The Carl Martin Tone Tweaker is a combination 12 dB clean boost and 3-band EQ pedal, built by Carl Martin1. Carl Martin positions it as "a precise EQ and clean boost pedal for refining and empowering your guitar tone without altering its character"1. In practice that means two jobs in one box: a Level knob that pushes your amp harder with up to 12 dB of clean level, and Bass, Mid and Treble knobs that each cut or boost their band by up to 12 dB12.
Delicious Audio's Paolo De Gregorio described it as a tool for players who want to "add warmth to your mids, brightness to your highs, or depth to your lows," and called it equally at home live and in the studio2.
What the Tone Tweaker does to your sound
The pedal splits its job between level and tone. On the level side, it is a clean boost: Pedal of the Day described it as a "clean, transparent boost that preserves the integrity of your original tone," and said it is good for "pushing any amp you've got into the sweetest of spots with ease," cutting through the mix on solos and adding punch to rhythm playing3. That is the classic boost pedal use: hit the front of your amp a little harder so it breaks up earlier and sings more, without changing the character of the guitar.
On the tone side, the three EQ bands let you shape what the boost carries. Delicious Audio called it "a versatile 3-band equalizer, offering precise control over Mid, Treble, and Bass frequencies"2. Because the EQ and the boost live in the same pedal, you can, for example, lift your mids and add level at once for a solo voice, or trim bass and add a touch of treble for a tighter rhythm sound.
The controls: Bass, Mid, Treble and Level
Four knobs, laid out in the maker's own words as follows4:
| Control | What it does |
|---|---|
| Bass | Cuts or boosts the low-frequency band, up to 12 dB each way1 |
| Mid | Cuts or boosts the midrange band, up to 12 dB each way1 |
| Treble | Cuts or boosts the high-frequency band, up to 12 dB each way1 |
| Level | Sets the overall output level, up to +12 dB4 |
Guitar Pedal X's Stefan Karlsson lists the control set as "Mid, Treble, Bass, Level (+12dB)"4. With all three EQ knobs at their center positions, the pedal works as a straight clean boost; moving any of them turns it into an active tone shaper. Carl Martin describes the ±12 dB range on each band as "precise, musical tone shaping"1.
A single footswitch engages or bypasses the effect1.
Bypass and signal path
The Tone Tweaker is not true bypass. Both press sources describe it as a buffered bypass: Pedal of the Day says it "preserves signal strength and tone quality, ensuring your sound remains consistent even when the pedal is not engaged," and Delicious Audio likewise notes that "its buffered bypass preserves signal strength and tone integrity"32. For a player, that means the pedal always has a buffer in the signal path, which can help drive long cable runs, though players who want a fully passive path when the pedal is off should know it is not that.
Power and connections
The Tone Tweaker runs on 9V DC only. Guitar Pedal X notes that some rival EQ/boost pedals accept 9 to 18V for extra headroom, "where the other 2 are 9V only," the Tone Tweaker among them4. Feed it a regulated 9V supply, not a higher-voltage one.
The published power specification3:
- Voltage: 9V DC, regulated
- Current draw: 60 mA minimum
- Connector: 2.1 mm female plug, center negative
That is the standard boss-style plug found on most pedalboard power supplies. The maker's product page lists the power input simply as "9V DC"1. No battery option appears in the published specifications.
The input and output jacks are top-mounted, which Pedal of the Day pairs with the compact design as being "designed to take up minimal space on your pedalboard"3. Top jacks mean patch cables run up and over the top of the pedal rather than out the sides, so pedals can sit closer together side by side.
Build and background
Pedal of the Day reports that the Tone Tweaker "is encased in a robust housing, ready for the rigors of the road," and that it was "conceived, designed, and built by the same team of engineers who have been behind Carl Martin pedals for decades"3. Delicious Audio adds that the pedal "has been in development for a considerable time" before reaching players2. Carl Martin is a Danish maker with a long history of boost and EQ designs, including the Hot Drive and Boost and the Contour & Boost.
How it compares
In Guitar Pedal X's four-way roundup of 3-band EQ boosts, the Tone Tweaker sits alongside the EarthQuaker Devices and Kuro entries, which Karlsson notes "offer more headroom, where both have 9-18V inputs, where the other 2 are 9V only"41. The trade-off is straightforward: the Tone Tweaker's fixed 9V keeps its power requirement simple and standard, while the higher-voltage rivals can run at 18V for more clean headroom before clipping.
Videos
Leon Todd
Brett Kingman
Pedal of the Day
Questions
Is the Carl Martin Tone Tweaker true bypass?
No. The Tone Tweaker uses a buffered bypass. Both Pedal of the Day and Delicious Audio describe it as a buffered bypass that preserves signal strength and tone quality, so your sound stays consistent even when the pedal is switched off. A buffer in the bypass path helps drive long cable runs on a larger pedalboard.
What power supply does the Carl Martin Tone Tweaker need?
It runs on 9V DC from a regulated supply, drawing 60 mA minimum, through a 2.1 mm female plug with center-negative polarity. That is the standard boss-style 9V adapter plug used by most pedalboard power supplies, so it fits most isolated and daisy-chain supplies.
Does the Carl Martin Tone Tweaker take a battery?
The listed power specification covers only a 9V DC external supply with a 2.1 mm center-negative plug, so there is no battery option in the published specs. Plan on a pedalboard power supply or a standalone 9V DC adapter.
How much boost does the Tone Tweaker give?
Up to 12 dB of clean boost. Carl Martin and Delicious Audio both describe it as a 12 dB boost, and Pedal of the Day calls it a clean, transparent boost that preserves the integrity of your original tone rather than adding grit or coloration.
Does the Tone Tweaker change the tone of the guitar?
With the EQ knobs at their center positions it works as a transparent clean boost that leaves your core tone alone. The Bass, Mid and Treble controls each offer up to 12 dB of cut or boost, so you can use it purely for level, purely for EQ shaping, or both at once.
Where are the jacks on the Tone Tweaker?
The input and output jacks are top-mounted. Pedal of the Day and Delicious Audio both note the top-mounted in/out jacks and compact design, which is meant to take up minimal space on a pedalboard since patch cables run up and over the top rather than out the sides.
Sources (4)
- Tone Tweaker, Carl Martin, 2026
- Carl Martin Tone Tweaker Boost/EQ, Delicious Audio, 2024-06-18
- Carl Martin Tone Tweaker 12dB Boost & 3-Band EQ, Pedal of the Day, 2025-04-10
- Guitar Pedal X, Guitar Pedal X, 2024-06-18
