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The Zishan dsd's corner

Discussion in 'Portable Source Gear' started by neog007, Nov 17, 2016.
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  1. Merlin-PT
    The list are some that I liked, but only based on stock/availability in arrow.com and size that could fit:

    There are more cap brands/models recommended by others that I want to try.

    Regarding opening the box, there's one more thing to add about the gold color buttons, they are loose, they are not fixed to any place and will fall.

    If you open the box, with the buttons side up and slide the LCD screen out into the buttons direction, the buttons will fall inside the box into the LCD and scratch it.

    So never slide the LCD screen out of the box in the direction of the golden buttons, the boards must go out slowly in the other direction.
    Also have the buttons side facing down, so they don't fall into the board and scratch it.

    This problem was reported by some users and is a great warning for all of us.

    I decided on those you see in the last photo because of small size, it's a compromise for size/capacity/price.
    We need 6.3 V, low ESR, high capacity, up to 2200uF is recommend in the datasheet.
    I was already happy with 1000uF, but used lower capacity (2x220uF = 440uF each side) because of size/price.
    If you have space inside the box, Ivan recommends better options, because of higher capacity.
    There are a few more posts after the one I quote.
    Last edited: Mar 17, 2019
  2. Themilkman46290
    Thanks dude, i appreciate it.

    is the side where the white box underneath it gets bolder the - side or is that the +?
    Last edited: Mar 17, 2019
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  3. Merlin-PT
    I always double check the PCB paint, with the position of capacitor that was soldered in there and the meaning of it's polarity markings.

    See the bellow wikipedia picture text:
    In non solid electrolytic capacitors the line/mark in the capacitor identifies the negative - capacitor side.
    In solid electrolytic capacitors the line/mark in the capacitor identifies the positive + side.

    This wikipedia picture is worth a thousand words:

    So in the photo I posted the white line in the stock solid capacitor is the positive (+) PCB pad.

    Note: With circuit power on, we can also use a multimeter to find the voltage polarity at the caps legs.
    Last edited: Mar 19, 2019
    DBaldock9 likes this.
  4. AxelCloris Administrator
    Please keep the discussion focused on the Zishan DSD and not one another. Thank you, everyone.
  5. nesty
    Hi @Ivan TT , on item#5, you mentioned there are four capacitors around the lpf opamps... may we know the value of these capacitors and type? thanks
  6. DBaldock9
    I think he's talking about the 100uF electrolytic audio series pass capacitors, between the DAC chip and the LPF op-amps. They're the large ones that are laying down over the OP275 op-amps.
  7. calico88
    what happend if using 220uf or 470uf in this case ?
    what happend to the sq ?
    HeyManslowdown97 and DBaldock9 like this.
  8. Ivan TT
    Off the top of my head they are 100uF 10V caps.
    Since there is a 10kOhm resistor to ground on their output they form a HPF, cut-off frequency 0.16Hz
    AK4497 evaluation board has 10uF/20k arrangement (0.8Hz cut-off frequency)
    So based on this I don't believe increasing the value would improve anything sound quality wise.
    Also, I believe 6.3V caps could be used here as AK4497 output is well below that voltage.
    Themilkman46290 and DBaldock9 like this.
  9. calico88
    @Ivan TT,
    would you repost your Mod List that has been deleted on page 152 ?
    I just want to try other parts than can bring more detail.

    I can see the "future"
    Last edited: Mar 17, 2019
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  10. Ivan TT
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  11. calico88
    yess, why it's on page 149 ? it was #2276 page 152.
    nevermind, thank you.

    I'm getting parts from arrow and ae ... let the mod and the mood continues
    Merlin-PT and DBaldock9 like this.
  12. DBaldock9
    While the Thread was locked, several pages worth of off-topic posts were purged.

    Has anyone here experimented with using a pair of cascoded N-Channel JFETS, to provide Class A biasing for your op-amps? - https://tangentsoft.net/audio/opamp-bias.html
    The article refers to 2N5484 / 2N5486 devices, but the TO-92 package style is obsolete now, having been replaced by the SOT-23 package (MMBF5484 / MMBF5486) transistors.
  13. Ivan TT
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  14. DBaldock9
    Out of curiosity, what is the size of the footprint for the DAC VREF capacitors (the ones where you used 2x 220uF)?
  15. Merlin-PT
    I used 2 in parallel for each side, for a total of 2x220uF = 440uF each side:

    I measured the PCB pads distance and PCB space before I ordered them, then I searched for a cap size in arrow that could fit the space.
    From the arrow link, this cap measures:
    size (mm): 3.5 X 2.8 X 1.9

    The larger size is 3.5mm, that fits on top of the PCB pads, with only a tiny bit of the PCB pads still showing.
    2.8mm is how tall they will be in the PCB, because they are soldered side way.
    1.9+1.9 =3.8mm is the 2 caps in parallel sandwich size, this size fits without any remaining space left in the PCB.

    I can't measure them now, because they are soldered, but the datasheet has all the details.
    I also found much more expensive options with higher capacity that could fit the space.
    The ones I got had a good price/capacity/size relation, they are "ultra low" ESR and I like the brand.

    The 100uF stock cap that was there measures 3.45 x 2.88 x 1.92 mm.

    The second photo here has a better view of the caps I used:
    Last edited: Mar 19, 2019
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