LogicDeLuxe
Registered User
Joined: 03 Aug 2004
Location: Germany
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 Posted: Thu Sep 02 2004 12:35
Resonance produces loud noise at low mixer rates |
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http://www.gratissaugen.de/files/REZ-BUG.MT2
It's present in 2.5RC3 as well as in 2.32.
Try to play this with several mixer frequencies! Especially with 22050 Hz and lower, you will hear strange noises in Track 00. Also notice the difference between effect parameters (Track 00) and automation (Track 01). I'm not sure if that difference is on purpose, but the noise isn't for sure.
Apparently the resonance intensity depends on the mixer frequency: There is merely a light resonance present with 96000 Hz while it becomes very strong at 11025 Hz. One should expect an identical frequency response in the lower 5500 Hz in both cases, don't you think?
Also you can't fix those noises by lowering the sliders on the mixer. |
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D Vibe
Registered User
Joined: 04 May 2003
Location: Sweden
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Posted: Thu Sep 02 2004 16:40
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Err. If you didn't know, the mixer frequency limits how high frequencies you can hear; or often, it get distorted if it's over the limit. And resonance adds high frequencies to the sound.
According to the Nyquist frequency, the half of the mixer frequency is the limit of how high frequencies it can keep. 22khz can only play maximum 11khz for example.
Haven't heard your examples...
/Daniel |
https://www.dvibe.se |
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Inge
Man-At-Arms
Joined: 04 May 2003
Location: Nieuw Lekkerland @ Holland
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Posted: Thu Sep 02 2004 16:50
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Wait till you hear it. You'll be amazed.
Very odd. The automation/coding difference in filter did struck me earlier: I never *really* understood the MT filters, and had loads of discussions about them on the old forum (for instance, the default filter (so with synthesizer disabled) is something like the value 6700, whereas enabling the filter can result in 11000, making the sample much sharper. Another thing is changing from high-pass to low-pass or vice versa on one sample. The filter can then completely lock up.
But hey...atleast FT2 doesn't have filters, so things can always get worse! 
Inge |
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Yannick
MadTracker Author
Joined: 16 Apr 2003
Location: Belgium
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Posted: Thu Sep 02 2004 17:04
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| Inge wrote: |
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for instance, the default filter (so with synthesizer disabled) is something like the value 6700, whereas enabling the filter can result in 11000, making the sample much sharper.
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That's new to me. 
When the filter is disabled, no filtering is applied at all. I don't know where this 6700 value comes from...
The fact that enabling it and setting it to the max (11000Hz) makes the sound brighter is due to the slight resonance at 11kHz.
Besides, I've heard the noise in the example file. But I'm more concerned about the problems with higher frequencies (such as 96 kHz). Playing at 22 kHz is far from recommended.
Yannick |
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Inge
Man-At-Arms
Joined: 04 May 2003
Location: Nieuw Lekkerland @ Holland
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Posted: Thu Sep 02 2004 17:57
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| Yannick wrote: |
When the filter is disabled, no filtering is applied at all. I don't know where this 6700 value comes from...
The fact that enabling it and setting it to the max (11000Hz) makes the sound brighter is due to the slight resonance at 11kHz.
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So what is the default setting if synthesizer is disabled? There would be no filtering at all, and the sample would thus correspond with the least amount of it (thus the highest filter setting, and thus 11000 hz). Or am I sadly mistaken here on theoretical matters?
| Yannick wrote: |
Besides, I've heard the noise in the example file. But I'm more concerned about the problems with higher frequencies (such as 96 kHz). Playing at 22 kHz is far from recommended.
Yannick
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Hehe...yes, it would be like to flame Microsoft for not getting Windows 3.11 to work on your dual Opteron + raid 5 sata setup 
Inge |
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Yannick
MadTracker Author
Joined: 16 Apr 2003
Location: Belgium
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Posted: Thu Sep 02 2004 18:36
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| Inge wrote: |
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So what is the default setting if synthesizer is disabled? There would be no filtering at all, and the sample would thus correspond with the least amount of it (thus the highest filter setting, and thus 11000 hz). Or am I sadly mistaken here on theoretical matters?
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If the filter was perfect (but nobody's perfect), the default settings would be the playback frequency / 2 with no resonance at all.
Yannick |
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LogicDeLuxe
Registered User
Joined: 03 Aug 2004
Location: Germany
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Posted: Thu Sep 02 2004 19:37
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| Yannick wrote: |
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Besides, I've heard the noise in the example file. But I'm more concerned about the problems with higher frequencies (such as 96 kHz). Playing at 22 kHz is far from recommended.
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That's funny. Then why is there 11025 Hz in the dropdown list, but no 96000 Hz which you have to type in manually? (I'm talking about the playback menu, not the wave export menu) It just suggests the opposide of what you just said.
Anyway, I think, low frequencies should work as well as they can serve as "draft quality" when you have placed a lot effects and/or VST and you just reached the limit of the available CPU power. Lowering the frequency lowers the CPU demand drastically while you still can get the full quality with the wave export.
@c-frog: Yes, I'm aware of the sample theories. Though this one is a different issue. |
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Inge
Man-At-Arms
Joined: 04 May 2003
Location: Nieuw Lekkerland @ Holland
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Posted: Thu Sep 02 2004 22:19
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| LogicDeLuxe wrote: |
| Yannick wrote: |
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Besides, I've heard the noise in the example file. But I'm more concerned about the problems with higher frequencies (such as 96 kHz). Playing at 22 kHz is far from recommended.
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That's funny. Then why is there 11025 Hz in the dropdown list, but no 96000 Hz which you have to type in manually? (I'm talking about the playback menu, not the wave export menu) It just suggests the opposide of what you just said.
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That's your soundcards limitation, appearantly. It works perfectly fine here (Terratec DMX 6fire 24bit/96khz).
| LogicDeLuxe wrote: |
Anyway, I think, low frequencies should work as well as they can serve as "draft quality" when you have placed a lot effects and/or VST and you just reached the limit of the available CPU power. Lowering the frequency lowers the CPU demand drastically while you still can get the full quality with the wave export.
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True. But since the wave export will also remove the bug you describe, the problem already gets minimalized. Eventhough, in a perfect world, the playback would be bugless at lower frequencies. I guess it doesn't really have a high priority at the moment, but please remind Yannick of it once the final release of MT 2.5 is available
Inge |
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