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YANAB - Yet Another Noob Amiga Build - A cry for help

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  • YANAB - Yet Another Noob Amiga Build - A cry for help

    Noob warning, sorry. I did try to search the forums first, but I'm afraid maybe I don't know the right lingo or something? I'm not finding answers though. I'm building the Amiga MT kit. I wired up the crossovers and tested them connected to the speakers, and both the woofer and tweeter produce quite a noticeable buzzing sound as soon as the receiver is turned on, before I even start playing any music. When I start playing music it sounds nice, but the buzzing remains and can be heard quite well over the music.

    I've never wired up a crossover before, and to be frank, I've never even soldered anything before. I'm a true noob here. Seems like there are a lot of things that could go wrong, so I'm thinking a decent place to start is to make sure I haven't screwed something up in the crossover. Both crossovers produce the buzzing.

    Thoughts I've had, including some beyond the crossover are
    1. The receiver is very old, maybe there is something wrong with it? I don't have any other receiver that takes these kind of bare wire inputs though to test that theory. But I could try to figure something out if this is a likely culprit.
    2. I connected 6 wires in one hideous embarrassment of solder in the middle of the board. The diagrams seemed to indicate this was ok, but I'm not confident in readng the diagrams. I did twist all those wires together first as best I could.
    3. The corners of the 2.4 and 5.1 resistors are very close to each other. Is that ok?
    4. For testing, I've been connecting the wires to the speakers with either painters tape or binder clips. Is this ok, it wouldn't cause buzzing right? I don't have any alligator clips but I could go get some.
    5. Sometimes I see comments about checking the polarity. I think that just means switching the plus and minus wires? I've been hesitant to try that before clarifying cause I'm afraid I don't know if it could damage the speakers. I assume the wire labelled woofer plus goes to the woofer terminal with the plus on it, but maybe it's backwards to that for some reason I don't know.

    This is also my first post to the forum, apologies in advance if I missed any etiquette, I didn't see anything specific in the stickies. And thanks in advance to anyone who reads this or offers help, it's much appreciated.

    If the picture isn't good enough or some areas could benefit from zoom, I'd be happy to provide. Hope y'all are having a good day! Thanks!

  • #2
    Crossover looks fine to me. It needs to be seriously bad connected to cause artifacts.

    Buzzing sounds like an input problem to me - if it's audible over the music.

    What do you feed the amp with? Do you have very thin wires in a big pile mixed with power supply cables? - Can cause problems :-)

    Have you tried connecting your phone to the amp directly with a jack to phono?


    • #3
      Fairly sure this won't be the crossover. Connect directly to the woofer - if the buzzing continues its a problem with the amp/source.

      If the amp and source are in fine working order you can also look some information on "Ground Loops" and their effect on audio equipment. This could be the problem although I've never experienced one that is as loud as music.


      • #4
        That's great to hear that the crossover looks good, thank you.

        And you both sound confident that there is a greater likelihood of the source being the issue. The amp (is that the same as a receiver? Maybe some receivers have amps in them and some don't?) as I mentioned is old. It is a Tandberg manufactured in 1979 and hasn't been used in probably 25 years. It was kept nicely, but I understand that capacitors and who knows what else can go wrong in that time.

        I'll try these things in the morning.
        1. Make sure all wires are not jumbled
        2. Google ground loops and see if anything sounds familiar
        3. Try to find a different amp to test with (I think I could do this at the inlaws)

        The set up currently is: input from either a radio antenna or record player into the receiver. Then 16 ga speaker wire out of the back of the receiver to the crossover inputs. Maybe I'll take a picture of that tomorrow and add it. I gotta go to sleep, y'all must be in a different timezone lol, it's late as all heck here.

        But thank you! I don't do a lot of internetting and it's so cool to see how helpful people can be.


        • djg
          djg commented
          Editing a comment
          1979. Not used in 25 years. There's your problem. Put the Tandberg on ebay, some idiot will buy it. Or someone competent to fix it.

      • #5
        Yup, your XO looks fine. Nice solder flow!


        • #6
          First read you had never soldered anything and was expecting a blob-tastic crossover, then looked at the pic. The soldering looks nice.

          Maybe you have a cheap woofer or speaker laying around? Could hook this up to the receiver to narrow down the possibilities.


          • #7
            Is the buzz in both left and right?

            Do you have headphones you can plug into the Tandberg and check for the buzzing that way? You may have to get a 1/4"->1/8" adapter.

            Unplug the Tandberg and take every single switch and knob and cycle it back and forth / in and out a whole bunch of times. I highly suspect your issue is corrosion in some switch / pot in there, I've gotten these exact symptoms before from dirty switch connections. In particular if it's got a speaker selector, cycle that a couple times, and if you hear the sound with the receiver on, try giving the selector a twist and see if the sound changes. Don't get any clever ideas about spraying WD40 inside anything, that's a terrible idea.

            If that doesn't fix it, try unhooking the record player entirely (RCA jacks and ground wire) and see if you still get noise.

            Generally these days it's hard to find clean signal and dialing in both FM antennas and phono inputs to minimize noise is going to be difficult without confidence in the downstream end. Consider picking up a headphone jack to RCA adapter so you can use your phone or similar as a known good source.


            • #8
              You guys are great! I didn't think of the headphones. My phones have a 1/4" end already anyway and that went straight into the receiver. Plugged them in and sure enough, same buzz. You were all right, it's the receiver! So that's great news, I just have to either get a modern receiver lol, or think about cleaning up the old bird.

              I've read some places about Deoxit for cleaning "pots" so I might consider that first. Any time I even jostle any of the buttons on the front I can hear the buzzing change through the headphones. So I think Prana really hit it on the head about the corrosion in there. But he specifically said not to spray anything in there so I might have to do a little more thinking about it. Obviously a new receiver is easiest and probably best solution, but I do have a little attachment to this old guy too.

              I have a good stereo place down the street too, I may see what they think.

              Either way, I'm glad I can just continue on with the speaker build. Can't say thanks enough. If I get everything back to tip top shape I'll pop back in and give an update later.

              Oh and thanks for the nice words about the solder! That cracks me up, I was hilariously nervous doing it, and now I'm psyched that I didn't make a dog's breakfast out of it.