04 July 2024, 10:08 | #41 |
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04 July 2024, 12:21 | #42 |
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Chris Huelsbeck rules!
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04 July 2024, 15:28 | #43 |
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05 July 2024, 09:51 | #44 |
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Just to clarify, I know Portia and Paula in all systems is a fixed spec, ignoring the by product of 56khz when productivity screen modes are used.
I am literally talking about the quality of motherboards and the relative effects in changing the reality of what is output on a top end hi-fi by the introduction of unwanted noise/sound altering effects diminishing the potential the chip offered. Many CD players use the same off the shelf DACs but there are noticeable differences in the quality and range of frequencies output from the device. This has nothing to do with the tech specs of the DACs, all CD players had the same DAC specs but they didn't sound the same from model to model, they had slight differences in quality. Of course the health of the 3-4 decade old motherboard components will effect quality too in reality, like the dreaded crackly sound of duff CD32 mobo etc. An R1 SID in a first production run silver label NTSC C64 has more bass and less treble output at the monitor port audio out than a final production run of the PAL silver label machines, identical tech specs so it's a motherboard thing not a sound chip thing. Audiophile magazine testing type difference. |
05 July 2024, 10:21 | #45 |
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05 July 2024, 10:32 | #46 |
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A1200
Great audio output, allows more top end and good volume. A600 Due to an error in the audio circuit design it sounds really muffled. This can be fixed by removing C321 and C331 from the underside of the board then it matches the A1200. The only drawback is it reduces the overal output level and thus brings the noise floor up a little. A500 Muffled output when compared to the A1200. I don't know of any fix for this. I've run side by side comparisons of the 1200 / 600, before and after the fix listed above and it truly is night and day. Sadly I don't own a CD32, A2000, A3000, A4000 or A1000, but I would hazard a guess that the CD32 matches the A1200. |
05 July 2024, 12:13 | #47 | ||
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Quote:
Data is not sound. It is only a set of characters that might represent sound. So this in essence means that Paula generates its own tones internally and does so on its own, feeding itself from the memory field to which it is pointed. The way Paula interprets the data given to it determines the sound characteristics that are produced. The difference here is that Paula has access to the outside world to pull data from, while SID is limited to its internal 24-bit phase accumulator. But the sound is prepared and rendered inside, in both cases. Quote:
If you manage to not spoil the test by reading the description you may check it by yourself [ Show youtube player ] Last edited by no9; 05 July 2024 at 12:19. |
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05 July 2024, 13:44 | #48 | |
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Quote:
Last edited by ShK; 06 July 2024 at 16:56. |
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05 July 2024, 13:58 | #49 |
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05 July 2024, 14:31 | #50 |
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Brilliant! Also, you can mod all Amigas' filters, e.g. to be the same as A1200. This thread has component values.
Probably an audio expert could improve a little on the circuits and provide a mod to lower the noise floor and provide a nicer filter. In the synth and amp world, what you want is not necessarily and open filter. I think it's the same for samples and softsynths. You want a filter that's not in the way of what you want to do, and it's not often you want to do synthesis/instrument/modulation stuff very near the limit of Paula (close to 28kHz) because of the coarse steps in period - notes will be off key, vibrato and slides will be steppy. I guess you also want the filter to have a nice curve and not be a cutoff filter completely, for instruments where high pitch modulation is sampled in. Where also the melody is sampled in (straight sampled loops or playing .wavs), especially distorted high pitch stuff like metal solos, cymbals/hihats, parts of speech etc, you might want the filter to be almost completely open for those parts to not be filtered out. But more than that, you want a nice filter. You'd be surprised how much sound is filtered out by old synth and amp circuits, that the users say is "how it should sound". I think the nice filter part IS the job of the amp, and the line level signals should be as pure as possible without raising the noise floor (e.g. by picking up any flaws in the circuit). As it is though, it's good that the Amiga provides the service of filtering a bit, so you can connect studio monitors, or good amps+speakers that have very little filtering in them, without getting TOO raw/noisy output. It saves having to put something external and dial it in until noisy artifacts are gone per song/game/demo. Last edited by Photon; 05 July 2024 at 14:52. |
05 July 2024, 14:52 | #51 |
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FYI would never use the filter because it's shit
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05 July 2024, 15:04 | #52 |
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Yes, except lowpass filters since all Amiga models have a fixed lowpass filter in their audio output circuit that cannot be disabled. These are typically RC (resistor-capacitor) filters implemented in hardware.
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05 July 2024, 16:31 | #53 |
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05 July 2024, 21:17 | #54 | |
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Quote:
I suppose I could get a 32 band spectrum analyser and test all my kit but who knows what condition the SMT components on the boards of my 600/1200/4000 is like. |
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05 July 2024, 22:00 | #55 | |
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Quote:
Btw this kind of test content can be misleading (due overall low sample rate and lot of antialiasing audible in samples - it should be probably some sampled sound - probably period 128..124). |
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06 July 2024, 05:20 | #56 |
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06 July 2024, 10:09 | #57 | |
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Quote:
This example represents the real-life experience of an Amiga user in a common situation, not an abstract edge case. The way Amiga, as a whole system, operates on sound defines the quality that users face. There is nothing misleading in this, and it is far more representative of the Amiga in common applications such as games or demos. |
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06 July 2024, 11:56 | #58 | |
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This is what I always challenge those who say that the Amiga has 'simple' 8-bit PCM audio. The 'colour' of its sound is perfectly recognisable, and is due to a number of factors. And the more you raise the frequency and use advanced modes and machines with different filters (A1200), the more its distinct sound gets 'lost' This doesn't mean that the sound of the A1200 is bad (indeed, it is the machine with the 'best' audio output), but it is a bit different from the 'classic' Amiga sound. The first time I heard it I was quite disappointed, it sounded too 'shrill' and full of perfectly audible aliasing, which degrades the quality at low frequencies. Then obviously the greater memory and quality of the samples and frequencies used made the difference and now it is undoubtedly the best. Yes, the Amiga sound, compared to any machine, is much 'fuller' and different from any existing PCM (because in fact it is not, at least in terms and for what is available and used now). I didn't say in absolute better, but different, and I like it |
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06 July 2024, 16:16 | #59 |
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I would like to add, that the strange filter design of the A3000 (RC lowpass with built-in load) has just -4 dB/oct after the cutoff frequency (6kHz-12kHz) and -5 dB/oct on higher frequency (12kHz - 24kHz)
So all in all it sounds quite nice compared to an A500 or A2000 |
06 July 2024, 16:58 | #60 |
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Thanks for the input! Here's the updated table:
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