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vmp Series
Using the
Follow this guide for initial SETUP
Firstly, turn all of the Output Levels fully counter clockwise to 0, then plug
in the mains power to your unit. Switch it on and leave the valves to warm up for at
least 10 minutes before use. All valve equipment produces considerable amounts of
heat and all preamplifiers are, by design, very sensitive, so the unit should be kept
away from sources of electrical noise such as power amplifiers, heaters, computer
monitors etc and plenty of airflow should be allowed for cooling.
Next, connect the XLR output to your recording device. A balanced cable
will give the best signal to noise ratio but make sure that you are connecting to a
line level input, not a microphone input. Many modern computer recording interfaces
have 2 or more XLR microphone inputs and several TRS line inputs. In this case,
use a balanced XLR to TRS cable or if unavailable, use a balanced TRS to TRS
cable from the vmp's secondary output.
DON'T connect a balanced line level output directly to an XLR Mic input,
the signal levels will not be matched, resulting in increased noise and possible
distortion, and there is a chance of damage ocurring to the line level unit if phantom
power is switched on.
If you require a separate monitoring signal, you should connect a balanced
or unbalanced cable from the TRS output to your mixer.
Connect a microphone to the rear XLR input. Apply phantom power if
required. Alternatively, a line level signal or instrument can be used via the DI input.
Start with the EQ set to flat and the pad set to -30dB, unless the signal is very
weak. You can now carefully increase the channels output level and you should get
a signal through to your recording and monitoring systems. Adjust the output level
according to your recording systems input level meters.
If all is well, listen to the effect that the pad has on the 'colour'. Drop
the output level back to 0, switch to -15dB pad and increase the level again. The
signal will be much louder, but also 'warmer'. Now try the 0dB pad position. If you
have a hot signal such as a modern condenser microphone or an active bass, it may
be distorted on this setting, but that is not always a bad thing.
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Next, try out the EQ switches. Don't make any assumptions here, some-
times deep is not good for bass, maybe bright is better. The EQ consists of high
and low shelves, and can also be thought of inversely as a broad mid-range
bandpass filter. For example, a high and low boost is the same as a mid cut. Allow
yourself time to know the E.Q settings and how the air is factored by the pad
control. Remember that it is better to boost the high frequencies at the start and
then cut them later than to try and boost them later and also bring up all the noise
that has been added along the way. This is especially relevant if you are recording
to tape or if you only have mediocre EQ available during mixdown. Most software
EQ's and lesser hardware EQ's have an ugly top end boost, it is better to use
them for cutting. Also, it is better to cut unnecessary low end at recording time, as
excessive low end will lower the headroom available.
If more gain or more 'valve' is required, it is possible to daisy chain
channels together. Use an unbalanced patch lead from the TRS output of one
channel into the DI Input of another. The output level of the first channel now
controls the amount of signal driving the second channel and the individual pad
and EQ controls expand the possibilities. Be subtle or be extreme, chain more
than 2 channels together... This can be useful for low output microphones such as
ribbons or as a heavily coloured signal chain for guitar, bass or keys.
The DI Inputs are able to take up to a +20dBu line signal and the unit can
be very useful for further processing during mixing and mastering. Try running
stem mixes through a vmp for added punch and clarity.
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