--> If you’re not careful in constructing your tone, misplaced/misused pedals can kill your sound. Now then, all you steely-eyed guitar killers, what have we learned about our beloved


From The Lab
If you’re not careful in constructing your tone, misplaced/misused pedals can kill your sound.
Now then, all you steely-eyed guitar killers, what have we learned about our beloved distortion? Let’s take a moment to recap.

First off, we should have a good understanding of the terms overdrive, distortion, gain, and volume. As luck would have it, all of these aspects of our guitar sound are closely related and overlap somewhat. As a result, they are often incorrectly used to refer to one another. If you’re still a little hazy on the differences, please consult our last four discussions (available online at premierguitar.com). But if you’re short on time like the rest of us, the following is a quick rundown.

Overdrive is essentially the result of pushing a signal above “normal” limits. This can cause distortion, an increase in volume, and, in technical terms, an increase in gain. The confusion among the terms is becoming understandable now, isn’t it?

Distortion occurs when something causes the signal to bend or square off from its original shape or amplitude. Remember, amplitude is the “height” of the signal, often measured in a voltage. Whatever is causing the distortion can be overdriving the tubes or components. These can be wave shaping devices such as pedals designed for this purpose or even the speakers when pushed to their limits. It should be noted that most distortion is not very musical. In most cases, the more distortion the less original tone, which is why true tube amp distortion tends to sound better than the pedalderived kind. That is the main problem guitarists face with distortion pedals – they stray too far from the original tone of the guitar and amp. Keeping the tone intact is difficult but pedals work great for achieving distortion at less than ear-damaging levels – see the trade off?

Gain interplays with volume, overdrive and distortion. It is usually a function of a circuit, whether it is an amp, mixing console, etc. Gain is usually referenced at the beginning of a circuit and can increase the volume of the signal, up to a point. After the operating parameter of the circuit is reached, the signal will begin to become distorted – a classic example of overdrive. Continuing to add gain at this point will not increase the loudness but will add to the amount of distortion. This is often described as “thick.”

Volume simply refers to loudness, period. It doesn’t matter if it is a clean or distorted signal – loud is loud. Pushing the pre or post-volumes may cause overdrive, which then gives us distortion. Around and around we go.

In parts two and three we looked at some signal waveforms on a osciloscope. Review these photos to get a good “visual” representation of what they represent. Part two also covered the communication aspect of the music we play – I cannot over emphasize how important this is in relation to overdrive and distortion. It is paramount to remember that less is more in a band situation. When you are playing with a band the guitar signal has to “fit in the mix” and not compete with the vocals and cymbals. When practicing alone you can distort all you want – and it sure sounds good – but use that same amount of crunch with the band and I can assure you the band will sound like hammered mud.

Part three spoke about the ins and outs of pedals, and our love/hate relationship with them. Pedals can be great tools to achieve heavy distortion at lower volumes, but as the volume rises the sound starts going south. Pedals have an inherent “tone robbing” aspect and often take your original tone far from home. This too is not always a bad thing, but it is a pity to have the tone of a $3000 guitar killed by a $100 pedal. Pedals must be kept in their proper place as you work on achieving killer tone.

Our fourth article covered speakers and hopefully you did your homework and checked out the speaker websites – if not, “git ta steppin’!” There is a ton of really great information on those sites. What is your tone worth? Do you want to sound really good or just be average? You have to figure out which type of speaker, amp, pedals and guitar work for you – not me, Eddie, Ted, Dan, Zakk, Stevie or Chet. You have to work this out – it’s your tone.


Gary "Sarge" Gistinger
President, Creation Audio Labs, Inc.
creationaudiolabs.com

This month we will examine an aspect of distortion that has a substantial amount of control over our sound because it is the last physical component before the signal

From The Lab This month we will examine an aspect of distortion that has a substantial amount of control over our sound because it is the last physical component before the signal hits our ears – the speaker.

Speakers come in about a million different flavors, and no single design can work in every situation. We must keep in mind that for every purpose or requirement there is likely a type of speaker best suited for the job, plus a bunch of them that simply won’t cut it. Speakers come in many different sizes and compositions, but for guitar and bass applications, we are generally concerned with 8”, 10”, 12” and 15” sizes.

The 8” speaker is usually found on very small amps, such as the Fender Champ, Valcos, or Silvertones. An 8” speaker usually doesn’t sound very good for rock n’ rollers, but sometimes a mini can do well with pedals at low volumes. 10” air pushers find their way into medium amps, and exist in groups of two, four, six or eight. 4x10 cabs can really kick – four 10” speakers move more air than one 15”, which is why we see 4x10 bass cabs in great numbers.

The big 15s are usually relegated to bass, but they can work for guitar. Like the little 8”, try your amp with a 15” speaker and a few pedals. The sound should be perfect for low-end grunge, heavy seven strings and dropped tuning! Try some good, oldfashioned Black Sabbath tunings – total drop to C# – played through a very dark pedal and a 15”. If done correctly, there is the great possibility of trauma for innocent bystanders. In this situation, be careful not to use too much volume and learn to listen for the speaker bottoming out.

That brings us to the 12”– the most common speaker size for guitar. Many 12” models are specific to the guitar, and there are many derivatives within this class. The power handling, ohm load, cone and dust cap types and magnet composition are all variables that must be taken into consideration for achieving a particular sound. For more information on these parameters and how they’ll affect your tone, visit the websites of companies like Celestion, Jensen, Eminence, Weber, Scumback and Tone Tubby. They all have a lot of great information and if you can’t find an answer to your question, look closely, most questions are addressed. Drop a line to Ted at Weber or Jim at Scumback and tell them Sarge sent you.

So what does this all have to do with distortion? Speaker distortion occurs similarly to the over driving of electronics: If a speaker is pushed physically beyond what it can cleanly reproduce, the resulting sound can become distorted as the speaker begins to move “out of round.” An entire speaker typically moves back and forth equally all the way around. Gas ‘em up, and, depending on how well the speaker can deal with the signal, some parts of the cone may move further than other parts, creating distortion. Guitar specific speakers are usually less stiff and have lower tolerances staying true than their counterparts designed for PA or hi-fi use, which is why we can say a Celestion “breaks up” better than a JBL.

It should be noted that speaker distortion exists in a very limited area of musicality. Tube distortion is normally more musical than pedal-derived distortion, with speaker distortion falls last on the list as “musical” however, speaker distortion becomes the icing on the cake when you have great tube distortion. The ability to choose a speaker for its mechanical break up is somewhat arbitrary – it is not dependent on one variable, like speaker size. You need to ask lots of questions. What kind of amp are you using? What kind of guitar tone do you want? How loud do you want it to go before break up? The best way to determine the particulars is to carefully identify what you are looking for in terms of tone and to review the speaker manufacturers’ websites (remember our homework assignment?).

But is over driving your speaker safe? Definitely, as most of our favorite music from the sixties and seventies would attest. Of course, there is a fine line between musical and death to the speaker. Players need to listen to their speaker and become very aware of when it is being pushed too far. For the trained this is instantly obvious; for the unaware, speakers will burn out and put out crummy sound. This is an area that I can get mad as a wet hornet over – more often than I’d like to recall I’ve heard speakers hitting the wall and the player was off in a fog of his/her own fantasy. The key here is to listen and quit “just turning it up to 10.” Great tone is elusive, but it isn’t that hard either. Listen, listen, listen.

Keep in mind that there are no good or bad speakers, unless the speaker is not functioning correctly. Speakers must be used in the application best suited for their design characteristics and the desired sound. Because of that, I have 30-plus amps, five 4x12 cabs, three 4x10 cabs, a 2x15, a single 15, a 6x10, two 2x12s and two single 12” cabs – all with various speaker types. I tend to follow an old maxim:

“How many guitars, amps and speakers does one man need?” “As many as he can get.”


Gary "Sarge" Gistinger
President, Creation Audio Labs, Inc.
creationaudiolabs.com

In last month’s column, we looked at images of sound waves with and without distortion. I’d like to examine those photos again for some more analysis. In Figures 1


In last month’s column, we looked at images of sound waves with and without distortion. I’d like to examine those photos again for some more analysis.

In Figures 1 and 2 we can see that the waveforms have about the same amplitude (vertical height when viewed on an oscilloscope). Amplitude corresponds to the size of the signal in volts or electrical strength, thus the bigger the waveform the louder the signal. This is a general rule and there are always exceptions – test equipment can be set to see things in many different ways. However, for this discussion, remember that a bigger wave represents a louder signal.

In Figure 1 we have a nice, round sine wave. This represents a clean signal with no distortion. Figure 2 shows a square wave and believe me, it is nasty sounding. In the lab, we “look” at audio gear with a square wave running through it. A square wave, although not pleasing to the ears, can visually represent how a particular piece of gear is performing; in this case, the squarer the wave is, the better the gear is passing the signal without altering it. For applications requiring pristine audio, the wave should be very sharp and uniform. Introduce EQ, filtering, overdrive or distortion and the wave begins to take on non-linear shapes.

A particular piece of gear or its components all have a limit on how much signal, voltage and amperage that they can handle accurately. After a certain point, distortion begins to occur. If we were to add to the signal level in Figure 1, there would come a point that the gear could no longer handle the increase and the sine wave would begin to flatten and take on the appearance of the square wave in Figure 2. In this case we would be overdriving the limits of the particular piece of equipment or the component’s ability to cleanly pass the signal, thus the term “overdrive.” Overdrive is the easiest way to cause distortion.


From The Lab


Looking at Figures 3 and 4 we can see how a pedal affects the signal. Milder distortion is shown in Figure 3 and total annihilation of the signal is shown in Figure 4. In Figure 4 we see total compression of the waveform; the amplitude is diminished as compared to the wave in Figure 1. Although the wave is smashed down, it is very rich in harmonic frequency content and can sound as loud as the sine wave in Figure 1. Figure 4’s wave shows the same fundamental frequency as in Figure 1, except with about a zillion harmonic derivatives induced by the pedal’s circuitry. While amplitude is relative to loudness, so is the complexity and harmonic content of a signal.

Distortion and overdrive pedals basically derive their sounds by two types of processing. The first and easiest way is to increase the gain (amplitude) of the signal. The second way is to change the shape of the original signal by adding, subtracting, filtering, etc. We can use transistor gain staging, diode clipping, harmonic regeneration/feedback, opto circuit manipulation and many other exotic circuit derivatives to cause distortion. However, it should be noted that both methods come with a price; overdrive or distortion obtained by a function of gain usually has a corresponding increase in noise, while circuit manipulation of a signal is often described as “tone sucking” and alters the original sound of the signal.

Great examples of this are FET transistorbased pedals (the typical “Tube Screamer” type of pedal). FETs are an easy and inexpensive way to obtain gain, but they get noisy as the gain increases. They also produce a loss of low-end frequency response, mid frequency peaking and harshness in the upper frequencies. The gain increase and mid boost is killer for pushing a 100-watt amp into orbit for a solo, but the loss of low-end response and increased noise is not acceptable for bass players. Note: Many Tube Screamer-type pedals have IC chips as their major component (in particular the beloved 4558), but the chips are based on FET technology.

And always remember the basic premise of overdrive and distortion: when you are practicing by yourself soak it up to the top, but cut it way back when you get with the band.

Come see us at the Orlando, Nashville, Spartanburg, Dallas, and Summer NAMM shows where the boys and I can give you an earful. We enjoy teaching, ‘cause rock n’ roll ain’t noise pollution (most of the time)!

Sarge out.


Gary "Sarge" Gistinger
President, Creation Audio Labs, Inc.
creationaudiolabs.com
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