The GigPro Single-Channel Preamp is a tiny, belt-pack style acoustic preamplifier that packs a lot of features in a lightweight and pretty compact package. In addition to its passive* bass and treble controls, it has a tool many bass players find a necessity: an adjustable low-cut filter. The GigPro also has a phase control, as well as the ability to supply the 9v phantom power that most mini condenser mics require. While aimed at acoustic guitar, its feature set makes it an excellent choice for use with upright bass.
The photo above shows Bob at a Gospel Bluegrass affair in September 2010, where he paired the LR Baggs GigPro preamp with the Fishman Full Circle pickup on his pre-war Juzek bass. While his amp wasn't too far away he had very handy volume and tone controls. Also shown in the photo inset is the Meisel COM-90 tuner.
We've added our own notes to some of the feature keys on the illustration in the photo array, to better describe their use in the real world.
- A. Treble: passive*
- B. Bass: passive*
- *Passive tone controls can throw those of us used to active tone controls for a loop, since they behave differently than one might expect. Lots of preamps have active EQ controls, meaning that they boost or cut a specific band of frequencies using active and extra circuity to accomplish it. However, old school instruments, for example, have a tone knob that is passive, meaning at the full-on position you get all the frequencies, and rotating it the other way cuts that frequency band. That's how the treble and bass controls on the GigPro work. So, start full-up and trim away highs or lows as needed.
- C. Trim: The Trim Control is an adjustable 12dB/octave low cut filter that is adjustable from 27Hz to 200Hz. Also referred to as a High Pass Filter, this useful tool lets you choose a frequency and gently suppress notes below that choice. It's ideal when your pickup is sending a lot of "rumble", "boominess", and useless lows that muddy up your sound.
- D. Volume Control that affects the output signal sent to the amp or next device.
- E. 1/4” Output: This is a regular unbalanced output for a standard mono cable. A standard mono cable is necessary as it switches the preamp on.
- F. Invert: This control changes the polarity, also described as phase, of the signal. Reversing phase can often get you a few more dB when you are close to feedback.
- G. Battery Status LED: The battery status LED remains on at all times when the unit is plugged in. As the battery weakens the light will gradually dim.
- H. Battery Compartment: To change your battery, remove the two screws adjacent to the belt clip using a screwdriver or a dime. Slide the preamp out of the housing and replace the battery.
- I. Phantom Power Switch: If you are using a mini-mic that requires phantom power, open the Gigpro's case. The phantom power switch is adjacent to the input jack.
- J. Gain Control: The adjustable gain allows you to tailor the preamp's performance for lots of boost for a low signal pickup, or trim gain back to handle a very hot signal, such as an instrument that has an onboard preamp.
- K. 1/4” Input: This is a regular unbalanced input for a standard mono instrument cable.
- Size: 4.75 x 2.85 x 1.25
- Weight (with battery): 6.6 oz.
- Battery Type: Single 9V
- Power Consumption: 1.6mA
- Battery Life: 300+ Hours
- Class: Pure Class A, all discrete
- EQ: Passive
- Treb: +/- 6dB @ 7kHz
- Bass: +/- 6dB @ 80Hz
- Low Cut: +/- 6dB @ 80Hz - (adjustable) 27Hz to 200Hz
- Gain: +6dB to +28d
- Signal-To-Noise: -90dB, 27Hz-20kHz unweighted
- Input Impedance: 10 Megohms
- Output Impedance: 800 Ohms
Need to figure out some of the more in-depth features of this product? Here's a copy of the manual, in PDF format, here.
You may wish to visit the manufacturer's website to see if a more recent version is available.