[Maarten]

LBH1021/01 (without the -, but that could have slipped in as Japanese manufacturers almost always write model numbers that way) is a valid Philips model number from their Electro Acoustics department. They didn't always make their own amps, especially the cheaper models. It doesn't look like it was ever touched by Philips, no type plate, etc. but I think the model number is too much of a coincidence.

I'd say it's not 1990's but 1970's.

Philips model numbers starting with LB are all professional audio products, the third letter and first number indicate the sub-category. Unfortunately the letters LBH1 didn't exist yet according to the 1967 model number decoding key that I have (it goes up to LBG1), but if I were to take a guess, I'd say the model was commissioned by a local Philips ELA department, for example that of the UK.

Either that, or it was made by a Japanese manufacturer that was great at trolling (I'm not sure whether Philips could claim copyright on the number format Lxxnnnn).

Could you maybe take a picture in which the specs on the back are a bit more zoomed in? I'd like to transcribe them in my Philips numbers database (with a tick in the box "more info wanted" so if anything turns up even a few years from now, I know to go back to this topic). Pictures of the inside, possibly from markings that could help determine the OEM and build date, would be nice as well.