They are indeed made for Otari tape decks. I was surprised that they could handle mic level signals, but it seems they can. I can't find anything else about them though, like if they have phantom power for example, or what kind of output they produce.
Most people using old four and eight-track Otaris seem to have used these kinds of preamps to record, so they probably should excellent. The question is if they are useable with anything other than otari decks, and the answer is: Probably not without some rebuilding. They even seem to get their power from the deck...
