Droneo and Srutibox users: while you wait for the astounding Droneo 2.0 to come out ... me too actually ... I think I've discovered the Lost Chord, and you can play it with Srutibox and Droneo,and also online at
The Lost Chord
http://en.wikipedia.org/wiki/The_Lost_Chord , http://www.funtrivia.com/askft/Question75430.html
Actually lots of people have discovered the Lost Chord, but didn't know it or call it that. It's actually a whole class of lost chords. Coming from me, I bet you can figure out that you can't play them in equal temperament.
If you recall Harry Partch's "One Footed Bride" and other measures of interval consonance, you'll see a big lump - the foot if you will - near the octave (2/1):
The Bride's missing left foot (1/1) is actually where the Lost Chords reside. That is to say, the mind altering, fascinating, hypnotic chords of song and story are the extremely close intervals near 1/1.
Anyone with a comb filter or chorus/flange effect could have told you that, but here's the thing: as the interference beats get slower, the more this timbral fusion passes from a perceived effect to a composition itself. Also, you need a really stable and pure bunch of sound sources, which these two apps amply provide.
Sir Arthur Sullivan - or rather Adelaide Anne Proctor - appropriately provides a clue in that the Lost Chord is played on an organ, which has the feature of rather stable tuning and lack of modulation - which means a pair of really closely tuned reeds or pipes could actually produce "Lost Chords". In fact, it's hard to imagine any meaningful practical microtonal research without the stability of reed and pipe organ "oscillators". Strings - except for Ellen Fullman's Long String Instrument - have too many unstabilizing influences!
So... how does one experiment with the Lost Chords using SrutiBox or Droneo?
Pick a base frequency that you like - your'e going to hear it for a while, like 200 (an A) or 432 if you are one of those 432 people. You actually might like the lower octaves better.
Set up the first reed to play it (setting the interval to 1/1 or 0 cents).
Set up a second reed to just a tiny bit sharp or flat - so tiny that its cycle is 8 or so seconds or more. an easy way to do that is to set it to a ratio like:
(f+(1/cycle time))/base Freq, so, 432.125/432 should have a beat of once every 8 seconds.
Because these are Fractions, which you all learned about in New Math, you could multiply these numbers up by a few hundreds to make them easier to type, e.g. 432001/432000 would beat once in 1,000 seconds.
Obviously, if you move the base frequency down, say, an octave, the beat will also correspondingly move down. The important thing is to keep that interval below, say, 101/100 or 1.01 cents. There's actually a big perceptual difference the slower you go.
Now you can change the timbre to something other than a sine and hear a really slow comb filter effect. Add a few more harmonically (rhythmically) related close intervals and bask in the Lostness. You can also fiddle with a mix of these intervals using the Churn and chorus features of these two apps.
Droneo/Srutibox are pretty accurate in the frequency department, but they do have some limits since they are basically phase incremented wavetables. Droneo 2.0 will have a floating point interpolated phase that probably would be accurate enough for years.
Happy music making!