Audio Sprockets

ToneDexter II Tone-Correcting Preamp

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  • ToneDexter II Tone-Correcting Preamp - top angle view
  • ToneDexter II Tone-Correcting Preamp - controls closeup
  • ToneDexter II Tone-Correcting Preamp -preliminary pre-release info
  • ToneDexter II Tone-Correcting Preamp -preliminary pre-release info
Expected Availability: FALL 2023

We ship worldwide! (Read this)

New Tonedexter II coming SOON!
Audio Sprockets has had to redesign ToneDexter due to parts shortages. The orginal ToneDexters are no longer available.
The good news is that it has allowed them to incorporate more powerful features, a new color screen, and improvements to ease of use.
However the ability to plug your pickup into ToneDexter II and the output to the PA or your acoustic instrument amp, select a WaveMap, to make your live pickup sound match your studio mic, remains the same.

We will keep you apprised of the situation as it unfolds. New units are expected to be available Fall 2023!


Tonedexter II is coming soon!

Audio Sprockets has announced that the new Tonedexter II should be available in Q1 of 2023! We'll post more information as we are made aware of it. Here's their announcement:

Due to a worldwide shortage of computer chips following an unprecedented demand due to Covid related supply issues, we have had to redesign ToneDexter. The orginal ToneDexters are no longer available.

The good news is that has allowed us to incorporate more powerful features, a new color screen, and improvements to ease of use.

However the ability to plug your pickup into ToneDexter II and the output to the PA or your acoustic instrument amp, select a WaveMap, to make your live pickup sound match your studio mic, remains the same.

Features New to ToneDexter II

  • Color screen, context sensitive controls and labels
  • All parameters can be stored and fully recalled in 64 available presets, including all input and output levels
  • Firmware upgrade and Preset management via USB
  • Support for stereo and dual source pickups with switchable 9V mic bias on Ring
  • Enhanced EQ controls adds parametric mid boost/cut and high-pass, along with low and high shelf/bell
  • Stereo capable Effects Loop with separate Send and Receive jacks
  • Aux in for playing along with stereo input sources
  • Headphone output can also be used as a stereo line output

Note that some of the other information below is subject to revision as we learn more.


Original product information below.

With ToneDexter, getting "mic'd up tone" in your live performances is as easy as...

Copy and Paste

At first blush, the ToneDexter looks like a pretty standard preamplifier for acoustic instruments. While most preamps offer helpful features like EQ, high-impedance buffering inputs, and notch filters (so does ToneDexter) - ToneDexter is a lot more. This baby has got some serious DSP technology under the hood.

Here is what the ToneDexter does, simply put, and I've put it right at the top of the page to make sure you don't miss it:

  1. The ToneDexter compares the acoustic sound of your bass (using a microphone) to the sound coming from your pickup.
  2. It then creates a WaveMap; a sonic signature, of sorts, which corrects the sound of your pickup, making it sound much more like the microphone signal.
  3. The preamp stores this WaveMap (and up to 21 others), allowing you to recreate that acoustic tone in a live situation, using just your pickup.

So you're essentially copying the tone from a microphone, and pasting it to your pickup.

Includes our exclusive Gollihur Music tipsheet to get the most out of your purchaseNow, this thing sounds "tech-y" - and if you're not a "gear nerd" like me, that might scare you a bit. But it's actually pretty easy to wrap your mind around.

To make it more clear: The problem with pickups, generally speaking, is that they don't sound like a mic. Usually, they have a more "direct" tone that lacks the open "airiness" that a microphone has. The reason is fairly simple: the microphone actually gets the sound out of the air - like your ears do - while most pickups provide their sound from the wood vibrations created by the instrument.

So, when you first get your ToneDexter, you do a one-time "training session" with both a mic and the pickup plugged in at the same time. While you play during this training session, ToneDexter listens to both signals simultaneously and "learns" the differences between how each of them "translates" the vibrations into sound. ToneDexter figures out how to correct for the pickup’s deficiencies, and restores the missing "body tone" to the pickup signal. It's basically bringing back that realism that the microphone "hears" but a vibration-sensing pickup usually doesn't. It also adjusts for the best gain levels for optimal tone.

ToneDexter then allows you to save the resulting WaveMap, with a simple press of a button, in one of 22 available preset locations.

The next time you play live, you leave the mic at home, and just use your pickup, and the ToneDexter's WaveMap applies those corrections to your pickup's signal, making it sound a lot more like the microphone. So you get much more realistic acoustic sound, while still using a far more convenient (and generally much less complicated) pickup.

The training process is not difficult at all. All you need:

  • a quiet room
  • your bass and pickup
  • a good quality microphone (small diaphragm condensers work well)
  • a set of headphones is also very helpful, as you can monitor the process if you have headphones on.

You plug both the mic and the pickup in, and just follow the prompts to start the training process. Mostly, your job is to just noodle around on the bass - the preamp does all the heavy lifting. You don't even have to play anything in particular - just do some scales, or some of your favorite basslines. And you can do it several times, as there are multiple locations to save the WaveMaps you create. So if you have several basses and/or pickups, you can save WaveMaps specific to each instrument.

So, yeah -- too good to be true, right? I hear you. We had to try this thing for ourselves before we'd buy into the hype; so I got a unit on loan from Audio Sprockets about a month before we committed to sell the unit. Even with our half-hearted first attempt, using a so-so mic and no headphones, the unit gave us noticeably better sound with the pickup. When we later put more effort into the process (grabbed a good set of phones and a nice Oktava mic from my studio) the results were even better.

This thing is legit.

What pickup works best? In talking to the folks at Audio Sprockets, and experimenting here at Gollihur HQ, we've found that bridge wing pickups are among the better choices - specifically, the Kremona (KNA) DB-1 worked best with the ToneDexter, and the K&K Bass Max and Schatten Design RB1 worked pretty well too. The Fishman Full Circle and David Gage Realist Lifeline also work nicely, as they have mostly full-range sound. Pickups that don't necessarily reproduce all of the tonal spectrum - like the David Gage Realist, which can be somewhat "dark" - don't work so well. And those close to the strings - like the K&K Double Big Twin or Fishman BP-100 - can have some difficulty getting as natural a tone, because they tend to emphasize string detail and require excessive "correction" to sound more "mic-like."

So, is this a preamp or a modeler? You could call the ToneDexter's process "digital modeling" - and I suppose it's a reasonably accurate description of what it's doing. But their patented process is proprietary (say THAT five times fast!), and the modeling it does is of your own bass (rather than some generic "upright bass" sound that the maker of the electric bass preamp threw in at the last moment to give it more marketing appeal). So it legitimately captures YOUR sound. From YOUR bass. And gives it to you live without hassle.

So cool.

A note about Firmware Versions

The ToneDexter was originally developed for use with guitars and other higher pitched instruments. However, it was designed to be able to be upgraded with new features through upgrades to its firmware. Since introducing the ToneDexter, Audio Sprockets discovered how well it could work with basses, and developed a specific firmware (operating system) for bass instruments.

This alters a few key features; specifically, the WaveMap is longer, time-wise, operating on a different time base and sampling rate -- this allows for the lower range to be more accurately represented. Also, the EQ and notch ranges are optimized for bass frequencies.

As a value-added service for our customers, we update the ToneDexter to the most recent BASS firmware version for you before shipping it to you, so you don't have to deal with finding a memory card, downloading the firmware, locating a memory card reader, etc.

Are you planning on using it with a different instrument? No worries. Switching out is easy by downloading the alternate firmware versions from the Audio Sprockets website.) We also do try to keep 1-2 units set at the "General Firmware," which Audio Sprockets recommends for Guitar, Dobro, Viola, Cello, Bazouki, Mandola, Mandocello, Baritone Guitar, and other similar instruments. If you'd like us to send one of THOSE units, so you don't have to re-flash the firmware, just let us know in the text box at checkout.

Some Specs

  • Works on any acoustic instrument, with most active or passive piezo pickup systems
    • 1 MegOhm input impedance, and is switchable to 10 MegOhm if using a TRS (Tip/Ring/Sleeve) cable with the "ring" disconnected
  • Stores 22 custom WaveMaps, selectable via 11 position rotary switch and bank select switch
    • Support for transferring WaveMaps in and out is now included with the v1.5 firmware. Requires Transfer Utility available at the AudioSprockets website.
  • Mute switch that activates a built-in high precision tuner, accurate to within 1 cent
  • Boost switch for solos with 0-8dB of settable gain via rear panel pot
  • Bass and treble EQ
    • Bass EQ control is now a variable highpass filter when cutting.
  • Sweepable notch filter for feedback suppression
  • Character control which adds additional punch to the WaveMap
  • Latency less than 1ms
  • Effects loop (TIP send, RING return)
    • Loop stays "Active" when mute is pressed
  • 1/4" pickup input, high impedance (1MO)
  • 1/4" line output with output level pot on front panel
  • XLR DI output, with rear panel option switch for fixed level or level that follows output level pot
  • Analog boost and mute circuits positioned after effects loop, so no headroom loss when boosting
  • XLR mic input with 48V phantom supply, used for training
  • Headphone output
  • Phase (polarity) switch on rear panel
  • +-15V internal supplies for professional headroom and dead quiet operation
  • SD card slot for field upgrade of software
  • 6.3" W x 5.9" D x 2.3" H
  • Forward-thinking design means that updated functionality may be available in the future with a simple downloadable firmware (operating system) update


  • Do you need to store a separate wave map for pizzicato and bowed playing?

    No, and in fact, you probably shouldn't. I recommend doing both pizz and arco when creating your tone map(s) - the response of the pickup will then emulate the sound of the microphone no matter how you are playing. James, at Audio Sprockets, recommends doing some bowing when tone-mapping (even if you don't play arco), as it provides a better overall map, anyway.

  • I see it has 22 Tonemap memory locations. Why do I need so many?

    It seems the primary purpose for these is so that during the learning process you can try "recording" from several different microphone positions (or even different microphones) and then later pick the one you like best.

  • But could I keep up to 22 profiles and easily switch between them?

    I can imagine different songs in my repertoire, perhaps played in different ranges on the instrument, or maybe calling for different tonal "feel" based on the mood of the song. So, sure!

  • Is that possible, and fairly easy to do in a gig situation?

    It's easy to switch profiles - just a turn of the knob (with a digital readout confirming the location number) but again; you'll probably create that one setting that just sounds the most like your acoustic bass, and use that for everything; changes in your tone will mostly be done with your hands. That said, there's no reason that you couldn't create "tones" using different mics (like an old crystal mic, or some other timbrally distinctive mic) and dial them in for particular effect.

  • Can I share my WaveMaps from my ToneDexter with someone else?

    Starting with the firmware v1.4, released Aug 8 2018, there is now support for getting WaveMaps into and out of the unit. It requires a separate procedure using the Transfer Utility which copies all WaveMaps onto an SD card, and optionally writes externally saved WaveMaps back into the unit. WaveMaps may be archived in libraries, sorted and/or renumbered to create new sets for reloading. WaveMaps are stored in a proprietary file format that only works in a ToneDexter.

  • Will someone's WaveMap of their amazing carved bass make my crummy, beat up doghouse bass (or electric upright) sound amazing?

    Unfortunately, it doesn't quite work that way; the Tonedexter crafts the tonemap to the characteristics of the particular bass (and the pickup that’s on it.) So the resulting tonemap is tailored specifically to that bass and pickup. “Tailored” is a good word to use; it’s kind of like asking, “I got a suit custom-tailored to fit me; I’d like to know if it will look good on my friend if he borrows it?” The answer is, “maybe” – it depends on how similar his physique is to yours.

    So while we could create and share wavemaps made on, for instance, my fully carved bass using a high-end studio mic, we know that the micro-EQ and phase alignment changes that the ToneDexter applies will make that pickup on my bass sound very much like the mic I used for training. However, on a totally different bass (yours) with quite possibly a different pickup, those changes that the WaveMap applies to the pickup signal will not necessarily have the same effect -- and will almost certainly not produce the same tone. The real magic comes from getting the exact signature sound from your bass from the pickup you’re using to be "matched" to your bass' actual mic'd sound – and that's how you get a WaveMap that actually works well. That said, it would be fun to experiment with trading "patches" with other players, they might bring some interesting results.

    Also of note, we've been working, on and off, to create (using some complex home-studio trickery inspired by James at AudioSprockets) WaveMaps that can be applied to NS Design Electric Upright Basses. Since those basses are all made to be highly consistent, using the same pickups, it stands to reason that a WaveMap that made my NS Design WAV4 sound good would also work on yours. We haven't come up with anything that works just yet, but we're hopeful that we may arrive at a WaveMap that can bring a lot more realism to the sound of those basses. Stay tuned!

Confused? I hope not, but we're here to help if you have specific questions. We also, as usual, include a Gollihur Music Tip Sheet along with your purchase to help you get the most out of this unit when it arrives!

Product Manual

Need to figure out some of the more in-depth features of this product? There's a copy of the manual, in PDF format, in the "Product Manual" tab. (You may wish to visit the manufacturer's website to see if a more recent version is available.)




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5 Reviews

  • 5

    Posted by Clyde Stats on Jul 23rd 2021

    The gold standard for upright bass amplification has always been a high quality mic sent to the FOH to be mixed with the performer’s pick-up by an experienced sound person from a spacious stage in an acoustically friendly venue. Unless you’re a nationally known artist, the majority of your gigs are likely to be an a cramped stage using an instrument amplifier with no FOH support in an acoustically challenged environment where using a mic involves dealing with feedback and bleed from other instruments. If this describes your situation, you need a Tonedexter! I have used this product for over two years in a variety of situations and am completely thrilled with the results. Everything written in the product description is 100% true; it really does create the sound of your bass played through a mic, but without the problems of feedback and bleed. I have done “blindfold” tests comparing my bass through a mic with the TD, and most folks are unable to tell the difference. Even if you are not particularly tech savvy, don’t be put off by the “training” procedure required to make a wavemap, as the directions given are clear and non-technical. Also, the company is continually making upgrades to improve the TD, which they post as firmware updates on their website, so having the latest and best version of the TD is about as difficult as downloading an update to your computer’s software. Finally, the company is extremely responsive to questions and problems with the TD. In short, I don’t understand why every bass player doesn’t have one. When I read these long online forums on which mic to mix with which pick-up, I want to scream at my tablet, “Get a Tonedexter!”

  • 5
    I love the ToneDexter!

    Posted by Fred J. on Oct 30th 2019

    Last week, with the help of an audio engineering friend of mine, I successfully trained my ToneDexter in a recording studio on several high-end microphones. I used a Schoeps CMC6, Neumann U87, and a Royer 101, all close-mic’ed near one of the F holes. The best results came with the Royer, a passive ribbon mic which I used with an in-line Cloudlifter CL-1 Mic Activator so it would cleanly and safely function with the ‘Dexter’s 48v phantom power. The sound is truly amazing, and at a gig last Friday at a venue where I have played before, both my fellow musicians and several members of the audience asked me what I had done to my bass since “it sounded different.” Different indeed—rich, clean sound; more headroom; and no feedback!

  • 5
    So glad I splurged

    Posted by Doug W on Dec 14th 2018

    Just wanted to thank you profusely for the service you provide. We exchanged as few emails regarding strings a few months ago. Since (thanks to your string recommendation) my bass was sounding the best ever acoustically, I decided to splurge on the ToneDexter. It took me 12 tries to get a good WaveMap, but I was able to use it on a gig that evening in a room I've played in dozens of times, and it truly made a world of difference. I recently installed to Realist Lifeline (also ordered from y'all!), which is a very good pickup, but my god, the ToneDexter really points out how much no pickup actually sounds like your bass. I think I'm the first San Diego local bassist to try the ToneDexter, and I suspect you will soon send many more out this way! I may never have tried any of these products without your info-packed website & support. Thanks again!

  • 5

    Posted by Tom B. on Sep 25th 2018

    I just want to mention also, how impressed I am by [the Audio Sprockets ToneDexter]! I can't believe how much it improves the amplified sound. I gigged it this week for the first time, here in London. It really sounds like the acoustic sound of the instrument, but at a volume you can hear it over the drums etc.

  • 5
    It’s fantastic

    Posted by Bill M on Apr 3rd 2018

    I got my ToneDexter... this is probably the one tool that makes the biggest difference for me...

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