help troubleshooting first synth attempt

lalo · 16 Jan 2005

i did'nt analyzed your schematic in a deep way.. but i can tell you that i tend to obtain this kind of sounds out of SM when i feed things with values very out of range accepted from the different modules inputs...generally the amplitude related stuff is in the -1/+1 range.. the phase stuff us between 0/1...try to make little tests with values and connect to a wave display after an analyzer (you find both if you click on the 'graphì connector symbol in the left toolbox) lalo

jorge · 16 Jan 2005

antialias, its great when we see someone trying to create a synth with synthmaker. I'm having a look at your schematic and I'll try to show here some of the issues. This is also a good way to highlight possible problems with SM. I'll split my reply in several posts while I keep analysing your schematic.

first minor problem I found is with your slider:

What you're trying to do is a good idea for connecting sliders in series as in your schematic:

As you can see, each slider module is also showing the GUI for the sliders that come after, a better way would be:

Now, each slider module only shows its own GUI:

like I said, this is a minor problem, doesnt affect the sound and not even the front panel of your synth.

jorge · 16 Jan 2005

ok, moving on to your lowpass filter section:

you're multiplying the cutoff by 11025 but the cutoff doesnt work in Hertz, it works from 0 to 1 where 1 corresponds to 22050Hz. I can easily change the cutoff to work in Hertz but I think it is better to work in zero-to-one as often it avoids additional multiplications/divisions. For example, an ADSR output works from 0 to 1, when it is controlling the cutoff of a lowpass filter it can be directly connected to it. As a general rule in synthmaker, units go from zero to one.

You're also adding cutoff with cutenv and cutlfo. It's a good idea to combine those 3 but when you add values in frequency you get results that vary as you go up and down the scale. For example, 1KHz cutoff added to a 1KHz cutenv would generate a cutoff at 2KHz which is one octave above while 2KHz cutoff added to 1KHz cutenv would generate a cutoff of 3KHz which is not 1 octave above 2Khz, to be one octave above it would have to be 4KHz.

A better aproach when controlling the cutoff of a filter is as in the example schematic that loads with version 0.9.0h, basically it works by adding pitch and converting to frequency. Pitch is similar to midi notes with 57 being 440hHz, each time you add 12 to pitch you're moving one octave above or doubling frequency. Adding pitch is similar to mulptiplying frequency, for example multiplying frequency by 2 is the same as adding 12 to pitch.

jorge · 16 Jan 2005

inside your module named synth you have the following:

It's very useful to follow your schematic, it highlights the fact that its not easy to know the units accepted by each component. In this case, you're assuming that phase is in degrees when, once again, it goes from 0 to 1 with 1 being 360 degrees.

jorge · 16 Jan 2005

When debuging your schematic, it is often useful to look at the actual waves generated, it often gives clues about what is wrong. I'll give you an example how to do that. Inside your synth module copy and paste the part of the schematic you want to analyse:

now insert two knobs to control pwm and frequency, one analyser and one wave display as follows:

as you move the knobs you'll be able to see the wave changing

malc · 16 Jan 2005

jorge wrote: it highlights the fact that its not easy to know the units accepted by each component

I better get the connector label enhancements sorted then 😉

(as suggested here: GUI suggestion and here: Mouse-over Help for Ranges )

lalo · 17 Jan 2005

malc wrote: jorge wrote: it highlights the fact that its not easy to know the units accepted by each component

I better get the connector label enhancements sorted then 😉

cool 🙂

i'd suggest the idea to have a little number box on cables showing the actual values passing through...may be can be a kind of shortcut thing to spare resources...i mean..if you hit a key or a combination of mouse and key or whatever a little box appear showing the value passing in the cable.

lalo

bManic · 27 Jan 2005

I agree. This would be very handy. A little box that shows what current value is going trough, min & max values and average during the time you hold the "modifier" key/button (that shows the value in the first place) held.