Orban BX-20 (1970s)

Name: Orban BX-20
Brand: Orban

The record on this one is confusing. The Orban BX-20 is a spring reverb, but it is not an Orban design. The BX-20 was built by AKG. It's the AKG BX-20, part of AKG's Torsional Transmission Line reverb line, and it shows up in period studio gear lists as the "AKG BX-20" or "AKG BX-20E." A page filed under "Orban BX-20" is almost certainly a misattribution, and it's better to say so than to invent an Orban reverb that never existed.

The period record documents the AKG unit. In Recording Engineer (October 1978, p.107), a studio owner describes rehabbing a spring reverb that arrived rusted, sanding it down and re-tensioning it with new springs. That kind of maintenance only makes sense for a mechanical spring tank. The BX-20 was a staple of late-'70s control rooms. Mix (March 1980, p.58) lists an AKG BX-20 in Santa Barbara Sound's echo/reverb rack, Mix (October 1980, p.41) lists an AKG BX-20E among a studio's reverb systems, and a 1980 Recording Engineer equipment list for "The Tonight Show" rig includes an "AKG BX 20 E1" reverb. Engineers clearly treated it as a serious, room-filling reverb rather than a budget effect.

It was a line, not a single box. The AKG BX-10E2 and BX-20E are the professional rack units. The later BX-5 was a single transmission-line system with balanced stereo in/out, priced at $1,195, and AKG described it as sharing features with the BX-20E and BX-10E2. The BX-5 used AKG's patented Torsional Transmission Line system, a set of springs whose parameters were statistically varied for accurate reverb characteristics. AKG claimed the TTL design was the only reverb device, live chambers included, whose output contained none of the dry input signal. The BX-20 belongs to that family.

There is no reliable Orban-specific spec sheet for a "BX-20," because there almost certainly isn't one. Treat any listing that calls it an Orban as a cataloging error. If you're hunting one today, search AKG, not Orban.