Electronics Pit Message Board
« SSM version 1 »

Welcome Guest. Please Login or Register.
Jan 6, 2010, 7:20am

[Home] [Help] [Search] [Login] [Register]



Electronics Pit Message Board :: Electronics Pit :: Simple Sound Module :: SSM version 1
   [Search This Thread][Send Topic To Friend] [Print]
AuthorTopic: SSM version 1 (Read 101 times)
Eddy-B
Administrator
*****
member is offline




[homepage]

Joined: Jun 2008
Gender: Male
Posts: 19
Location: Netherlands
Karma: 0
SSM version 1
« Thread Started on Jun 20, 2008, 7:04pm »
The first version of the Simple Sound Module contains only a few basic functions. The code consists of several parts:
  • a waveform generation subroutine;
  • an ADSR enveloppe;
  • a pseudo-random number generator used for white noise;
  • and a mixer module that mixes the voices together and implements the main volume.
When incorporated in the Mega-Console each of these parts is called every other scanline (making the sample frequency 7.8kHz on PAL systems which starts creating some audible artifacts above 2kHz - still accaptable for musical applications).

The waveform generation is on-the-fly, using linear interpolation to make it fast enough to fit within a PAL horizontal sync: only 3.25 microseconds are required for each voice.
The ADSR envelope and random number generation also requires 3.25 microseconds.

As a stand-alone module, it would be possible to increase the sampling frequency to 31.25kHz and still be able to probably fit in 8 voices.
Link to Post - Back to Top  IP: Logged
-- www.ElectronicsPit.com --
Eddy-B
Administrator
*****
member is offline




[homepage]

Joined: Jun 2008
Gender: Male
Posts: 19
Location: Netherlands
Karma: 0
Re: SSM version 1
« Reply #1 on Jun 22, 2008, 12:19pm »
After some more testing with ring modulation, i found an interesting new waveform today: ring-modulated sawtooth.

The sound is similar to regular ring-mod, but the sharp edges of the sawtooth create a distinct pattern in the sound. By altering the difference between the base frequency and the modulation frequency i can create a waveform that sounds a lot like an airplane propeller.
And when there's only a very slight offset between the two frequencies (or one of the overtones), you can create a distinct sweeping sound that many MOD-trackers use.

As a matter of consequence i've included ring-modulated pulsewave, but it doesn really create interesting sounds when modulating 2 pulsewaves.

As for noise: no use modulating random signals, they'll still be random!
Link to Post - Back to Top  IP: Logged
-- www.ElectronicsPit.com --
   [Search This Thread][Send Topic To Friend] [Print]

Click Here To Make This Board Ad-Free


This Board Hosted For FREE By ProBoards
Get Your Own Free Message Boards & Free Forums!