No fuss, great sound, and bulletproof construction.
Sometimes you like to keep things simple. If you're considering adding a preamp to your rig, but you're not the type of player who likes fussing around with more knobs and controls than the International Space Station? The AC-Driver might be right up your alley.
It's got a 10 MegOhm input impedance to get a wonderfully balanced sound out of piezo pickups, drops in a low cut filter to roll off excessive low frequencies and reduce "boominess," and adds a phase switch and a notch filter to reduce feedback and get the best tonal response from your acoustic instrument when amplifying. That's it! No semi-parametric, duo-timbral, hypertonic accelerator shenanigans. Just good, honest tone, from your bass to the audience's ears.
The rest is the basic stuff - a built-in mute switch allows you to take a break, or tune silently (there's a dedicated "tuner out"!), a 1/4" output for your stage amp is on the side, and a high-quality DI with a ground lift is on the back panel. And it's made in Canada, in the very typical heavy-duty, gig-worthy construction that Radial is known for.
Tremendously useful: The low cut filter (also known as high pass filter). Piezo pickups have an incredibly wide range of frequencies - including those that are too low to even be heard! By reducing the output of the very lowest, subsonic frequencies, this can reduce the likelihood of certain types of feedback and can help reduce the workload of your amplifier.
The Notch Filter is a special sort of EQ control, that cuts a thin slice of the tonal spectrum. Why? Usually, there's a "hot" frequency that excites your particular instrument, and causes it to feedback when volumes get higher - the sound of the amp reflects to your bass, and gets it vibrating. HummmmmmmmmmmmmMMMMMMMMM! The notch filter lets you find that frequency, and with surgical accuracy "slice" it out of the signal - it has very little effect on the overall tone, but lowers the output of that frequency to reduce the likelihood of feedback. Cool!
Phase reverse. Why? In some instances, as you move around the stage, you will notice that feedback or resonance seems to increase in certain spots between the wedge monitor and your personal amp. This is caused by nodes either amplifying each other or cancelling each other out at various frequencies. You can reverse the (absolute) phase with the 180° polarity reverse. This can often help minimize this occurrence.
(You can learn more about how to use these controls in our "Learn your amp" FAQ!)
Oh yeah -- the "MUTE" switch is always ready for a quick, silent onstage tune (or just to quiet an instrument not being actively played). But the tuner output stays active.
As you've probably guessed, we're primarily offering it as a rock-solid preamp for use with upright bass, but it's equally useful for ALL acoustic instruments, like acoustic guitar, banjo, violin, cello, mandolin, bouzouki or lute (among others). It has lots of flexibility and can be used to enhance the sound of virtually any acoustic or electric instrument.
Here's a diagram of a common hookup using a Upright Bass:
- Audio Circuit Type: Class-A FET
- Noise Floor: -97dBu
- Dynamic Range: +107dBu
- Maximum Input: +10dBu
- Input Impedance: 10 MegOhm
- Output Impedance: 44 kOhm
- Ground Lift: XLR Output
- Low Cut Frequency Range: 10Hz-300Hz
- Notch Frequency Range: 60Hz-500Hz
- Power: 40mA, 9VDC (center pin negative) (not included from factory)
- Construction: 14-gauge steel chassis & outer shell
- Size (LxWxD): 475” x 375” x 175” (120 x 95 x 44mm)
- Weight: 1.4 lbs (635 grams)
- Warranty: Radial 3-year, transferable
IMPORTANT - This preamp DOES NOT INCLUDE a power supply as received from Radial. It uses a very common 9v power adapter, center pin negative - if you have any guitar pedals, you probably have one lying around. If you don't, we can supply a very nice name-brand one, just order the version "with power adapter."