Increasing output to +4dbu

Discussion in 'Amps and Cabs [BG]' started by aaron f., Oct 4, 2002.

  1. aaron f.

    aaron f.

    Oct 21, 2000
    I know that compressors or mixers can be used to increase a preamps signal to +4dbu, but is there a small inexpensive gizmo designed specifically for this? Just curious.
  2. +4dBu is 1.23v RMS. This voltage is a standard reference level for pro audio equipment operating at LINE level.

    Some bass preamps, such as my SWR Interstellar Overdrive, put out much less. My IOD puts out 0.7 volts (-0.88dBu) at maximum volume using a 140 mV input (passive bass) at 100 Hz. It will put out a higher voltage with an active bass that provides more than 140mV output.

    My QSC PLX power amps require 1.7 volts input for them to reach full amplification.

    What you are looking for is a LINE to LINE level amplifier for voltage gain. This can be any LINE level device that has greater than Unity Gain. My solution is a Rane MX22 crossovers and Rane GE30 EQ in my signal chain. Both have greater than Unity gain, and both increase the voltage to the PLX.
  3. An active DI box with adjustable output gain might be what you're looking for. Most DIs can only attenuate, but some can also amplify the signal voltage.
  4. aaron f.

    aaron f.

    Oct 21, 2000
    Cool, thanks for the help
  5. Bob Lee (QSC)

    Bob Lee (QSC) In case you missed it, I work for QSC Audio! Gold Supporting Member Commercial User

    Jul 3, 2001
    Costa Mesa, Calif.
    Technical Communications Developer, QSC Audio
    Yup, Radio Design Labs ( makes some small gizmos that can do that task.
  6. Ebtec makes a line level shifter which coverts back and forth between -10dBU and +4dBU signals. It's a two channel device. It sells for around 60-something bucks. You can pick one up at Guitar Center at the Pro Audio counter.