01 March 2018, 12:56 | #41 |
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If you listen carefully to MIDI patches for example, you can also hear that they use different samples for different ranges. One sample may only cover one octave, and then you notice that the timbre changes a bit from one key to the next as it moves to another sample.
For a synthetic sample like a square wave or triangle, one sample can be used for all octaves, but for a recorded acoustic instrument, it will not sound right if you move too far from the recorded sampling frequency as daxb writes since the harmonics will not be right. |
01 March 2018, 15:41 | #42 |
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I assumed as much, but wanted to be sure I wasn't missing anything. It did sound like a load of old shit.
Here lies an advantage of a machine that has a tone generator, you can get more octaves sounding out of it. Sure its sounds are simpler, but the range makes it very accessible right off the bat (this is why people shouldn't compare DACs to tone generators). Anyway yeah, multisampling, which is what demolition describes, is always the way to go with a sample-based machine, it sucks that tools like Protracker don't support something like that directly (creating an instrument where you specify different samples for different ranges). I believe there were other trackers that did, like Musicline. but it's not a feature I really ever used back then. Also about this, even if you use a one cycle wave sample, on the Amiga, you still can only map it to these pitiful 3 octaves, and resample it much, and it will start sounding wrong. But they are tiny, so generating by other means 4 or 5 samples at different octaves should take no space and be very possible (until you hit Protracker's ridiculously low sample slots amount ) |
02 March 2018, 16:14 | #43 | |
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Paula distortions are usually more complex natures as in Paula volume regulation is implemented PWM like way. Problem is that in Amiga times all samplers was quite poor quality and also people had limited knowledge - nowadays as samples can be processed on PC and converted properly to Amiga this should be not a problem. Most imperfections you referring to are outcome of 80's/90's. I bet that DAC in Paula should give noise floor around -45 .. -43dBFS at least. And i agree - Paula lacks for variable low pass filter (but i understand that in time when Amiga was designed there was no sane way to implement such filter as it will require some DSP and modern DSP was born only few years before Paula was designed - uPD7220 1980 and TMS32010 1983) Last edited by pandy71; 02 March 2018 at 16:21. |
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02 March 2018, 16:23 | #44 | ||
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Last edited by demolition; 02 March 2018 at 16:29. |
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02 March 2018, 16:45 | #45 | |
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They should have created 4 discrete voices and add an analog filter to each. Which I am sure is what Yannes proposed before leaving C=, forming Ensoniq and taking that idea with him to make the Mirage. Last edited by Amiga1992; 02 March 2018 at 17:45. |
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02 March 2018, 18:31 | #46 | |||
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Paula in theory could use switched capacitor filter but still such techniques was too costly to be implemented in Paula (and practical implementation may be not possible due a way how signal level is handled by Paula). Quote:
Last edited by pandy71; 02 March 2018 at 18:40. |
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02 March 2018, 19:39 | #47 | |
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The Ensoniq Mirage is a variable rate 8-bit sampler with discrete, low pass, variable analog filters. The ESQ-1/SQ-80 are wavetable synths with, again, same filters. There's always a limit to a reconstructing filter if you wanna keep costs down, so no, you can't go to 56Khz (the Amiga does not even go ther eso I don't understand why this mention), the MIrage only lets you go up to 32k or something, but you could buy a replacement filter package that let you go to 48K. |
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02 March 2018, 20:13 | #48 | |
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DBLPAL/NTSC / Multiscan screenmodes are 56KHz. If you fiddle the display enough (preferably with the video signal off) you should be able to get some silly high frequencies from poor old Paula. (AFAIK some gfx cards have a 56KHz setting that makes sure this is active when viewing gfx-card modes.) |
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02 March 2018, 20:45 | #49 | |
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You can't actually, like, track music, if you have no screen. This claim approaches the "9 octaves" marketing blurb. |
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02 March 2018, 21:21 | #50 |
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02 March 2018, 21:41 | #51 | |
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Whether the popular trackers support these capabilities is another matter, of course. |
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03 March 2018, 14:00 | #52 | |
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And reconstruction filter limitation are always trade-off between implementation cost and efficiency - nowadays such filters are implemented digitally and with help of oversampling they require very cheap and simple analog reconstruction part (btw Amiga has reconstruction filter always active - filter frequency is controlled and with clever programming some intermediate frequencies can be achieved so you can simulate different cut-off frequencies). I've mentioned 56kHz as it is frequently used "feature" (for ECS/AGA by HW, for ICS/OCS it should be possible to be simulated by CPU with Copper). Technically you can go way higher than 56kHz and with help of aggressive noise shaping push Paula above 16 bit quality (anyway reconstruction filer cut-off should be around 20 -21kHz maximum). Any sane RTG compatible tracker can benefit from increased horizontal frequency. Last edited by pandy71; 03 March 2018 at 17:19. |
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