D.W. Fearn VT-1 Operating instructions manual - page 26

D.W. FEARN

VT-1 & VT-2 Microphone Preamplifers

26

The phantom powering circuit used in the VT-2 is suitable for use with all Neumann micro-

phones, AKG 12 and 48 volt microphones, B&K phantom powered mics, all Schoeps mics,

Shure SM81 and 85 mics, Crown PZM mics, and virtually all other phantom powered mics

that require any voltage between 12 and 48.

When turned off, the phantom-power resistors are completely disconnected from the circuit

in the VT-2.

Attenuation (3)

The Attenuation control (3) is between the second and third amplification stages of the VT-

2. It should be adjusted to provide the desired output level to the console or recorder.

In some situations, the Attenuation control can have an effect on VT-2 distortion, but at +4

dBm output the input stages will overload before the output. If you find that you need to run

the Attenuation control near the bottom of its range, the input level may be too high and you

might want to experiment with the microphone pad (if it has one), the VT-2  Input switch

position, or both. Let your ears be the judge. Slight to moderate overdriving of the VT-2 often

adds “edge,” “power,” or “excitement” to the sound.

If it is necessary to operate the Attenuation control near the top of its range, the input level

is too low and any padding at the mic or on the VT-2 should be reduced or removed.

Phase (4)

This switch reverses the polarity of the output of the VT-2. A detailed discussion of the appli-

cation of phase reversal of individual microphones is beyond the scope of this manual.

Even when there is only one microphone being recorded, it may be useful to try the

“Reverse” position of the Phase control. Although there is supposed to be standardization in

polarity throughout the professional audio equipment industry, it is possible that a wiring

error or the use of vintage equipment built before standardization may reverse the polarity in

the recording/monitoring chain. The effect of reversed absolute polarity is subtle, but signif-

icant with some sounds. If the “Reverse” position sounds better, use it.

With more than one microphone on the same sound source (or picking up leakage from

another sound source), the Phase switch may have a profound effect on the audio quality.

Whichever position sounds best is correct. A check of monaural compatibility (by summing

the various mics) should also be performed.

VU Meter and VU Meter ON/OFF (5 & 6)

The VU meter (6) measures the output level directly across the secondary of the output

transformer, through an isolation amplifier. It is calibrated so that a +4 dBm output will indi-