Banjo Head Tension & the Pocket-Dial Tool
Among all the factors that can affect the tone of your banjo, head tension is perhaps the most important and least understood.
Unlike a fine guitar or mandolin, where the tone is dependent upon the thickness and tonal properties of the instrument’s wooden top and bracing, the tone of a banjo is primarily dependent upon the tension of the banjo head.
Fixed & Variable Banjo Parameters
Features such as rim size, wood choice and tone ring design certainly affect the tone of a banjo, but these are fixed per instrument and cannot be adjusted. Other items, such as bridges, tailpieces, string gauges or head types can be more easily changed and experimented with, but for the most part remain constant.
Given a banjo with its particular configuration of head type, bridge, tailpiece and strings, the primary if not only variable affecting tone that can be adjusted is the head tension.
Because proper head tension is so critical to tone and playability, in the late 1800s banjos were re-designed with tension hoops and hooks to make adjusting the head tension not only possible, but a relatively straightforward task.
Head Tension versus Tone
Very slight adjustments to the tension of a banjo head will have surprisingly large effects upon the resulting tone. A head that is just slightly on the “loose” side will produce a warmer, richer or even fuller sound. Conversely, a head that is slightly on the “tight” side will produce a brighter tone with more projection, snap or ring and tend to feel more responsive. A balance between these two is a head tensioned just enough to have a clear tone and projection, but with an appropriate measure of underlying fullness and body.
Whether you prefer a (a) warmer, (b) brighter or (c) balanced tone, it is surprisingly easy to have too much of a good thing. A head that is too loose will dampen the energy being transmitted throughout the head as well as to the tone ring and rest of the instrument. The result will be a clouded, tubby, or even warbly tone.
On the other hand, a head that has been tightened too much will overly restrict the amount the head can vibrate, thus reducing the fabric or complexities of overtones being generated. The result will be a choked-out or tinny sound, akin to trying to sing through clenched teeth. Beyond this, over-tightening can also lead to splitting or damaging the head itself.
Head Tension Measurement
Even among those with decades of playing experience and well-trained ears, an accurate and precise method to help evaluate and measure the tension of your banjo head is invaluable. A precision dial indicator, like those used in metalworking machine shops, can be used to measure the deflection of the head under a fixed singular point load. The resulting deflection, measured in thousandths of inches, is proportional to the tension of the head.
Adjustments of a few thousandths in either direction, easily measured with such a device, will produce correspondingly warmer or brighter tones as preferred. A Dial Indicator facilitates precise adjustments for beginners and experienced players alike, eliminates any guesswork, and offers a repeatable objective standard.
How a Dial Indicator Works
With the Dial Indicator-Method, a precision-loaded spring pushes a small probe tip gently onto the head of the banjo. This results in a small but measurable deflection of the head surface in the area immediately under and around the probe tip. A good analogy to think of is pressing a single finger down onto a cushion.
This deflection, measured in thousandths of an inch increments, provides an accurate indication of the banjo head tension within the ranges commonly preferred by banjo players. Neither this method (nor any of the other aforementioned methods) measures the actual tension within the head membrane in pounds or other units. Rather, the tension of the head is inversely proportional to the deflection of the probe tip.
A looser head will deflect more; a tighter head will deflect less. Again, think of pushing your finger into a soft cushion versus pushing it into a firm cushion with the same amount of force.
Pocket-Dial Measurement Tool
The Pocket-Dial is a simple, convenient and precise tool that employs the Dial Indicator-Method to evaluate, measure and adjust the tension of your banjo head. The Pocket-Dial has also been designed to be small, lightweight, and easily fit in your banjo case, ready to use when you need it. The unit features three scales to choose from:
Simple Scale (blue)
The blue “Simple” scale is based upon a simple 0 to 10 point scale. Most banjo players consider a reading of “10” to be balanced. A point or two higher will produce a correspondingly tighter and brighter tone; whereas a point or two lower will produce looser & warmer tones.
Skin Scale (brown)
The brown “Skin” scale is intended for banjos with natural heads like goatskin or calfskin and presents a target “green-zone” corresponding to the range of readings preferred by most players with natural skin banjo heads.
Standard Scale (black)
The black “Standard” scale utilizes the standard machinist’s dial scale as found on other precision mechanical measuring instruments. A reading of “90” on the Standard scale corresponds to a reading of “10” on the blue Simple scale.
How to Use the Pocket-Dial
Step 1 – Select Scale and Calibrate Device
If you have a synthetic banjo head, choose the Simple Scale (or Standard Scale if you are accustomed to other dial indicator measurement tools). If your head is made of natural skin, choose the Skin Scale.
Hold the Pocket-Dial down firmly on a hard flat surface like a glass table or granite countertop with the probe tip pressing towards the flat surface. Slightly loosen the thumbscrew that locks the dial face, then slowly twist the dial face until the needle points exactly towards the calibration mark (the “target” symbol above each scale name) corresponding to the scale you wish to use. Finally, gently re-tighten the thumbscrew to lock the dial face orientation in place. The tool is now properly calibrated and ready to use for the scale you have selected.
Step 2 – Take Measurements
Hold the Pocket-Dial firmly on the surface of your banjo head near the outer edge and note the reading. If you press really hard, particularly on a very loose head, you can distort the reading. Lift, relocate and place firmly again (like a doctor’s stethoscope). Do not drag or slide the Pocket-Dial across the head surface as this may cause scuff marks.
Check the measurement at 5 to 6 places around the outer edge of the head and note the readings. You can do this with or without strings installed as it will not measurably affect the reading in the target tension range.
Step 3 – Adjust as Needed
If you have a resonator style banjo, carefully remove the resonator back. Using a properly fitting wrench, tighten or loosen the tension nuts as needed. Turn them only just a little bit at a time, – perhaps just an 1/8 or 1/4 turn each, working your way all around the perimeter of the rim. Check your readings again, then repeat as needed until target tension is achieved.
If your banjo has a synthetic head, try to optimize your tone by adjusting a little more or less in certain areas to get the same number reading across the entire surface. If your banjo head is natural skin, don’t worry about specific numbers, – rather use the skin scale and aim for readings grouped in the “green zone.”
Target Head Tension
Use this table as a guide to help determine your target reading.
Please note that every banjo and every ear is different. A reading that sounds best on one banjo may not sound best on another banjo, even if it’s the same model instrument. The most common issue is a head that is too loose, particularly in the case of heads made from natural skin.
By using a precise measurement tool like the Pocket-Dial, it becomes easy to experiment with different readings and different sounds.
Once you have adjusted your head to the preferred tension, take note of the value so it can be referenced and repeated as needed.
Head Types versus Tension
Synthetic banjo heads (Remo Frosted, Renaissance, WeatherKing, etc.) are uniform in thickness, stiffness and density, As such, it is both possible and desirable to adjust the tension of the banjo head at several locations across the entire surface to give a uniform reading. Otherwise, the vibrating head will generate conflicting and often competing overtones across its surface, resulting in a much less clear tone.
Heads made of natural skin, like goatskin or calfskin, are not uniform in thickness, texture or stiffness. As such, it is very difficult to adjust the tension to the same value across the entire surface of the head. Also, aiming for a specific value in multiple locations can lead to over-adjusting one or more areas of the head, resulting in an uneven tension hoop or possibly damaging the skin. With natural skins, it is advisable to aim for an acceptable range of measurements (indicated by the Skin Scale “green zone”), versus a single number, with readings typically being slightly looser than those preferred for synthetic heads.
Unfortunately, most of the changes to the tension of a banjo head happen slowly over time, with our ears becoming accustomed to the loss of preferred tone. Regular and precise measurement and adjustment is necessary to make sure your banjo always sounds and plays its very best.
For banjos with synthetic heads, it is advisable to re-check your tension each time after you change strings or travel with your instrument. Banjos with heads made from natural skin will need checked more often, particularly in response to changing humidity, weather or seasons.
Pocket-Dial & Case $149.00
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“I need my banjo to sound its very best before we hit the stage, and the Pocket-Dial helps me do that!”
– Russ Carson, Banjo Player for Ricky Skaggs & Kentucky Thunder, @81crowe
“I really like it! Takes a lot of the guess work out and sure makes the banjo sound a lot better!”
– Mike Snider, Grand Ole Opry Member & National Banjo Champion
“It works, it’s easy to use, and the option of having a scale specifically designed for natural hide heads really appeals to me. I truly enjoy using mine!”
– John Balch, HideBanjoHeads.com
“It’s small, lightweight, fits right in my banjo case, and really easy to use. I recommend one for all my students who want their banjo to sound the very best it can!”
– Banjo Ben Clark, Banjo Instructor and Founder of BanjoBenClark.com
⚠️ WARNING: This product can expose you to chemicals including lead, which is known to the State of California to cause cancer. For more information, go to www.P65Warnings.ca.gov.