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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. bobsherman
    I see,but there are more than one seller on Ali listing a 4495 this way. Maybe just a 799 with the older dac chip?
     
    LaughMoreDaily likes this.
  2. Themilkman46290
    I asked the store about 2 weeks ago, they still do not answer, I have asked twice
     
  3. Themilkman46290
    Well I finally got a response from nicehck, they say it's not a typo, guess I need to start saving Screenshot_20190612-064940.png
     
    LaughMoreDaily and Merlin-PT like this.
  4. DBaldock9
    Is there some advantage that the AK4495 has over the AK4497?
     
    LaughMoreDaily likes this.
  5. Themilkman46290
    Still waiting on details, but I would think it would be like the ak4490/4495 versions, having low output impedance, otherwise why else would they downgrade?
     
    LaughMoreDaily and DBaldock9 like this.
  6. DBaldock9
    The DAC chip probably isn't ever directly driving the output.
    It's driving an op-amp (or two) in the Low Pass Filter, which then drives either the Line Out, the Headphone Out, or another op-amp that drives the Headphone Out.
    It will be the design of the op-amp circuit, which has the series resistors, to protect the op-amp from delivering too much current into a short.
     
  7. Themilkman46290
    I understand that, I never said it was because of the dac chip itself, but the other ak4495 is low impedance, and so is the ak4490, but the newer more expensive ak4497 didn't seem to get as good of circuitry as the other two, why would they sell the ak4495 version as an upgrade unless the output impedance has been fixed, or the circuitry upgraded to sound as good as the other two, only disappointment I had with ak4497 was output impedance
     
    LaughMoreDaily likes this.
  8. bobsherman
    Does the 4495 have a lower current draw, giving longer battery life? I wonder if there is much sonic difference between the AK chips in general? Specs do get better, but possibly the circuit, output, opamps etc make more of a difference.
     
    Last edited: Jun 12, 2019
  9. Themilkman46290
    No idea about the current draw, could check the datasheet, but I don't think it will make much difference
     
  10. Merlin-PT
    It sounds as good as the weakest link allows, the dac is part of the circuit, so it also makes a difference.
    Better dacs have better sound, but also need better circuits, power and speakers to retrieve it.

    Here the price, size and portability limits the circuit, the components quality and the power supply, so the dac sound quality is limited by all that.
    I notice a lot of improvements in all zishans (ak4490, ak4493, ak4497) with several circuit upgrades and mods, so the circuit and component choice (size and price) was (and still is ) limiting the dacs. I absolutely love the sound of all of them after modded.
    The biggest difference I noticed between all my _modded_ zishans, is that ak4497 has more _detail_ than my Z2 ak4490 or Z3 ak4493, It has a better dac and circuit design. I still want to try some more things on some of them.
     
  11. miammiex
    Can I remove the battery completely and use it as USB DAC? Does it work for Zishan AK4497EQ? I have Shanling M3S and I have swollen battery problem because of using mainly as USB Dac :frowning2:
     
  12. buzzbuzz
    Zishan dsd is selling for $95.40 usd, Z3 AK4493 $39.6, Z3 AK4490 $38.4 during the "mid-year sale" at AliExpress starting 2 days from now. Not bad.
     
  13. citral23
    Hello, I'm scratching my head and searching everywhere to find out the most "elegant" way to get a near 0 output impedance to drive my BAs in the best possible way, and read a hint at replacing the opamp with one that has shorts protection and removing the output resistors, sounds like the best idea to me so far, apart from plugging a ifi ematch between the player and the IEM, which I find too expensive for what it is/does.

    Has anyone done this mod IRL and can validate it's working? What model of opamp would suit? Thanks in advance!
     
    Last edited: Jun 22, 2019
  14. DBaldock9
    During the AliExpress Sale, I've ordered another Zishan DSD (AK4497) - so that I'll have one as a reference, while modding the other.

    The easy output to achieve 0Ω on, is the Balanced (2.5mm TRRS) jack - since the outputs of the two soldered-on OP275 op-amps are connected directly to the 22Ω series resistors.
    So, installing 0Ω resistors in-place of the 22Ω resistors, would mean low impedance output on the Balanced jack.
    But you'd probably want to replace the OP275 op-amps, with higher current models, that have short-circuit protection.
    .
    The Single-Ended (3.5mm TRS) jack is driven by a set of transistors that follow the socketed op-amp, so the op-amp is isolated - but the transistors may need the 22Ω series resistors.
    If the circuitry between the socketed op-amp and the jack is removed, including replacing the 22Ω resistors with 0Ω resistors, then there'd be a low impedance Single-Ended output.
    .
    According to several posts in this thread, replacing the 3.3V & 5.0V Low Dropout Voltage Regulators for the Digital circuitry makes a noticeable difference in the audio performance.
    .
    For maximum performance from all three op-amps driving the output jacks, the high voltage Analog power supply circuitry may need to be upgraded - I'm not sure what its V+ & V- output current rating is.
     
    endia, Merlin-PT and hakuzen like this.
  15. citral23
    Indeed there is no mention of short-circuit protection on the OP275 datasheet, so the 22 ohm resistor is most likely there for that reason.

    Ah well I don't really want to mess with the dsd, I've ordered a z2 to try my hands on this first, I'm too new to this (not to soldering, but to audio electronics).

    That one appears to be even more extreme with 100 ohms output, but according to it's specsheet its opamp LM4562NA does have an integrated short protection, so why they raised the output impedance so much is a bit beyond me. I'll have to look at it in detail when it's here and do more research because I want to *understand* the implications of changing anything there.
     
    DBaldock9 likes this.
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