Like I pointed out in the first post, this technique has the „bad“ guitar player in mind. But I am sure that some of the ideas useful for real guitarists, too.
Let's begin with some theory: If you modify audio files, this task will create artifacts. Some actions like time-stretching will let the computer guess information which will sound unnatural, other ones will have an impact to harmonics and formants – like pitch shifting. The human ear is trained to hear tiny differences in a voice, so processing a human voice is one of the greatest challenges at all. You can easily identify a formant change – especially for known natural sources. What’s about an electric guitar? If you are watching shoot-outs between valve amps vs. modeled amps, you will get an idea about how well a guitarist’s ear is trained…
Let us think about
the nature of a recorded electric guitar sound. It is the combination of:
- Guitar
- Amp
- Loudspeaker
- Room
- Microphone
- Preamp
- Etc.
There are even more things with an impact to the sound like
- Pickups
- Pleks
- Strings
- Cables
- Stomp boxes
It
looks like a puzzle, but it is more like a
process chain. The whole stack defines the resulting sound.
As a synth-guy I am thinking about the guitar as a mighty controller over pitch, envelope, and tone – my
VCO. A hard driven amp adds harmonics and works a little bit like a Buchla W
aveshaper. The cabinet is like a
bandpass gate – cancelling out deep bass and harsh high frequencies. The mic and preamp are additional
filters, which allow the user to change the overall frequency spectrum of the signal by placing the mic right. All the other gear is like additional Eurorack modules – nice to have and a great business opportunity for companies.
If you ever dealt with a modular synth you know that you
can compensate a weak but stable VCO. If the other components are weak you are in trouble. This idea in mind, let us
start with the practice:
Recording of the guitar signal: You need the clean D.I. signal of your guitar, because you want the information about pitch,the envelope and the tone. This signal has the lowest amount of harmonics or formants. There are some formants for sure, they define the different sound of guitar models, but this post is not about Jazz… Every step later in the process chain will add up with challenges at the tweaking activities. Essentially, it is the characteristic attach phase followed by a sinus-like signal.
If you are recording straight into the DAW via HiZ you have the signal already. If not, use a D.I. box in order to record the clean guitar signal and use re-amping later (always a good idea).
The first demo track was recorded at my personal maximum tightness and speed – meaning eights notes at 50 BPM. Even for Doom Metal way to slow. If you believe it or not, I used a metronome ;)
https://soundcloud.com/drvdd/demo-mettttal-original-stuporous-record Get the timing right: The D.I. signal of a palm muted guitar is great for Audio-Snap. Strong transients, short signal length and clear separation from the next event. Select your track, go to the Inspector (key I) and select Clip. Then select AudioSnap and enable it. Select the high quality offline rendering and “follow project tempo”. Within the clip the transients should be marked with lines. Press Q to open the quantize options and quantize everything by say 95%. Not too much, otherwise it will sound too much machinegun-like.
Now the speed: Change the project tempo. I went from 50 BPM to 220 BPM (!). If you listen to the processed track, I am quite sure that you are not able hear artifacts, because it only affects the first stage of the signal process chain. Remember: Only the D.I. signal were increased by the tempo change - the amp sim will
simulate like before.
Create the riff Like I wrote, I am not able to utilize the left hand properly, because the lack of training. To create the riff, the next tool will be Melodyne (the essential version is just fine). Bounce the Audiosnap-clip in order to have a clip which can be used in Melodyne.
In Melodyne you will see all the events as blobs. They should be all at the same note, d in my case (Drop-D tuning). If Melodyne put them to different octaves, fix the note identification. Now it is time to change the pitches of single events. You can go as wide as two octaves before the artifacts will be audible at the end of the signal chain. I went for one octave in the demo clip. Don’t think about how you would play it in practice – this will be the challenge for Cover bands!
Beware that the quality is not optimal until you render the Melodyne clip to an audio clip!
Amping and EQ To get a thicker sound, duplicate the clip you created into another track. Than use an amp sim like TH3 with two different amp models and pan the tracks hard left and right. You can enhance the sound, if you identify the sweet spots of each model and increase that frequency by 3db and lower the same frequency on the other track by 3db. It doesn’t destroy the sound of each individual track but creates a great difference between the tracks. 3dB+3dB = double signal level…
If you are using a real amp, now it is time to use your re-amping box to inject the signal into your full stack.
The Bass Take the clip and copy it onto a MIDI track. Because it is a D.I. signal the resulting MIDI notes are pretty accurate. Delete some of the notes and put a virtual bass vst onto the track. Tweak the sound with TH3 until it fits to the guitar tracks and you are ready to go.
Result:https://soundcloud.com/drvdd/demo-mettttal-processed Conclusion:The way described is useful, if you have to deal with heavy distorted guitar sounds. The cleaner the sound is, the more impact artifacts from time correction and pitch shifting will have.
Instead of simply doubling a clip it is way cooler to use a different part of the original recording and do the same tweaks on different source material. There will be differences in timing and tonality which results in a much richer sound – it is like two independently recorded takes.
If you have ideas to improve this way to record and tweak (rhythm) guitars, I would be glad to read about it.