RezX Resonance Modulator for Upright Bass (Rez-x, Wolf Tone Suppressor)

The "Rezx"​ resonance modulator is a patented device with which to improve or change the tone of a stringed musical instrument. It helps the musician achieve the sound they desire from their instrument without making any alterations to the instrument.

Is it used to suppress or eliminate wolf tones? Although we reference suppressing wolf tones in the title, that's not necessarily its main intent. It's more of a "tone adjuster." BUT... Modifying the tonal character of the instrument (as well as altering the mass of the top) can very commonly have the helpful side effect of "shifting" or "eliminating" wolf tones, though, and as a result, addressing problem wolf tones is a very common use for this device.

What is a "Wolf Tone?"

Put simply, it's an artificial overtone. It occurs because your bass has a frequency at which - due to its physical size - it naturally over-resonates. It's kind of like a drum having a particular tuning at which it sounds best (which is fine for drums, but we bassists have many different notes to play on the same instrument!) On a bass, when you play the note that is of that same resonating frequency (or very close to it), you get a sustained overtone along with the pitch of the string being played. This can cause a note that "jumps out" more than other notes, as well as cause that "beating" sound you hear when you play the same note on two strings that aren't quite in tune with each other.

It's probably called a "Wolf Tone" since that "beating" can be reminiscent of the howling of that animal. Since basses generally have fairly similar sizes, the wolf tone (when found) on a bass is often around "G."

So, as mentioned, the patented REZX Tone Modulator can certainly function as a wolf tone eliminator, but what it really is designed to do is to modulate the response and tonal balance of an instrument. It attaches to your instrument magnetically, and by shifting the mass into different parts of the bass top by essentially "sliding it around," it alters the vibration characteristics of the instrument.

You can change the placement of the modulator on the body quickly and easily by simply sliding it around - it has a felt covering, so it won't scratch your varnish or finish.

Experiment! Tweak your tone and maximize your instrument's response. It's non-permanent! It's gluten-free! It's more fun than Jell-O wrestling*!  Easily make tonal adjustments "on the fly" to suit daily conditions and moods - without making costly, permanent changes to your valuable instrument.

^{* Okay, maybe it's not as fun as Jell-O wrestling, though I suppose that the level of fun depends on whom one might be wrestling. Also, "Jell-O" is a registered trademark of Kraft Heinz, and the use of this product's name does not constitute any sort of endorsement by that company, or us of the product - it's just here for the sake of the Dad joke, folks.}