Whirlwind MIX-5 manual Theory of Operation, Unconnected

Block Diagram:

Right channel sections and pan pots apply only to the Mix 5 Stereo.

THEORY OF OPERATION

All of the XLR and 1/4” input and output jacks are active, electronically balanced circuits. The input section and all critical gain sections of the Mix 5 use the same IC for gain as top professional mixing boards. This IC, along with careful component selection and PC board layout, enables the Mix 5 to achieve professional quality signal reproduction. All the gain controls o n the Mix 5 (Channel Gain, Aux and Master) have a range of -60 to +20dBm. With the input and output switches in the Line position and both the channel and master volume controls at the same settings, unity gain is approximately at the 9 O’clock knob position, 10dB gain at 12 O’clock, and 15dB gain at 3 O’clock. At the 5 O’clock position the unit provides 35dB of gain. The Mic position of the input switch provides another 20dB for a total of 55dB of gain. This feature allows the Mix 5 to adequately mix equipment with a wide range of audio level outputs. 60dB of attenuation in the Off position allows the Mix 5 to adequately “turn off” line level signals at the Mix 5 inputs.

The output section of the Mix 5 was designed to accommodate any configuration – line or mic level; XLR or ¼”; balanced or unbalanced. Each channel’s

output jacks are individually buffered so that usi ng any combination of the outputs at any impedance will not affect the other outputs. With the Mic/Line switch in the Mic position, the XLR output is reduced 20dB (this switch does not affect the 1/4” jacks). The Mix 5 uses an H-Pad resister network at the XLR to maintain the signal to noise ratio, regardless of the position of the Mic/Line switch. For the XLR outputs, if ground lifting of pin 1 is desired, jumpers JMP 84 and JMP 85 inside the unit can be clipped. Then, in Line mode pin 1 of the XLR is completely lifted and in Mic mode the XLR’s pin 1 is ground isolated and referenced to pins 2 and 3. If unbalanced operation is desired from the XLR outputs, pin 2 is hot, pin 1 is ground, and pin 3 should be left

UNCONNECTED.

The Mix 5 utilizes a dual primary power transformer that is configured with internal jumpers for 120 VAC 60Hz or 230 VAC 50Hz operation. There is an internal fuse on the hot side of the AC cord, and the power switch makes and breaks both the hot and neutral legs of the AC cord.