08 September 2010

Vintage Marshall BluesBreaker vs. General Guitar Gadgets Kit

I need to write something about how gear lust is a reaction to the unfulfilled desire to improve as a musician. It is most common among guitar players, and I think the reason is that guitar is the hardest instrument on which to improve.

Assuming that I do legitimately need a piece of gear once in a while - or I have earned the extravagance of a new overdrive pedal by reaching some goal - there is a lot of almost-helpful information on the web to assist in selection, but most of it leaves me frustrated - asking impossible questions of my mute computer monitor. The following demonstrates a more useful method for demonstrating gear.

In this case I am demonstrating a General Guitar Gadgets overdrive pedal kit. First of all, I am comparing it to the original vintage unit of which it is a clone. Generally it is a good idea to get ahold of the original unit for comparison. Anything that is rare and collectable isn't likely to get any less rare/collectible/valuable, so an eBay purchase of a rare overdrive is a pretty safe place to stow your money. If you are patient and do the tinest bit of research, it's pretty easy to consistently make a few bucks on each pedal.

The usual method for demonstrating gear is as follows:
  • Talk for about 90 seconds about what I am about to do, as if the audience won't figure out what's going on as soon as I start the actual demonstration. This should include lots of insignificant minutae about my guitar while leaving out lots of other critical information.
  • Record the audio with the built-in microphone on my webcam. This ensures that you will hear the gear in the most true-to-life signal path, assuming that you listen to all music by IM'ing your friends and asking them to play music for you in a video chatroom.
  • Play with the guitar by itself. This helps alleviate the stress you might feel if you knew about weaknesses in the pedal's sound before you actually bought and tried it. If you hear it with a band it may scare you off or make you think it's not that special.
  • More opining. This reasserts the focus of the video, which is me, me, ME!
I propose a more useful method:
  • Make or acquire a simple backing track in your DAW of choice.
  • Record some dry guitar parts.
  • ReAmp the exact same parts using different overdrive pedals (or whatever you want to compare)
The above image shows how I played a simple blues, which allows for 1:1 repetition of musical fragments or whole phrases. I then cut up the original take so that the repetitions were identical waveforms on separate tracks. In other words, when you hear a phrase repeated, it is the same waveform I played the first time, just cut and pasted later in the timeline on a track that will be reamped with a different overdrive pedal. This gives a much fairer basis of comparison than simply playing the same thing twice; by about your second recording session you learn that there is a lot of accidental magic happening when fingers and picks touch strings, and even a very accurate, consistent performer will give better sounding takes.

Next I reamped each track with the repeated material. The image to the left shows the Routing Matrix in Reaper DAW software. I am using a 2x2 interface, so audio goes out on the right channel and comes back - reamped - on the left. I solo one track at a time and record one track at a time.

The conversion from digital to analog - then back again - causes some latency on the reamped track. To compensate for this, I use the nudge feature in Reaper (Shortcut N). A workable rule of thumb is to move the audio by the number of samples in your hardware buffer (in your soundcard's ASIO control panel) - but if you want real accuracy you need to do more to determine the exact amount of latency - either with a test or by eyeballing the pre- and post-reamped waveforms to make them line up.

The next image shows the tools needed to do this. You'll notice right off that they are all extremely common items - no special tools needed.

  • Very common, familar, clean amp (Peavey Classic 50)

  • Very common, familiar, clean speaker (EMV12L not shown)

  • any passive DI with a halfway decent transformer - doesn't have to be anywhere near high end

  • a balanced cable to connect your audio interface with the DI

    • probably a 1/4" TRS plug to a female XLR, which you can make with cheap parts

  • Very common, familiar, clean microphone (SM57)

    • ...which actually has an irritating, colorful midrange hump, but

      • people are very used to hearing it

      • anyone wanting to compare to their own recordings probably has one

  • Very common, familiar, clean guitar (strat)

    • rosewood fingerboard and alder body

    • vintage style steel bridge

    • most middle-of-the-road electronics possible
In general, everything about this setup is as close archetypal "guitar" as possible. No hot or bright pickups. No boutique amps. No exotic woods. It should sound the way it's going to sound when you plug your strat into your clean amp.

Oh, yeah - one more thing. The numbered labels and relative rotation of knobs on guitar equipment are almost perfectly meaningless. The idea that setting all knobs at 12:00 will give you a neutral sound is just plain wrong. Even pedals from the same production run will hit the exact same sweet spot at different settings. In this particular test, I noticed that the original, vintage BluesBreaker was much darker sounding than the one I built a few hours ago; it could be that component values have drifted over time, or maybe something else. I liked the darkness of the vintage pedal so I turned down the tone control of the new one. Making no effort to match sounds between the pedals would misrepresent both of them; that would be like recording two Marshall JCM800 amps and insisting that the one that is cranked sounds better than the one with volume on 2. I.e. the same circuit with the exact same component types will sound the same under the same conditions (e.g. transistor bias) - but you may have to tweak knobs to get those similar conditions.

I think this method yields a usable comparison, in which there is some real-life context - or as close as I'm going to get with the amount of time I'm willing to put into this. The only thing that changes between tracks is the overdrive pedal.

I hope something like this catches on. Even if people started playing the same lick to a looping backing track with different pedals engaged - even with crappy webcam audio - it would be a vast improvement over the current state of gear demos.

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