27 June 2012

Pedal Effects: What they do? - Part 3

Category Gain Pedals

Even that most of our gain needs can be obtained with the proper amp, not everybody can have more than one amp and, even having just more than just one amp, not always it is possible to crank the amp to obtain its best.
Some Gain pedals help the tubes to break earlier at lower volumes, some copy the sound of a cranked amp, and others work just like emulations of very particular amps.

Anyway, it is difficult to see a guitarist without at least a single gain pedal in his pedal board.

Family Dynamics
There are some pedals that are modifying the dynamic range of the signal. The Dynamic Range is the difference between the highest peak of the signal and the average signal level.
This family of pedals is not always well known or understood.

A compressor is a pedal which focus its attention on the volume envelop of the signal (search ADSR Curve, for further info). What at the end does is to flatten the peaks, to raise the average signal level and, eventually, to increase the release time of the note. Usually, a Gain control will increase the average signal level, an Attack or Compression control will slightly or hardly flatten the peaks and, a Release control will maintain the tail of the note to add sustain to the sound. A compressor can be used to balance the average level of music, avoiding high differences between peaks and valleys.

A sustainer is some kind of specialized compressor, more oriented to the tail of the sound, to provide more sustain but, without affecting the attack phase (peaks).

For sure, there pedals that have both effects together but, some are very specialized in attack phase (compressor) or release phase (sustainer).

A Noise Gate is also a very specialized compressor that works as an electronic gate. In every signal, there is a certain amount of floor noise. Such a floor noise becomes more and more evident when we begin to stack gain pedals or raise the gain in our amp.  Pedals are treating all the signal the same and, are not able to distinguish what is noise and what is music.
A Noise Gate is some kind of electronic gate that will allow to trespass the gate to such a signals that reach some determined level. The level where the gate opens is usually called Threshold.
Once the gate is opened, it will close when the sound level goes down to the threshold value during a certain time (take into account that we are talking always about few milliseconds in dynamics).
What the noise gate does is to use a downward compressor for the noise, dramatically reducing its level. Since the difference between the sound (above the threshold) and noise (below the threshold) are now higher, the noise is less perceived.
Some Noise Gates have full controls to configure the different values of threshold, gate open time (how much time must a signal be raising the threshold for the gate to be opened), gate close time (how much time must a signal drop under the threshold to the gate to be closed) and, even downward compression ratio.
The drawback of Noise Gates is that the boundaries between noise and signal aren't stable in time and clearly defined. Sometimes some of our signal drops down below the average noise level. If we force the threshold really low, part of the noise will pop up and, in an intermittent way, what is really ugly.
If we raise the threshold, we can loose the subtle of the tails of our sounds.
So, a Noise Gate well setup can be awesome but, a Noise Gate of bad quality or wrongly setup can be a real hell and, way worst than support the noise.

All pedals affecting dynamics are affecting the signal level (volume envelope) in one or more ways and, because they tend to raise the average signal level, they are prone in increase the floor noise (in the same amount as the signal is being pushed).

Family Equalizers

Equalizers are gain pedals that drop or raise the signal level but, of certain range the frequencies.
The audible spectrum is divided in several bands and, for each band, the equalizer allows us to raise or drop the signal level, therefore enhancing or reducing some particular frequencies.
The equalizer is, probably, the most important weapon for a Sound Engineer. It is the tool which one the engineer is able to let every instrument be clearly distinguishable from the rest in the mix.
So a equalizer in a pedal format should serve for the same. The equalizer will help to enhance those frequencies that better differentiate the guitar' sound from the rest of instruments, dropping the levels of those frequencies that can be in fight with other instruments.

But, equalizers can also serve to emulate signature sounds of some amps. Every amp has its signature way to enhance or dismiss every band so, with a single equalizer we can achieve a wide range of well knows sounds, without having to change the amp or the guitar.

Used after overdrives, distortions and fuzzes, can help to fine-tune the resulting sound to our taste and, this can dramatically change the sound of our distortion.

Being a gain pedal, the use of an equalizer increases the floor noise, as well.

Family Overdrives

The boundary between a booster and an overdrive is tinny but, while the booster wants an increase in gain, volume or both, without specially coloring the signal, the overdrive wants it.
There are two types of overdrives: overdrives that push the tubes to break and, overdrives that emulate the sound of a certain drove amp.

Overdrives that push the tubes are used to help an amp to break-up early and to produce their wanted harmonic distortion before the spot (volume level) where they would naturally do. The good thing is that we are achieving the best distortion character possible, the one generated by the amp. The drawback is that, even being early that spot, the amp increases clearly its loudness and, maybe we cannot go so loud in our environment.

Overdrives that emulate drove amps, doesn't need to change the loudness of our amp, they just deliver a sound similar to a certain amp (which they emulate) going overdrive.

The most famous overdrive of all the times is the Ibanez TS-808 (this one pushes but coloring), widely used in lots of recordings and, very often seen in pedal boards, even today. Another highly used overdrive was the Boos SD-1 (this one emulates).

The epitome of current days seems to be the Klon Centaur but, to get the best from this pedal, you need a good amp that can be pushed hard, otherwise, the sound of the Klon can be sterile.
Another well acclaimed overdrive is the Tim (or the Timmy) and, the Fulltone FullDrive and OCD are both widely used today, also.

There are overdrives for every taste and need. Overdrives that push tubes usually work better in tube amps while overdrives that emulate a driven amp work better in solid state amps, where there is no way to obtain that kind of sound.

The most of designs are based or on the Tubescreamer (Ibanez TS-808), or on the boss SD-1.
The way as those distort is different, the harmonics that they produce are of different order, being the TS warmer and undefined, while the SD-1 is cool, thicker and defined.
Lately there is a wave of new designs trying to emulate the driven sound of mythical amps that are really hard to have (because of their limited units and prohibitive price).

Family Distortions

Once more, the boundaries between an overdrive and a distortion can be really tinny. Let say that a distortion pedal wants to go further than the drive level of an overdrive, to produce highly saturated distortion. While overdrives try to preserve the foundational tone of your guitar, adding just a bit of color and those exciting harmonics that tube generate, distortions forget all that and go for producing a wall of sound, with highly distorted and colored sound (on some units, it doesn't matter what guitar are you playing and to which amp are you plugged, you get the sound of the distortion, that's all).

For sure, some distortion units want to give you in-a-box the amazing sound of high gain amps, that were set away producing their own signature high gain distortion sound (as the Soldano SLO-100, the Peavey 5151, the Mesa Boogie Triple Rectifier, Bogner XTC, etc.).
Some have their own signature sound and, not particularly copying a determined amp.

Some distortions are so sweet (MXR Distortion+) that, most than a distortion unit seem an overdrive and, most of the distortion units are able to deliver some kind of colored overdrive at very low gain levels.

Once more, the best distortion we can get is always from our amp cranked to the max but, distortion units allow us to fake this, using the clean channel of our amp at any volume level.
While overdrives are more sensitive to gain and volume levels of our amp (because they want to push the tubes), distortions will generate their own sound, independently of the volume that we setup in our amp.

One of the most famous distortion units is the ProCo RAT, a very organic type of distortion, that can go from light overdrive to fuzz territory and, everything in between. Very classy and widely used in recordings.

Family Fuzzes

Probably, the first pedal effect used with electric guitars. During the time of big orchestras, the guitar had not the protagonism that they have today. They were just creating some pads to support rest of instruments. The Fuzz was designed to provide a sound similar to a Sax and, was firstly designed to be used with keyboards (electronic organs).
Guitarists liked the idea to make their guitar to sound as a Sax so, they tried it and "Satisfaction" was reached.

There are mainly two kind of fuzz units. The one drived by a set of Germanium transistors (that have reversed polarity) and the one drived by a set of Silicium transistors. As in the case of the TS compared to the DS-1, the germanium units deliver a warmer, more organic and wild sound that the silicium units, that can sound cooler, more synthetic.

Even this, they are two main voices: British and American. British fuzzes are voiced brighter, with less gain (more as a dirty overdrive), thinner in body and sometimes harsh. American ones are thicker in body, more obscure in sound and with way more gain.

British models are based, more or less, in the first Vox ToneBender model, so you will see a lot of MKI, MKII, MKIII tones around. The ToneBender was in fact based in the Maestro Fuzz, designed in USA. The Electro-Harmonix Big Muff is maybe one of the thicker fuzzes around.

Fuzzes started to highlight when songs like "Satisfaction" of Rolling Stones started to climb the Hit Parade lists. Jimmy Page used very often a ToneBender MKII fuzz.
Prices of clones built with same components and same specifications as vintage units have prohibitive prices today. 

A vintage fuzz is awesome if it is the only pedal in our chain but, it can be a real headache if we have to integrate it in a full-equipped pedal board. In one side, the reversed polarity of germanium fuzzes require to use isolated power sources, to avoid the mix with "normal" polarity pedals. In other side, since the Fuzz was initially designed for organs, the impedance levels (way lower) were appropriate for such an instrument so, when we are stacking that fuzz, we can have some impedance-related issues with rest of pedals and, even a pedal before the fuzz can dramatically change its sound.
This is way most of people that loves fuzzes try to keep them in a separated loop and, out of the circuit the most of time.

Fortunately, not all the fuzzes available today are just re-creations of the mythical vintage units. There are some people there creating their own designs from scratch and, providing units that work flawless with rest of pedals, because the design is now created for a guitar, instead of an organ.

The fuzz is the most synthetic sounding of all the gain pedal families. Its the gain pedal with the highest sustain and thicker wall of sounds of all (except for very vintage units). Very used during '60s to '70s and, not so favored nowadays.

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