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SoftAmp PSA

AXP's picture

SoftAmp PSA

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SoftAmp PSA is a virtual-analog guitar pre-amp supplemented with noise gate and compressor, all modeled after famous guitar gear that needs no introduction.

At its core there are 5 distortion stages. First three are based on op-amps with zener diodes in the feedback chain, while the last two are just op-amps being overdriven into saturation. They are followed by tonestack, speaker simulator and an output level control. Each overdrive stage has a distinct frequency shaping quality according to their names. See the EQ plot in the bottom right corner for details.

All stages are modeled as nonlinear filters with their outputs depending on both the frequency and the amplitude of the input signal. It gives the most accurate digital representation, compared to cascaded filter/static waveshaper approach.

In addition to the basic controls, there are two more knobs that control the speaker simulator parameters - Shape and Rolloff. With both knobs at 0, the speaker simulator is completely bypassed (for example, to be used with external impulse loader).

Giving even finer control over the gain structure, there are two more buttons - Asymmetric and Soft-Clip. The former applies to the zener diode stages and replaces the default 4.7v/4.7v zener pair with intentionally unbalanced 3.3v/4.7v pair to saturate the signal with even harmonics. The more the first three stages are overdriven, the more pronounced is the effect. See the clipping LED indicators to have a feel of which stage gets the most saturation from the signal. The Soft-Clip function applies to the two overdriven op-amps and changes their open-loop gain from 1 million to just 200. This effectively makes the transition from linear to saturated region much more softer, making the distortion less harsh and also helping the fading notes sound smoother.

The PSI Denoiser is noise gate with adaptive release time. It has a handy "Learn" function. Don't play anything on your guitar and hit the Learn button. As soon as the LED goes off, the gate threshold will be automatically set to match your noise level. The noise gate is applied directly to the input signal.

The Squeezo Range compressor is applied to the signal right before entering the PSA pre-amp. It's a very nonlinear, but musical sounding device. It acts as both upward and downward compressor depending on the gain and bias setting. In the original device those controls were not available for user adjustment.

This plugin was made for KVRAudio Develope Challenge 2016. If you like it, and happen to have a KVRAudio account, please consider voting for it before December, 18th!

Version History: 

1.0.00 - 01.12.2016
- Initial Release

1.0.01 - 06.12.2016
- Double click now properly resets the knob position
- Drive knob now has a correct range (extended towards lower gain)
- Version update availability text is now properly colored
- Default preset now initializes all the controls
- Fixed a bug that could affect the compressor/gate gain plot when multiple instances are launched

1.0.02 - 16.12.2016
- Fixed a bug that affected channel balance of Squeezo Range in stereo mode


AXP's picture

Now comes with a user manual! 

Anonymous (not verified):

Ya bugger! Almost got me with that "leave blank" in the regisration page! Off to make samsapy noises with the new toy. Good luck in the challenge!

AXP's picture

Haha, you woldn't want to know how much spam I have to fight with!
And thanks!

Declan White (not verified):

This is incredible. thank you!

AXP's picture

You are welcome! Thanks!

DiegoC (not verified):

You did such a great job in this plugin that I was sincerely expecting people to put you in the top five list of the developers challenge this year (if not in the top 3 or even as winner).... And not that simple "volume checker" as winner...weird world.. However..all my respect and, thanks for this and for releasing it as freeware.
Best Regards

elizza (not verified):

so ttrue

AXP's picture

Thank you! Audio tools and generic effects are apparently used by wider audience than guitar amps. 
I'm not disappointed though, I got a lot of positive responses from guitar players. Also I think the guys who won have put in as much work as I did and their results are well deserved.

I'll continue to do what I'm doing regardless of the contest results :)

SadamJR (not verified):

Are there any presets?

Michele (not verified):

Thanks, thanks, thanks! I use PSA presets with Wall of sound (bypassing the PSA cabinet emulator) in Reaper and it's really wonderful!

urival (not verified):

Congratulations for this great amp simulator. I rated it with the highest score at KVR Developer Challenge.
I use it to play guitar live in the studio with Cantabile Lite (2 and 3) host. It souds gorgeously.
But every time I start the host with Softamp PSA inside, it makes a annoying loud noise click. This only happens with this plugin. How can I avoid this?
Thanks for sharing your wonderful creation.

AXP's picture

Thank you!

At the startup all the capacitors are charged up to their DC voltage, so there might be a click. 
Ideally, the algorithm should precompute the bias values and initialize the caps, that would alleviate any startup transients (the click you hear).

I'll add that to my bug list and fix it in one of the updates.

urival (not verified):

Thanks!!!! :-)

Flo (not verified):

This really nice!! thanks so much!! its about the sound..... but look really pretty also, just awesome.

AXP's picture

Thank you!

Chelo (not verified):

Hello, this plugin is really good, I was able to try it on a windows system, but I work mostly on Logic and PT on a mac, in PT i have the PSA-1, but I would love to use this in Logic where I do most of my mixing, will you ever make this an Audio Unit? please????

AXP's picture

Thanks! I'd like to, but I don't have time for this at the moment. It's not as straightforward as I'd like it to be, since I would need to get a Mac and learn to write code for it first.

Have you tried Juce?

AM (not verified):

You can also try the great and free WDL-OL/Iplug framework. Mr. Oliver Larkin the main developer is planning a substantial update and cleanup with vector GUI resizing, et cetera.

Pat Autrey (not verified):

Norton 360 immediately uninstalls the app after install - Im not saying there is anything infectious, but Norton is certainly uncomfortable. Perhaps it's a false positive detection. Would you please ask them to update their virus definitions, so me and others in similar circumstances can use yo0ur product

AXP's picture

Hi, thanks for letting me know. What do you mean by installation? Unzipping the DLL?

As far as I remember Norton marks as suspicious everything that is not installed on many PC's, and my plugins apparently fall into that category. And from Norton's perspective I'm just one of shady developers who might put any malicious code into their applications. So I think the only way is to manually override your antivirus warnings. I'll see what I can do on my side.

Mister Fox (not verified):

Hey there - any updates of the PSA FR's I sent in a couple of weeks ago via mail? It's been radio silence since our last contact - just checking in if things are all right

Any chances for Mac Version?

Don Chagas (not verified):

Excellent. Thank you

luken2000 (not verified):

Man, this is incredible, i use it mainly for guitars, recordings and stuff with an external cab emulator, and even without it, this sounds insane!!! I was actually looking for this one for a loooong time and now, somehow I got to it (thank you google)...I actually own a rack unit and gonna do some comparison, but it won´t be a surprise to find out that I could shape the tone even more within the plugin. Your work is fantastic! Thank you

Joshua (not verified):

Hey! Just wanted to let you know that this plugin is awesome! Really satisfies my need for a Sansamp plugin since I don't use Pro Tools much anymore. Awesome stuff

Anonymous (not verified):

Thanks you very much for this.
I just recently switched from Protools to studio one (after 12 years) and was looking for a sans amp replacement. Thanks you for doing this!


Alexander Bingham (not verified):

will there be a version for mac/Logic Pro ?

Cochonnet (not verified):

Hi !
It sounds great !
Do you plan to add more preset slots ?

Lego (not verified):

Hi guys! Is this just a guitar preamp, or I can use it for bass, like the PSA1 in Pro Tools? Many thanks!

George (not verified):

Hi guys!!Great work!!!How could i transfer presets from the hardware unit?The parameters on the hardware reach 250+.
Happy new year!!!

AXP's picture

They values should be simply scaled proportionally. So if the hardware range is 0..255, then 128 on hardware would be 50 in this plugin.

Mange (not verified):

Fantastic amp. Could you please add some presets in the next version so we can focus on playing guitar instead of turning knobs for hours, trying to find the right sound :-)

Dolurum (not verified):

If you are using Reaper, there is a set of presets on the Reaper Stash. Search for "SoftAmp PSA"

Even if you don't use Reaper as your DAW you could use it to look at the settings.

Ghettosynth Berlin (not verified):

MAN! This one is so great.
No unneccesary bells and whistles. I know, it's modeled after the SansAmp PS-1
but the original does not have that great cabinet simulator.

A tip for the noise gate: make it multiband, so the gate only affects the upper frequency range.
That way you can play palm mutes with full treble gain but the signal would neither be cut away nor
be noisy.

I'd really love this one as a piece of hardware *__*

Dan Cairney (not verified):

I was going to say that too. I just sold one of the original ones and yes, exactly.

AXP's picture

Thank you!

Regarding multiband gate: initially that was my plan, but I couldn't find the schematics of the rack Decimator which IS working exactly as you describe. The pedal one lacks that but is still quite good. And I wanted to have true faithful models in this model, not something designed from scratch. I may have my own take on the frequency-dependent gate at some point or modify this one further, but that would be a separate plugin.

Palco KHTV (not verified):

Amazing! Looks like gear!

Lukas Schmidtke (not verified):

Thank you so much for this wonderful wonderful plugin! You're a genius AND a saint.

AXP's picture

Wow, thanks :)

Dan Cairney (not verified):

This is my favorite distortion unit. Sounds better than Amplitube, Revalver and more. Smooth, controllable and clean. Thank you!

AXP's picture

Thank you!

William Compeau (not verified):

It is excellent on bass too on a parallel channel especially when recording..Thanks so very much! When I get some money I want to shoot you some for all your very hard work!

AXP's picture

Yes, that's how I use it myself! 

Angus Jones (not verified):

This looks great, is it usable in OSX? If so, what should I do with the dll file, my understanding is they're a windows file extension?

AXP's picture

Hi Angus, unfortunately it's Windows only at this moment. It's quite a common request, so as soon as have the opprotunity I will port my plugins to OSX.

Dolurum (not verified):

Hi, I found this wonderful plugin via Honest Amp Sim Reviews.

It sounds really good and is so flexible. It looks great too! Thank you so much for making it free to use. I am sure you have helped many people.

AXP's picture

Thank you! The HASR indeed hosts a few very favourable reviews of my plugins.

M3l15 (not verified):

Hi! Are you planning to implement it to osx as well? It would be awsome!