Topic by PTQfan

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  • PTQfan
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Topic: Organteq and phase correlation

A question to Modartt team: there’s an “issue” in Organteq: in many presets “out of the box” many stops (e.g UM8, NQ2 2/3, etc) or at least some notes of them (e.g E3) are out of phase (some of them are even in antiphase) which is noticed both by ear and by correlometer. It seems like the phase can be adjusted by experimenting with Stereo Width and C/C# Separation parameters and this can be really tricky (maybe because I’m doing it without any particular system/rule/formula, just by ear and checking myself with correlometer). For example in “Baroque Cathedral I” phase of E3 of Z2 (pedal) and a combination of NQ2 2/3 plus WF2 (Schwellwerk) can be adjusted by setting C/C# Separation to 1.0 and Stereo Width to 0.68, still E3 of UM8 (Ruckpositiv) remains out of phase, so making all of those three E3 in phase requires Stereo Width set to 0.52 and C/C# Separation set to 0.43 (and I’m sure there are lots of other Width/Separation combinations for doing this). I’m 1000% sure this “issue” is not a bug or error but somehow connected to organ’s physics/pipes location (that’s why I’ve put an “issue” in quotation marks), i.e it’s a simulation of organ in real world which is absolutely great, still quite tricky to solve. So my question is: what’s the RIGHT and PROPER way to make everything in phase and at the same time to get nice stereo organ? Am I right at all trying to solve it by experimenting with Stereo Width and C/C# parameters? And if yes, is there any particular rule/formula/”easy way” to get it without spending too much time on checking every stop/note after every change in Width/Separation values? And last but not least – can this be solve for 100% at all? Or there will be still some limitations like “try to avoid combination of stop/note X and stop/note Y because the only way to get everything in phase is to set both Width/Separation to 0”?

Last edited by PTQfan (Yesterday 08:37)

Reply by Klangpost

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Re: Organteq and phase correlation

When you say that a particular note or stop is “out of phase”, what exactly do you mean by that?

Do you mean that the left and right channels show a low or negative correlation in the correlometer, and that you therefore consider this undesirable? Or do you mean that two different pipes/stops playing together are cancelling each other acoustically because you believe their waveforms should ideally be phase-aligned?

I’m asking because, in a real pipe organ, two pipes or two stops are not necessarily expected to be “in phase” with each other. Their physical positions, propagation times, spectra and radiation patterns naturally produce frequency-dependent phase differences. In particular, an 8′ stop and a 2 2/3′ stop playing the same key are not simply two copies of the same waveform that should be phase-aligned.

So I’m curious: what is your reference for deciding that the phase relationship is “correct” or “incorrect”? Is your goal to reproduce the physical/acoustic behaviour of a real organ, or is your goal to maximize stereo correlation/mono compatibility?

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Reply by PTQfan

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Re: Organteq and phase correlation

Yes, channels show negative correlation (which I guess is natural for organ) and the goal is to maximize stereo correlation/mono compatibility. I’m not looking for a sound of "cinematic organ", nor am I trying to achieve the widest possible stereo image. I’m aiming for a balance between the natural stereo sound of a pipe organ and excellent mono compatibility.

So my question is: how can I achieve this in an acoustically correct way directly in Organteq, rather than mangling the organ by cutting frequencies, collapsing parts of it to mono (except for very low end of course), etc.?

It seems that one possible approach is to adjust the relationship between Stereo Width and C/C♯ Separation, since there is a interaction between these two parameters and this does help to some point. The problem is that I don’t know how to approach this systematically and acoustically correctly. There may also be other factors involved besides these two parameters, such as the parameters of the individual pipes themselves.

What I need are some basic rules or algorithms, even at a conceptual level—for example, "the higher you set parameter X, the lower parameter Y should be" or "the higher is parameter X for one stop/pipe, the lower it should be for another stop/pipe".