SDA-1C Crossover upgrade - Journey Begins

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  • robosdad
    robosdad Posts: 48
    Yeah, the higher temp worked. I thought with leaded solder I should go lower. Learning....

    One last question and then I think I'm done! After I remove the component in C4, so I put in a little jumper or just leave it open?
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  • Gardenstater
    Gardenstater Posts: 4,502
    edited May 2023
    robosdad wrote: »
    Yeah, the higher temp worked. I thought with leaded solder I should go lower. Learning....

    One last question and then I think I'm done! After I remove the component in C4, so I put in a little jumper or just leave it open?

    I'm not familiar with the designations on the PCB. If it is the little blue polyswitch, you have to jumper it or use a small value resistor because it is in series with the tweeter.

    If it is one of the little dual lobed brown 750pf silver mica capacitors you can leave it open.
    Post edited by Gardenstater on
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  • F1nut
    F1nut Posts: 50,663
    C4 is the 750pF bypass cap. Remove and leave open.
    Political Correctness'.........defined

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  • robosdad
    robosdad Posts: 48
    OK, one done and one to go. So far it works! I didn't have a .5 ohm resistor so I just used a jumper across the S1 polyswitch. So far sound is different, I think, but hard to pin down. A bit brighter? I'll do the other board tomorrow and then put some overnight hours on them to break them in.

    I'm just glad I didn't ruin it. The hardest part, easily, has been soldering the leads of caps I'm running in parallel. They're so thick (the Clarity ones at least) that I think it just takes a lot of heat to get them both hot enough for a good solder. I'll need to compile a list of mistakes I made and almost made for the next person...

    Thanks again for the help. I certainly wouldn't have been able to do it without you all.
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  • txcoastal1
    txcoastal1 Posts: 13,306
    The .5 ohm resistor will pad down the highs
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  • robosdad
    robosdad Posts: 48
    Gotcha. Ok I might do that then. I’ll try it with just a jumper in the meantime. Should I use the Mills MRA-12 like the op suggests? Is there a less expensive route?
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  • txcoastal1
    txcoastal1 Posts: 13,306
    edited May 2023
    robosdad wrote: »
    Gotcha. Ok I might do that then. I’ll try it with just a jumper in the meantime. Should I use the Mills MRA-12 like the op suggests? Is there a less expensive route?

    $30 is worth it do to accuracy.

    I sell/install fire alarm for over 30years. These circuits are supervised by resistors. It's amazing how far off these off the shelf resistors are in a 10pack.

    I have thrown away more resistors than I have installed. Resistors are can be rated +/-5% -to- +/-10% tolerance

    So if you you 1 speaker -7% off value and another +5% now you are talking about a 12% difference in value between to speakers.
    2-channel: Modwright KWI-200 Integrated, Dynaudio C1-II Signatures
    Desktop rig: LSi7, Polk 110sub, Dayens Ampino amp, W4S DAC/pre, Sonos, JRiver
    Gear on standby: Melody 101 tube pre, Unison Research Simply Italy Integrated
    Gone to new homes: (Matt Polk's)Threshold Stasis SA12e monoblocks, Pass XA30.5 amp, Usher MD2 speakers, Dynaudio C4 platinum speakers, Modwright LS100 (voltz), Simaudio 780D DAC

    erat interfectorem cesar et **** dictatorem dicere a
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  • robosdad
    robosdad Posts: 48
    Both crossovers are replaced and everything seems to work. I just used a jumper in lieu of the .5 ohm resistor where the polyswitch (S1) was. Will order some resistors when catch my breath...

    They sound a little different but nothing too dramatic. Maybe a bit crisper and more dynamic- a bit more separation? The muffled mids (low to mid piano and horns) are still there (that's why I initially decided to recap the crossovers) which is disappointing. But maybe it's not fair because my previous speakers were Klipsch Forte III, whose mids were incredible. (But otherwise the SDA 1c, in my opinion, competes well, especially with the soundstage and more defined lows).

    I look forward to seeing if there is a change as the capacitors break-in. In the meantime, THANK YOU for the help! @joebass3 @F1nut @Gardenstater @txcoastal1 and whoever else I missed!
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  • SeleniumFalcon
    SeleniumFalcon Posts: 3,842
    You can place a small amount of solder on the tip of your iron to help solder flow easier when you apply it to the join.
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  • pitdogg2
    pitdogg2 Posts: 25,583
    SeleniumFalcon wrote: »
    You can place a small amount of solder on the tip of your iron to help solder flow easier when you apply it to the join.

    I find this also helps to remove old solder.
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