Recording with DSP and FPGA: the advantages at a glance

Suppose you’re ready for a different audio-interface or you want to upgrade your current one. In that case, it may be worth taking a look at the options that include an external DSP chip. DSP stands for Digital Signal Processing, and the DSP chip (co-processor or accelerator) takes some of the load off your computer when you’re working with plug-ins. You might already know that this is what you want, but have you also heard of FPGA? This blog post can help point you in the right direction when choosing your new audio interface. DSP en FPGA

DSP: What does it do?

If you work with DAW software, then you’ll know how to work with software plug-ins. The output of a plug-in (the effect) is calculated and processed in real time by the processor in your (laptop) computer. When you use a large number of plug-ins in your project, the processor can end up working very hard, making the system less responsive. With a DSP chip—either on an internal expansion card (though this is becoming less common) or built into an external audio interface—these processes are handled by the chip instead. The result is that your computer’s processor is relieved of that workload, leaving you more ‘headroom’ for other tasks.

Other tasks?

In practice, this means that while recording, mixing or mastering your project, you keep more capacity available thanks to that extra processing power. You can use the freed-up ‘space’, for example, by running more plug-ins. One example would be fully mixing a recorded drum track—made up of a good number of tracks—using the plug-ins from an audio interface with a DSP chip onboard. On top of that, you could place a mastering plug-in on the master bus of your project, also from that same interface. The tasks are then handled entirely by the DSP chip. Your computer’s processor is effectively relieved, and you can process the remaining instruments and any vocals using software plug-ins—there’s now enough capacity for it!

DSP: How does it work?

As mentioned, the DSP chip sits on an expansion card (although this is becoming less common) or on the circuit board of an external audio interface. The best-known and most widely used DSP-equipped audio interfaces come from Universal Audio. Alongside the Apollo series, they also offer external UAD interfaces that feature a dedicated DSP processor. The UAD DSP processor then handles the processing tasks for the plug-ins. The big difference compared to software plug-ins is that, with audio interfaces equipped with a DSP chip, the plug-ins live inside the interface or card itself.

So what is FPGA?

The field-programmable gate array is also a chip, but it’s less rigid than a ‘standard’ DSP chip. An FPGA contains programmable logic components, and programmers assign logical functions to them. Without going too deeply into the technical side, this means you can keep expanding what the chip can do until the available number of ‘gates’ or ‘blocks’ is filled. Antelope Audio is a manufacturer of high-end audio components (clocking generators, audio interfaces and preamps) that uses FPGA chips. Examples of their audio interfaces featuring an FPGA chip include the Zen Tour, Zen Studio, Orion Studio and the Goliath.

The differences and similarities between DSP and FPGA

An FPGA chip is more flexible than a DSP chip. After all, an FPGA chip can be programmed, while a DSP chip is static and is essentially ‘just’ a processor. So FPGA is NOT a DSP chip! However, just like a DSP chip, it does handle the calculations. Antelope Audio provides its plug-ins via updates, and these are offered free of charge to the user. With Universal Audio, you pay for them, but at the moment there’s more content available. That said, you can see the FPGA platform expanding very quickly in terms of content. Interfaces from both manufacturers can be a significant investment, but in return you get exceptional quality—of the converters, preamps and the plug-ins themselves.