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Karlos
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Re: Audio processing, effect simulation, that sort of thing... Posted on 11-Jan-2023 19:42:14
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Joined: 24-Aug-2003 Posts: 4843
From: As-sassin-aaate! As-sassin-aaate! Ooh! We forgot the ammunition! | | |
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| @Wol
That specific equation looks rather like amplitude/ring modulation to me. Mixing is just summing, what you show is modulation. Last edited by Karlos on 11-Jan-2023 at 09:39 PM.
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QuikSanz
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Re: Audio processing, effect simulation, that sort of thing... Posted on 11-Jan-2023 20:09:11
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Joined: 28-Mar-2003 Posts: 1236
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| @Wol,
Any audio being played will produce harmonics, it's how a quartet gets a fifth voice.
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Karlos
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Re: Audio processing, effect simulation, that sort of thing... Posted on 11-Jan-2023 21:38:32
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QuikSanz
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Re: Audio processing, effect simulation, that sort of thing... Posted on 12-Jan-2023 0:50:02
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Joined: 28-Mar-2003 Posts: 1236
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| @Karlos,
Four voices in perfect pitch can create 6 or more voices.
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Karlos
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Re: Audio processing, effect simulation, that sort of thing... Posted on 12-Jan-2023 7:36:52
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| @QuikSanz
Presumably this is because the human voice is harmonically rich to begin with. Try it with just sine waves playing the same fundamental note pitches. I suspect that will not result in the same effect. _________________ Doing stupid things for fun... |
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QuikSanz
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Re: Audio processing, effect simulation, that sort of thing... Posted on 12-Jan-2023 13:58:22
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Joined: 28-Mar-2003 Posts: 1236
From: Harbor Gateway, Gardena, Ca. | | |
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| @Karlos,
Yes, must have 2 notes from different octaves, voices have more components lets say than a sine wave so there is a lot going on in the interaction of the 2.
Chris
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Wol
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Re: Audio processing, effect simulation, that sort of thing... Posted on 12-Jan-2023 18:48:13
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Joined: 8-Mar-2003 Posts: 1005
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| @Karlos
The example equations actually Multiply the 2 incoming frequencies together, any Modulation be it; Amplitude, Phase or Frequency that is present on any of the incoming frequencies will be also emposed on the output products.
Your analogy of a Ring Modulator is correct, when a carrier frequency is mixed (Modulated with a lower band of frequencies ie: Audio), the result is the carrier + sidebands which are the carrier Plus and Minus the Audio frequencies.
Example: 100khz + 10Khz
Will give an output of 90Khz and 110Khz.
Intermodulation can appear almost anywhere, somtimes deliberate in mixers/modulators, and other times in amplifiers and filters etc where it is not desired.
Wol..
PS: I got into this stuff while building a Superhet Radio reciever for a learning project. ( Down converting high frequencies to lower more manageable ones. ) 
Last edited by Wol on 12-Jan-2023 at 07:08 PM.
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Karlos
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Re: Audio processing, effect simulation, that sort of thing... Posted on 12-Jan-2023 20:51:12
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| @Wol
When I think of phase modulation, I think of something more explicit, e.g.
π/2 * sin[ fC * 2πt + m * π/2 * sin( fM * 2πt ) ]
Where fC is the carrier freq, fM is the modulator freq and m is the modulation strength.
This is how I've implemented it, except that I have functions other than sin and pretty much every other parameter is some other function of time. _________________ Doing stupid things for fun... |
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Deniil715
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Re: Audio processing, effect simulation, that sort of thing... Posted on 12-Jan-2023 22:03:19
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Joined: 14-May-2003 Posts: 4238
From: Sweden | | |
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| @Karlos
It's very CPU intentive, yes. If you actually try to model a room, the X1000 doesn't have a chance to do it in realtime. So I added some shortcuts so you only need a rudimentary "room description" and some filters and plain echo/reverb of that model makes it sound quite fat. _________________ - Don't get fooled by my avatar, I'm not like that (anymore, mostly... maybe only sometimes)  > Amiga Classic and OS4 developer for OnyxSoft. |
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QuikSanz
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Re: Audio processing, effect simulation, that sort of thing... Posted on 13-Jan-2023 20:18:48
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| Not sure we need all that but, back in the day a some stereos had a "Wide" setting that really stretched out the stage. what if at the digital level you could do this and wrap it around a bit?
Chris
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Karlos
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Re: Audio processing, effect simulation, that sort of thing... Posted on 13-Jan-2023 21:26:16
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Joined: 24-Aug-2003 Posts: 4843
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| @QuikSanz
I think that widening thing was done by converting stereo to sum and difference streams, amplifying the difference and then converting back to regulars stereo. Other tricks just used comb filters to separate mono signals into stereo ones. _________________ Doing stupid things for fun... |
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QuikSanz
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Re: Audio processing, effect simulation, that sort of thing... Posted on 13-Jan-2023 21:36:11
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Joined: 28-Mar-2003 Posts: 1236
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| @Karlos,
Sounds reasonable, probably used some subtle phasing along the way as well.
A bit much for Paula, maybe a clip type chip on top of Paula could do it.
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Karlos
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Re: Audio processing, effect simulation, that sort of thing... Posted on 14-Jan-2023 13:55:02
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QuikSanz
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Re: Audio processing, effect simulation, that sort of thing... Posted on 14-Jan-2023 16:01:19
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Joined: 28-Mar-2003 Posts: 1236
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| @Karlos,
Actually I was thinking of a better stage, but more thought says no. The Amiga itself has only 4 channels, Nothing you make with it needs it, Recorded stuff works fine but CD's could still use it.
Last edited by QuikSanz on 14-Jan-2023 at 04:05 PM.
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Karlos
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Re: Audio processing, effect simulation, that sort of thing... Posted on 14-Jan-2023 17:15:37
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From: As-sassin-aaate! As-sassin-aaate! Ooh! We forgot the ammunition! | | |
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| @QuikSanz
This actually reminds me of an unfinished project I had. I have an "alternative" to 14 bit Paula that may or may not sound better. If I ever get around to writing the actual replay routine and not just relying on a simulation of it. _________________ Doing stupid things for fun... |
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QuikSanz
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Re: Audio processing, effect simulation, that sort of thing... Posted on 15-Jan-2023 2:06:12
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Joined: 28-Mar-2003 Posts: 1236
From: Harbor Gateway, Gardena, Ca. | | |
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| @Karlos,
The word I think is " Ambience " terribly " lacking. Partly the nature of a CD. Even in my good PC it lacked until til I put a Logitech card with some pseudo modes.
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Karlos
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Re: Audio processing, effect simulation, that sort of thing... Posted on 15-Jan-2023 10:40:23
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Elite Member  |
Joined: 24-Aug-2003 Posts: 4843
From: As-sassin-aaate! As-sassin-aaate! Ooh! We forgot the ammunition! | | |
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| @QuikSanz
I guess this comes down to preference. Ideally you want the sound on a CD to be a faithful representation of what was recorded. If it was a live performance in a hall, one would hope that some of the acoustic properties of the space it was recorded in.
However for a lot of modern electronically produced music this is a non sequitur. You may be dealing with something that was never originally an acoustic source. The best you can hope fornthere is what the person creating it heard. Except they will have heard it in their studio, and that won't be the same as your listening experience. _________________ Doing stupid things for fun... |
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QuikSanz
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Re: Audio processing, effect simulation, that sort of thing... Posted on 15-Jan-2023 16:53:01
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Super Member  |
Joined: 28-Mar-2003 Posts: 1236
From: Harbor Gateway, Gardena, Ca. | | |
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| @Karlos,
Your logic is solid for a live performance. Now days each person is in their own cubical, All done separately in a room that is for the most part a vary dead room, " Acoustically wise". The result being a very flat, non 3D sound.
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QuikSanz
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Re: Audio processing, effect simulation, that sort of thing... Posted on 16-Jan-2023 3:21:18
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Super Member  |
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| I've into audio for around 55 years since a kid, probably the most useful tool I can can think of is a simple reverb with adjustable decay, room size, A 1000 foot long room will take up to .4 second to return, that's a big room. add an adjustment for how much you want to blend with the original signal. Your done!
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Karlos
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Re: Audio processing, effect simulation, that sort of thing... Posted on 16-Jan-2023 7:57:45
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Elite Member  |
Joined: 24-Aug-2003 Posts: 4843
From: As-sassin-aaate! As-sassin-aaate! Ooh! We forgot the ammunition! | | |
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| @QuikSanz
Every point along the walls of your room are a source of reflection, otherwise just simulating a single distance will result in a delay echo, not a reverb.
The simplest digital reverb was discussed somewhere earlier in the thread. Generally a number of delay lines combined with filters, with feedback to simulate the re-reflection. In this model, the room dimensions are controlled by the delay line lengths and output tap and pan levels (for stereo). The frequency dependent attenuation and reflection is usually handled by the filters. In order to more accurately simulate the initial response from a room, you often have a separate feedback path for early reflections that are handled more like a vanilla echo.
Good quality implementations of this model can sound quite realistic but generally, digital reverb has a tell. As SHADES points out, anyone whose ear is suitably attuned (no pun intended) will be able to sense there's something off about it. There are better algorithms but they get more expensive. For a while or was all about finite impose response modelled reverb where the acoustic reaction of a real space to a burst of noise was captured and FFT used to analyse the frequency/decay response and using that to implement a more realistic filter model. Ray traced audio, or something approximating it seems to be the state of the art now, if some neural net method hasn't taken the top spot. _________________ Doing stupid things for fun... |
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