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SoftAmp 3OD

AXP's picture

SoftAmp 3OD

Latest Version: 
Last Update: 
15 Sep 2013

A single triode stage circuit typical for guitar preamps is captured in this plugin. The model engine is based on a system of non-linear ODEs. Some smart calculation techniques are used to reduce the computational load.

This effect could be used to apply mild tube overdrive to add some presence to your tracks, or you could chain a couple of instances together for a full-blown high-gain overdrive. You may want to throw in some EQ as well to better shape the signal and use a poweramp/speaker simulater afterwards.

The plugin UI has a real-time transfer characteristic plot display. It provides an overview of the things going on inside the tube. It also has a peak-detecting algorithm that will flash a line when the level exceeds 0dB. You can monitor stereo channels separately or at once by clicking the corresponding buttons under the plot display.

16x switchable oversampling is also implemented to reduce the aliasing effects. Please note that for the most time the aliasing is low enough to switch off the oversampling. When oversampling is enabled, the plot display will not be of much use, because of the phase smearing introduced by the oversampling filters. Still good enough for monitoring the in/out levels.

The model has 3 core controls to configure the circuit:

  • 3 different triode models: 12AX7, 12AU7, 12AT7.
  • 3 different plate voltages: 150v, 250v, 350v.
  • 3 different cathode capacitors: 0.47uF, 1uF, 22uF.
  1. The gain/level controls are combined into a single knob that is operated with left and right mouse buttons.

The "Normalize Output" control enables the normalization of peak-to-peak output voltage swing across all triode configurations, particularly different plate voltages. By default it's turned off to reflect the natural triode stage behavior, which could be regarded as a normalized small-signal gain.

Please note that output signal is not clipped at 0dB to let you overdrive chained stages using more that one plugin instance connected in series. Make sure to watch the output level or use a hard limiter somewhere in your signal chain.

Clicking on the SoftAmp logo in the plugin will bring up the "About" window with a version number and contact details.

Thanks to everyone who has voted for SoftAmp 3OD in the Developer Challenge and used it in their work.


Unzip the archive and put the "AXP SoftAmp 3OD.dll" or "AXP SoftAmp 3OD x64.dll" to your VST folder. Make sure to select the one appropriate for your system (Win32 or x64).
  • It is my hobby to develop the VST audio effect models. I'm not getting paid for it and I use my own limited spare time to do this work. If you like my projects and would want to encourage the future work please consider doing anything from the following list:
      - Tell your friends about my site and my plug-ins
      - Send me audio samples you've made with my plug-ins
      - Drop me a line or two with any comments and suggestions
      - Make a small donation through my web site
This software is licensed for an unlimited usage by everyone, including personal, commercial and scientific applications. You are NOT allowed to modify it (including both the binary code and the copyright information) or sell it, in either stand-alone or bundled form. The plug-in is provided "as is" without a warranty of any kind. In no event I shall be liable for any damage associated with the usage of this software. I encourage further distribution by sharing a link to the effect web page.
Please send your questions and suggestions to my e-mail or post them on the site.
VST is a registered trademark of Steinberg, GmbH
AXP SoftAmp 3OD (c) 2012-2013 Alexander Petrov-Savchenko
Version History: 

1.0.6 (15-Sep-2013):

  • Added 64-bit version
  • Fixed memory leak on UI close
  • Size optimization
  • Different stability improvements
  • Added more presets


1.0.5 (20-Dec-2012):

  • Fixed a bug with UI not opening if another instance of the plugin is closed.


1.0.4 (10-Dec-2012):

  • Significantly reduced the amount of "clicks" during the parameter change. More user feedback is appreciated.
  • Reworked GUI code to fix some drawing problems. The plugin scanning/loading should be come much smoother across different hosts. Thanks to Martin LeFever for reporting this one and helping to narrow-down the issue.


1.0.3 (5-Dec-2012):

  • "Normalize" feature wasn't working as intended. Fixed, added description.


1.0.2 (16-Nov-2012):

  • Prevented possible floating-point underflow.


1.0.1 (10-Nov-2012):

  • Fixed dependency on MS CRT library.
  • Changed signal phase to allow external dry/wet mixing.
  • Fixed UI buttons half-lit at startup.
  • Optimized CPU load (should no longer cause audio dropouts during parameter change) and model accuracy.
  • Slightly reduced audible clicks during triode mode/plate voltage change.


1.0.0 (20-Oct-2012):

  • Initial release for DC-12.


Leandro Maccan (not verified):

This is really great! I don't understand why aren't demos yet on internet

Craig Freeman (not verified):

Agreed. This is a really fine piece of preamp emulation software. Well done.

John P (not verified):

Thankyou for your generosity in sharing these plugins of yours, very nice sound.

AXP's picture

Thanks John, you are welcome!

Nic (not verified):

Awesome effect. I was able to reproduce a complete Marshall Style preamp with this VST and some low cut Eq between each stage (for coupling cap simulation). I have used Tone Deluxe for the Tone Stack, Power amp and Cab sim and the result is very very good. If you know how to modify a real amp, you will love this little Vst app.

AXP's picture

Hi Nic, 

thanks for sharing. This is indeed something I've done myself too! Actually this plugin was born during my experiments with different tube amp topologies. I've made my own tone stacks though based on a few popular guitar circuits.