Polyphony Questions

Is there a downside to raising the polyphony level too high or more than is needed ?
I am aware what happens if the polyphony level is set too low, but what happens if it is set too high ?
Antoni

[mdyde]

Hello Antoni,

Yes: the reason that Hauptwerk has a polyphony limit setting is so that you can set it low enough to ensure that your computer's CPU won't get overloaded. Overloading the CPU would result in nasty audio glitches, which would also be visible as the 'CPU' meter on Hauptwerk's "Audio, MIDI and Performance" large control panel going into the red. (You can use "View | Large floating control panels .." to open that control panel if it isn't already visible).

The easiest way to set the polyphony limit is to load the relevant organ, make sure that the "Audio, MIDI and Performance" large control panel is visible, then draw the biggest registration on the organ that you would ever be likely to use (or simply draw all stops and couplers for good measure). Now play as rapidly as you would ever be likely to play. If the 'CPU' meter on the control panel goes into the yellow or red (and/or if you hear nasty audio glitches without the audio level meter on the control panel going into the red) then reduce the polyphony limit setting a little, and repeat until you can no longer get that CPU meter to go into the yellow/red when playing.

For more details, have a read through the "Performance tuning: Determining and limiting polyphony" section in the main Hauptwerk user guide (on the Help menu in Hauptwerk; pages 302-306 in the Hauptwerk v7 version of the guide, or pages 314-318 in the v8 version).

Hello Martin:
Thankyou for your informative reply. The only reason for my question was that I had noticed that my polyphony was set at 1900 and never thought anything about it. I had calculated that my polyphony level should have been around 4000 based on a 66 stop organ in surround. The maximum number of depressed keys ( 8 manual and 2 pedal) would be 10 x 66 stops = 660 x 16' and 4' couplers = 1980 x 2 for surround = 3960. I wasn't sure if Hauptwerk considered one note from an 8 rank Mixture as one or eight.

Playing as rapidly as possible and with every stop and coupler engaged, there were no audio glitches even at 10,000 polyphony. I set my polyphony to 6000 . Just as an experiment I raised the polyphy to 24,000 and only after several seconds of rapid playing did I experience what you were describing (nasty audio glitches).

Just as a side note, I have enjoyed almost daily use of my Hauptwerk from 2008 to the present and though all of the iterations, and have never experienced one software issue. Quite remarkable.

Antoni

[mdyde]

Thanks very much, Antoni. Excellent. You're very welcome.

I had calculated that my polyphony level should have been around 4000 based on a 66 stop organ in surround. The maximum number of depressed keys ( 8 manual and 2 pedal) would be 10 x 66 stops = 660 x 16' and 4' couplers = 1980 x 2 for surround = 3960.

Just a quick note on that for background interest: to calculate the minimum polyphony that would be needed for an organ to avoid *any* release tail fading at all (assuming you had a CPU powerful to handle it in its entirety without audio glitches, which won't be the case for most people with very large surround organs), you would also need to take into account playing speed because release tails continue to consume voices of polyphony until they have entirely finished. There's a detailed explanation of that in the document that's available here via the "Technical info" link near the top-right of the page:

https://www.hauptwerk.com/requirements/

However, testing in the way I suggested above (as you've now done) is still the best way to set the limit appropriately for your CPU anyway. (A small amount of release tail fading is fine and normal, and the polyphony management system is specifically designed in such a way that it can do that automatically whenever needed without it being noticeable.)

Hello Martin:
Thankyou for the update. I used 6000 polyphony and with all stops and couplers on and very rapid big chord playing ( i.e. Widor Toccata) have experienced no nasty audio glitches or oddities.
Antoni

[mdyde]

Thanks, Antoni. Excellent.