From: paul@everest.tandem.com (Paul Duffy)
Subject: Intonating thirds (was Re: Q: What are power chords?)     
Organization: Tandem Computers Inc., Cupertino CA
Date: Tue, 28 Jul 1992 03:25:04 GMT

In article <1992Jul28.011226.15450@cis.ohio-state.edu> fullerto@tortoise.cis.ohio-state.edu (timothy dwight fullerton) writes:

    ( original post deleted)
>
>
>	Drew,
>
>	A power chord IS a triad without the third.
>
>	They are necessary because of the way distortion works. This will be
>like explaining how to tie a necktie over the phone, but here goes...
>
>	Picture, if you will, a sine wave (I'd draw one if I could). This
>is a fourier representation of a fundamental pitch. Now... when you apply
>distortion, the amplitude of this wave is increased (it gets bigger), and the
>heads are chopped off. Now it looks s/thing like a rounded square wave.
>
>	If you include all of the harmonics with that fundamental, your
>sine wave gets very choppy. Distortion boosts and decapitates all of these.
>
>	Now. Consider an interval. With perfect intervals, it's still rela-
>tively serene harmonically speaking, but with other intervals, the harmonic
>activity that they produce can become quite complex. Throw in a third note and
>all hell breaks loose.
>
>	If distortion is applied to that, especially with the technology
>from 40, 30, 20, 10 years ago, it sounds like dogshit. So...styles of
>music which utilize HEAVILY distorted guitars couldn't do much more than
>simultaneous perfect intervals.
>
>	Now, with the amps of today and tasteful application, you can get away
>with more when you have a lot of distortion.
>
>		Hope this answered it for you.
>				Tim

Chords with thirds can sound great even with lots of distortion.  The
trick is to intonate the third correctly on the guitar.  The way the thirds
come out on the neck is well-tempered, and thirds are the main victim
of well-tempered instruments.  On a well-tempered instrument thirds are
something like 13 cents off from being perfect.  This produces ugly beat
frequencies, and the more gain you have, the more the beat frequency is
compressed upward until it is very noticeable.  The beat freq is not
musically related to the tonic at all.  The more gain the more of a mess
the beat freq makes.  
But if you intonate the thirds by bending the strings a little you can play
perfect thirds that sound great, and produce none of those disgusting
beat frequencies.

For instance, on a minor seventh chord such as: 

                ---1------
                ---12-----   1 is barre
                ---1------   2 is 2nd finger 
                ---1-3----   3 is third finger
                ---1------
                ----------

(I am not used to writing out tab, that's the common minor seventh chord) 
even with a lot of gain you can sweeten the third by pulling down a 
little with your 2nd finger until it is just perfect.
There are a lot of ways to play thirds and sixths of course and they can
all be played sweet if you memorize the corrections that you need to make to
the basic chord by pulling up or down on one of the notes in the chord.

LIke: 
                ----------
                ----X-----   
                ----X-----   X's are fingers you'd use
                ----------    for this
                ----------
                ----------

everyone probably uses different fingering for the third I just tabbed
out.  It'll sound ugly unless you sharp the note on the third
string a little.  Once you intonate it add a little vibrato and it
sounds wicked.

Or:
                ----------
                ----3----- 
                ----------  (The numbers are fingers not frets)  
                ----2-----  
                ----------
                ----------

That major 6th will sound a lot better if you sharp the note
on the 4th string a little.

One rule is "widen minor thirds, close major thirds" as far as the
correction to their interval width.

Hope this helps.  A lot of alt.guitar readers probably already know
this anyway, but if not it should help your intonation.
If you memorize the corrections to all the intervals you'll sound
like your tone is way better.

BTW, as far as barre chords there's almost no way to flatten
the 3rd on the common "E-form" chord so that's a case where you
just have to not play it, if you are not playing with a clean sound
(--> power chords I guess)

                          Keep on chunkin'