User Manual

CONNECTING YOUR PREAMPLIFIER

There are two inputs and two outputs for each channel on the Mic Preamplifier. You generally only

have to use one input and one output per channel.

On the back panel are female XLR's labelled MIC INPUT A and MIC INPUT B. The signal from

the MICROPHONES get plugged in here. There are a few warnings and suggestions. These connec-

tors also "send" PHANTOM POWER to the mics. Some mics can be damaged by the 48 volts of

phantom power. A few dynamics and a few ribbon mics have been known to "fry" when fed phan-

tom power. The suggestion is to ALWAYS have PHANTOM switched off when switching mics,

cables, patches that involve mics etc. You ONLY use phantom power for SOLID STATE

CONDENSOR MICS. Tube mics, dynamic mics, ribbon mics and battery powered mics should

have phantom switched "off". This is true for all mic pre's. With this MIC PRE you "PULL THE

TOGGLE to SWITCH PHANTOM". It is a locking toggle to prevent "accidents". The second great

reason for not using phantom if you don't have to is that - if you change a connection with phantom

on, then the pre amp will be fed a quick burst of 48 volts (when it normally is amplifying about a

hundredth of a volt), which can then be monitored - usually once. After you have replaced your

speakers, you have learned a valuable lesson about turning down the volume of the monitors before

changing mics or mic patches. This is a good idea with phantom on or off. Consider a variation of

this - any mic connection just a little bit bad, it will be extra noisy with phantom turned on. This

goes for cables, patchbays, patch cords etc. Suggestion #2 - Avoid running mic signals through

patchbays. Some patchbays "ground" all the "sleeves" which can add a ground loop into your deli-

cate mic signal. Suggestion #3 - Set up the Mic Pre in the studio near the mic and use a short mic

cable. Why ? Microphones often have "light duty" line drivers and you can lose an audible amount

of signal in long cables. You can get the best fidelity by having the Mic Pre close to the mic at the

"cost" of having to walk into the studio to adjust a level control. You also avoid almost all of that

phantom power / patching problem because now you are patching a line level signal only. Sugges-

tion #4 - If you have a weird cable plugged into the mic input that has either pin 2 or pin 3 shorted to

ground, and you turn on the phantom power, you will probably fry the input transformer. You

probably do not want to do this. Check your cables...

The MIC INPUT XLR PIN OUT is :

PIN 1 = GROUND

PIN 2 = HOT or positive going phase

PIN 3 = LOW or negative going phase

(provided that the PHASE SWITCH is set to "0˚")

There is a 1/4" (mono) jack on the front panel for plugging instruments in directly. It is not

quite the same thing as a "Direct Box" designed for guitar or bass but it works fine and is remark-

able with keyboards. The PHASE SWITCH should be set to the "DIRECT IN" (middle) position

when using this 1/4" jack or else the signal may be loaded down. The Direct Input is always on and

switching to the middle position disconnects the MIC input and Mic transformer. Almost always the

DIRECT IN sounds better in the middle position. Of course, you can also use any "direct boxes" you

may have with the mic input with either the 0˚ or 180˚ settings. Check whether it may need phantom

power, otherwise leave it off !