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GO and reverb

e9925248

New member
I don't understand why GrandOrgue cannot load a stereo impulse response file's both channels and use them both if output is at least stereo. It's certainly possible with jconvolver (though it's not done in the .conf files I provided earlier). I understand that it will complicate the code, yes but it should be doable!

Using only one channel is the best compromise at the moment.

As already written, the GO audio output is not stereo. It supports 1 - n channels on 1 - m sound cards. A stereo reverb does not fit in this model - GO also needs a multi-channel reverb with an apropriate, user friendly configuration. This multi-channel solution will certainly be capable to handle the standard stereo case.
 

e9925248

New member
If signals are out of phase in the two channels they cancel.

Could you please explain the effect or provide a test case? The reverb of both channels should be independend with the same settings. As both channels receive the same processing, I have trouble understanding, why it introduces a different behaviour?
 

scush

New member
If a high frequency wave is recorded in stereo .
Due to different distance's between the mic's and the source of sound, or reflective surface's.changing the path.
the wave the mics recieve can be 180 degree,s out of phase.
When they are combined into a mono signal they will cancel one another out.
In our case leaving us with a pipe that can not be heard.
also this effect will cause some sounds to be louder than others.

please can we have stereo.
 

e9925248

New member
If a high frequency wave is recorded in stereo .
Due to different distance's between the mic's and the source of sound, or reflective surface's.changing the path.
the wave the mics recieve can be 180 degree,s out of phase.
When they are combined into a mono signal they will cancel one another out.
In our case leaving us with a pipe that can not be heard.
also this effect will cause some sounds to be louder than others.

Are you able to reproduce it or is this a theoretical fear?
In my option, cancel with reverb should only happen, if cancel happens without reverb.
 

scush

New member
Yes, some sounds will have no reverb.
I can't get Ambisonics out of my mind .
When I was playing around with that buffer.
I may have been getting an improved result.
I will keep testing.

PS.
I looked at some of lars recordings in an editor.
In the ones I looked at there is a phase difference of 30 degree's
between the channels even at mid frequency's.
 
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scush

New member
Hi

I have done a few builds with different value's for that buffer.
In my opinion reducing 4000 to 1000 gives the sound much more brightness.
set at this it makes my alesis microverb sound dull.
 
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L.Palo

New member
Hi!

In (most of) my recordings I use a technique called near-coincident (mixed stereophony) that records both time arrival differences (phase) and intensity differences. Usually phase differences are not problematic until you try to mix down both the channels to mono (often done for radio transmissions). Any real organ builder will tell you that the pipes in a real organ might have phase issues with each other, there's even music pieces written (for instance by Bengt Hambraeus - Constellations/Interferences) that exploit the phenomena. It's certainly nothing to be scared to death of, nor is it a goal to only use the x-y stereo recording technique to avoid the phase differences. It actually creates much more space and depth in the sound to record as I do.

As Martin explained, there shouldn't be any problems specifically with phase as GO now handles reverb (a mono (in effect) ir-recording is equally added to both the channels), but what does happen is that the ir-reverb "colours" the sound and will amplify certain frequencies and suppress others. Also my ir-recordings are different from each other because balloon popping is really a bit random in how it will excite the room (and it's certainly not flat over all frequencies) from one pop to the other, but I think they are usable for different effects.

I can only agree that for the time being this implementation is good enough, but eventually we'll want to add the multiple channels of the recorded ir too. I think that it would be nice to be able to decide how the reverb should be routed too. For instance one could want to have front speakers output the original recorded audio while surround speakers (or back) would output the convolution reverb sound only... Just a thought. Of course, in theory it could be multiple channels of recorded audio that (perhaps only some) will be processed by the reverb into their own audio streams that could be routed to any number of different audio devices (different) output speakers. It quickly gets complicated, but for most common use cases it will rarely be. Many will be happy to just process the normal recorded stereo audio with respecive channel of the stereo impulse response reverb that then will get mixed together and enjoyed over simple stereo speakers connected to a single audio device... Besides, there are no free multi-channel recorded samples available (except the normal stereo of course, yet...) compiled into a GO sampleset, nor does GO support reading such files (again, yet).

Kind regards

Lars P
 

scush

New member
Usually phase differences are not problematic until you try to mix down both the channels to mono

This is all that I mean lars, I will make some samples with sound in one channel only to see if I understand what is happening.
 
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scush

New member
I have made 2 samples left only and right only.
the reverb is only heard in the channel that the sound is in.
therefore no interchannel mixing takes place.
sorry for my misunderstanding.
 

scush

New member
Regarding latency.
I believe if there was a reset after the samples are loaded / reloaded, or the samples were loaded before the reverb was built.
Everthing would work as intended, on my machine at least.
 
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e9925248

New member
@scush: You have reported a windows crashes.

Could you please try to reproduce them with the current version and try to gather some information about the crash?
I have posted a list of gdb commands to gether the data a few days ago in this forum.
 

scush

New member
The good news is that I have not had any crashes since running GO on a new windows account.

After I load a sample set with reverb enabled, or reload it, there is always a long latency and/or distortion.
It has only taken one push of the reset to fix this, every time.
So for me things are working very well.
Not until a build is released will any more be known

PS
I have also built win32, no sse3, etc they all behave in the same manner, on different maschine's
 
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scush

New member
IR's.

If all balloons were popped from the position of the organ, Then the mirophones moved to different locations in the the hall, some made close to the organ.

When using the IR's in GO it should be possible to listen to the organ from the locations that the microphone's had been placed.
.
 

wehtam721

New member
Good evening all,

I have been playing quite a bit with the latest windows build over the past day or so and my initial response to the changes is that it's spectacular. Things are very much improved over the previous build (related to reverb) and as far as I can tell, things sound great. I have tried lots of different IR files and GrandOrgue switches between them and loads them seamlessly and plays wonderfully (as scush has reported). I have experienced a relatively large latency with reverb when first starting GrandOrgue, but this can be fixed by changing the audio settings in (seemingly) any way. Once reverb has been turned off and back on again, a new IR file has been chosen, dirac pulse adjusted, pressing the "panic" button etc. the latency problem is solved. I believe that this has been mentioned before, but I can confirm that this is happening on my machine as well.

If there are any specific settings that could benefit from some testing, please let me know. I'd be happy to run some tests and provide some feedback. In the meantime, I can confirm that the other issue brought up by scush about the samples per buffer is also happening on my machine.

I hope that all is well and I can't thank you all enough for your continued work on GrandOrgue. It sounds better and works better on a constant basis.

Take care,
Matt
 
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scush

New member
Hi
I don't have access to a pipe organ to experiment.
But some time ago spent a few hours with a small organ with a pneumatic action.
When playing the subbass in a staccato manner, The effect was that of a plucked string.
This occured after the foot had left the pedal.
With the success of the reverb, This effect would be easy to achieve using multilple releases.
My question is does a tracker organ behave in a similar manner, and if so are low notes on the manuals affected to any extent.
 
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e9925248

New member
I have experienced a relatively large latency with reverb when first starting GrandOrgue, but this can be fixed by changing the audio settings in (seemingly) any way. Once reverb has been turned off and back on again, a new IR file has been chosen, dirac pulse adjusted, pressing the "panic" button etc. the latency problem is solved. I believe that this has been mentioned before, but I can confirm that this is happening on my machine as well.

The latency behaviour sounds strange. What audio configuration are you using?
 

wehtam721

New member
I'm attaching a pdf document here to show the audio settings panes in GrandOrgue. I took screen shots of the panes. It seemed easier to show everything than to guess what pieces of information would be most useful. If I'm missing something, please let me know and I'll respond with whatever is necessary.

I have downloaded and installed the latest build for windows (rev 1178) and can confirm that the same problem occurs when first launching this new version of GrandOrgue as well. I have been able to replicate it many times. As I mentioned in my previous post about this, changing any of the audio settings (including settings other than those on the reverb panel) will solve this problem until GrandOrgue is closed completely and opened again.

I have also tried loading one sample set, confirming that the latency is higher than expected, then loading other sample sets. Other sample sets also experience the same problem until a change is made to audio settings.

Again, as always, if any other information would be useful or if there's anything you'd like me to try, please just let me know.

Take care,
Matt
 

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