Sound Chip?

[SlithyMatt]

14 minutes ago, thetraintomars said:

I'm trying to find tech docs

This is the best one I've found: http://map.grauw.nl/resources/sound/yamaha_ym2151_synthesis.pdf

 

[ZeroByte]

On 6/21/2021 at 2:40 PM, thetraintomars said:

I've been using a Yamaha DX Reface and each operator has it's own independent envelopes, I take it the YM2151 is designed to work in a similar fashion?  I'm trying to find tech docs so I can understand what the chip can do and what features will need to be programmed.

I'm of the belief that FM synth is best understood "interactively" - i.e. you get more of a sense of what it does by noodling around with the knobs and sliders to experiment with the effect they have on the sound produced. It's still a deep concept that having some basic understanding of what's going on is quite useful.

I.e. I think it's more of a "right-brain" thing than a "left-brain" thing, but left brain can help guide the right brain in the process.

To that end, I suggest downloading Deflemask and using the instrument editor to play around with the settings and see what you can come up with. The new paid version is actually a lot better for this than the previous freeware version, but the freeware version is still available if you don't want to shell out $15 for something you're not going to get much use out of long term.

I'm thinking it might be cool to do a "YM2151 workshop" some weekend, like on a livestream or something, and explain the basics of FM synth and how to do this on the X16. Would folks be interested in such a thing?

[JimmyDansbo]

30 minutes ago, ZeroByte said:

I'm thinking it might be cool to do a "YM2151 workshop" some weekend, like on a livestream or something, and explain the basics of FM synth and how to do this on the X16. Would folks be interested in such a thing?

I would be very interested. Please be sure to advertise it ahead of time and record the live-stream for future reference.

[ZeroByte]

Just now, JimmyDansbo said:

I would be very interested. Please be sure to advertise it ahead of time and record the live-stream for future reference.

Absolutely!

My goal is to dispel the myth that the YM is hard to use while PSG-style chips are easy.

In my opinion, it's EASIER to use an FM synth to make nice-sounding music. Sure PSGs have a much simpler interface, and it's easy to wrap your head around making sounds come out of them. But if you want to unlock the full potential of these chips, they require you to do all kinds of advanced stuff yourself. FM chips have more knobs to tweak and that's intimidating. If you take a step back and realize that once those knobs are set, all you have to do is poke notes onto it, suddenly it won't seem so daunting. It sounds great w/o any further work from your program. With an FM chip, there's no need to modulate the frequency, volume, or pulse-width yourself to get rich tones.

I'm certainly NOT a musical expert and there's more to cover than practical for a single stream, but I know enough about the chip that hopefully I can get people with more talent than me onto the path of making awesome FM sound.

[thetraintomars]

On 6/21/2021 at 3:55 PM, SlithyMatt said:

This is the best one I've found: http://map.grauw.nl/resources/sound/yamaha_ym2151_synthesis.pdf



 

Thanks that’s exactly what I was looking for!

 

On 6/24/2021 at 11:00 AM, ZeroByte said:

I'm of the belief that FM synth is best understood "interactively" - i.e. you get more of a sense of what it does by noodling around with the knobs and sliders to experiment with the effect they have on the sound produced. It's still a deep concept that having some basic understanding of what's going on is quite useful.



I'm thinking it might be cool to do a "YM2151 workshop" some weekend, like on a livestream or something, and explain the basics of FM synth and how to do this on the X16. Would folks be interested in such a thing?

I agree that hands on use is very important but when I look at a new synth things like number of lfos, effects, fm operator patterns, envelopes etc is important especially in this case where some features might need to be coded. So the specs/data sheet were a big help. 

 

I’ve got experience with coding and making music on synths (not at the same time) and I’d be really interested in a workshop myself. 



Does anyone know how the 2 chips/3 sound sources will be mixed? Seems like there are a few ways it could go with hardware or software. 

[ZeroByte]

9 minutes ago, thetraintomars said:

Does anyone know how the 2 chips/3 sound sources will be mixed? Seems like there are a few ways it could go with hardware or software.

TL/DR: the analog outputs are just hooked together with at most some discrete components that make sure the audio is clean. Nothing software controllable.

For VERA, we already know how the PSG and PCM are being mixed prior to analog output: Per-channel volumes on PSG and a PCM volume setting in the PCM ctrl register. I.e. no master volume for PSG and no master volume or mixer controls. As to how it actually does the final mix internally, I couldn't say. Ideally, the outputs of PSG and PCM are mixed by just adding them together with enough headroom to avoid clipping or needing to do any kind of dynamic range compression stuff. Finally, we know it's being output to the system as an analog signal.

The YM has its own DAC and amplifier. Watch Adrrian's Digital Basement episode where he helped troubleshoot the Prototype 2 board - he does briefly mention the op-amp ICs on the YM.

From this video; from some conversations I've had with Kevin; and from other posts that I've seen the past couple of years, I'm pretty confident to say that the two analog outputs are just hooked together on the board and the combined signal is sent to the audio out jack. There's no mixer circuitry, at least none that can be interacted with to give master volume + level controls for YM and VERA.

Essentially, if you want to mess with volume, you have to do it on each and every channel of input.

Don't take this as "word of God" as I'm not involved with the actual hardware design in any way, shape, or form. But I'm quite certain this is how it's going to be. The most I would expect to see as far as level adjustment between the VERA and YM outputs would be a pair of pots on the board, but I don't think we saw anything like that in pictures of the latest board.

[thetraintomars]

On 7/2/2021 at 10:41 AM, ZeroByte said:

TL/DR: the analog outputs are just hooked together with at most some discrete components that make sure the audio is clean. Nothing software controllable.



For VERA, we already know how the PSG and PCM are being mixed prior to analog output: Per-channel volumes on PSG and a PCM volume setting in the PCM ctrl register. I.e. no master volume for PSG and no master volume or mixer controls. As to how it actually does the final mix internally, I couldn't say. Ideally, the outputs of PSG and PCM are mixed by just adding them together with enough headroom to avoid clipping or needing to do any kind of dynamic range compression stuff. Finally, we know it's being output to the system as an analog signal.



The YM has its own DAC and amplifier. Watch Adrrian's Digital Basement episode where he helped troubleshoot the Prototype 2 board - he does briefly mention the op-amp ICs on the YM.



From this video; from some conversations I've had with Kevin; and from other posts that I've seen the past couple of years, I'm pretty confident to say that the two analog outputs are just hooked together on the board and the combined signal is sent to the audio out jack. There's no mixer circuitry, at least none that can be interacted with to give master volume + level controls for YM and VERA.



Essentially, if you want to mess with volume, you have to do it on each and every channel of input.



Don't take this as "word of God" as I'm not involved with the actual hardware design in any way, shape, or form. But I'm quite certain this is how it's going to be. The most I would expect to see as far as level adjustment between the VERA and YM outputs would be a pair of pots on the board, but I don't think we saw anything like that in pictures of the latest board.

Thanks, that makes a lot of sense given that it is the cheapest option.  Isn't the DAC a separate chip though? My dream would be for the VERA to handle all of the DAC since that would let me code some simple bus effects (like echo, ring mod and a simple reverb) for all or some channels.

I'm curious how the first few gen Sound Blaster cards handled the PCM and FM mixing, or if it was an either or operation.

I haven't checked out the Digital Basement video but will once I'm done family holiday time, since I forgot my earbuds :)

[ZeroByte]

On 7/4/2021 at 8:28 AM, thetraintomars said:

Isn't the DAC a separate chip though?

Yes. There's a 'proprietary'(?) time-divided serial protocol between the YM and the DAC where it transfers data alternating between the two channels.

Soundblaster had an on-board mixer of some type or other, because there were DOS and Windows mixer apps that you could use to adjust the levels and the master volume. SBPro even had a physical volume wheel on the back of the card itself.