Understanding the Retro Sound Aesthetic
If you want to achieve the desired retro sounding aesthetic in your sound design, it's important to focus on three key elements: your noise source, tape distortion, and frequency modulation. These elements are responsible for the high-pitched sounds found in iconic anime explosions, movements, and attacks, as heard in Gundam, Evangelion, Gurren Lagann and even Dragon Ball. You're only as good as those three elements. You'll have to create mountains of different modulations for your frequency shifter, hear through oceans of unusable garbage, and distort the hell out of your sound until you hear something usable in the distance, then it's sculpting time.
Experimentation in your DAW
To verify this concept, try this quick experiment in your DAW. Start with a standard white noise, apply tape distortion to filter out the high frequencies, and experiment with frequency modulation. You'll sometimes find a sweet spot, and it'd just needs some sculpting to already sound like something usable.
Sculpting the Sound
Sculpting the sound is the challenging part. To achieve the retro aesthetic, utilize various sound sources like explosions, hydraulics, heavy vehicles (tractors, tanks, planes), metal crashes etc. These cacophonous noises serve as ideal candidates for transforming into mecha-like sounds. Volume automation is a powerful tool to tame the chaos and shape the sound.
Embrace Modern Tools
Let's get something out of the way: you WILL NOT sound exactly like the old school sound engineers. You do not have access to the same tools and sources they used. But that's a two way street. You have the advantage of using modern plugins. If you do have access to analog tools, then absolutely go for it. Since you probably don't, dive headfirst into digital plugins.
Some useful effects are: u-he Satin for tape distortion, xfer OTT for beefier sound, FrqShift for frequency shifting, iZotope Trash 2 for distortion.
While for generating sound sources I recommend: Sonic Charge Synplant, Arturia ARP2600, Native Instruments Absynth.
If you want to experiment with classic sound banks that where for sure used in the animes you grew up watching try these: Hollywood Edge Premiere Edition 1 & 2, Sound Ideas Series 6000 and 4000, Sound Ideas Warner Bros. Sound Effects, Sound Ideas Hanna-Barbera Sound Effects (you'll find your cherished anime sound effects inside CD 3).
These soundbanks where around in the time the sound engineers worked on your favorite animes, and definitely where used for sources when sound designing for mecha sounds. But you'll have to sort through a lot of unrelated sounds.
Besides that, two tools that are industry standard for layering and manipulating your sound sources are: Twisted Tools S-Layer and Tonsturm Whooosh. And if you are extra geek, a deep dive into Reaktor's community to scrape for experimental noise generators and effects can go a long way.
Further Reading and Asset Packs
For additional insights and inspiration, two recommended reads are "Anime Sound Effects: Recreating Recognizable Sounds of an Iconic Genre" and "Vintage Anime Sound: A Guide to Capturing the Essence." They offer valuable information and techniques for recreating the retro sound aesthetic.
To conclude, I created TWO ASSET PACKS based on the discussed techniques. One pack contains designed sounds ready for drag-and-drop use, while the other pack is tailored for sound design geeks, featuring pre-made sound sources that can be molded and sculpted into unique mecha sounds.