API 525 Compressor Limiter 500 Series Stereo Pair Vintage 1969-1970

For sale is a very rare pair of early vintage API 525 Compressor Limiter 500 Series Stereo Pair. These match nicely with our vintage API 1969 console we have for sale in a separate listing. This is a very early pair as they have the first version Automated Processes Inc, Studio System Division opamps (which are pre Melville and pre Huntington, estimated to be made around 1970). These are so early we can't even find an appropriate schematic that documents them accurately. We did some minor servicing as best as we could assess and they are tested and working (passing signal, doing some compression), but we can't tell if they are 100% functional as originally intended. We found some aspects such as meters response and knobs don't always function in the normal way we would except compared to a modern API 525, but we can't tell if this is due to malfunction, or perhaps due to being an early version with operational quirks and limitations (which were improved upon and resolved with later revisions). Due to this uncertainty, they are sold as-is, no warranties, guarantees, refunds or returns. They are guaranteed to power up, work, pass signal and compress, but we can't say for 100% certainty if it's exactly as original intended and if all features work exactly as they should. They do have some great API 525 sound to them (gooey, thick crushing compression). These are highly desirable especially with early opamps and it's very unlikely you'll find another original pair like this with vintage opamps.