KNUCKLEHEAD?

"What's a Knucklehead?" you might ask. Knucklehead (KH) is a device that utilizes the classic 'Twin-T Filter' configuration found in many of the 1980's approaches to a synthetic drum/percussion generator with a very high Q resonance, that can be triggered into oscillation when 'excited' and ultimately returning to stability, creating the decaying 'envelope' associated with percussive instruments. This decay can be adjusted via the trim-pot, from a 'tight' woodblock like resonance to a self-oscillating (yet still excitable) drone and all the envelopes and responses in between.

But why 'Knucklehead?'...well, we'll get to that presently.

It is important to note that exciting the filter begins with a true analog audio representation via a condenser microphone coupled to the cylindrical, tubular input passage that you see perpendicular to the board itself. With this in mind, any distortion presented to the microphone will manifest in the final filter stage. Since the input stage is quite sensitive, this means you should only present very subtle stimulus to the initial stage of KH and especially avoid too nearby stimulus (your mouth/lips for example) to ever completely enclose the input cylinder or risk damaging the membrane of the microphone.

There is a 'sweet spot' to fully realizing fidelity which is analogous in learning any instrument without discrete articulation. Another consideration is the very high sensitivity of this microphone; keep as distant from the final amplification as is possible, particularly at high volumes or you'll experience feedback and accompanying distortion (unless that is your goal).

To get started, the object is to target the input passage and then lightly tap your cheek to present the ensuing air current to stimulate the microphone, varying the relative intensity of this action. You will need to find a nice compromise between too much velocity and volume of air and not enough entering the tube to take advantage of the dynamics and variations of the envelope of the filter, keeping your lips (in a shape you might whistle) a small distance from the tubes entrance. Play with KH's trimmer potentiometer to witness the various envelopes available (be gentle with this adjustment without twisting the body of this variable resistor) and realize a very small motion can create a fairly exponential variation.

Any musical instrument (or even striking the platform KH is on with some drumsticks; see video #1. Here we're picking up a lot more of the pen's tap because it's closer than the output, but you get the idea) will cause KH to react. Some sources work better than others (distortion wise).

Play Knucklehead Video 1

But that's not all; since Knucklehead's sensitivity is so great, placing the board nearby any other 'sharp', percussive sound source, the filter can be triggered by the rhythm and dynamics of this source as in our example of accompanying a nice, 80's disco beat (see video #2). You'll need to experiment with the distance you place the board from the source for best results.

Play Knucklehead Video 2

Imagine for a moment adhering Knucklehead to different spots on a guitar ('Scotch' makes a nice restickable series of different sized pads for this) and having the device follow your rhythm and attack as translated by Knucklehead.

You can even tap the back of the board near where the microphone resides and get some interesting results. Tightly grasping the board in using KH in this manner avoids the subtle input distortions that can occur from any of the mechanical 'distortion culprits'. Like any musical instrument, one needs to practice it.

As much as we don't advise this and to answer our first question, the name Knucklehead began when we discovered that with lips slightly parted very close to the input tube, lightly striking your forehead creates the desired effect and translates the sound of your 'noggin. Again, in our opinion, anyone attempting this would surely be a 'Knucklehead'. You can see this unadvised variation of this behavior and head banging in video #3 where first-time users are enthusiastically smacking their faces as a substitute for finding that 'sweet spot' mentioned earlier. An easy mistake to make. Really if you find that spot, so little action triggers the necessary stimulus.

Play Knucklehead Video 3

We'd like to suggest you use a 1/8th inch to 1/8th inch audio cable (stereo is ok) with one end fitted to a 1/8th inch to 1/4-inch adaptor to accommodate plugging into a common amplifier jack. A flat cable makes using the device more comfortable since we provide a clip for lanyard for KH to reside around your neck and these flat cables allow for a better and more flexible residing of the board and one such example can be found here: Click here for cable

One more thing, the battery used in Knucklehead (Duracell-MN21/23) may not seem very common to you, however it is quite readily available. The choice to use this battery was based on its 12-volt potential which improved the dynamic nature of all stages. As the battery gets depleted, you may notice a greater opportunity for distortion.