1. Plugins
  2. »
  3. AXP
  4. »
  5. SoftAmp 3OD
  6. »
  7. Details

SoftAmp 3OD

Vacuum Tube Model Plugin by AXP
SoftAmp 3OD
SoftAmp 3OD
SoftAmp 3OD by AXP is a Virtual Effect Audio Plugin for Windows. It functions as a VST Plugin.
System Requirements
SSE2-capable CPU (at least Pentium4 or Athlon64)
32-bit display color depth
Windows XP SP3 or later
Copy Protection
My KVR - Groups, Versions, & More
41 KVR members have added SoftAmp 3OD to 14 My KVR groups 54 times.
Not In Your MY KVR Groups
(or group limitation prevents versioning)
+11 in private groups

KVR Rank

Overall: 4071   3854

30-Day: 3258; 7-Day: 2096; Yesterday: 3736

AXP SoftAmp 3OD
Vacuum Triode Stage simulator.

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 simulator 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.

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.

Change history:

1.0.6 (15-Sep-2013):

  • 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.


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).


  • This plug-in requires the Windows Imaging Component library. It's included in all Windows versions starting with Windows XP SP3. If you are using Windows XP SP2, you can get it as a stand-alone library here: http://www.microsoft.com/en-us/download/details.aspx?id=32
  • 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.

Latest User Reviews

Average user rating of 4.00 from 1 review

Reviewed By The Telenator
December 16, 2012

Let me say, first of all, that I was extremely pleased to be asked to write a formal review of this charming VST plugin effect. Of the many plugins I have encountered in my visits to the KVR website, the SoftAmp 3OD clearly rates as one of the best. More officially described as a vacuum triode stage simulator, I believe more VST users would know it in its common name as a "preamp tube sim." And although adding analogue-styled sounds of tube and tape warmth and saturation to our digital recordings these days is in vogue and all the rage, a device of this type is probably more in demand primarily by players of instruments, the guitar being first and foremost, followed by keyboardists and drummers. The need is for some degree of overdrive and tube warmth, which is most often added up front in the signal chain to colour the sound of the instrument or further signal amplification that follows. In this role the SoftAmp 3OD is superb. As one of the many guitarists who record using today's digital audio workstations, I am constantly on the hunt for the better overdrive device, and over the years I have tested and used almost all of them with varying degrees of success. I can honestly state that this one has quickly become one of my favourites. The main reason for this is that it truly does sound more like the real preamp tubes used in the preamp stage of practically every guitar amplifier ever made, but more on this shortly. This year's designers' contest, the Developers Challenge 2012 had the most offerings of any year so far I believe, some 55 in total, and there were several new ones that were simply irresistible, including several new synthesizers, a bundle of new presets for popular softsynths, and effects devices, this one included. I eagerly downloaded my selected half dozen and put them through my standard tests. It is all too common for some in each D.C. contest to come with an assortment of bugs both large and small. The SoftAmp 3OD was no exception, featuring an annoying clicking sound when changing some of its settings and also displaying a bit of odd behavior in two of my host programmes. I commented about the discovered bugs, was quickly located and contacted by AXP, its creator, and this is how my involvement with the plugin began. A few fast releases later and I'm happy to report that all issues have been corrected, based on my further testing of the device. Since then also I have had more time to really listen to the plugin, as I've been going through the many possible sounds and settings offered by adjusting its rather simple controls. Those of you with some knowledge of preamp tubes will quickly recognize the three 'tubes' used as the most common to tube amps, each capable of a different output level, the 12AX7 being the highest and most-used in the V1 socket of amps. What's nice about SoftAmp 3OD is that it also offers simulation of three different plate voltages to 'feed' the chosen tube, as well as a choice of three different capacitors. These features alone would be more than enough for a tube sim saturator or overdrive, but AXP goes on to include a 16X oversampling (can come in handy for more extreme, higher gain settings), a normalisation control, and a graph on the far right. So, what about the sound of this plugin? Well, having a fair amount of experience using the real thing -- tubes in many classic designs of tube guitar amps -- I can tell you that this unit sounds practically identical to the preamp of an amp for each grade of tube it includes and from lower levels all the way up to the woollier highest gain settings. Especially on the higher gain settings, this device can benefit from some EQ in the signal chain and following immediately after it. Try to imagine it for what it is or sounds like -- the preamp stage of a very good tube amp but without a tone stack with treble, bass and middle controls included. Note that on the lower, more subtle gain settings, much more like what would be used merely to create analogue warmth on a track, adding EQ may be unnecessary. I already have a folder of VSTs that are designed specifically for saturation. My purpose in using the SoftAmp 3OD is to add one more stage of overdrive gain before sending the signal into a full-blown modern amp sim. Even though the guitar amp sim I use these days is one of the very best, if not the best indeed, it's a common problem we guitarists often encounter: In our efforts to produce the massively overdriven modern electric guitar sound, including particularly those players in the heavy metal camp, we find that most of today's amp sims need one more good and solid stage of gain to push the amp 'over the top.' Here is where the 3OD really shines. All the way from just a touch of extra overdrive on up to my previous description, this plugin does perhaps the finest job of it that I have yet heard or experienced. This is the kind of plugin I believe most guitarists -- and probably many keyboardists and synth players, too -- will call a real 'keeper.' It is that good. In fact, since this VST was perfected in its latest 1.0.4 release, I have removed a couple of the better clones of the famous 'green' overdrive and deleted them. I'll be using the 3OD instead for my professional work. This SoftAmp 3OD probably deserves a full 10 rating; however, I reserve that grade for VST/VSTi creations that are sure to last for a century or more as forever freeware classics, such as Ichiro Toda's Synth1, Fuzzpile's Oatmeal and Magnus at smartelectronix with the Ambience reverb. The SoftAmp 3OD easily attains to a 9.Read Review

Products similar to SoftAmp 3OD...

Comments & Discussion for AXP SoftAmp 3OD

Discussion: Active
9 November 2012 at 1:05pm

very good tones but sometimes cubase (the 5 in my case) doesn't recognise it

9 November 2012 at 10:02pm

Alb, thank you for feedback.

I will try to reproduce it. Could you please provide more details? It doesn't find it when it scans the VST plugin folder?

10 November 2012 at 8:39am

yes it sometimes appears and ad sometimes it doesn't appears.

it's annoyng because this plugin is great on vocals and now I want in in every session

10 November 2012 at 1:25pm

I still can't reproduce it in Cubase (5.1.0)

Can you provide a more detailed description? Does it happen when Cubase scans the VST plugins on start, or when you do it manually from the Devices->Plugin Information menu? What do you do to make it reappear?

10 November 2012 at 3:26pm

when cubase scans nothing happens, when I go to devices->plugin iformation it doesn't appears

I restart windows and when I'm lucky the plugin appears.

Maybe I need a format and a fresh SO install, but some other VST had this issue and the developer fixed it but I don't know how

18 May 2019 at 9:22pm

good 4 mastering too.

9 November 2012 at 6:26pm

Really sexy sound, the only downside is the delay because I have to route a signal through two channels if I want to mix the dry signal into the wet signal because adjusting the dry/wet knob in the mixer in my DAW just gives me phasing from the delay.

I still route it through two channels though it's totally worth it on my drums to make the kick into this earthquake fart sound.

9 November 2012 at 10:08pm

Hi Ligidium,

thanks for feedback.

That's a really interesting one. There are two places where the delay could be introduced. One is the cathode capacitor, but that's inherent to the modeled circuit and shouldn't cause any problems (try the 22uF setting just in case). The other one is the oversampling. It will introduce 8 sample delay. You can try to turn off oversampling and see if it helps (button in the upper part of the UI). Unless you drive the tube very hard you can get away without oversampling.

I will check if there are no other glitches with delays and get back to you shortly.

Now it comes to my mind that a delay-compensated dry/wet mix know could be handy.

10 November 2012 at 12:01am

Ok, I think I've got something. The nastiest phase interaction comes from the fact that it's an _inverting_ triode stage. I've kept it as is in the model but nothing is keeping me from changing it to non-inverting.

Cathode cap indeed introduces some phase shifting and will attenuate some frequencies when output is mixed with dry signal.

Oversampling severely affects the phase, so dry/wet mixing is not possible with oversampling in the current implementation. After DC-12 is finished I will add mix control in the future version that will be phase-corrected. As a positive side effect it will make the transfer function plot in oversampled mode a bit more meaningful as well.

I'm going to fix the invertion and release an updated version soon.

10 November 2012 at 9:07pm

Please try out the new version (1.0.1) and see if it helps.

12 November 2012 at 8:05am

Alb, could you please check if the new version works for you? If it doesn't then could you please give me the name of the other VST plugin that gave you similar issues?

Renan L.B
Renan L.B
2 December 2012 at 4:44pm


Are there plans to release a x64 windows version of SoftAmp 3OD?

2 December 2012 at 7:44pm

Hi Renan,

Yes, it's on a list. Though I still have to set up my environment, so it won't be ready before the end of DC-12.

20 December 2012 at 3:03am

thanks for the review

Please log in to join the discussion