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Vintage Grundig rebuild

Discussion in 'Hardware Lounge' started by Mike, Jun 5, 2017.

  1. Mike

    Mike Bon Vivant

    Thanks David. I am going to strip out the cabinet today.
    What if I did this?

    wiring..jpg
     
  2. Mike

    Mike Bon Vivant

    Look what I found. Super tweeters? 1496929128262-476362037.jpg
     
  3. DYohn

    DYohn Well-Known Member Donor

    Top Poster Of Month

    re: your wiring diagram. NO. connecting both channels to the woofer will blow the amp. one POS to the woofer POS, the other POS to the woofer NEG is the only way to get a pseudo mono signal without using another device.

    I assume you are talking about buying a stereo set of crossovers, and trying to use the existing speakers? Risky. Are you planning to buy new speakers too? If so then that makes things more possible.

    The little square things could be anything. I noticed them on the schematic but had no idea what they are.
     
  4. capsuleri

    capsuleri Well-Known Member

    Oh man! This is super cool. I recall one of my relatives had one of these.
     
  5. capsuleri

    capsuleri Well-Known Member

    Dep3nding how much you want to spend - you may find vintage Grundig receiver and turntable to replace both on Ebay. Or perhaps something more easily found, both receiver (e.g. Marantz) and turntable (Dual or Garrad) from the 1970s.
     
    Mike likes this.
  6. Phil A

    Phil A Active Member

    Mike likes this.
  7. Mike

    Mike Bon Vivant

    This is now what I have for power. 1496941511311730552988.jpg 1496941553125-1881631463.jpg
     
    Last edited: Jun 8, 2017
  8. Phil A

    Phil A Active Member

    Nice - I think that will work well. Gives you FM and phono too.
     
    Mike likes this.
  9. DYohn

    DYohn Well-Known Member Donor

    Top Poster Of Month

    So... do you intend to try and power the existing speakers with it?
     
  10. DYohn

    DYohn Well-Known Member Donor

    Top Poster Of Month

    From a "Vintage Radio" forum:
    "They are electrostatic tweeters. And the probability is high that they are nonfunctional. Test by disconnecting the permag speakers so that just the tweeters are hooked up, then tune to a strong local FM station. If you hear anything at all, they are working. Even when brand new, the contribution of these speakers to the overall sound output of the unit was miniscule."

    Also, they say the Grundig 7080WF is circa 1957.

    I am looking for the impedance of the other speakers to see how they can be used with your receiver.
     
  11. Mike

    Mike Bon Vivant

    David, my hope is to use the existing speakers. It would just make life much more simple.
    Picked up the receiver for 120 bucks. Lights up purple. :)
     
  12. Mike

    Mike Bon Vivant

    It had two things I was looking for, a phono-pre, and A/B speaker capability. I understand they were manufactured by Marantz.
     
  13. DYohn

    DYohn Well-Known Member Donor

    Top Poster Of Month

    OK, so I cannot find any information on the electrical rating of the speakers. So I will make a few assumptions and design a simple crossover for you. Stand by.
     
  14. Phil A

    Phil A Active Member

    Mike likes this.
  15. DYohn

    DYohn Well-Known Member Donor

    Top Poster Of Month

    Here's what might work, assuming my estimates are OK.

    IND 1 =low-pass inductor. "Dayton Audio 2.5mH 18 AWG Perfect Layer Inductor Crossover Coil" from www.parts-express.com!
    CAP 1 and 2 = high=pass capacitors. 2 of these: "Dayton Audio DMPC-20 20uF 250V Polypropylene Capacitor" from www.parts-express.com!

    Operate the receiver with speaker selector in "both" position and connect like this:
    grundig 2a.jpg

    Might sound like ass if my impedance guesses are wrong. Might sound like ass if the speakers are crap. But nothing should blow up.
     
  16. Mike

    Mike Bon Vivant

    Amp has a mono switch on it. Any way that can play into this at all?
     
  17. capsuleri

    capsuleri Well-Known Member

  18. Mike

    Mike Bon Vivant

    I can order up those parts. Thanks David...I owe you something. :)

    The speakers work fine, the amp that was in it was producing sound, there was just a really bad hum (not the speakers) and none of the selector buttons worked except the turntable one. And the turntable made a mechanical grinding noise. It was all pretty unusable, but the speakers all worked fine.
     
  19. Mike

    Mike Bon Vivant

    Last edited: Jun 8, 2017
  20. Mike

    Mike Bon Vivant

    I have ordered he parts. We shall see.
    I have gutted the cabinet and begun refinishing it.
    Will install the electronics over the next few day in prep for the parts arriving so it should be a quick install.
     

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