Massdrop x Grace Design SDAC - a budget beast

Discussion in 'Dedicated Source Components' started by project86, Sep 1, 2017.
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  1. mindbomb
    The individual dac chips (and headphone amp chips for amps) are not that expensive. The expense largely comes from getting it to perform as well as the spec sheet indicates it can perform, since that's under idealized conditions that are hard to replicate. That's why there can be multiple dacs that use the same chip at different price points with different amounts of performance.
    bidn, volly and Pharmaboy like this.
  2. TWerk
    Not $30 dollars in parts when the most expensive component (ie the DAC chip in the DAC) costs less than $4.

    If total parts cost 10 (probably less than that), there's still 70 dollars in there per unit and I wouldn't worry about paying workers 5 cents per hour. I'd wager the actual amount of manual work on each unit is very, very little on these.

    I'm sure this took them very little R and D considering it's the same DAC used in their other DAC/AMP combo. They probably just slightly reworked, and voila, now they have use for the extra chips they bought for that last product that didn't sell so hot. Pretty smart move, I guess. Just pull out the DAC from the DAC/AMP combo and you have another product to make more coin. The budget beast!
    Last edited: Sep 3, 2017
  3. project86 Contributor
    Wait, who else is offering $80 DACs backed by an engineering pedigree on par with Grace Design? You make it sound like they're everywhere. Please name a few.

    Me? I don't see much out there, aside from random no-name eBay stuff straight from China. Schiit has some nice budget stuff, and the Audioquest Dragonfly series is worth a look. Other than that, the Cambridge DacMagic XS is $129, the Audioengine D3 is $189, iFi Nano iOne is $199, and it just climbs from there.

    You must have skipped my initial post. Had you actually read it, you'd know that this thing has gone through an extensive design evolution to get where it is today. It is completely different from the M9XX, including using a different DAC chip. But don't let those details hold back your speculation.

    As someone who seems to enjoy Ultrasone headphones, I'm not sure I can take your ideas on value seriously. Do you really think designing a nice product, buying the parts, paying for assembly labor, running a QA process, paying for packaging, shipping, and support after the fact, is a cheap process? Just add a $10-20 profit per unit over BOM and you're all set? If that was the case, why do Ultrasone products sell for so much?

    This brings us full circle to your first post, and my question about it - where are all the companies getting rich off a scheme like yours? There aren't any, because it isn't a viable business model.
    Last edited: Sep 4, 2017
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  4. Zapp_Fan
    I get how that looks bad, but it's worth considering that even if you were to personally buy this particular chip and build a functioning DAC around it, it would be very difficult or impossible to do it for less than $80. Hell, it's hard to get an aluminum housing like this (in a quantity of 1) for less than $10-20... and that's before any of the other components are added in, and this is valuing your time at $0.00 per hour.

    I'm not necessarily saying you should find this particular deal attractive, just pointing out that single component costs can be very misleading when it comes to the production of a consumer electronics product. You need to figure in all the other components, along with engineering, manufacturing, packaging, shipping, and customs, before you can draw a truly fair comparison. My guess is that the raw parts of this product cost somewhere around $20-30, all-in - but that's less than half the story.
    Last edited: Sep 5, 2017
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    bidn likes this.
  5. project86 Contributor
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  6. FedeVi
    Hope to not get crucified for asking...

    As a complete newbie of anything audiophile related i wonder if it's possible to drive some low impedance headphones directly from this DAC. Will the audio quality/volume be adequate till i get the funds for an amplifier?

    Present headphones: Creative aurvana live, to be upgraded in the near future.
  7. mindbomb
    I can't speculate on how much exactly this costs to make, but I'm curious how it compares to the likes of the topping d30, smsl sanskrit 6, schiit modi, and jds ol dac. From there, you can make value judgements.
  8. guisess93
    Hi there, I'm a completely newbie in DAC/amp area (since I always have been using IEMs). Can you provide any useful link where I can start learning about the DAC specs? I'm considering this SDAC, Fiio affordable portable DACs, Centrance Slim, Dragonfly, and some people are also suggesting the upcoming Shanlin M3S that will act well as a DAC too. Thanks a lot
  9. thewind32
    Were you able to check whether both outputs can be used at the same time?
    Also, I'm currently using a Fiio E10K as DAC-only, feeding into a Project Ember amp & HD600. Would replacing the E10K with the SDAC be useful? Or will I not get much improvements until I change to something that costs much more? Thanks!
  10. PeteMtl

    It would be great if you could find your CCK adaptor to see if the SDAC works right out of the iPhone and iPad. I'm tempted to push on the button to join the drop, and a positive answer on this issue would be the deciding factor for me... anyways, thanks for your feedback.
  11. CEE TEE Contributor
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  12. project86 Contributor
    Will it work? Yes. You'll have to use software volume control obviously. Will it sound great? Probably not so much. The 1/8" line out was not intended to be used this way and likely has too high of an output impedance. Masdrop doesn't give the spec but I'd guess it was several hundred ohms, give or take. Damping factor will be terrible, frequency response of any headphone used will be all over the place, and bass will be really loose. In short, probably not a good idea. Might as well just use onboard audio for the moment.

    I've had a lot of budget DACs come through here over the past year. So many that I can't even keep track. This is one of the very few that I find noteworthy. Sorry, no direct comparisons, but Schiit might be the only real competition out of everything I've tried thus far. The AQ Dragonfly models are pretty decent as well, but I'd still choose the SDAC over a comparably priced Dragonfly.

    Eh, it's been some time since I've heard the Fiio. I'm pretty confident the SDAC is superior but by how much.... that's a tough question. A difference that matters to one person might be hardly noticed by another, so it's really tough to say for sure. For me, the Fiio was a bit harsh and "digital" sounding, which is an area the SDAC performs way above its price. If you don't find the Fiio bothersome then it may not be worth the trouble.

    Sorry, it seems to be gone from my stash of odds and ends. But I see it has been confirmed that it only works with another power source. That may or may not matter for your needs.
    thewind32 likes this.
  13. thewind32
    I don't find the Fiio bothersome, but it's the only DAC that I have so I may not know what I am missing out on, or in what ways the Fiio is worse compared to something else.
    I guess I'll hold off for now, thanks.
  14. mbgrace
    Hi All,
    I thought I would provide some technical details about the SDAC design that are not evident by reading the specifications.
    I posted this on the Massdrop discussion as well...

    When we were approached to design a USB DAC that could provide equal or better performance than the other DACs in this price range, but be more affordable than our m9XX, we jumped at the challenge. The SDAC contains mostly new circuitry for us and there was not much we could reuse from previous products we have built in the past. Successful DAC design begins with the understanding that a DAC chip is in essence a mixer. The output from a DAC is a mix of four primary inputs: 1) Digital audio data 2) Clock Jitter 3) Power supply noise 4) Analog circuit distortion.
    Modern delta-sigma DACs have vanishingly low noise and distortion so the "sound" of a DAC is really less controlled by the actual IC selected for the design and more by the quality of the clock, power supply, and analog amplifiers. Also, to a lesser but significant degree, passive components like capacitors and resistors in the analog signal path. The SDAC employs asynchronous data transfer from the USB host, which allows for the use of fixed crystal oscillators rather than phase locked loops (PLLs) or digital clock synthesis. A low noise fixed crystal oscillator is the lowest jitter sample clock and there are two in the SDAC: One 22.5792MHz crystal for 44.1kHz and 88.2kHz sample rates, and one 24.576MHz crystal for 48kHz and 96kHz sample rates. These are located very close to the DAC.
    I should note that asynchronous mode allows for the use of a high quality clock but it is not intrinsically better. It is certainly possible that there asynchronous designs out there that use low grade clocks and therefore are not benefiting from asynchronous mode. The power supply for the DAC is designed for very low noise and good noise rejection. This is critical to the overall performance and is not easy to do given the constraints of USB bus power operation. There are separate voltage regulators for the DAC, processor, and analog circuits, which minimizes interaction between these circuit areas. The analog output circuits are based on very low noise and low distortion amplifiers. With harmonic distortion below -120dB, they are well below the distortion floor of the DAC. The SDAC is direct coupled with no capacitors in the signal path, which gives low frequency response that is perfectly flat and free of phase shift. Following is a list of some of the technical features of the SDAC:
    • XMOS X200 USB streaming controller operating in asynchronous transfer mode.
    • IDT XLH series oscillators provide and exceptionally stable and low noise sample clock for DAC. 12kHz to 20MHz phase jitter is 750fs. Note that the jitter below 12kHz is generally more important in audio applications but the 12kHz-20MHz specification is commonly used for specifying oscillators so it is useful in comparing to other clocks. In the SDAC the clock jitter artifacts are well below the DAC noise floor so they are essentially irrelevant.
    • AK4452 DAC provides 32 bit internal processing , 115dB dynamic range, and the same architecture as the AK4490.
    • Output amplifiers are Burr Brown OPA1652. These are extremely low noise low distortion FET input amplifiers with excellent output cable drive capability. Note that the output impedance is set at 150 Ohms so the SDAC is not intended to drive headphones. While it will not harm anything to do so, the fidelity will not approach what is possible with a good headphone amplifier.
    • The negative audio power supply is generated with a switched capacitor circuit that operates synchronously to the audio sample rate to eliminate any possibility of power supply related spurs in the output spectrum.
    • DAC power supply is regulated with the TPS793 low noise linear regulator to reject any contamination from noisy USB power.
    • 4 layer FR-4 circuit board with careful attention to high speed digital layout, power supply grounding, and low noise analog signal routing.
    I will attempt to upload a fft plot showing the SDAC passing a 10kHz sine wave. Notice that there are no visible jitter sidebands (spurs that appear evenly spaced on either side of the fundamental tone). The line at 20kHz is the first harmonic at -92dB. The level of the noise floor suggests that the upper limit of random jitter in the SDAC clock is around 1.5ps at any given frequency. If anyone has questions let me know.
    I will try to check in here as time permits...
    Michael sdac_10khz_fft.jpg
    Last edited: Sep 8, 2017
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