Amiga soundchip (Page 1 of 2)

it is  a sampling chip, it have no synth in it,
so i would say no

Did you know that the Paula chip is technically capable of doing rudimentary FM synthesis? If you're going to do a standalone project with it, I vote that you do the first midi-box Paula FM synth!

Paula also has a nice butterworth low-pass filter so I say that given the many neat things that Paula can do that it's not a worthless project, but would require a decent amount of research and almost certainly some understanding of assembly programming.

Last edited by jefftheworld (Aug 3, 2013 12:41 am)

I don't know if there is a way to incorporate what ahxtracker/hivelytracker does into a standalone amiga soundchip, but maybe take into consideration that AHX/THX/HVL is an Amiga softsynth module format that attempts to sound like the C64 SID chip.

I don't know the details of how the sound is generated in an AHX module or how applicable the existence of this Amiga music format is to your situation/goal, but I hope it somehow helps you to know that there is a Software Synthesizer music format for Amiga.

Last edited by SketchMan3 (Aug 3, 2013 5:47 am)

Yeah, you're correct in saying that the chip works heavily off of DMA, but features like the filter and the modulation make it better than a boring old DAC.

A regular passive DAC won't do all the neat things that Paula will. I'm not saying that it's a project that I think has a wide importance, but if I had an extra chip sitting around and a MC68302 or something similar, it wouldn't be overly complex to utilize the Paula as a value added output for your microcontroller projects.

aren't most filters typically butterworth anyway? :v

gimme a chebyshev doe

e: nvm i thought it was just a name for the response pattern. d'oh

Last edited by Victory Road (Aug 3, 2013 4:35 pm)

The filter settings are on/off as far as I know (or rather a lot/not so much). I'm not sure why you'd remove it; in its "off" setting the sound is quite crisp. The channels have independently variable playback rates, which I think is the most characteristic feature of the chip. The DACs are not quite linear resistor ladders. There is a mixing stage where you can scale the output of each channel from 0-100% in six bits. I'm not sure how exactly that's done but I'm guessing it's in the analog domain, probably not a lot unlike how the SID envelope modulation is done (analog multiplier and two DACs per channel) The mixing is done in such a way that any mixer setting will still give you the full 8-bit range of the sample output. It seems most likely to me that AM/"FM" (period modulation) was intended for sound effects and low frequency modulation like vibrato and tremolo. Unlike Yamaha "FM" (phase modulation) it's probably musically useless at audio rate modulator frequencies, but I can see AM being useful for ring modulation. Looking at Mapping the Amiga, it seems like you can turn off the audio output of the fourth channel, which probably isn't meant to assist in AM/FM since channel #4 can never modulate another channel. Debug feature? The documentation of these rarely used features could be wrong, though. I don't think the 6-bit scaling of the modulator has any effect on its modulation level since that would either require digital multiplication or a set of ADCs. That would also have made the AM/FM useless for vibrato or tremolo, since silencing the modulator would also zero the modulation level out.

In short, the AM/FM features were almost never used for a good reason, and the remaining features aren't particularly exciting on their own. The software is IMO much more important to the "sound" than the chip itself, but that's not to say that the hardware didn't play a huge role in the design decisions that shaped it. A midibox design based around it would either be a boring sampler or a tracker-in-a-box.

That's all the Amiga ever was to me anyway. Samplers are only as boring as the user.