26 June 2012

Pedal Effects: What they do? - Part 2

Families of Pedal Effects

We classified pedals depending on their high level functions and link types. Now it is time to see the most common families within those categories.

Category Signal Recovery

Family Line Drivers

Line Driver pedals were designed to recover the slight lost of signal that can happens when guitar signal travels accross the guitar cable. Basic idea is to restore the original signal level, without add or substract anything else.
Line Drivers are different from Buffers and Boosters, in the sense that they are only trying to raise a bit the signal level, with total transparency.
Anyway, we will see that many pedals are crossing several boundaries and, do more than one function.

One of the first pedals of this kind was the Electro-Harmonix LPB-1, followed by the MXR Micro Amp (that colored the signal and it's something between a Booster and a Line Driver).

Family Boosters

Boosters were designed to increase the gain and volume levels of the signal. So, they aren't just for restore the original signal level but, they can change the gain (intensity) of the signal.

There are clean boosters, that just do that, to increase gain or level or both and, there are specializated boosters, that specialy boost some frequency ranges.
Clean boosters are specially interesting to give just that bit of body to weak pickups. This helps with sustain and with an overall rounder tone.

One typical booster is a Treble Booster, since the first that is rolled off by a guitar cable is just the high end content. Treble boosters, despite of increase gain/volume, have an special enfassis in high-end frequencies. Brian May's had always a treble booster on his pedal chain. Of the first treble boosters was the Maestro RangeMaster.

Other typical specializated booster is the Fat Booster, that works similarly to a treble booster but, having special care of the low end.

Family Buffers

A buffer is a pedal designed to re-adjust impedance levels so, increasing the input level up to a reasonable level (at least, the 1 MOhm impedance that an amp's input expects) and decreassig the output level (the closer to zero Ohm as possible).

It's very strange to see a Buffer Pedal Effect on the chain of most of guitarists but, every designed pedal board that Peter Cornish make for their renamed artists includes his own designed buffer.

Even that, a priory, a buffer can be of great help, it can also introduce some issues when used before some vintage effects (that weren't specifically designed for electric guitars, by example) but, we will talk about this later.

Family preamps

Preamp pedals are some kind of boosters but, with a colored signal, equalizated to mime the goods of a mythical amp. By example, the Xotic AC Booster mimes the AC30, the Xotic BB pre-amp the BluesBreaker, Wampler Plexy Drive the Plexy, etc.
Those pedals are, more or less, copying the behavior and nuances of the preamp stages of those amps that they emulate.

There are other colored boosters not clean and not specializated on trebles or basses, that also doesn't mime any special amp but, that they clearly add some color to the signal. This is the case of the old MXR Micro Amp (that adds that sweet warm), the Xotic EP Booster (that mimes the preamp stage of an EchoPlex unit) and, many others.

As in the case of boosters, preamps want to raise the signal gain and volume up to a level that helps to achieve the right gain on amp's input but, with a distinguishable color. While in buffers, we usually two knobs (volume, gain) on clean buffers and, one more knob (treble, fatness, etc) in specializated boosters, in the case of pre-amps we can have a full tone-stack (treble, bass, mids).

Category Signal Followers

Family Tuners

The tuner is a must have pedal on any pedal board. The tuner helps us to maintain the affination of our guitar flawless. Usually, there are two kind of tuners: digital and analogic.
Some time ago, digital tuners had less accuracy than analogic ones and, the response time of the analogic ones was clearly superior so, to tune the strings was easier (and expensiver) with an analogic tuner.
Nowadays, things seem to be reversed and, there are outstanding Tuners.
Usually, we want the tuner to be true bypass (to don't affect our signal), transparent related to impedance levels and, as accurated as possible, with a quick response to the pulsation of the string.
Current digital tuners have an accuracy (1 cent) better  than the smallest interval that a human ear can distinguish (about 5 cents of tone) but, luthiers use very accurated tuners for their specializated work, with higher accuracy levels (0.1 and, enen 0.01 cents of tone).

The tuner is clearly a signal follower. It needs the cleanest signal directly coming from your guitar, to be able to catch the frequencies with accuracy.

Even that, in principle, it seems a "dummy" pedal, be sure you check the responsiveness of your tuner before choosing one and, be sure it works in true bypass mode and that, when switched on, it mutes your guitar (to tune in silence). Also, be sure you understand the display and that this one is highly visible in a natural position (pedal on floor and you standing up), even under high illumination levels.
Also, if you are using alternate tunings, be sure that your tune is able to let you to set up such a tunings, to help you in your work.

A tuner can be used also as an OFF switch. When pushed the guitar shuts up. If it is at the beginning of the chain or before time effects, last echo trails will be heared before complete silence.

As any signal follower pedal, its natural position is as early in the chain as possible. In principle, the tuner should be the first pedal but, we will see that sometimes, this is not possible.

Family Pitchers

Pitchers are pedals designed to "read" the input signal and then to create one or more parallel signals with a different pitch (some tones up or down). You can imagine that to do a nice job, they need the purest signal possible, otherwise, the resulting pitch can be wrong, because of a "dirty" signal and pedal's difficult to understand what note came.

One typical pitcher is an Octaver, that creates a secondary signal an octave higher or lower than the original signal, mixing both on the output but, Boss designed long time ago some Pitch Shifter units that were able to produce a secondary signal of any musical interval (second, third, forth, etc.).

We have also arpeggiators, that given an input note, create a sequence of notes following some pattern refered to some scale. Other similar pedal is the harmonizer, that creates one ore more different voices, with different intervals that are re-adapted depending on the scale.

The famous Whammy is some kind of harmonizer-pitch shifter pedal so, you can expect this one working best as early in the pedal chain as possible.

Family Filters

There are some other pedals that aren't creating a second voice shifting down or up the original signal but, they need a clean note to work properly.
This is the case of Auto-Wah or Filter-Q pedals, which response varies depending on signal's strenght, attack, phase, etc.
A typical filter pedal is the Wah, which natural position is quite well at the beginning of the chain.

Family synthetizers

Yes, even in our analogic world there are synthetizer pedals available, as the Electro-Harmonix Pog.
Some other pedals, like the MXR Blue Box, create a secondary voice that sounds very artifficial (synthetized) and, work better early in the pedal chain, as the rest of signal followers.

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