via this Reverb listing
"Fully functional original Fricke Rhythmusmaschine MFB-501. Reissued a few years back, and it might be my imagination, but I'd say – with all due respect to the MFB-501 'Pro,' it was very cool of MFB to do that, esp. considering the original price it went for – this, to these ears, sounds considerably better; deeper, and, though this is not a real thing, I know, but I'll go ahead and say it anyway: more analog. I take it back, that sounds awful and stupid. It sounds really good and it is fully analog (but so is the Pro, which adds the MFB Kult's samples and MIDI, which this one all lacks (it has trigger input though, which is cool), and but so be aware of that).
At the time, the 501 outsold Roland's TR 808 by far in Germany, and over a 5000 units were sold. This from one guy in Berlin, hey, follow that. Nowadays they're nevertheless quite rare, as far as I know. Well, I'd keep it if I could afford it.
For its age it looks pretty great (see pics), all the switches working like charms, sounds kind of amazing. Someone wrote the voltage and polarity on top; this can be cleaned but I thought it looked cool. It comes with a Euro PSU that adapts to that info, BTW."
