John T
I've not done any objective testing on it, but to my ears, it doesn't leave any frequency range completely untouched, wherever you set it. The switch seems to bias it one way or the other, but in practical use, it always comes down to flipping the switch back and forth and using trial and error to get the a sound that does what you want.

 
I agree, John.   When set to "Keep High" there is a bias towards the highs being "saturated", but all frequencies are affected.  The opposite when set to "Keep Low".  I have not often found a situation for using the "Keep Low" setting, personally.
 
For vocals I often use the VX-64 EQ section to apply saturation to only the highs.  Sometimes this works better, sometimes the Softube Knob sounds better.

The Tape Sim is pretty good. I, however, have not had good results from the Saturation. Everything I've tried it on seemed to fare better without. Not to say it isn't a good plug-in, but rather to be used very sparingly.

brconflict, i concur!
 
 
Anyway, Softube seems not to state clearly exactly which mode does what, but a careful read of their comments would suggest that they have labelled the graphic face-plate obtusely. 
 
From the Softube website... "If you want to squash a drum loop but 'keep the bass drum fairly intact', you can for example use the Keep Low mode."
 
I have done some quick tests of this plugin just now and found their instruction to be correct, although they could have worded the modes a bit more pertinently; i myself would have written different wording on the graphics face-plate, something like...
 
1: Hit mostly High freq
2: Hit Full Spectrum
3: Hit mostly low freq
 
The current wording on it suggests the opposite of what it actually does.
 
Anyway, it seems my understanding of this plugin was influenced by only 'one' of the 'two' webpages describing the Softube saturation plugin at the Presonus website; they have used more articulate wording showing that it is not a Tape saturation emulation on another of their webpages: strange that Presonus have two different webpages to explain the ins-&-outs of the Softube saturation Knob... I just found this second load of spiel over at the Presonus website as follows... "The Saturation Knob is an easy-to-use, versatile way to add 'tape-saturation-like' distortion to your tracks. The knob controls the amount of saturation, and you can switch between three different distortion characteristics.
With the switch set to Neutral, the entire frequency spectrum of the sound gets distorted when you turn up the Saturation knob. Put it on "Keep High", and the saturation will mainly affect the lower part of the frequency spectrum, while the top end stays clear. With "Keep Low" selected, the low end will retain its clear sound, and only the high-frequency components of the sound will get distorted."
 
Anyhow, after my own tests i still continue to find this plugin inadequate for the majority of my purposes, it seems to introduce a type of brittle harshness even at the lowest 0.1 setting and yet it doesn't do anything at 0, so it appears that it is more suited to adding aggressive distorted tone when needed, but i definitely have very little use for such an effect.
I would think that the reason Softube gives this away free to Cakewalk, Presonus and Avid for their DAWs is because Softube have deemed it not good enough to sell and that there are 'free' plugins that perform as good and even better, and thus they give it away to these DAW manufacturers to serve a better purpose of free advertising to keep the Softube brand fresh in our minds. 
 
Over at Propellerheads in the "Extension rack" section of their website, there is an official quote from a big-time producer about the Softube offerings which i found quite ridiculous, like the following...
 
"Softube is so good, after using it the first time, I could speak french. Mainly because I kept saying: Pardon my french, but these plugins are f-ing unbelievable! The FET Compressor in particular is probably the warmest, fattest compressor plugin on the market."
 
 
My response to that would be that this guy obviously hasn't used the Slate Digital compressor emulations. Which leads me to ask, is there any such thing as a "Warmest, Fattest compressor"? From what i've heard of Softubes compressors the answer is definitely no! But from what i've heard of Slate Digital, well it really doesn't get any warmer and fatter than that. Slate Digital's compressor emulations are the only ones i would ever dare to call "The warmest, fattest compressor plugins on the market"
 
Secondly, it's strange how Softube requires 330mbs for a single compressor emulation and Slate Digital only requires 80mbs for what is clearly a superior product. Obviously the world of coding emulation algorithms is a jungle.
I also remember Native Instruments have some of their high-end compressor and EQ plugins provided by Softube and i was not impressed with them at all, and that was 'before' finding-out that they were made by Softube for Native Instruments!

LA2A From what i've heard of Softubes compressors the answer is definitely no! But from what i've heard of Slate Digital, well it really doesn't get any warmer and fatter than that. Slate Digital's compressor emulations are the only ones i would ever dare to call "The warmest, fattest compressor plugins on the market"
 

Srsly, what's the deal with you and your impressions of Slate Digital's products? If you're going to push the plugs, can't you at least pretend/admit having used them?

I like both the tape saturation and soft-tube plugs.
 
I have one friend I usually put a touch of the soft tube on. He plays a sweet acoustic guitar with a flat pick and it's nice to give his guitar a little bite.
 
It can take some of that fret rattle and make it a bit crunchy... kinda Dave Matthews style.
 
I think it sounds great on that.
 
And I sometimes split a bass sound using a multiband and soloing low and high freqs separately and the applying a touch on the higher freqs.
 
I would miss it for sure if it was gone. I use it on as many projects as I do the CA2A.

sharke

Sanderxpander
I'm not sure about Sausage Fattener's 64 bitness but it works fine in Sonar 64 bit.

I am not sure either, I need to check it out. The only problem I've had with it is that sometimes when you have the GUI open it seems to make everything else sluggish. However since the controls are so simple you can set them quickly and close it immediately. Great on bass and drums.

Okay, cheers mate. 

Here is a great video showing the Saturation Knob doing its magic in a mix :-))

http://youtu.be/_ALJpZpHWKo

All the best
Jan

LA2A
 
Anyhow, after my own tests i still continue to find this plugin inadequate for the majority of my purposes, it seems to introduce a type of brittle harshness even at the lowest 0.1 setting and yet it doesn't do anything at 0, so it appears that it is more suited to adding aggressive distorted tone when needed, but i definitely have very little use for such an effect.
 

That's the results I typically get from Saturation. I'm suspecting it was a discontinued plug-in from their own website, so, it could be deprecated code. I don't want to slam SoftTube or CW on this, but LA2A did state what it does (for me) better than I could.

jps
Here is a great video showing the Saturation Knob doing its magic in a mix :-))

http://youtu.be/_ALJpZpHWKo

All the best
Jan

Thanks jps for this video connection, I hadn't seen this one before.... Interesting conclusions that he makes in the video with the material he was using it on.
 
That may be the bottom line.... how you use it and on what material.
 

SvenArne

Seriously, what's the deal with you and your impressions of Slate Digital's products? If you're going to push the plugs, can't you at least pretend/admit having used them?

I have and 'own' Slate Digital's VCC (Virtual console collection), plus the VBC (virtual bus compressors) also the VTM (virtual tape machines) plus the VG-X mastering plugin. They are the first and only third-party plugins i have found that actually do what the 'real' hardware counterparts do, they sound exactly like real hardware, to the letter! I couldn't continue to make music without them. 
 
Previously i was using the Overtone FC70 (A Fairchild Holy Grail 670 emulation), also the DCAM Dynamics (including the DCAM Bus compressor emulation), plus the revered "The Glue", plus Izotope's Ozone 5 and Alloy II products, and 'many' others (too many to name), and 'none' of them 'ever' reproduced the 'actual' tone and exact response characteristics of the 'real' hardware with associated real-life sonic signatures, not even close. My point... Slate Digital's plugins were a revelation to me! I simple couldn't make music without them now.
 
In fact, now that i think about it, i'm gonna contact Slate Digital begging them to do an La2a emulation; i would love to finally have an emulation mimicking exactly what the real-life La2a does (apparently there were four versions of the real-life La2a as shown by Motu with their "Masterworks Leveler"); IMO if Slate Digital were to do an La2a emulation, that would finally give us this legendary compressor set-in-stone forever, and all inside our DAW, wow! I have the Cakewalk CA2A and it does not convince me, i am not impressed by it, same goes for the IK Multimedia versions of legendary compressors.