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Vintage Grundig rebuild

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

  1. Mike

    Mike Bon Vivant

    David, this??? If this is correct, you just saved me many hours of work and I need to buy you a beer. :) Graphic2.jpg
     
  2. Mike

    Mike Bon Vivant

    Mike, this thing has been reworked, and poorly. There are spliced in wires tied together and masking tape used for the connections. The tuner is FM and several short wave bands. As far as I can tell it is cooked. I get not a peep out of it. This is not a good financial investment for a repair. Plus, for re-sale purposes (I will likely sell it sometime) most people will want the electronics replaced anyway.

    I plan on keeping with a period look for the electronics. One of the silver faced receivers with more knobs than you can shake a stick at. Then I will build the cabinet out around it so that it looks built it. I will bolt it down of course.

    I think the turntable will go and I will cover the hole with finished wood to match the cabinet and remove the record wires. Funny thing about those record wires, you cant fit an LP in them with the jacket on it. You were supposed to place the records in that wire thing, out of their covers...Arrrghhh! I will put my cable box and a small blu-ray player in the console where the turntable was and run my television sound into the amp. That will allow me a cool looking "soundbar" so to speak and give me the ability to play CD's if I wish.

    The really important thing is to maintain the visual integrity of the piece. The light that comes on when the top is lifted etc.
     
  3. DYohn

    DYohn Well-Known Member Donor

    Top Poster Of Month

    Mike, the installed speakers have some sort of crossover. The three in the system all connect together into one set of wires. You use those wires to go to Left=pos and Right-pos on your new stereo amp. I'll see if I can correct your image.

    If you replace the speakers they too will need some sort of crossover.
     
  4. DYohn

    DYohn Well-Known Member Donor

    Top Poster Of Month

    Mike, I don't have any good drawing tools on this laptop. Your connections go from Left POS to each speaker's POS, and from Right POS to each speaker's NEG. But there is either some sort of crossover in the system or all the speakers are running full range and they are high-impedance drivers of 16 ohms or more. You need to do more investigation before you can just swap things in.
     
  5. DYohn

    DYohn Well-Known Member Donor

    Top Poster Of Month

    Looking at your first photo it looks to me like the two "tweeters" are actually full-range drivers and are wired in series with one zip cord feeding them. It also looks like there are two small green wires soldered to one terminal of the woofer in addition to the zip cord feeding it. Where do those go? And what are the two small square plastic things? Where do the two zip cords go?
     
  6. DYohn

    DYohn Well-Known Member Donor

    Top Poster Of Month

    I suspect the woofer is 16-ohms and the two full-rangers are 8-ohms each. I also suspect the full-rangers are wired in series, and then they plus the woofer are in parallel to the amp, providing a net 8-ohm load. It is possible there is no crossover and everything is running full-range, which was often done in the early days. What is the vintage of this unit?
     
  7. Mike

    Mike Bon Vivant

    Probably late 60's. I believe it is as you say, full range on everything, unless the small plastic cases on either side of the woofer are crossovers.
    I will take more photos later this evening.

    I am beginning to think that two full range speakers running off the "A" outputs of a vintage receiver, and a dual voice coil woofer with an 80hz crossover in-line running off the "B" receiver terminals and the receiver set to A+B on the speaker selector switch may provide the best sound. I am debating if I want to drop 500 bucks (receiver and speakers) into it when I am about to lose my job in 5 months though. :)
     
  8. Mike

    Mike Bon Vivant

    Untitled-1.jpg


    So this?
     
  9. Chris Slade

    Chris Slade Active Member War Zone Member

    Cool as heck, reminds me of days in the sitting room with my grandfather. He was legally blind, there was a system like this in the room he used to sit and listen to, pretty sure there was an 8-track player in the one he had.
     
    Mike likes this.
  10. DYohn

    DYohn Well-Known Member Donor

    Top Poster Of Month

    Yes. That. Although after looking at the photo, as I indicated, the two small full range speakers may actually be wired in series. Once I get to a PC with some drawing software I'll show you how I think it is currently wired and how that could be adapted to a stereo amplifier.
     
    Mike likes this.
  11. DYohn

    DYohn Well-Known Member Donor

    Top Poster Of Month

    Mike, this is how I think your machine is currently wired:
    grundig.jpg

    Replacing the amp with a stereo unit will change it to this:
    grundig 2.jpg
     
  12. Mike

    Mike Bon Vivant

    Thanks David. I will verify and let you know. Much appreciated.
     
  13. Mike

    Mike Bon Vivant

  14. Mike

    Mike Bon Vivant

  15. DYohn

    DYohn Well-Known Member Donor

    Top Poster Of Month

    Yep. I was right, except there IS a crossover. There is a first order filter: single element high pass for the "tweeters" (the 20uf capacitor labeled what seems to be C206, with the two FR tweeters in series) and a low pass for the woofer (the inductor labeled - can't quite read it - 2027?) This means the drivers might be 4-ohms for the tweet and 8-ohms for the woofer but the schematic does not say. If the tweets are 4-ohms, two in series creates an 8-ohm load and with a 20uf cap that creates a 6db/octave crossover at ~1Khz.
     
    Last edited: Jun 6, 2017
  16. DYohn

    DYohn Well-Known Member Donor

    Top Poster Of Month

    Bottom line is this: tell me how much money you wish to spend and I'll design a good sounding setup for you. :)
     
  17. Mike

    Mike Bon Vivant

    It is more about it maintaining its appearance than sounding good. It would be great if I could just buy an old receiver and use the speakers in it currently without having to replace them. Re-wiring is not an issue as I am going to strip the cabinet bare anyway.

    It doesnt need to sound any better than a typical TV soundbar. :)
     
  18. DYohn

    DYohn Well-Known Member Donor

    Top Poster Of Month

    Blasphemy!!


    Sent from my iPad using Tapatalk
     
  19. Mike

    Mike Bon Vivant

    Perhaps, but this is the type of music it will be playing, and likely only during cocktail parties. Otherwise it will be used as a TV soundbar. :)

     
  20. DYohn

    DYohn Well-Known Member Donor

    Top Poster Of Month

    I can still help. Once you decide on the new amplifier let me know and I'll advise.
     

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