ADVICE ON USE OF VINTECH AUDIO MICROPHONE PREAMPLIFIERS 

There’s not much to say here except that we have found that in general, it is best to keep the  “Output Gain” potentiometer set to all the way up (or close to it) and to use the “input sensitivity” switch to adjust the operating level of the microphone preamplifier. Of course, if after attenuating the input signal all the way ( at -20 on the dial) the signal output is too hot, just back the output gain pot down until your output signal is at the desired level.  

On all models except the Dual 72:
1). The phase toggle switch should be toward the right hand side of the unit to be “in” phase from input to output.
2.) To reduce the possibility of 60 cycle hum being induced into the output signal, please keep the outboard power supply at least two feet away from any modules being powered.  

On models 273, 473 and X73i:
1.) When using the line input XLR located on the back of the unit, please depress both the “impedance” and “mic/line” black push buttons on the front of the unit. This will present a 10k ohm impedance at the input.
2.) Normally, it is recommended that the 1200 ohm input impedance selection be used for most microphones, but the 300 ohm selection may be more appropriate for certain microphones and to obtain a more desirable sound under some circumstances. 

On all models: Direct instrument input. (Use with mic/line switch and impedance switch in the "out" position). This 1/4 input should only be used as an alternative input for instruments. We recommend using a high quality outboard d.i. and then going from that into the "Mic" XLR input on the back of the unit. Also, if using the d.i. jack on the front panel, please disconnect any microphones plugged into the xlr microphone input on the back of the unit because plugging into the onboard front panel d.i. does not automatically disconnect the mic xlr connector on the back of the unit.