Part III - Auxiliary and expressive effects and signal chain considerations
INTRODUCTION
Whereas Part II of this guide focuses on the subtler applications of effects, Part III directs its gaze towards more overtly affected sounds.
Part III is broken into two parts: the first is on effects themselves while the second is on how their order in the signal chain affects how they work. Please note that the taxonomy below (filter, gain, modulation, time, etc.) is somewhat arbitrary as many effects in Part III operate in multiple domains of the signal.
There's a lot of ground to cover here, so let's get started.
A. GAIN - OVERDRIVE AND DISTORTION, FUZZ, AND VOLUME
A.1: Clean/gain boost and compression - see Part II
A.2: Overdrive and Distortion
When a clean/gain boost is put in front of a tube amp, that boost can be used to push the amp to the point that the power tubes begin to distort. As the output volume of a tube amp increases, the power tubes begin to compress the signal. Once this compression reaches a certain point, the power tubes begin to distort the signal in the following ways:
- the dynamics become noticeably compressed
- peaks begin to form at the even-numbered harmonics
- the most prominent peaks and valleys of the waveform are sheared off, resulting in clipping
Together, these features "saturate" the sound and create a type of distortion many listeners find pleasing; however, this sort of tube amp distortion is usually achieved only in an amp's upper volume tiers.
Overdrive and distortion are both attempts to recreate this effect at somewhat lower volumes. Overdrive pedals combine a focused EQ boost designed to push a tube amp into distortion at lower volumes with a harsh level-dependent distortion coming from "soft" clipping diodes in its circuit. In contrast to overdrive pedals, distortion pedals rely less on a gain boost to the amp and instead saturate the signal themselves.
Most overdrive and distortion pedals feature the following controls:
- Gain/Distortion - alters the amount of distortion applied by the pedal
- Tone - functions as an EQ. The exact behavior of this knob varies with the type of overdrive
- Level - level of the output signal
In addition to these controls, some overdrive and distortion pedals provide 2- or 3-band EQ controls (whether these controls affect the signal before or after the distortion is applied varies with the model).
Neither of these effects will work as intended in most amplified 'ukulele contexts. The focused EQ boost of overdrive pedals will not push most PA or monitor speakers into distortion but will instead function as a signal coloration, and the nail noise and harmonic complexity picked up by piezo transducers will make many distortion pedals sound harsh and fizzy. A pseudo-solution to the former problem exists in the form of either guitar amps or amp modellers (see section E), but the latter problem is inherent to the design of the offending distortion pedals themselves.
Special note: anti-feedback tools are often necessary to render overdrive or distortion usable at anything above bedroom sound levels.
A.3: Fuzz
Fuzz represents an attempt to reproduce the sound of a fundamentally broken amplifier (usually punctured or torn speaker cones or misaligned tubes). First pedals to make tubes distort, then pedals to replace distorted tubes, and now pedals to reproduce the sound of broken speaker cones and misaligned tubes; what is up with people and malfunctioning tube amps?
Anyways, fuzz pedals press the signal into a square waveform, resulting in a sonic texture that is fuzzy or wooly. This adds a harsh squelch to your tone that almost completely destroys any hint of 'ukulele, but it's a loveable sound nonetheless. Unfortunately, WILL BE DEVELOPED IN A REVISION.
Special note: fuzz is a *very* feedback-inducing effect, with many fuzz pedals creating spontaneous feedback in certain settings. Anti-feedback tools are strongly recommended here.
A.4: Volume
Volume pedals are probably the least interesting of all the pedals in Part III, and because I love you all so much, I'm going to spare you the details and get to the point.
Just kidding. I am going to microscopically analyze volume pedals with a level of detail so precise you're almost guaranteed to find it literally excruciating.
Volume pedals come in several physical form factors: rocker pedals, knobs, and rollers. Rockers are the most common and are useful for swells, maintaining constant volume across a decay, or for dynamically phrasing in; knobs take up less space on a crowded pedalboard and are good for "set and forget" operation (typically to keep levels in check towards the end of a signal chain), and rollers (at least the single model I know to exist) offer a compromise between the two form factors.
Different rocker pedals also feature differing amounts of travel. Since most volume pedals use the rocker format, I feel it necessary to discuss the two most prominent rocker designs: potentiometer, or "pot", and electro-optical. In an pot-based design, a drum connected to logarithmic potentiometer mounted to the base of the enclosure is connected to the enclosure lid via a string. Rotational movement of the lid is transferred to the potentiometer via the string and drum in one of two ways:
- Spring method - in this method, a spring takes up any slack in the string. The string makes several loops around the drum and passes through a ring on the underside of the lid and a shaft located along the posterior margin of the base. Both ends of the string are affixed to hooks on either end of a spring that takes up any slack in the system
- Set screw method - the necessary friction comes from a small loop around a set screw screwed into the drum. Both ends of the string are affixed to mounting plates located on the underside of the lid on either side of the potentiometer. The length of the string is wrapped around the drum in two partial loops connected by a perpendicular loop around a set screw. Any undue slack in the system resulting is easily removed by pulling more of the working ends into the mounting brackets
In contrast, electro-optical designs are mechanically simple. A light mounted to the underside of the lid moves either closer to or further away from a photoresistor, thereby controlling the output signal level.
In addition to these differences in construction, the following functional differences persist between the two designs:
- Maintenance - pots, strings, and springs all wear out and require periodic replacement (a simple operation). The only moving part in an electro-optical design is the lid itself
- Smoothness of swell - since a potentiometer cannot be "half-on", pot-based design always exhibit a bump in volume when the rocker is moved from "fully off" to "slightly on". Electro-optical designs provide continuously variable output all the way down to completely off
- Passive vs. active - pot-based designs come in both passive and active variants. Electro-optical designs, requiring current for the aforementioned light, are always active
As noted in the list above, volume pedals can be either passive or active. Passive volume pedals don't require external power and are basically guitar volume knobs in rocker pedal format. When they feature a tuner out, the output is usually split between the tuner out and amp out, and this can create high-end rolloff in the signal due to the tuner loading the signal when powered up (a true bypass tuner can solve some of this problem when turned off alhough this defeats the point of a tuner out). Active volume pedals require a power supply and usually provide a buffer (see section E) or low-gain preamp and isolated tuner output.
Passive volume pedals also come in varying input impedance. The most common values are 25 kOhm, 50 kOhm, 250 kOhm, 500 kOhm, 1 MOhm, and 10 MOhm. If you are using a passive pickup with no preamp and intend to use a volume pedal, you should seek a volume pedal with an input impedance of no less than 1 MOhm (10 MOhm wwould probably be preferable). Alternatively, a buffered pedal (not true bypass) placed between your instrument and volume pedal will allow you to use a 25 kOhm passive volume pedal, but you'll still have to worry about loading from the buffered pedal itself.
And in the end, all a volume pedal does is place a volume fader at your foot, usually in a rocker pedal format. Roll forward to increase volume or roll back to reduce volume.
Simple, ain't it?
Ready to tar and feather me yet? I promise I won't do that to you again, so stay tuned for the rest of Part III.