Mentioned by FOH engineer Dan Green in this AudioTechnology magazine article about the Ghost Stories Tour.

AT: I’m fascinated by your 500 series lunchboxes at front of house. What’s going on there exactly?

DG: Anyone who’s worked on a Midas XL4 will remember how you really only needed to give it some gain and push up the fader and you were good to go. Now with digital consoles — and as happy as I am with the Digico SD7 — you don’t get that, especially on drums.

In my search to rediscover that instant ‘analogue’ sound I began to play around with effects pedal-style boxes, but they were a bit flakey. On the other hand, I’ve always found Radial gear to be super-reliable. When it came out with the 500 series Workhouse, I tried out a few different pres, and settled on eight modules of Neve 1073 (which work really well on Chris’s SM58), four of the Helios Type 69-500 EQs (I love what the Helios high/mids do to the guitars) and four Shadow Hills Mono GAMA mic pres.

If anything does go awry with those, there’s a macro on my SD7 that’ll instantly flick back to the preamps on the SD stage rack.

Used for room microphones. This can be seen as part of the rack-mountable equipment in the studio in this video.

“My mic pres are… let me walk to my rack and shine a light so I can have a look… I have API 500-series mic pres, and two Neve 1073LBs and my two overhead and two kick mics go through my four Helios Type 69s. The overheads then go through a Manley Vari Mu limiter/compressor, and I have another Altec 1567a mixer which I send my two snare mics through before they go through a Urei 1176. I also use a distant Beyerdynamic ribbon mic on the drums, which goes through a Standard Audio Level-Or, and an important part of the drum sound on Sia’s record came from an RCA 77 ribbon, placed just in front of the kick. On some of the songs it was the only drum mic I used!"

Four Helios 69 full size modules can be seen here at 35:02 in the video.

At 0:06 in the video titled "Moses Schneider: Drums With Character" by Sound On Sound magazine, a pair of Helios Type 69-500 Series mic pre/EQ modules can be seen in the Fredenstein Bento 10 rack within Moses Schneider's studio.