Stereo to Mono sample conversion, GrandOrgue/Hauptwerk difference!

  • The mono (dry) sounds are more effective in a multi-channel system, for example inside a church.
    I have noticed a significant difference between Hauptwerk and GrandOrgue.
    If I am not mistaken Hauptwerk only amplifies the left channel. I had compared the stereo waveform with that mono.
    For GrandOrgue would simply view the source code, but at first listen it seems that the mono sound of GrandOrgue is brighter and more open than Hauptwerk. Of course it does not happen for all sounds.

    Hauptwerk and GradOrgue were tested in parallel with the same audio system and the Casavant Freres stereo pipe organ.

    Is there someone who has noticed this fact?

    Thanks

  • GO mixes both channel 50:50 to mono and plays that signal via left+right channel of the audio group.

    If you only want to use the left or right channel, put the stereo samples into a seperate audio group and add only their left (or right) signal to an sound output.

  • thanks Martin for your reply but there is a problem with your solution. stereo mapping creates inconsistent state. the levels of the two channels are used to place the sound between the two speakers, but if you want to use only one channel then you have to "normalize" the levels in some way. This happens especially with mono recordings which are artificially mapped in stereo for panning.
    Regards
    Elia

  • Audio/Midi -> Audio/Midi Settings -> Audio Output -> Channel x -> ...
    it is very flexible and allows you to do things you could not do with Hauptwerk.

    This solution (left+right mix) is good when the left and right channels have the same phase (=derived from the same monophonic recording).

    To be precise, it would be incorrect to mix the left + right channels especially if they are registered with two different microphones.

    Hauptwerk acts only on a single channel (left) of the stereo file to avoid phase problems into the left+right mix. Also it act dynamically on the level of each individual left note to return the left+right level of each individual note (for "stereo to mono sample conversion").

    I know that I'm talking about an unusual situation (most *.organ files on the website refer to wet and surround pipe organs, dry recordings are designed for specialized use). Probably I am forced to solve this problem outside of GrandOrgue reconstructing all the wave files with a script or a specific program...

    Thanks

  • "If the two speakers produce equally loud sounds, the signal combinations at both ears are identical, so there are no apparent time‑of‑arrival differences and the sound image is perceived to be directly in front of the listener, as a 'phantom centre' image. Varying the relative levels of the two channels introduces apparent time-shifts, and offsets the perceived source position towards the louder side. Although the exact level offset needed for a given position varies slightly with hearing acuity and the monitoring conditions, a figure of 12‑16dB is generally sufficient to place a sound firmly over to the louder side."

    In practice, the combined level of both channels is used as reference for amplifying one of the two channels for obtaining the same level.

    The most crude way is:
    - make the left+right sum
    - calculate the maximum RMS of the combined waveform ( http://www.csounds.com/manual/html/rms.html )
    - amplify one of the two channels to achieve the same maximum RMS

    Obviously this is just a starting point.

  • For completeness, I quote the words of the Hauptwerk developers:

    "If you load/route a stereo pipe in mono then Hauptwerk picks the loudest of its sample's two channels and plays just that one (to avoid phase cancellation through mixing the channels together), with its amplitude adjusted to match the average amplitude of the original two stereo channels.
    Hence the result is about as convincing as it could feasibly be, but of course you're still inevitably discarding one of the channels so the result will be less realistic in that regard."