One of Fender''s oldest factory mods features a stacked potentiometer
Fender.com describes their TBX tone controlāwhich stands for āTreble Bass Expanderāāas follows:
āThis detented, stacked 250k/1 Meg control enhances your tonal palette without the use of a battery. From 0 to 5, the TBX is your standard tone control, but once you pass 5 you start to decrease the resistance, which allows more bass, treble, presence and output to flow to your amp.ā
A lot of people think of the TBX tone control as a treble boost, but thatās not quite accurate. The TBX control actually consists of a custom dual-ganged pot (aka a āstackedā or āstereoā pot), a resistor, and a capacitor that cuts the bass and treble out of the circuit, depending on which way you turn the knob. This can add some new dimension to your solo parts, especially if you are going for those bright, crystal clear Jeff Beck tones.
The basic configuration of the TBX control (Fender part no. 0992052000) changed several times over the years. Fender used several different values for the two pots, the capacitor, and the resistor. The first few versions also lacked a center detent function. The current version consists of a detented 250k/1 Meg stacked pot, a 0.022uF standard film capacitor, and an 82k-ohm carbon-film resistor. In a nutshell, the TBX tone control is a special pot that cuts either treble or bass instead of a normal tone pot, which cuts only treble. This is done with the dual-ganged pot, which is wired to work as a low-pass filter in one direction and a high-pass filter in the other. The center detent in the middle is provided for the off or āflatā position.
The dual-ganged pot is cleverly designed, meaning you canāt substitute a normal stereo pot to make your own budget TBX control. How does it work? The bottom pot (with the shaft up) is pot B on our drawing and is the normal tone control we all know. Itās a standard 250k audio pot with a range from 0 to 5 on the knob. At the detent (middle) position, it goes open and acts like a no-load tone pot, remaining out of the circuit from 5 to 10 on the knob.
The engineering behind this is actually very clever. Normally, the resistive material ring inside of the pot is a band of carbon-containing gunk that is printed onto the phenolic wafer. On the lower TBX pot, only half of the ring is conductive, as the other 50 percent is made out of a non-conductive material. So we can say it is a no-load tone control pot, but instead of going open at approximately 98 percent of its rotation, it goes out of the circuit at exactly 50 percent.
The other pot, which is labeled A, acts in the opposite direction. It also has a split resistive material ring inside, but instead of non-conductive material, metal is used for one half of the ring. This means that between 0 and 5 on the knob, its resistance is at maximum. After the detent position, the normal function takes place from 5 to 10 on the knob. This 1 Meg linear pot comes into the circuit in series with the resistor after the detent position. Because of the high resistance (1 Meg ohm), the load added to the passive guitar circuit is very low.
The diagram shows you how to wire the TBX tone control on your Strat. The red wire is the input for the TBX control, and the green wire is a short jumper wire, connecting pot A to pot B. The TBX control can be wired as a substitute for any normal tone control for any pickup, as well as a master tone control for all pickups. Any mod that works with a normal tone control works with this one as well, so be creative.
Weāve talked about this subject several times before, but on pot B (the normal 250k tone control that operates from 0-5 on the knob), you can use any value of tone cap you want to achieve different tonal shades. On pot A, there is an 82k-ohm carbon-film resistor. As you turn the knob from 5 to 10, the added resistance reduces the effect of that resistorās load on the pickups until it reaches 1 Meg, where it has almost no effect. Trying several resistor values and materials is another great adventure to be had. Personally, I like the value of the resistor to be 220kāgive it a try. Notice that one end of both the resistor and the capacitor is soldered to ground on the TBX pot case.
The TBX tone control isnāt rocket science, but it is effective. The addition of this unique control can add some tonal options to your palette without altering the classic appearance of your Strat. Next month, weāll talk about more possible mods for the TBX control. Until then, keep on modding.
Dirk Wacker
Dirk Wacker lives in Germany and has been a guitar addict since age 5. He is fascinated by anything related to old Fender guitars and amps. He plays country, rockabilly, and surf music in two bands, works regularly as a studio musician, and writes for several guitar mags. He is also a hardcore DIY-er for guitars, amps, and stompboxes, and he runs an extensive webpage (singlecoil.com) on the subject.
- Fender Unveils Gold Foil Series - Premier Guitar āŗ
- Fender Unveils Cutting-Edge Amp Tone Master Princeton Reverb - Premier Guitar āŗ
- Fender Honors Legendary Session Player Michael Landau - Premier Guitar āŗ
- Fender Unveils the CuNiFe Pickup Series - Premier Guitar āŗ
- Fender Unveils Squier Sonic Series - Premier Guitar āŗ
- Fender Honors Steve Lacy with Signature People Pleaser Strat - Premier Guitar āŗ
- Fender Honors Shredder John 5 with Signature Telecaster - Premier Guitar āŗ
- Fender Announces Mikey Way Signature Jazz Bass - Premier Guitar āŗ
Day 9 of Stompboxtober is live! Win today's featured pedal from EBS Sweden. Enter now and return tomorrow for more!
EBS BassIQ Blue Label Triple Envelope Filter Pedal
The EBS BassIQ produces sounds ranging from classic auto-wah effects to spaced-out "Funkadelic" and synth-bass sounds. It is for everyone looking for a fun, fat-sounding, and responsive envelope filter that reacts to how you play in a musical way.
A more affordable path to satisfying your 1176 lust.
An affordable alternative to Cali76 and 1176 comps that sounds brilliant. Effective, satisfying controls.
Big!
$269
Warm Audio Pedal76
warmaudio.com
Though compressors are often used to add excitement to flat tones, pedal compressors for guitar are often ā¦ boring. Not so theWarm Audio Pedal76. The FET-driven, CineMag transformer-equipped Pedal76 is fun to look at, fun to operate, and fun to experiment with. Well, maybe itās not fun fitting it on a pedalboardāat a little less than 6.5ā wide and about 3.25ā tall, itās big. But its potential to enliven your guitar sounds is also pretty huge.
Warm Audio already builds a very authentic and inexpensive clone of the Urei 1176, theWA76. But the font used for the modelās name, its control layout, and its dimensions all suggest a clone of Origin Effectsā much-admired first-generation Cali76, which makes this a sort of clone of an homage. Much of the 1176ās essence is retained in that evolution, however. The Pedal76 also approximates the 1176ās operational feel. The generous control spacing and the satisfying resistance in the knobs means fast, precise adjustments, which, in turn, invite fine-tuning and experimentation.
Well-worn 1176 formulas deliver very satisfying results from the Pedal76. The 10ā2ā4 recipe (the numbers correspond to compression ratio and āclockā positions on the ratio, attack, and release controls, respectively) illuminates lifeless tonesāadding body without flab, and an effervescent, sparkly color that preserves dynamics and overtones. Less subtle compression tricks sound fantastic, too. Drive from aggressive input levels is growling and thick but retains brightness and nuance. Heavy-duty compression ratios combined with fast attack and slow release times lend otherworldly sustain to jangly parts. Impractically large? Maybe. But Iād happily consider bumping the rest of my gain devices for the Pedal76.
Check out our demo of the Reverend Vernon Reid Totem Series Shaman Model! John Bohlinger walks you through the guitar's standout features, tones, and signature style.
Reverend Vernon Reid Totem Series Electric Guitar - Shaman
Vernon Reid Totem Series, ShamanWith three voices, tap tempo, and six presets, EQDās newest echo is an affordable, approachable master of utility.
A highly desirable combination of features and quality at a very fair price. Nice distinctions among delay voices. Controls are clear, easy to use, and can be effectively manipulated on the fly.
Analog voices may lack complexity to some ears.
$149
EarthQuaker Silos
earthquakerdevices.com
There is something satisfying, even comforting, about encountering a product of any kind that is greater than the sum of its partsāthings that embody a convergence of good design decisions, solid engineering, and empathy for users that considers their budgets and real-world needs. You feel some of that spirit inEarthQuakerās new Silos digital delay. Itās easy to use, its tone variations are practical and can provoke very different creative reactions, and at $149 itās very inexpensive, particularly when you consider its utility.
Silos features six presets, tap tempo, one full second of delay time, and three voicesātwo of which are styled after bucket-brigade and tape-delay sounds. In the $150 price category, itās not unusual for a digital delay to leave some number of those functions out. And spending the same money on a true-analog alternative usually means warm, enveloping sounds but limited functionality and delay time. Silos, improbably perhaps, offers a very elegant solution to this canāt-have-it-all dilemma in a U.S.-made effect.
A More Complete Cobbling Together
Silosā utility is bolstered by a very unintimidating control set, which is streamlined and approachable. Three of those controls are dedicated to the same mix, time, and repeats controls you see on any delay. But saving a preset to one of the six spots on the rotary preset dial is as easy as holding the green/red illuminated button just below the mix and preset knobs. And you certainly wonāt get lost in the weeds if you move to the 3-position toggle, which switches between a clear ādigitalā voice, darker āanalogā voice, and a ātapeā voice which is darker still.
āThe three voices offer discernibly different response to gain devices.ā
One might suspect that a tone control for the repeats offers similar functionality as the voice toggle switch. But while itās true that the most obvious audible differences between digital, BBD, and tape delays are apparent in the relative fidelity and darkness of their echoes, the Silosā three voices behave differently in ways that are more complex than lighter or duskier tonality. For instance, the digital voice will never exhibit runaway oscillation, even at maximum mix and repeat settings. Instead, repeats fade out after about six seconds (at the fastest time settings) or create sleepy layers of slow-decaying repeats that enhance detail in complex, sprawling, loop-like melodic phrases. The analog voice and tape voice, on the other hand, will happily feed back to psychotic extremes. Both also offer satisfying sensitivity to real-time, on-the-fly adjustments. For example, I was tickled with how I could generate Apocalypse Now helicopter-chop effects and fade them in and out of prominence as if they were approaching or receding in proximityāan effect made easier still if you assign an expression pedal to the mix control. This kind of interactivity is what makes analog machines like the Echoplex, Space Echo, and Memory Man transcend mere delay status, and the sensitivity and just-right resistance make the process of manipulating repeats endlessly engaging.
Doesn't Flinch at Filth
EarthQuaker makes a point of highlighting the Silosā affinity for dirty and distorted sounds. I did not notice that it behaved light-years better than other delays in this regard. But the three voices most definitely offer discernibly different responses to gain devices. The super-clear first repeat in the digital mode lends clarity and melodic focus, even to hectic, unpredictable, fractured fuzzes. The analog voice, which EQD says is inspired by the tone makeup of a 1980s-vintage, Japan-made KMD bucket brigade echo, handles fuzz forgivingly inasmuch as its repeats fade warmly and evenly, but the strong midrange also keeps many overtones present as the echoes fade. The tape voice, which uses aMaestro Echoplex as its sonic inspiration, is distinctly dirtier and creates more nebulous undercurrents in the repeats. If you want to retain clarity in more melodic settings, it will create a warm glow around repeats at conservative levels. Push it, and it will summon thick, sometimes droning haze that makes a great backdrop for slower, simpler, and hooky psychedelic riffs.
In clean applications, this decay and tone profile lend the tape setting a spooky, foggy aura that suggests the cold vastness of outer space. The analog voice often displays an authentic BBD clickiness in clean repeats thatās sweet for underscoring rhythmic patterns, while the digital voiceās pronounced regularity adds a clockwork quality that supports more up-tempo, driving, electronic rhythms.
The Verdict
Silosā combination of features seems like a very obvious and appealing one. But bringing it all together at just less than 150 bucks represents a smart, adept threading of the cost/feature needle.