and the chassis ground together. In this configuration, no other studio grounds should be used.

NOTE-

The circuitry associated with the insert send and return is bypassed when not in use,

(the bypass circuitry senses either the presence of a jack in the insert return

connector or the position of the front panel switch. When active, this circuitry is the limiting factor in the system headroom.

· Side chain input

Nominal signal level of +4, balanced input, normalled source from the insert return circuitry. Provides access to the control circuitry for use in Deessing or Ducking.

· Side Chain Couple

Provision for coupling multiple units. Both source and input are carried via this port, and the signal at this port is the active DC control line. The signal(s) are summed on this port and it should only be used with other BA-660 limiters. The protocol for direct operation of the gain cell is available upon request from the manufacturer.

· Line Output

The line output is a balanced and floating solid state class A type power stage that can have either leg taken to ground without degradation of either headroom, gain, distortion or noise. Care must be take however to select the correct polarity to be grounded with the Un-Balance switch on the rear. The ground will be taken at the output of the unit, and should not be take at the input to a single ended device. Rather, wire as balanced and have the single ended input pick up it's reference from the output of the BA-660. The shield is source’d at pin 1 of the XLR. Pin 2 is wired as plus (+) and Pin 3 is wired as minus (-)

· Signal Gnd (Black)

This is the ohmic contact to the technical earth of the BA-660 and ties via a #12 cable to this point. If any studio grounds, aside from the 3rd pin of the power cord are supplied, they should be referenced to this binding post. The link should be removed when the 3rd pin is attached as well as the studio ground wire. If the 3rd pin is not attached, and the link is lifted, severe hum is likely. There is a small degree of safety provided by 2 cross shunting diodes and a .047m cap that internally ties these two points together.

 · AC Input

The IEC power input connector ties to a small PC board internally that carries a 2 Amp Slo Blo 3AG fuse and voltage selection to accommodate an input voltage range of 90 to 250 VAC. Refer to the schematic diagram for the appropriate switch settings outside of the US.