Behringer TUBE ULTRA-Q T1951 User Manual page 10

like feedback. In live applications uncontrolled feedback can cause damage to loudspeakers and amplifiers.
By means of the INPUT control you can adapt the sensitivity of the TUBE ULTRA-Q to the input level. The
sensitivity can be varied within a range of -15 to +15 dB. Set the INPUT control so that the PEAK LED lights up
only rarely, it should never light up constantly. If the LED lights up it means that the level directly after the
INPUT control is exceeding +18 dBu, this means that there is still approx. 5 dB headroom until the
TUBE ULTRA-Q starts clipping.
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Please note that extreme levels can be achieved with this unit. When a high input level is
combined with an extreme setting or multiple filters boosting the same frequency range, over-
loading can occur even though the input level was set correctly. This can not be contributed to
a malfunctioning of the unit but is a consequence of the settings that were chosen. If this
occurs please lower the input level or choose less extreme settings.
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If extreme equalizer settings are necessary to achieve a usable frequency response, the alarm
bell should start ringing!
The shelving filters
In contrast to graphic equalizers with fixed frequencies and bandwidths you can freely set all filter parameters,
center frequency, bandwidth and gain, with a parametric equalizer. The two outer filters of the TUBE ULTRA-Q
can additionally be switched between shelving (SHELF) and bell characteristic (PEAK).
In the setting SHELF the filter resembles a normal tone control on a hifi amplifier, but with the possibility to alter
the start frequency and the slope of the filter. The frequency can be set within a wide range with the
FREQUENCY control. With the BANDWIDTH control the slope can be altered. When the control is turned
counter-clockwise the slope becomes steeper, turning the other way results in a more gentle slope. The
LEVEL control sets the amount of boost or attenuation. Use the shelving filters to control rumble, plop/
breathing noises and wind or tape hiss. With the freedom to set the frequency, slope and gain, the
TUBE ULTRA-Q can be tailored exactly to your needs giving you much more flexibility than any other standard
low-cut switch.
The parametric filters
When the first and the last filters are set to PEAK, they are identical to the two other filters. In that case the
filters have a peaking response or a “bell” curve. Start by boosting a fairly broad frequency band to locate the
frequency band you want to adjust. It is easier to locate problem frequencies by boosting them first. When the
problem frequency is located you can adjust the bandwidth to isolate the correct range. Now you can cut or
boost this range to suit your needs. The filters are set up in such a way that they cover the entire spectrum from
20 Hz to 20 kHz, while overlapping each other over a wide range. After finding the right setting you can tweak
the setting of each band to achieve maximum results.
During operation you can switch on and off the individual bands to make an A/B comparison between the
equalizer effect and the unprocessed signal. Due to the complex and partly difficult settings of parametric
equalizers such a facility is indispensable. Still, most parametric EQ’s have no band-specific in/out switches
which makes it difficult to keep track of what the various switches and controls do.
Adjusting the overall level
It is possible that you have to correct the overall level after setting the equalizer. It is possible that the effect of
the filters result in a higher or lower level than the original signal. Use the INPUT control to adjust the total level.
You can compare the processed and unprocessed level with the help of the IN/OUT switch.
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Please note that the IN/OUT performs a hardware bypass. The input signal is fed directly to the
output. The INPUT control has no influence.
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TUBE ULTRA-Q T1951
2. OPERATION