Podcasting often occupies a space on the low end of the audio recording spectrum. All you really need is a computer, suitable software, and a microphone. Some users, however, might wish to avoid this most basic scenario. You might ask, "If I'm going to all the trouble to set up a studio for podcasting, what else can I do with it?" Or you might want your studio to grow into something more sophisticated. Perhaps you are a musician yourself? Or you wish to host live music – or other performance alternatives that require mixing and multiple mics.

In these scenarios, you could easily outgrow the simple mic+Audacity configuration. If you're looking for something more, try Ardour.

Ardour [1] is still considered the reference application as a free tool for recording and mixing on Linux. A variety of alternatives also exist – for instance, Muse is a good option if you are composing music with MIDI, and Qtractor offers some innovative features for working loops and samples – but when it comes to mixing and mastering, Ardour is unsurpassed.

This article describes how to get past the most basic podcast configuration and equip your studio for live recording. I'll also describe some of the hardware you might want to incorporate into your studio. Although the setup described in this article might be more detailed, and more sophisticated, than a basic Audacity configuration, it is still relatively simple and inexpensive. Professional recording studios spend way more money on hardware.

Mastering Live Performance

Mastering, putting the final touch to a finished mix, requires something more than "it sounds pretty good on my headphones." If you want to make sure that the mix still sounds good enough on a single smartphone speaker while performing well on various stereo systems, you need to test it before releasing it.

Recording live performances raises another issue. Laptop concerts are commonplace, and these kinds of performances can easily be managed today using free software on Linux and the stereo output of a simple USB interface. But today's technology gives you far greater opportunities. The options range from simple pre-monitoring options for DJs that let you sync the sound source precisely with the beat to analog mixers as musical instruments.

Hardware

The step from a simple USB microphone to a mixer is affordable nowadays. I used the Mackie ProFX10v3 [2] mixer for this article, priced at around EUR250 (Figure 1). The device is the result of more than three decades of experience in building analog mixers. In addition to all the qualities you can expect from it, there is also a built-in USB interface that goes about its tasks without treading on anybody's toes.

Figure 1: Mackie's ProFX10v3 mixer only has dials instead of channel faders, but it can sit next to a normal laptop on your desk.

Thanks to the JACK audio server built into most Linux systems, generic USB devices of this type now work well, but the generic ALSA driver does not provide controls for the device's software mixer for some devices. The ProFXv3 also shows up as a mixer section in QasMixer; in other words, everything this piece of hardware can offer on a computer is fully available (Figure 2). For the specs, see the "ProFX Mixer Details" box.

Figure 2: Immediately after connecting, the ProFX shows up with two inputs and four outputs for jackd (with the Carla audio plugin host here), which you can control with QasMixer.

ProFX Mixer Details

The mixer offers a great deal on a small footprint. To use the inserts in the first four channels, you need a stereo jack plug to route one channel out with the other receiving the processed signal (Figure 3). The FX in the mixer's name stands for digital effects computed by the GigFX engine in the mixer. These effects can be inserted into each channel. For the complete version 3 series manual, visit the Mackie product page [3].

Figure 3: The inserts cannot be controlled; they only loop the signal into the channel. The switch below is responsible for the Low Cut EQ.

The first thing you notice about the ProFX10v3 mixer is its very solid build. All of the controls, switches, and connectors are easy to reach and leave the user with a reliable impression. Nothing wobbled, and I didn't encounter any annoying noise during operation. Everything is clearly legible and sensibly labeled. Thanks to illuminated mute switches, the ProFX10v3 mixer is also useful for live gigs in poor lighting conditions.

The 10 in the name ProFX10v3 stands for the analog inputs whose stereo output is routed to the two PCM inputs of the USB interface. The mixer's master control does not affect the signal's volume, which means you can record the overall mix of a band, or two channels at once, discretely by turning the balance controls all the way to the left or right.

Scenarios

The first thing you need to find out is how to use the hardware in combination with Linux, the jackd package, and the application stack. The 2x4 interface lets you output the sound sources to two separate targets: Main Mix and Control Room. The Control Room target also serves the headphone output, to which you could connect another amplifier and speakers if required (Figure 4). When you are working on a recorded mix, this lets you use different output systems at the same time. I normally use two active near-field monitors by Tannoy for tests. These classic speakers allow very accurate and analytical listening, although they can also be a bit unforgiving because they reproduce the sound as naturally as possible. On the ProFX, you can test what the same mix sounds like on a stereo system at the push of a button. You can also connect Bluetooth speakers and similar playback devices, as long as they have an analog input.

Figure 4: In Ardour, a foldback bus effectively gives you a second master output in the mixer that you can route to another output.

The main mix is sent from the mixer via balanced XLR cables, which guarantee an interference-free signal at distances of 50 meters or more. One of Mackie's trademarks is that the mixers are totally silent if no signal is being transmitted. The ProFX delivers on this promise even if you route the main mix out 2 to 3 meters away using simple jack cables.

Many of today's popular sound manglers combine incoming stereo signals into a single channel either physically or in the software. Many errors that you will not notice in stereo playback do not sound right if output in mono. Once your mix sounds good on decent stereo monitors, set up the mono output in the same way, switching between the two output modes. If your work also sounds acceptable in mono, you can assume that it will sound okay on a smartphone speaker.

The live performance scenario is far more complex. Whether you want to stream live on Twitch and add music, voice chat, or mix a band to perfection, the options that a mixer like the ProFX offers for controlling the signal flow quickly become indispensable. You will soon discover that it is much more satisfying to work with real dials and buttons than with virtual buttons on the screen.

The insert connectors in the first four channels of the ProFX are a rare feature in this price range. The connectors allow the signal to be routed to external devices, which then process it and feed it back into your mix. All of this reaches Linux via JACK as a stereo mix and can be recorded in Ardour.

But you can also send signals from any JACK-enabled Linux software to the sound systems connected to the mixer output. This means that a band can use, say, the Hydrogen drum computer while simultaneously playing a soft synth like Yoshimi or VeeOne via MIDI keyboard – along with signals entering the mixer via microphone or guitar (Figure 5).

Figure 5: Ardour has much work to do here; Hydrogen and Yoshimi are wired in parallel in Carla.