Sunday, December 2, 2012

Cause and Effect

“So you want to be a rock & roll star…..if you hit the charts the girls will tear you apart!” – Tom Petty

Before you order the bands tour bus and decide what to include in your contract rider, let’s discuss a few basics about your sound/tone.  Unless you are a Rush tribute band, chances are there is another guitar player in your band.  TURN YOUR SHIT DOWN!

Amplifiers - There are basically three types:
  • Valve (tube) pre-amp and valve power-amp. 
    • Traditionally preferred amp (warm overdrive tone)
    • Heavy
    • Expensive
    • Require some sort of maintenance 
  • Solid state pre-amp and solid state power-amp
    • Transistors replaced tubes (cleaner sound but less warmth in overdrive tone)
    • Requires less power
    • Less weight
    • Less expensive 
    • Printed circuit board (more difficult for amp tech to repair)
    • Less maintenance but more expensive when needed
  • Valve pre-amp and solid state power-amp (Hybrid)
    • Less warmth in overdrive tone but better than solid state
    • Less expensive
    • Less weight
    • Printed circuit board

What causes a valve amplifier to become distorted?  The amplifier is being overdriven and attempting to deliver an output voltage beyond its capacity resulting in waveform distortion.  When you turn the amp to 10, the signal can no longer be amplified any further and is simply cut off or “clipped”.  Amplifiers have built-in power ratings to protect the circuits, so if you install a volume pot that goes to 11, you might damage your amp. In solid state amplifiers, the output voltage is increased with transistors and operational amplifiers located on circuit boards.

What are the options for adjusting the tone of the amplifier?
  • Valve amp - Pre-amp volume high, master volume low.  Result is a warm, bluesy, clipped tone.
  • Valve amp - Pre-amp volume low, master volume high.  Result is a cleaner, trebly, chimy sound.
  • Valve amp - Mix and match, see what you get.
  • Solid state amp – Less flexible with output volume from guitar pickups but tone is cleaner.  Caution – If the pickups are too hot, the result through a solid state amp may be less than desirable.

Interesting side note:  Valve amplifiers supposedly aren’t the best at reproducing the tone from a guitar.  We are just accustomed to hearing the tone from a valve amplifier and consider it “the best” and it’s what we expect.  Thoughts?

Determine your budget (include allowances for accessories, effects, etc.).  Go to your favorite guitar store and play as many amps as you can.  Determine if you want a single or multi-channel amp and do you want an effect loop built in.  A single channel amp will be less expensive.  The “clean tone” can be set and the overdrive can be controlled through effect pedals.  Multi-channel amps will be more expensive but the overdrive tone can be set at the amp as well and then switched between clean and overdrive channels through a foot controller, reducing the cost of overdrive/distortion pedals.   Most amps will have an effects loop built in.  Congratulations, you know what amplifier you want!

Effect pedals/stomp boxes/ foot switches – There are basically 9 billion to choose from that sell for $20.00 – $whatever you pay on e-bay.00.   There are single pedals, double pedals (Steve Vai’s Jemini distortion from Ibanez), multi- effect processors (floor and rack mounted), home-made (bypass/loop), etc.

Order of effects – There are no set rules that must be followed when setting up an effects chain.  The following is a guideline that is typically followed.  You will not break your amp if you move effects in and out of this order.  Just keep in mind that the previous effect pedal impacts the next effect pedal in the chain.  Experiment and see what you like.

Guitar effects fall into three areas in a signal chain from your guitar to the speakers of the amplifier:
  • Pre-Gain
    • Utility Processors
      • Buffer
      • Tuner
      • Noise Suppression
      • Wah
      • Envelope Filter
    • Dynamic Controllers
      • Compressor
    • Intelligent Processors
      • Harmonizer
      • Pitch Shifter
      • Acoustic Simulator
      • Octave
  • Gain
    • Signal Changers
      • Overdrive
      • Distortion
      • Fuzz
  • Post-Gain
    • Time-based Modulation
      • Chorus
      • Flanger
      • Phaser
      • Tremolo
      • Vibrato
      • Rotary
    • Pure Time-based Modulation
      • Delay
      • Reverb

There are a few effect pedals that work in different places of the chain.  An equalizer can be placed in the post-gain area to control feedback or in the pre-gain area to control the signal for the entire chain.   A noise suppression pedal with a built in loop can be placed anywhere in the effects chain, cleaning up the effects in the loop circuit without changing the effect pedals downstream.  Consider leaving delay and reverb out of the noise suppression loop.

What are buffer pedals? Buffer pedals are used to maintain the input impedance of the signal through the effects chain and lengths of cable running from the guitar to the pedal board and from the pedal board to the amps. Without a buffer pedal, the signal loss through the effects chain will start to degrade your tone by losing the high-end.  The magic number is 18.5’ of cable before the high-end of your tone is noticeably decreased.  Why not just use a bypass switch? A true bypass switch will reduce the amount of signal loss through the pedals being bypassed, but does nothing for the capacitance of the cables involved in your total setup (typical in vintage pedals).  Newer effect pedals have built in buffer switches that will reduce the high-end signal loss (BOSS). Gain boost pedals can be used as a buffer pedal to bring your signal strength back but can also add a little punch by increasing the output volume for soloing.  Gain boost pedals can also be considered overdrive pedals. 

What’s the difference between overdrive/distortion and fuzz?  Overdrive pedals/gain boost pedals are little preamp pedals that can be used to punch the input of the tube amp without adding distortion on their own but can drive the amp into distortion with the volume control on the pedal.  Some overdrive pedals have some “clipping” capabilities that introduce mild distortion.  True distortion pedals have higher gain or “clipping” capabilities that result in heavier distortion.  Fuzz pedals were not intended to mimic overdrive or distortion.  They were meant to be over the top with no “natural” sound to them.  Mr. Hendrix used fuzz.  Put these pedals in order of least aggressive to most aggressive if multiple distortion pedals are in the chain.  BOSS makes a hammock full of different distortion pedals.

What is an envelope filter?  The envelope of your sound is how loud it is over a period of time.  The filter listens to the volume envelope of your sound and opens or closes the filter in an amount proportional to the envelope.  Its also know as an Auto-Wah.  The sound is choppy and funky.  Listen to Stinkfoot by Frank Zappa.

If the amp is being used for overdrive/gain, it becomes the gain area of the signal chain and the post-gain area of the signal chain should be moved to the effects loop of the amp.  Why?  The effects loop of the amp sits between the pre-amp and the power amp.  As mentioned above, the post-gain area of the effects chain follows the gain-area. By using the amps overdrive/gain capabilities while using post-gain type effect pedals before the input into the amp, the order of the “areas” have been disrupted.  Your post-gain area is before your gain area.  Fix it!

I wanted to talk about effect processors a little.  An effect processor is a device that can be rack mounted and operated by a foot controller or a pedal board that sits on the floor and controlled by your foot.   These are very cool devices and can produce a ton of cool sounds, but they can be very confusing to set up.  I have an ADA MP-1 and it’s fun to use, but took a while to set up especially when trying to daisy chain it with another effect processor.  I’ve also had BOSS processor that was fun to use but was awkward to switch between banks of settings.  Not very “gig” worthy in my opinion.

Home made pedals.  Don’t.

Hope this helps.

I guess some credits are due since I didn’t know all of this on my own. – overdrive, distortion and fuzz differences. -  BOSS pedals – Types of amplifiers
Tom Petty