I’ve had a thread going about my restored Blaupunkt TR Frankfurt De Luxe 32471 but this is for a specific question on wiring the speakers. I’d like to confine this thread to just speakers so as to sort out this issue. We all know these radios were dealer installed so there is not only inconsistency between installations but some speakers may be improperly wired by the dealer (mine was).
My radio was wired to the pin-outs as shown here. Call this Pic A:
I’ve been told that is incorrect and should not even work…but it does. This is how I’m told the speakers should be wired. Call this Pic B
I understand that the radio requires 8 ohm speakers but I cannot find an official reference to that requirement.
There is another drawing that John Carey uploaded for a more recent vintage Blaupunkt radio (mine’s from 1962) that shows a 3-wire speaker connector (available in 1964) and a wiring diagram that shows one pin alignment with a single speaker and the other pin alignment with two speakers wired in parallel. Call this Pic C:
Finally there is this pic from a different model Blaupunkt than mine but that shows the description of hooking up an “additional” speaker. Call this Pic D:
Here are my questions:
- Re. Pics A and B. Which is correct?
- Re. Pics A & B, if this is correct for my non-stereo radio would I wire this way with two 8 ohm speakers? Not in series, not in parallel, just separately connected.
- If I use just one connection, is there any reason I cannot wire two 4 ohm speakers in series so as to create an 8 ohm impedance.
- On impedance, I understand that impedance has a variable content that is frequency dependent. Whereas resistance is simply a static, linear measurement. This means that were you to wire a single 4 ohm speaker to the radio’s amplifier, at very low frequencies (like bass notes - especially if played loudly) your speaker output may approach a DC (direct current) signal…almost a short circuit. That will damage the solid state transistors. So we don’t want to do that. But two 4 ohm speakers wired in series should be perfectly fine (except for a high frequency roll-off you might not get with a single 8 ohm speaker). I am stretching my level of knowledge in this area, so please correct me if I am wrong.
I’ll start with these and see where the thread leads; I do have more questions depending on the answers.