Audio Workshop: Re-Amplification Techniques

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Written by Engineer Scotty O’Toole

Re-“Amp”imator

H.P. Lovecraft’s short story, “Herbert West: Re-Animator”, tells of a medical student obsessed with “re-starting” the dead. Well, I sometimes look at being an audio engineer the same way. A “sound scientist” bringing “dead” tracks back to life. For anyone training to become a music producer, exploring different approaches to ‘getting that sound’ can make you a more versatile engineer.  One technique that can be used to spice things up is what we call “re-amping”.

 RA51118 resized 600Re-amping takes an audio track that has already been recorded and re-records it. Usually it involves running the track through a speaker (typically a guitar amp) to re-introduce a sense of space, harmonic texture or full blown distortion and then we re-record the new sound with a microphone. It can also be used with effect pedals that are designed for use with guitar and bass players and make them a part of your outboard gear. Guitar and bass tracks are the usual suspects for this re-amping technique but it can be used for just about any track.

The “Techie” Stuff

Since the audio signal has already been recorded, there are some things we need to do to make it compatible with a typical guitar amp. The recorded audio to be re-amped will likely be at line level and likely be a low impedance (Z) balanced audio signal. Guitar amps and FX pedals are designed to deal with high impedance unbalanced audio signals. Simply plugging the audio output from the recorder output into a guitar amp or pedal is not recommended as there will be a level and impedance mismatch. The likely result will be overloaded and “pinched” sounding with some degradation of the frequency response. We must convert the recorded audio signal to an unbalanced and high impedance signal to properly load the input to the amp.

There are many boxes on the market that are designed to do just that and are referred to as “re-amp” boxes. Most have a level control as well. However, many of you may already have a box to do this. I’m talking about your typical passive D.I. box.

Direct Box as a Re-Amp Box – The Set Up

A direct box (or D.I. as it’s often called) takes an unbalanced high impedance signal, such as the output of a guitar or bass, and changes it to a low impedance balanced signal that we can plug into a mic input by means of a transformer. If we simply use the D.I. box “backwards”, we have a re-amp box! The transformer in the D.I. doesn’t care which way the audio is going. It’ll pass it either direction.

So here is the typical set up. If your on a console, I use a send from the channel I want to re-amp to feed the XLR balanced connection on the D.I. I use a send because it gives me the ability to adjust the level of the signal from the source. Next I take an unbalanced instrument cable and plug from the D.I. 1/4 inch connector to the input of the amp. Hit play on your recorder and adjust the amp to the sound your looking for. Mic it up and re-record it to a new track. If your hitting the input to the amp to hard, pull back the send a bit on the console. Adjust to taste!

The same set up can be used just as easily in a D.A.W. like Pro Tools, Logic, Ableton Live, or Presonus’ Studio One. Create an output or interface send on the track you want to re-amp and send it to an analog output of your interface. From there to the XLR on the D.I. and on to the amp from the 1/4 connector. Use the send control to adjust the levels as needed. It’s really that simple.

Here are some examples of how I use this technique on sessions:

-When recording guitars grab a D.I. signal from the guitar before it hits the amp and record it to a separate track at the same time your recording the amp signal. This way you will have the amp sound and the “plain” D.I. guitar sound. Later on if you don’t like the sound of the recorded amp, use the D.I. track and “re-amp” it with a different amp and re-record it! Do the same with bass guitar!

-Vocals are great re-amped with a bit of distortion. The smaller and cheaper the amp, the better!

-Try running the room mic for the drums through an overdriven amp. Add a touch of compression and things can really start to sound explosive.

-Re-amp an anemic snare drum to add size and sizzle

 RA50960 -Set up a send to feed a re-amp signal chain of guitar pedal effects. Take the output of the last pedal and plug it into a D.I. box the “regular” way and back into the board as you would a guitar or bass or keyboard D.I. signal.

Use it like Franks Red Hot and put that s!@# on everything!   😛

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