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Chord Mojo DAC-amp ☆★►FAQ in 3rd post!◄★☆

Discussion in 'Portable Source Gear' started by Mython, Oct 14, 2015.
  1. x RELIC x Contributor

    The digital value is a real voltage not a magical 0 or 1 (those are just abstract definitions for different voltage states - Signal over wire, or magnetic states - HDD, or electron stats - SSD). That voltage in a wire can be influenced by RF/EMI generated from other electrical components in the system. Rob has extensively explained through his listening tests that when there is extra RF in the signal it alters the sound. I'm not going to be able to verify or dispute his technical listening tests, but it does play out with what I hear in some gear. The assumption that data is data is false in our physical world because digital data is simply a sampled representation of a physical thing, which has endless possibilities to be influenced by other physical things, be it solder joints, poor S/PDiF port implementation, cable impedance, extra RF noise, etc..

    If you can't hear a difference then that's great for you. No need to discount what others are hearing. Rob has posted this extremely well written blog post about listening tests. It's a recommended read. - LINK -. You can also read about his take on such matters in the third post of this thread. I'm not going to hold your hand and spell it out for you. If you disagree with what he says then that's fine, not everyone has the same perspective.

    There is a definite difference feeding the Mojo from my AK100mk2 vs the AK240 or the X5ii (these latter two sound pretty much the same). The Ak100mk2 sounds more brittle, tizzy, harsh. It's easily noticable and unfortunate for me because it's what I WANT to pair with the Mojo.

    These are assumptions you are making.
    Mython likes this.

    These are related to bit errors. They would appear as a slightly higher noise floor and as single artifacts for 1/Fs seconds. Someone mentioned soundstage... That's a result of phasing and amplitude... Your bit error theory doesn't explain it.

    I'm not trolling.. I'm looking for an explanation that isn't pure, unfounded speculation.

    Sent from my E5803 using a highly trained, special forces carrier pigeon
  3. SearchOfSub

    You seem to have enough knowledge that you believe in to argue what I wrote. I suspect you somewhat enough basic knowledge of sound. So why are we trolling again?

    No. parts used not making any difference in digital chain sound is false. Otherwise, Retina displays wouldn't make a bit of difference to normal displays. It is same thing with sound.

    I have some knowledge as an FPGA and ASIC designer that works on DSP algorithms, and as an EE in general... Yes. But that doesn't mean I know everything and posed a question here looking for explanation. Instead I got a scavenger hunt that would have led me to irrelevant information and someone who says "I'm not technically knowledgable, but I'm going to speculate anyway". I'm not the troll in this scenario, sorry... Far from it.

    Your comparison is apples and oranges... The display technology you are comparing is completely different. If the analog front end were different, say DAP X to Mojo vs DAP Y to DragonFly, maybe your analogy would make sense. Here we are talking about moving the same data over the same interface to the same DAC but with different storage and somehow getting some incredibly specific changes in sound.

    Sent from my E5803 using a highly trained, special forces carrier pigeon
  5. SearchOfSub
    Display technology I used as an example is not any different. It's an example that hardware make differnce in digital devices and platforms.

    If all were same and transport making difference, it's hardware used in transport that is making difference such as psu, wiring etc. Mojo converting all 0 and 1s (if you were like to just put it this way after Relic explained it to you it's not just numbers) then sound of materials used in parts is changing signature since Mojo is keeping it transparent.
  6. x RELIC x Contributor

    You are asking difficult questions in a thread full of consumers, not in an audio engineering forum. The best person to answer your questions is the designer of the device who has repeatedly said that if the source is bit perfect then the sound should be the same. At the same time others have heard differences between some sources and while many of the differences may be explained by DSP or up-sampling, others can not be explained in the same way. My earlier AK100 mk2 example is something I can't explain as to why it sounds different feeding the Mojo, but I can guarantee you that it does. Everything I say explaining it would simply be a guess based on what I've read on the matter.
    jmills8 likes this.
  7. EagleWings
    That was me and I was simply trying to answer your question in my capacity. Just because someone is not technically sound, that does not mean that he/she should not attempt to speculate. Btw, this is not a Electrical/Electronic forums where the technical details are discussed on the level of an engineer. I always like having critics in the forums because, if it is not for such people, some manufacturers would find their way and make easy $$ selling snake oil. But beyond being critical, you are also condescending.
    You said that I might be an exception in the rule when it came to hearing a difference between 2 sources. But I showed you more posts on people sharing the same experiences. May be you have to do your home work, on your own, on finding out yourself, if the differences can in fact exist, and if it did, then why. 
  8. xtr4
    Hi Grumpy,
    From a purely digital standpoint, it is hard to fathom why the 1s and 0s differ from source to source but there is. How to explain this phenomenon is very much arguable due to the fact that the person perceiving.
    To me, after having owned the Mojo and trying different sources (USB, Optical and COAX), there is a perceived difference even with the exact same file. My analogy to this would be to use petrol (gas) as the music file, the gas companies Shell, BHP, ExxonMobil, etc. as the digital source (transport) and Mojo as the standard engine. As we know, not all fuel burns the same from differing companies. This is due to additives added to the fuel. Similarly that is what I'm perceiving to be happening when data is transmitted by the transport to the Mojo, somewhere along the chain, something is being added (directly or indirectly) when it goes through the whole circuitry before arriving at the Mojo. Because different transports circuits are built differently, that would explain the "additive" in the data.
    I guess that's how I would explain the scenario here.
  9. music4mhell
    This is why i am waiting for SD card module from Chord. :)
    I use my mobile with Mojo, but different music apps sound different even if it's sending bit perfect data.
    On the top of that quality USB cables, like pure copper or silver. There are so many ingredients which can change the taste of recipe.
    Chord please please try to publish the SD card module :)

    Okay, so the answer is that some DAPs apparently have some DSP logic in the processing chain that alters the values going out to the DAC... i.e. they are not bit perfect. That's a perfectly reasonable explanation, and I'm not sure why it was so difficult to get. Thanks for your reply.

    Sent from my E5803 using a highly trained, special forces carrier pigeon
  11. SearchOfSub
    Quick example. Go knock on a desk with a coin, your knuckle, and a box etc. Sound will be different every time even at same spot with different materials. I'm telling you man its hardware that's making diff. imo
  12. rkt31
    the reason for digital sources sounding different is simply the ability of brain to perceive even the minutest of changes to sound, caused by various factors, even if there are extremely low measurable changes. though jitter is handled in dacs by various  methods, still it can't be completely eliminated. emi and rfi can enter through usb and coaxial and can effect analog sections ( that's what i could gather from this forum) may be rfi emi introduces jitter and even if this jitter is immeasurable and removed still it may be there in extremely low quantity and again brain is sensitive to even the smallest of changes.
    so the source which has lowest jitter  may sound better ( or even poorer to some as presence of jitter can fool for extra details) so the matter of sounding digital sources sounding different is lot more complex. here we are talking about different sources, i would say even a single  bit perfect source definitely sounds different if someone changes cable length , cable type ( shielded or not ), cable material ( copper vs silver coated) and the biggest change is experienced by adding some cheap tweaks like a ferrite core. those who have not experimented with these ferrite cores can do this at a very low cost. however adding more ferrite cores than two or three can somehow rob the dynamics and emotion of music ( i can't explain this with digital transport) having said that, i would say the mojo is already so good in every area , that without any tweaks it beats many much more expensive cd players and dacs.
    one of my known who deals in vintage gear and swears by those old and big totl cd players of sony and other brand was not ready to listen to mojo but when he listened that hotel california xrcd version on it, he was just smiling and smiling, such is the quality of mojo.
  13. Sound Eq
    from my experience I noticed that indeed there is a difference in sound when connecting the mojo to an iphone, android, fiio x7, and cowon plenue s
    so do not expect all transports to sound the same with the mojo
    Forty6 likes this.
  14. x RELIC x Contributor

    I agree with our underestimation of our ability to perceive. The explanation for fer-rite cores and cable shielding affecting the sound of a digital signal, again, is simply that the digital signal is still a physical voltage which can be affected by outside influences. Digital simply means sampled data rather than continuous data (analogue), but it is still a physical electrical flow representing a sample of the original continuous signal. In a 'digital' electrical signal, simply, a voltage below a certain threshold will represent 0 and a voltage above a certain threshold will represent a 1, or however we choose to represent the data. This makes it no different from 'analogue' voltages except in the way we use/interpret them (fundamentally speaking). Pop over to the Yggy thread and read all the reports of external devices changing the sound for example. There are many examples from many different sources where outside influences affect the 'digital' signal, not just the Mojo.

    Rob has explained that in his listening tests he has listened to the different sound of solder. Oxidation. Clean power sources. Etc. All these things have proven to him to make a difference with different sources through careful and dedicated testing. His laptop plugged in to a wall sounds different to him vs running on battery. Admittedly the differences are small and may be overblown on these threads. I haven't put the dedicated time, don't have the experience/knowledge, nor have the resources to do the same detailed listening tests but I have no reason to doubt him.
  15. sabloke
    Thinking about getting the connection kit. We are being charged a lot more here down under for it than in the States, so I'm wondering if it's worth two hundred... What do people think about it? Would get it to make stacking with DP-X1 more palatable.

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