Frequently Asked Questions

Is there a meaning in the name?

Yep! It pays homage to the TurboGrafx-16 given the wavetable architecture is similar, though not identical. The 88 has dual meaning. It refers to having an 8-bit DAC and supporting 8 channels. It also happens to be the required speed to energize the flux capacitor in Doc Brown's time traveling Delorean from Back to the Future. And the year 1988 is around the time the TG16 was around where variable clocked DACs were more en vogue.

Why are you using an 8-channel DAC? Can't you just mix in software?

Yes you can! But it doesn't sound the same. Objectively, software mixing avoids some problems you can get in the analog domain, like ringing. But subjectively, the quirks are part of the fun! Software mixing can be too perfect and sterile and doesn't really capture the variable clocked DAC concept in the same way as using multiple channels and mixing them together, flaws in all, in the analog domain.

This is what makes the WaveBoy, our GameBoy inspired 4-bit wavetable Eurorack module, so fun and I hope to have a similar quirky sound for the TurboWave-88 too.

What is a variable clocked DAC?

Modern audio tends to run at fixed bit-depth and sample rates, like 16-bit/44.1 kHz (CD quality), 24-bit/96 kHz, etc. On early digital synthesizers and sound solutions, this was not the case. Instead the DAC was clocked at a variable rate as a way to change the resulting pitch. This is how the GameBoy's wave channel works. It is much simpler because it doesn't require software anti-aliasing, although there can be aliasing which is a function of the pitch, and this can be desirable for exhibiting a certain chiptune sound.

As the TurboWave uses 32-sample wavetables, that means the DAC runs at 32 the speed of the desired pitch for each channel. So for 440Hz (middle-A), the DAC would need to be updated at a rate of 14 kHz (440 * 32).

Since there are 8-channels, a parallel 8-bit, 8-channel DAC is used. Each channel/voice is clocked independently using its own timer. The means the actual amount of writes to the DAC can end up in the low-mHz range (and is one reason a parallel DAC was chosen over a serial one).

Is the TurboWave-88 open source / open hardware and can I make my own?

We are currently deliberating on this actively. We are OSHW and open source advocates though concerns over cloning and unethical companies training AI on code without permission has caused us to hold off on sharing the hardware design or source - for now.

What we hope to provide is a complete API such that folks can use that to implement their own designs should they choose.