CPU clipping in Hauptwerk

User question: using some sample sets of particularly large organs (e.g. Billerbeck or Frankfurt) and playing with the tutti, the CPU indicator signals a clip and the sound distorts, sometimes even leading to a crash that requires a restart of the Hauptwerk program.

If CPU indicator goes to the red zone (Audio, MIDI and Performance panel), it means that the CPU is weak and is not able to handle the data which Hauptwerk sends to it.

  • CPUred

The question is why it happens and you must find the cause. From my experience, you should concentrate on the following:

1.) Determine correctly the max. polyphony which your CPU can handle. The tool is called the "Polyphony Testing Organ" and you can find it in the sample set list in your Hauptwerk ("Load Organ" menu).  You should determine your max. polyphony and do not set it higher for any set. Your maximum is your maximum. So, if for some sample set, the recommended polyphony is 12.000 pipes, it is the recommendation from the manufacturer of the sample set to get most of the sample set. But if your computer is capable of max. 6.000 pipes, then, it is your maximum. You should set the polyphony to 6.000 pipes and not more.

  • polyphonyLimit

2.) Determine the perfect latency for your setup. Everybody would like the latency of the sound stream to be the absolute minimum. Well, not all computers and sound cards are able to achieve performance of -say- 5 ms latency. If the latency is set too low, your CPU will go to the red zone, causing problems. Set the latency to a higher value and your CPU should be OK.

  • soundDelay

3.) Check for audio optimalization of your computer. A lot has been said on the optimalization of a computer for real-time audio. Not all computers are capable of running real-time audio without problems, especialy computers based on a Windows system have problems. Search the internet (and the Hauptwerk forum) for recommendations on setting your computer optimally for real-time audio.

4.) Some Hauptwerk versions (to my knowledge Hauptwerk 6, Hauptwerk 7) had problems with multi-core CPUs and there was no real redemption to the problem. This problem manifested itself especially on systems built on the AMD CPUs. Version 8 of Hauptwerk solved this.

I hope my tips would help you.