Joy of Synths #34 Audio Interfaces

On 2/27/2025 I received my first new computer in roughly 15 years: a MacBook Pro. Is this needed for analog synth recording and editing? One could just as well record audio with a Windows 7 PC and an audio interface. The free DaVinci Resolve 19 and its Fairlight audio workstation page can run on Windows just fine with HD or UHD footage. While you need the paid DaVinci Resolve Studio ($299) to export 4K DCI or higher video and unlock all the really interesting audio features of Fairlight, I already own a 12 year old Resolve Mac dongle that will open the perpetually licensed Resolve Studio on Mac and 2017 PC.

However, if you compare apples to non-apples and spec out a laptop for DaVinci Resolve Studio, you’ll find that MacBook Pros and Alienware are two brands that offer those specs without a custom build. As is often said, DaVinci Resolve may be free but the computer isn’t.

In 2025, the upside of any Mac is integration with an iPhone and having access to Logic Pro, which is fun to use for recording and editing audio, as well as messing with MIDI rolls that you can send to a synthesizer like the Taiga Keyboard via its USB port. Logic Pro is like an amplified version of Apple’s Garage Band if you’re just using Logic Pro to record and label tracks. Logic Pro comes with a sizable sample instrument library that is an optional installation. Logic Pro also comes with a one-time cost of $199 with the educational bundle of Final Cut Pro for video editing and a couple of other apps you may never use.

If you’re up for reading the learning guides then you could do just as well with free DaVinci Resolve’s Fairlight. DaVinci Resolve is cross platform Windows and Mac and the same Resolve project can be opened on Windows and Mac, and the same project can be opened by paid Studio and free Resolve, back and forth. The effects will disable on the free version. Plus you can place a DaVinci Resolve project in their paid Cloud to access it from any workstation with the same version number of DaVinci Resolve that logs into the Cloud. The files can be stored in the cloud or locally on a portable external drive like an SSD.

I have not been a fan of computer recording only because I haven’t owned a dedicated computer running latest operating system in these 15 years. Nope. I’ve been wandering from one system to another, making it work. Keeping track of desktop audio files was a pain. Moving computer to computer means tracking the recorded files and the main project file. It can get messy, really fast.

Recording to a portable audio recorder like the H4N is much easier with the bonus of a practical backup if you don’t reformat the SD card once it’s full and all its files are transferred to an external drive for editing with software. Plus I can record a verbal slate audio on the H4N so the time, date, instruments, and any other notes are recorded within the audio file.

So while you could use the headphone jack on a computer if one is available, consider that the analog signal to digital numbers is being converted by a small electronics without notable preamps or gain control. This can introduce hiss that is solely coming from the jack. So that’s the point of an external audio interface- better analog to digital conversion. And more tracks to record in one go should you have multiple instruments playing at the same time.

My USB audio interface is a 2018-era Focusrite Scarlett 18i8, 2nd gen. (Focusrite went to 3rd gen and now offer an 18i16). I bought it to live record four mics in hopes of an “ambisonic” experience for 360 degree virtual reality video. I never did get it to work but it’s proven to be a nice way to listen to computer audio with its 2 independent headphone jacks.

This has four XLR/instrument cable inputs on the front with gain dials so you could take four analog mono synths and record them to independent tracks on a computer that can support recording four tracks at once.

If the synth has a stereo output like IMPLEXUS or Taiga Keyboard then you could connect the Left and Right (red band) outputs to Input 1 and 2, leaving Input 3 and 4 for Mono Synths.

In contrast, I have a multi-input mixer that only outputs 2 tracks despite having 4 inputs. It’s a mixer, so yes, it is mixing tracks down to a left channel and right channel. This isn’t ideal for multi-track recording that you may want to “un-mix” or silence/mute tracks at a later time.

To recap, the Scarlett 18i8’s front panel allows for recording the Taiga Keyboard output in 1 and 2 with the Scarlett’s input 3 and 4 receiving signal from independent monophonic (single channel) SV-1bs, or alternately, a mix of the two SV-1bs coming from the Stereo (2 channel left and right) Okapi Eurorack module by Pittsburgh Modular.

A lot of affordable audio interfaces will have a single XLR/1/4” Instrument cable input. Look for how many tracks it can output for recording if you have stereo output on your analog synth. You’ll need two tracks. Otherwise if you play and record a single monophonic synth then these audio interfaces will be fine if you’re okay with a 48 kHz signal.

Reading the specs of the audio interface is important. An interface is taking the analog synth audio signal and converting it to digital. The old CD standard of 44.1 kHz is fine. Digital Video is 48kHz. I prefer recording 96kHz 24 bit. This takes up more room on a hard drive or SD card but audio takes up way less space than HD video, never mind Ultra HD or 4K video.

The Scarlett 18i8 can record up to 192 kHz. A Behringer U-phoria audio interface tops at 48 kHz, which may be enough for you. While Logic Pro can be set to record 96 kHz, there’s no point in doubling your file size if you’re using a U-phoria that converts at 48 kHz. Always make sure the interface and software match frequencies (48 or 96 on both). If I want higher than 48 kHz then I don’t use the U-phoria.

To repeat, the recording frequency is set by the Audio interface. In theory 96 kHz should capture more dynamic range between loud and quiet and more range of frequency between bass and treble but that may not be your concern or interest.

The processing power of the computer is relative to what you’re trying to do with the audio software. If you are just recording one track straight into the software with no plug-ins or effects then a lot of computers and laptops will work just fine. It’s the addition of EQs and Compressors and other audio signal processing that affects the real-time recording, as well as the number of tracks you’re trying to record at once. Alas, you can add those effects AFTER recording, same as you can run a recorded signal through outboard gear and re-record the processed sound rather than baking it into the original recording. Or you can playback the recordings through an amplifier and record the amp’s sound (re-amping). It’s this mobile recording/playback that makes a laptop desirable, though folks are known to carry around iMacs and audio interfaces for recording/re-recording.

Vocal recordings do sound better with processing but one could argue that an analog synth’s sound is already processed before reaching the recorder. Get the sound right with the oscillator, filter, voltage controlled amplifier and effect modules on the synth, then post-recording work may be limited to adding EQ to manage the low low end or high frequencies, plus a -1dB True Peak Limiter.

To that end, analog synthesizer filters have the resonance dial that boosts frequencies, with some filters moving to self-oscillation and becoming a sound source itself. This presents a case for taking the signal and putting it through another filter without resonance cranked up to manage some frequencies. If this second (or first) filter has multiple outputs for low pass, high pass and band pass then you could take those 3 signals into a mixer and reconstruct the audio frequency range but that would take another semi-modular synthesizer’s filter or additional modules that have those free outputs. And you’d probably want to start with the Filter’s frequency dial at midway so the low pass filter passes through the low end frequencies, the high pass filter passes the higher frequencies, and the band pass allows a mid-frequency range to come through. Again, at least 3 channels on a mixer need to be free to blend these frequency ranges.

If you were playing a software synth then dirtying up the sound may be desired, opening the door to a lot of digital signal processing. Analog Synths can be equally clean but listen for hums or static that may come from the audio cables, audio connections, or nearby power cables. Sometimes the sound is self-noise from the synth itself. This can be filtered out with a Notch filter but it’s better to have a “clean synth” unless you like that sound. Clean AND Noisy is possible with the Taiga Keyboard without static, so this is a case for recording synths during the evaluation period to make sure it’s not introducing frequencies you don’t want.

Some synths use a headphone jack for the final audio output. It’s best if there are two audio outputs: one for headphones with a headphone volume dial and one for mini or 1/4” instrument cables. If you have a choice of the two, only record the non-headphone output. The headphone output has a lower signal so you may find yourself gaining up and bringing in self-noise that a dedicated output would not have.

In the case where there’s only one output then it should work okay. But if you hear things when the instrument is not playing then it may be the output jack itself, or a bad cable, or more likely, the synth’s output volume dial is set too low and the recorder’s input gain is set too high to compensate. Synths are loud- they have voltage controlled amplifiers.

Always start with the volume dials at full left before powering on any electronic audio gear. This includes the audio interface. Slowly turn the volume dial. Aim for -18 to -12 dB on the recorder/software’s audio meter. DeciBels are the measurement of power, and hitting 0 dB will cause unpleasant signal loss. This should allow enough head room for any sudden Voltage Controlled Amplifier (VCA) spikes in volume as you rewire the synth with patch cables.

Be careful with how you monitor the sound. Monitoring is simply listening through speakers (monitors) or headphones. These sudden spikes can be deafening and cause short or long term hearing damage. I use headphones as monitors, placing them on the table with the ear muffs turned out. Once I’m in control of the VCA range then these move to my neck, and finally over ears.

If the synth’s recordings turn out to be noisy, well, you now have to troubleshoot. It’s impractical to have multiples of everything, but that’s the way to isolate a problem. It may help to contact the manufacturer and see if this is a known issue. If it’s not, and you’ve isolated it to the synth’s output, it may be worth the repair or replacement. Again, it’s worth recording and reviewing the recordings of any new-to-you synth before committing to ownership.

Thanks for reading! If you have any questions or suggestions, please add them to the comments.

I missed the Feb publication dates due to a sudden illness. All better now! So while this was written intially about littleBits, then rewritten, it was revised to be about Audio Interfaces because the new laptop allows for more movement than a desktop computer.

Best, Anthony Torres, Joy of Synths.

All Contents Copyright Anthony Torres 2025. All rights reserved.