o I’ve received my Blaupunkt back from Vintage Blau (Ingo Prangenberg). And I plan to buy the speakers from Greg Thompson at Turnswitch, but I’m still looking. The radio rebuild cost me $500. I’m not sure that’s good value, but it is what I decided to do.
I have the radio up and running now. I hooked it up with a tiny 8 ohm speaker I have just to verify it works. It does. And I’ll measure the resistance of any speaker or combo I hook to the radio to make sure I’m over 8 ohms. On the little speaker I can’t apply too much volume as that little speaker is only good for 1/2 watt. I did put the little 2" speaker in the mouth of a glass jar…voila!..triple the sound output.
Then I tried the original speakers still installed in the center console but their paper cones are shot; they make sound but buzz awfully. So I looked those speakers over carefully and cannot find any reference to the impedance of the speaker. I noted they were hooked in parallel. So I measured them. 2.7 ohms! Not good!! The dealer who installed this radio 60 years ago did not know his stuff and installed two 4 ohm speakers wired in parallel. The radio seems to have survived so it must be pretty robust in its amplifier section. (It would have been all right had the dealer wired the speakers in series hence making 8 ohms as the radio calls for.)
I then wired to a pair of decent 4 ohm speakers in series (8.7 ohms measured) and that gave a better sound and volume, but they are way over rated for the amp at 160 watts. They also distort with any real volume. I’m not sure why that is except the tiny 4 watts cannot drive the high impedance speakers very well. Still, the volume where the distortion occurs is pretty high. So I then found a pair of 4 ohm speakers rated at 20 watts (I have junk around! 
) and I hooked them up in series and have a pretty decent sound and volume. Still distorts at about 3/4 volume though.
Does anyone know what the true power output of the Blaupunkt is? Radio Museum is stating 4 watts, but unknown distortion. A more correct question is, “what wattage rating for speakers should I use?”
Because there a lot more speaker choices for cars with 4 ohms vs. 8 ohms, and because I’d like a speaker on each side of the console I believe the best choice is to use 2 4-ohm speakers wired in series. Any comment on this idea?
I’d also like to know about the second speaker pin-outs. On the radio there is a second speaker output on the amp (much wider pin spacing that the one I’m using). A Blaupunkt brochure says it is for a “remote” speaker and suggests it is good for picnics or to mount additional speakers in the rear of the vehicle. I cannot tell however if the second speaker output is to be used with the first output. Can you advise me as to how Blaupunkt says it should be used? Or how I should test it to safely ascertain its output while the first pins remain connected? Can I use both outputs simultaneously?