Setting the Correct Gain Structure

ENGLISH

You’re now ready to establish the correct gain structure— the key to getting the best performance from the TM500, or from any mixer, for that matter. This is a simple procedure that ensures optimum input and output levels so that no unnecessary noise (caused by too low a signal) or overload distortion (caused by too high a signal) is created. Here’s a step-by-step description of how to do so:

a.With all connections made (as described in the previous section) but with the power off, bring all channel faders and the left-right stereo faders completely down (to their “∞ ” setting).

b.Turn all mono channel Trim controls fully counterclockwise and place both stereo channel Trim switches to their leftmost “+4 dB” setting.

c.Place all channel equalizer knobs in their center detent “0” positions and turn off the seven-band graphic master equalizer by setting the EQ On/Off switches to their “Off” (up) position.

d.Set the Meter/Headphone Source switch up (to its “L/R” position); this will ensure that the TM500 meter shows the continuous level of the Left/Right stereo output signal.

e.Turn all channel Aux Send knobs and the main section Aux Return knobs to their fully counterclockwise (“∞ ”) position. Turn the main section Tape In and Rev To Aux 1 knobs to their fully counterclockwise (“∞ ”) position.

f.Set both main section master Aux Send knobs to their “0” (2 o’clock) position.

g.Power up all devices connected to the TM500 channel line inputs and Aux Returns and set their level controls to unity gain or, if there is no unity gain indicated on their output control, to maximum. If you’ve got outboard effects processors connected to the Aux Returns, make sure they are sending completely “wet” (processed) signal, with no “dry” (unprocessed) signal mixed in.

h.If condenser microphones are connected to the TM500, turn on the Phantom switch.* Finally, turn on the TM500’s main power.

i.Play an instrument connected to one of the TM500’s line inputs** and, while doing so, raise the corresponding channel fader to the “0” position. You should see the segment meter begin to move— adjust the input Trim control for that channel so that the “0” segment lights frequently and the “+3” segment lights only occasionally. The Peak LED for that channel should not flash at even the highest level input signals. If the incoming signal seems too hot even with the input channel Trim all the way at its minimum

(+14 dB) setting, you may need to lower the output level of the instrument, though this will rarely occur. Conversely, if the signal is too low even with the Trim all the way up, something’s definitely wrong: in all likelihood, the connecting audio cable is faulty.

j.Once you’ve set the optimum level in step (i) above, continue playing the instrument and slowly raise the stereo left/right faders until you reach the desired listening level.

*CAUTION: Before turning phantom power on, be sure to verify that all connected mic(s) and/or active DI boxes require 48 volts. Also, disconnect all other signal sources (such as passive DI boxes) from the XLR mic jacks.

**If you’re using an instrument such as electric guitar or bass, connect it to the TM500 with a direct injection box to ensure correct impedance.