Radial Engineering

Tonebone AC Driver 1 Channel Preamplifier

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  • Tonebone AC Driver 1 Channel Preamplifier, preamp top
  • Tonebone AC Driver 1 Channel Preamplifier, preamp back
  • Tonebone AC Driver 1 Channel Preamplifier, input options
  • Tonebone AC Driver 1 Channel Preamplifier, controls diagram
Our Low Price: $209.99

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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.

More Detail:

Includes our exclusive Gollihur Music tipsheet to get the most out of your purchaseTremendously 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.


  • 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."

WARNING: Cancer and/or Reproductive Harm
According to California state law, if you are a resident of California, we
must notify you that this product contains chemicals known to the state
of California to cause cancer, birth defects or other reproductive harm.

Product Manual

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.



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Warranty Information

Standard Warranty:
All products sold by RADIAL come with a 1-year limited warranty. This limited warranty protects you against defects in workmanship. The warranty does not cover any consequential or inconsequential damage or any losses. Specifically, if you have a problem due to defect, you must make the arrangements and cover the costs to return the product to us with a copy of the original sales invoice and we will repair the product and return it to you at our cost. All warranty claims require a return authorization. Contact the RADIAL service department for details.

Transferable 3-Year Warranty:
Some RADIAL products come with a 3-Year Transferable Warranty. This means that if you buy the product and decide to sell it, the warranty can be transferred to the person that buys it, thus providing continuous warranty support and added value. This Transferable Warranty follows the same procedures and limitations outlined in the Standard Warranty. This means that if you sell the product, you must provide the buyer with a copy of your original invoice so that he, in turn, may be able to submit this should a warranty claim be required.

Warranty Limitation:
As with all typical warranties, only manufacturing defects are covered. Furthermore, parts that are subject to wear and tear such as switches, potentiometers and tubes are not covered under this warranty. This, however, does not mean that these will not be repaired or replaced free of charge. We pride ourselves in supporting the products we sell and will often exchange these parts free of charge pending the age of the device. This decision will be undertaken by RADIAL and in no way obliges the company to perform such tasks.
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