Hey guys! So I haven't ported this over to the Tempest yet, but I think I was able to create reasonably passable Roland hihats using two square waves, noise, and a highpass filter.
In any modern desktop browser - but preferably Chrome - go to
my Javascript Boss DR-110, and ignore the sequencer for now. This doesn't use sample playback, it uses the Web Audio API. The bottom row of your keyboard should correspond with the buttons on the drum machine. The "V" and "B" keys will trigger the open and closed hihats. Not too shabby, right?
I'm stupid busy these days. New position at work that's got me traveling a lot. Building a performing arts space with an apartment above it that I'll be living in. Unearthed some 18th century artifacts while doing that construction. Not a lot of time for deep diving into drum synthesis. Here's where you can beat me to the punch in bringing this to the Tempest, though.
It's javascript. Even if you didn't know how to view the source code in your browser, I've
put the whole thing up on Github. Part of my effort in making this javascript drum machine was to try and keep the javascript faaaaairly readable. So if you go to line 93, you'll see the secret sauce for the hats. The only thing that's not super apparent if you don't read code is that I'm using the following frequencies from an array (aka a list) that I defined earlier in the code: 780 & 1100. These don't match at all with
what's in this analysis, but when I used the numbers given there, it
definitely sounded wrong, so I kind of went by ear until things started to click.
In theory, you should be able to use two analog square waves, tuned to those frequencies, and then the 4k resonant noise digital osc, pitch-modulated by a triangle LFO, and then highpass the whole thing, and get similar sounds. It'll be as analog as a Roland hihat, considering that Roland also uses a digital source for its white noise (which it then runs through a modulated bandpass filter, which we're emulating by modulating the resonant noise filter with a free-running LFO)
As you can hear from the ride cymbal on the DR-110 page, I haven't QUITE got that down as well yet. That's four square wave oscs and a noise source, so on a Tempest, it would still require two separate voices to emulate well.