[sdiy] Building a Better Bass Patch

[Tim Daugard]

I do it the easy way. All my patches start at the bass guitar. From observing the
waveforms through my system, I have obsereved that a reall basse starts out with strong
harmonics. The harmonics die off over a period of time.

The waveforms don't show significant phasing (I know maybe to small to see). Proof of this
might be the method of tuning the bass with harmonics. Once the bass is properly tuned
using the harmonics the two tone can run for a long time without beating.

So, I believe:

- The primary tone is the first (fundamental) and third harmonics. I offer as proof, the
fact that taking a bass note and adding the divide by two signal doesn't do much for the
tone. Divide by three and add and you get a wonderful deep rich sound.

http://home.earthlink.net/~synthfred/h_fdv101.htm

- The third harmonic dies relatively quickly - can be heard in a whole note and definitly
in a note held for two bars.

Start with a square wave, or a sawtooth filter heavily to get the fundamenta and just a
few of the harmonics, then follow with a envelope controlled filter to further cut the
harmonics as time goes on.

- Fat of the finger verses nail / pick plucking makes a difference in the initial sound

Add a pulse from the trigger source.

Add a signal two or three octaves up (in sync) with a very short envelope - 0 attack time
32nd or 64th note length decay time. Decay to 0, no sustain or release.

- The tone swells in the first few cycles. I've never figured this out, but sitting here
now, it maybe a result of the build up of the mag/elec field in the pickup? My acoustic
basses respond faster, but that could be strings, technique (more effort required to get a
good volume tone), wood tone.

If you use multiple oscillators, the higher pitches have faster attacks. The fundamental
should take 2 to 3 cycles to hit full volume.

- The note never ends on a good bass guitar. Even without feedback a note can be held for
two bars, three bars, or even longer. part of the bass technique is muting notes as you
are done with them. I don't play stand up bass so I can't speak for them. I would say that
from listening to them, most of this applies, however, the notes do end relatively
quickly. A plucked note on a standup ends in less than a quarter note.

Tim Daugard
AG4GZ 30.4078N 86.6227W Alt: 12 feet above MSL
http://home.sprintmail.com/~daugard/synth.htm