====== Sound'n'ngSpice Examples ======

Various examples - work in progress. see [[start|spicesound]] for syntax and overview.




===== RC - filter =====

A simple bandpass filter. 

  * {{rcsim.cir}} - simulation - freq plot 
  * {{rcfilter.cir}} - audio processing RC circuit

the file ''rcfilter.cir'' reads

  capacitive bandpass filter
  
  v1 1 0 file /tmp/test.wav snd(0 0 1.0 0 0 1)
  r1 1 2 200
  c1 2 0 5u
  c2 2 3 1u
  rload 3 0 1k
  
  .sndparam /tmp/test-filter.wav 48000 wav24 1.0 0.0 1
  .sndprint tran v(1) v(3)
  .tran 2.08333e-05 5.0 0 2.08333e-05
  .op
  .end

This processes the first 5 seconds (the ''5.0'' in the ''.tran'' line) of the input file /tmp/test.wav (using the first channel - the last 0 in ''v1''..''snd''..''0'' line) writing ''/tmp/test-filter.wav'' which is a stereo file. first channel: unprocessed signal ''v(1)'' and 2nd channel: processed signal ''v(3)''

decreasing the time-step yields much better results: 1/96000 or 1/48000/4 ..

  .tran 1.04166e-05 5.0 0 1.04166e-05
  .tran 5.20833e-06 5.0 0 5.20833e-06
  .tran 2.08333e-06 5.0 0 2.08333e-06


I've used aliki to generate a frequency sweep from 20Hz to 20kHz: {{sweep_sin20_20k_5s48k.wav.gz}} - screenshots were made with rezound: the plotted result files show the original sound in the top and the processed audio in the bottom waveform. the spectrum plot was done with ngSpice ''iplot''.

{{bandpass.png?500|bandpass filter waveform screenshot}} 
{{rc-freq.png?201|bandpass spectrum}}

removing capacitor ''c1'' yields a high-pass filter which I found useful for testing the frequency response and ngSpice's timing accuracy.

{{highpass.png?400  |highpass filter waveform screenshot}}
{{highpass_zoom.png?400  |highpass filter waveform zoom-in}}




===== Jimi Hendrix Fuzz Face =====

{{git-fuzz.png?400  |fuzz face example waveform zoom-in}}
  * [[http://www.harpamps.com/schematics/jhfface.pdf|PDF schematic]]
  * {{jimi_fuzz3.oregano.gz}} - schematic for the [[http://arrakis.gforge.lug.fi.uba.ar/|oregano]] GUI
  * {{jimi_fuzz.cir}} - ngspice circuit using a sine wave as source
  * {{jimi_fuzz-snd.cir}} - ngspice circuit reading/writing sound files



==== Audio example ====

Produced with {{jimi_fuzz-snd.cir}} and {{gits.wav.gz}} (unzip to ''/tmp/gits.wav'' and run ''ngspince -b jimi_fuzz-snd.cir''). processed at 1s/(64*48k).

The output contains the //original// sound in the left and the //fuzz-processed// audio in the right channel. //Original// here is a test-clamp audio output, which includes ngspice resampling: it's not a copy from the source-file data.

  * {{git-fuzz64.wav.gz}}
  * {{git-fuzz64.mp3}}

Be aware that this example simulates an old fuzz distortion; recorded direct-in without any further processing. Therefore the //weird// sound is somewhat expected ;) -  the circuit still needs fine-tuning: eg. tweak the input voltage range of the //guitar// and fuzz/volume potentiometers.

===== foxxfuzz =====

{{:wiki:foxx.oregano.gz}} is modeled after:
  * http://www.geocities.com/CollegePark/Library/1355/tonemachine.gif
  * http://www.geofex.com/FX_images/foxxfuzz.gif

NOTEs: 
  * The simulated Diodes and NPNs are not the original, but the default models available with //oregano//.
  * the gain/sustain pot is modeled in R50/R51 - sum 50k
  * the tone pot is modeled in R60/R61 - sum 50k
  * flip the octave switch, by removing diode D1. w/o Diode = off

Beware: it's not yet debugged...