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ZiShan T1 Hi-Fi Player Thread

Discussion in 'Portable Source Gear' started by IcedFrosty, Jul 27, 2019.
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Is this the best DAP under $100?

  1. Yes

    11 vote(s)
    25.6%
  2. No

    10 vote(s)
    23.3%
  3. Way above the price range!

    4 vote(s)
    9.3%
  4. Could be

    18 vote(s)
    41.9%
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  1. Ivan TT
    Alas your unfounded and misplaced (as usual), but luckily for me I don’t owe you an explanation, especially if your suspicions and criticism are purely based on your lack of understanding or misinterpretation of what I say.

    But I’m always happy to help you with the answers, so here we go!

    1. Find my post with the photo of T1 PCB that has two red arrows in it. Note the frequency printed on the components they point at and compare to the frequencies of oscillators I posted. Then research why those two frequencies are used for DACs and how. Post your findings here clearing me of your misplaced suspicions.
    2. Find out the name of Allwinner CPU from the same photo. Google its darasheet and find out what clock frequency it usually uses, compare to photos of PCBs that use same CPU, compare to T1. Post your findings here clearing me of your misplaced suspicions.
    3. Create of find schematics of DSD Pro and T1’s output stages, note how specifically they are different (hint: there is a difference indeed, a clue is 22 - 10) Post your findings here.
    4. Find, re-read and quote my post directly using forum’s quote function, where I allegedly say that (I quote you) “you must remove the resistance or lower them” (sic!) asking for clarification of what I mean and if it the case in the mod photo I posted. Asking nicely would help, but not necessary.
    5. Research BJT transistors and double check if they are digital (or could even be digital). Post your findings here.
    6. When using phrases like “ It doesn’t appear to be the case based on the pic you posted.“ it is beneficial to use complete sentence, adding “to me” after “It does not appear “. This helps to aim the vector at the true source of mistakes and errors, helping to address and fix them.
    As long as you follow at least 5 out of 6 above I’ll be fine.
     
    Last edited: Sep 16, 2019
  2. HeyManslowdown97
    In the DSD PRO. Marked ”P1” ”P2”

    US $0.80 10% Off | 100PCS 2N5401 2L MMBT5401 2L SOT23-3 SOT23 Bipolar Transistors - BJT PNP Transistor New original
    https://s.click.aliexpress.com/e/CUHEqUKU

    The zener diodes are the ones that bypassed to 3.5mm in your pic are the ones marked ”W1” in the DSD PRO. If anything you are adding wire not removing anything

    US $1.31 10% Off | 100PCS SMD Zener diode 3V SOD-323 0805 0.25W SMD Diode BZT52C3V W2 MM3Z3V
    https://s.click.aliexpress.com/e/dsH4xHBa

    These aren’t the ones in the DSD Pro I believe have different specs 9966CB6A-08C5-44C9-9AD8-9E851E28A452.jpeg

    So removed them w/o know what they are?

    Shouldn’t you be telling ME what they are!
     
    Last edited: Sep 16, 2019
  3. Ivan TT
    Good!
    What circuit do they form and why “digital” is not applicable?
    PS: diodes are marked W1, transistors - 1P and 2F by the way.
     
    Last edited: Sep 16, 2019
  4. HeyManslowdown97
    45BA3982-D8B5-45EB-87BC-316D2B28284B.jpeg 92E4A31D-E6BB-4C83-AFC0-17A7F4B30F1C.jpeg
     
  5. Ivan TT
    Are they not?

    Compare to the ones in the centre square.

    [​IMG]
    PS: good point re: website using “digital” in the description, but when you will find what circuit they belong to you will understand why digital is not applicable.
     
    Last edited: Sep 16, 2019
  6. Ivan TT
    And your point is...?
     
  7. HeyManslowdown97
    You might wanna read what wrote about PWM in Audio and filters. Keep in mind before you use semantics the DAC is holistic so the digital filters are linked to the audio signal indirectly wouldn’t agree you?

    Also what you said about removing the lpfs in the Pulse Dense Modulation design that you juxtaposed to your headphone op amp mod in regards to your chart and slopes.
     
    Last edited: Sep 16, 2019
  8. Ivan TT
    Wrote who?
    I am aware that you formed an erroneous idea that DC-DC converter is somehow controlled by CPU and that analogue part of DSD/T1 is based on Class D design, but I choose not to argue with it as I see no point - I never saw you accepting even single argument I presented, no matter what.

    But I can help, search boost converter on Wikipedia and give it a good read, I’m not sure what else could be done to help you to understand actual principle of operation of both DC-DC converters and DSD/T1 analogue stage :frowning2:
     
    Last edited: Sep 16, 2019
  9. fabien32
    The seller said he have DIP. that's good?
     
  10. Ivan TT
    Not really, you need SMD.
    But to be honest, good starting point would be using maybe not as precise, but cheaper oscillators that fit well. Also they are tricky to solder, do you have hot air station or someone who has one?
    Maybe ask @HeyManslowdown97 what oscillators he used, if he can provide links?
     
  11. buzzbuzz
    Have to unsubscribe yet another Zishan thread, just to avoid the constant narcissistic assults by a specific poster. Life is short.
     
    Zerohour88 likes this.
  12. fabien32
    I have someone that solder for me
     
    Ivan TT likes this.
  13. HeyManslowdown97
    It’s not it’s based on SACD specifications and that’s why it follows the AK4497eq Evaluation board.

    The first thing you should have read is the what the Ak4497eq chip is made for.

    The digital filters are also using the pulse.

    The circle area are the filters slopes in the green. 23E7438D-20F3-4541-B0FB-6877AB7D0FA3.jpeg 2B1FF182-99DA-4B32-AC2E-B4094D5F8DBC.jpeg
     
    Last edited: Sep 16, 2019
  14. Ivan TT
    Feel free to stick to your opinion, it’s basic human right.

    Just giving you heads up that I strongly believe you’ve got this one wrong too, but see no point convincing you.

    So how’s the research on suggested topics 1-6 going? You will be able to resolve most of the points you challenged me on...
     
  15. HeyManslowdown97
    You were right you can play with uf values even the resistors to shape the filters but they are necessary and they too can be fine tuned and can be charted; You are missing this golden opportunity to get the balance right!

    The signal coming from the analog board is at a higher frequency then it’s down sampling that what through you off about the lpf and it’s measurements. Because there’s is much noise shaping going through the circuitry ONLY the audible signal is supposed to be coming in the output!

    The Digital filters are based on pulse outside the audio signal which effect bass response etc. it’s actually in the Datasheet.

    Yes there are other application for the chip but this is how the DSD Pro DAC was made.

    DSD= Direct Stream Digital aka SACD

    Hence, “Zishan DSD”
     
    Last edited: Sep 16, 2019
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