@Joe:Thanks for your answer and your effort to comprehend the phenomenon I was referring to. I guess the effect is not as subtle as you might think. It is nearly impossible to miss its occurrence. Probably my description was misleading.

Now, after a coincidental restart of Pianoteq, I can't hear this specific effect anymore. Instead there are other strange effects sporadically occurring. They are probably related. Sometimes a strike on the keyboard doesn't  trigger an action at all. Some key releases are ignored, that means that I have to hit the key twice in order to release it. There are “ghost-notes” ( not played) sounding. All this gives me the paranoid feeling that someone has hacked into my sequencer - but that's not true, of course :-)

So now I am nearly sure that it actually is a flaw, either in the linux version of Pianoteq or in my own self-compiled platform that I will use to build an integrated device - some day, hopefully. If the latter is the case, then the flaw is only triggered by Pianoteq 4. Other midi software, including Pianoteq 3 is behaving as expected. Maybe that this has to do with the availability/reliability of system timers or something like that. All in all, I think the response to this topic shows, that this is a rather exotic problem, most people shouldn't worry about. The next step for me is to try Pianoteq 4 on a common standard distribution like ubuntu.

Hello again Mr. hkalupa,

I was wondering whether what I heard was the same thing that you had heard.  The reason I say this, is that I heard a reinforced C note that rang at approximately 1046Hz, rather than the 523Hz (C above middle C) you had reported.

When you wrote that one of your reactions was that you felt someone had hacked into your sequencer, I suspected you might have a midi feedback loop of some sort.  When key releases are ignored and/or you hear ghost notes, this is often a symptom of Pianoteq receiving two simultaneous (or nearly simultaneous) note on / note off signals.

Just by chance, have you tried running Pianoteq in the standalone mode to see if these quirky problems still exist?  I say this, because you state that restarting Pianoteq seemed to change the problem of the 523Hz resonance.

Food for thought,

Joe

Now, after a coincidental restart of Pianoteq, I can't hear this specific effect anymore. Instead there are other strange effects sporadically occurring. They are probably related. Sometimes a strike on the keyboard doesn't  trigger an action at all. Some key releases are ignored, that means that I have to hit the key twice in order to release it. There are “ghost-notes” ( not played) sounding. All this gives me the paranoid feeling that someone has hacked into my sequencer - but that's not true, of course :-)

So now I am nearly sure that it actually is a flaw, either in the linux version of Pianoteq or in my own self-compiled platform that I will use to build an integrated device - some day, hopefully. If the latter is the case, then the flaw is only triggered by Pianoteq 4. Other midi software, including Pianoteq 3 is behaving as expected. Maybe that this has to do with the availability/reliability of system timers or something like that. All in all, I think the response to this topic shows, that this is a rather exotic problem, most people shouldn't worry about. The next step for me is to try Pianoteq 4 on a common standard distribution like ubuntu.

I tried your experiment with C4/C5, and then compared the sounds against the adjacent corresponding B and C# notes.  Listening through high quality headphones, I did hear an additional octave resonance at C6 (two octaves above Middle C), whereas the corresponding B and C# octaves exhibited higher amounts of a twelfth as their predominant harmonics.  This was heard in Pianoteq 4 using the two D4 presets that I tried.

The culprit note, in this case, is the fourth harmonic of the Middle C Note.  The harmonic/resonance you probably hear (C6), becomes accentuated when it is played along with the normal second harmonic of note C5.

Adjustments of this type are easily made on a single note basis in Pianoteq PRO.  Assuming you don't have the PRO version: If there is a particular preset in D4 you would like to be toned down, just let me know.  I am able to go into the Note Edit feature of Pianoteq PRO, and reduce (slightly) the fourth harmonic of Middle C in said preset, and will post an .fxp which you are then able to drop into your interface.

Personally, I do not consider this to be a "flaw" of Pianoteq, because real acoustic pianos regularly accentuate the octave harmonics in some notes, and accentuate the twelfth (octave + fifth) in other notes.  However, if this bothers you, then you will be listening for it, and it will aggravate you.  This is one of the benefits of owning the PRO version of Pianoteq that a person is able to make subtle adjustments to various characteristics of individual notes.

Cheers,

Joe

For me one of the very few remaing drawbacks is the dominance of lingering sound at about 523 Hz.
To hear what I mean please hit c5/c4 at forte level and then release all keys and pedals immediately.
Try the same a halftone higher/deeper - there is no such dominant sound.
At least for me this sound stands in the way when playing a piano passage or just slience short after.
But hey, this works as pedal point when playing slow staccato lines in the upper region of the keyboard. It's a feature...

Maybe that this is part of the aspired realism, but for me it is hard to belive that the loudness of this particular frequency is really intended. The only fix I found so far is to reduce the sympathetic resonance to a level at which the overall sound of the piano becomes boring. Am I the only one who treats this as a shortcoming. Is there any other workaround? Are there any signs that this will be fixed in the near future?

Thanks for your comments.