It would be good if the soft clip could be turned on and off. With soft clip always on, it's seems impossible to accurately profile a tube DI, or a Neve 1073 for instance, without the KPA adding its own soft clipping effect. To be able to profile the character of such devices would be rather nice.
The soft clipping is only taking effect in the last 6 db of the digital headroom. The rest is linear. This is a common technic, as you probably know.
We should have a section on the forum called 'Engineering & Audio Scientists'. 
Hmm, I'm definitely still hearing this sound/effect when playing around F#5 (14th on top E/19th on B) to B6 on the wet queen patch. Just disable the reverb and delay to hear it clearly on the Wet Queen patch.
Here's a clip showing the problem using firmware 1.0.9 : http://www.per-anders.net/general/aliasing120607_fw109.aif
First section is using a humbucker, secong using a piezo. You'll have to turn it up to hear the compression artifact clearly, but it sounds like a ballbearing rolling in the bg, or a phasey harmonic.
here´s a clip with the noisy attack pretty evident:
alienKPA
The profile is one of the latest Cobra profiles, gain maxed.
I usually do not max the gain, but this way you can clearly hear the aliasing. If you lower the gain, the noise diasappears step by step, but is still audible in a gain range I would dial in for a contemporary modern metal riffing sound.
Hey guys..................DON'T USE THOSE PROFILES IF THEY SOUND BAD.
There fixed. 
As I have announced earlier in another thread, we have addressed aliasing problems for the distortion stomps. In 1.09 they have the same quality as the amp itself. Before 1.09 there were no changes.
A system reset will not have an effect.
CK, that is interesting, because when I turned off everything (amp, eq, and cab), the distortion stomps seem very pure and almost totally free of aliasing by themself, and yet you say that "In 1.09 they have the same quality as the amp itself"--so if that's true, then shouldn't the amp be as aliasing-free as the distortion stomp? And, do you believe that you can overcome the amp aliasing in firmware eventually?
It's dependent in the gain. The amp allows much more gain than the stomps, and more gain than most tube amps. Where is your gain set to?
It's dependent in the gain. The amp allows much more gain than the stomps, and more gain than most tube amps. Where is your gain set to?
I have noticed the aliasing in the higher note register with nearly the entire range of gain in the KPA, from low to high from any profile, by any author. I have been profiling for the last several days, and when I A/B my source amp and KPA profile, it's very evident. Even if the aliasing is not jumping out at you, it kind of floats around in the background, almost subliminally.
I imagine that the sine sweep test by dhodgson would have likely demonstrated the noise with almost any amount of gain.
I have noticed the aliasing in the higher note register with nearly the entire range of gain in the KPA, from low to high from any profile, by any author. I have been profiling for the last several days, and when I A/B my source amp and KPA profile, it's very evident. Even if the aliasing is not jumping out at you, it kind of floats around in the background, almost subliminally.
I imagine that the sine sweep test by dhodgson would have likely demonstrated the noise with almost any amount of gain.
No, by physics the distortion aliasing level is a function of gain.
Hodgsons sine sweeps were high gain only.
I can easily create noticable aliasing on many modelers with sine sweeps.
Some stated to hear aliasing with clean guitar sounds. Yet to be demonstrated.
NM
My apologies for collecting several of CK's recent quotes and numbering them, but it makes things easier to reply to.
Quote from ckemperDisplay More
1) No, by physics the distortion aliasing level is a function of gain.
2) Hodgsons sine sweeps were high gain only.
3) I can easily create noticable aliasing on many modelers with sine sweeps.
...
4) It's dependent in the gain. The amp allows much more gain than the stomps, and more gain than most tube amps. Where is your gain set to?
...
5) Some stated to hear aliasing with clean guitar sounds. Yet to be demonstrated.
Patient: "My arm hurts when I do this."
Doctor: "Well, stop doing it then."
It doesn't look like the aliasing issue can be hand-waved away when Chris's points feel like non-answers. Yes they're true, but so? For example:
#1: Higher levels of distortion means higher (brighter) harmonics, which make aliasing more likely. Are you suggesting people address the problem by using less distortion?
#2: Redoing the tests with lower stomp gain would certainly demonstrate less aliasing (see #1), but running the Metal DS stomp at 10 is not irresponsible. Again, are you saying we should just use less distortion?
#3: If my tests had used more complex tones (an actual string, say) the effect would be worse still. The point is, the 1.04 method was a quality approach. ~16X oversampling is a KPA strength and a plus vs. competitors, but we're losing it.
#4: The hi-gain amps do voice nicely 
which speaks well for their oversampling. Unfortunately, since a low gain stomp+ hi gain amp sounds different from a hi gain stomp + low gain amp, you can't sonically trade one for the other.
#5: Aliasing may have been possible in a Nirvana-like hi-gain stomp + clean amp scenario given the "Patch A" demos. But if not, it probably means that the simpler Clean amp model is freeing up DSP for stomp oversampling now.
-djh
I just HOPE that the tone of the KPA never changes.
I'd rather not use the Metal DS stomp with gain on10 (never in a million years) than change the tone of the KPA so that the Metal DS stomp with gain on 10 sounds 'correct'. 
If you're hammering your arm and the doctor tells you to stop doing it, you should hear at him... 
I just HOPE that the tone of the KPA never changes.
I'd rather not use the Metal DS stomp with gain on10 (never in a million years) than change the tone of the KPA so that the Metal DS stomp with gain on 10 sounds 'correct'.
Well, i agree. I absolutely love how KPA sounds, and i love it even more with the 1.09, since it doesn't need to add "compression" and "clarity" in the amp section to sound less spongy and mode liquid.
But those digital artifacts are definitely there, we all can hear them from the clips. It is honest to say that you'll NEVER hear them in a mix (studio or live).
Of course an address of those little issues would be a plus.
But other features like Perform mode and more FX are way more important IMHO.
If you're hammering your arm and the doctor tells you to stop doing it, you should hear at him...
While the above is cetrainly true, do also think of this:
If you move your arm up and it hurts, and doc A tells you: "well, don't do it then", but doc B tells you "ok, let's see why this is happening and how we can cure it" - to which doc will ya go? 
I play hi gain sounds for more than 25 years. I´m carefully aware not to use too much gain, I have friends that begin there where I usually stop....
What I try to say is: I know hi gain quite well and I know the feel of it! To get into a gain range for a comfortable playing feel , which is as I pointed out much gain, but far from very much, the KPA makes those aliasing sounds clearly audible in EVERY profile.
So my working process for reamping at the moment is:
-use real amps for hi gain sounds
-use the KPA for the rest
I could use a POD or AXE-FX or some VST-plugins for hi gain without getting the aliasing at my usual settings......
Ok im going to make a suggestion but dont shout at me here ok : )
I never really hear these digital aliasing effects, but I dont use stomps, and I dont do high gain very much. - so I tested it here just locally.
With my strat (low output pups) - from 12 fret upwards, its fine.
Tele (vintage low output) again seems fine.
Les paul, PAFs - No problems
Ibanez active pups EMG's - Aliasing is here.. - took out the battery, Alliasing is gone.
Superstrat with EMG81's Alising is here (very HOT 15k)
Seems to me that the active pups are whats casuing the effects to be effident here. - so guitar and not KPA
This was not a scientific test by any means, just a quick test, but high gain pups seem to act differntly to the norm. (active, or boosted "HOT")
Rolling down the distortion sensi to a good level fixed a bit of it, but its still there slightly.
For those getting this a lot.. (DJH/Miles etc) try using a differt guitar? - as some folks are getting it worse than others, so lets do a process of elimination and find out what is what!.
Andy
every gain descreasing aspect lowers the audibility of those aliasing effects, so do low output pickups.
my sound example some posts above was done with very output heavy bareknuckle warpig pickups. But I get the same effect in a less clear way with my vintage strat with low output single coils.
Ok fair enough.. did you also try using just headphones? to try and eliminate any problems with routing?
yes, just headphones!
