JDS Labs Atom DAC — Official Release & Benchmarks

JDS Labs Atom DAC

Atom DAC is built to pair with the enormously popular JDS Labs Atom Amp, adopting our latest XMOS based USB Audio Class 2 input stage with MEMS oscillator and support for future firmware updates. Atom DAC is powered by a dedicated 15VAC transformer, ensuring consistency of noise performance when paired with other transformer isolated amplifiers like Atom Amp. A subtle light ring glows when in use. Atom DAC ships today for only $99 USD.

Design Motivation

We know expectations have been through the roof for Atom DAC since the day Atom Amp was released. Some customers hoped for benchmark records. Others asked us to drop a third-party board or JDS Labs OL DAC into an Atom case and call it done. As tempting as a shortcut sounded, we chose to follow our original plan of completing Element II and carrying over its new USB engine for Atom DAC, outperforming OL DAC with a sense of style.
Atom DAC weighs about 8oz by default, comparable to Atom Amp. Similarly, we can add additional internal weight upon request. No extra weight is necessary when used with JDS Labs Stack RCA Cables.

Firmware and Operation

Atom DAC runs on a branch of firmware developed for Element II, with a new feature suggested by a JDS Labs customer in Europe: The audio state is constantly monitored so that Atom DAC  automatically enters standby after 15 minutes of inactivity, powering down its light ring and D/A circuitry. Atom DAC wakes up and resumes audio playback within milliseconds. Standby mode can be disabled by loading alternative Sleepless Firmware if you prefer. We can make this change for you, or you may change over at any time using the provided XMOS DFU app. All downloads can be found on the Atom DAC page.
As designed, there is no need for a power button. Atom DAC powers up and down as needed. For the first batch only, we are shipping a free in-line power switch as well. [Sold out July 18, 2020!]

Drivers

No drivers are required by Windows 10 or modern versions of MacOS or Linux. You may optionally install Atom DAC’s XMOS drivers for proper ASIO support.

Current versions of Android and iOS have also been tested successfully. Please note that UAC2 support varies with mobile devices.

Performance

Atom DAC achieves <0.00045% THD+N @ 1k A-Weighted, or SINAD >106 dB*, exceeding the capabilities of our dScope Series III and Audio Precision APx515:

A 24MHz SiTime MEMS oscillator outperforms OL DAC’s USB jitter by a wide margin of 8dB @ 12kHz.

Atom DAC
Frequency Response 10Hz-20kHz (192k) +/- 0.15dB
SINAD 110 dB*
THD+N 20Hz-20kHz < 0.0008%
IMD CCIF 19/20 kHz -6.03 dBFS 0.00013%
IMD SMPTE -6.03 dBFS 0.0017%
Noise (A-Weighted) -109 dBu
Dynamic Range (A-Weighted) 117 dB
Linearity Error -90 dBFS -0.06 dB
Crosstalk -10 dBFS 100K RCA -104 dB
USB Jitter Components 12kHz -124 dB
Maximum DAC Line-Output, 100K 2.0 VRMS

*There has been hyper focus on measurements in recent years, in a race towards Bigger and Better numbers. JDS Labs has benefited due to our longterm focus on honest performance.  If the agreed threshold for “transparency” was 0.005% THD+N nearly a decade ago (only 86dB SINAD!), take a moment to consider that SINAD of 96dB is 10x cleaner , and 106dB is 100x cleaner than the previously agreed point of transparency. Whether you’re an objectivist or subjectivist, or somewhere in-between, please remember that our goal is to help you enjoy listening to the world’s best headphones. Audio performance is exceptional today.

EDIT June 11, 2020: SINAD of 110dB has been confirmed on an APx555 by Amir @ ASR. Thank you!

Features

OL DAC – USB Edition Atom DAC
Power Button None Auto Standby
USB Controller SA9023 XMOS XU208
PCM Support 24/96kHz 32/384kHz
Upgradeable Firmware No Yes
Oscillator CMOS Oscillator SiTime MEMS

Secret Release Dates

I know thousands of you have been begging for Atom DAC since the day we released the award winning Atom Amp. We were overwhelmed by Atom’s success and a matching DAC was not on our 2018 roadmap. Atom is a wildly successful experiment which required a flurry of concept refinement during a period of 90% growth. Early feature considerations were ruled out, as we recognized that the majority of customers adopting Atom wanted a competent, affordable USB DAC.

Two alternative Atom DAC featuresets were prototyped concurrently in 2019. The more complex featureset worked, but would have pushed cost higher unless we lengthened development time to omit the 15VAC transformer and revert to a USB powered design. We committed to proper AC mains isolation in our last generation of DAC designs, and our customers have been pleased with the consistency of AC powered DACs since then. Keep in mind that the “free” 15VAC adapter bundled with Atom DAC retails for $16.99 USD, so a healthy chunk of Atom DAC’s cost is our commitment to the benefits of an AC transformer.

Atom DAC was originally scheduled for release in November 2019. I began hinting that Atom DAC was close and would be released in 2019. Firmware was complete, enclosures had arrived at JDS Labs, numbers looked good, FCC/CE testing passed, and listening impressions had gone well for those of us at JDS Labs and for random customers (thank you to all who evaluated!). What could go wrong?!

Just days before we initiated PCB fabrication, I visually compared measurements of Atom DAC to the older JDS Labs OL DAC. Uh oh. I had ignored small 60Hz*n spikes, masked by numerically excellent A-weighted testing. We normally run both A-weighted and non-weighted measurements. I had skipped non-weighted testing on the fourth prototype after seeing strong performance of the first three builds. Knowing the cause and solution, I cancelled the Nov 2019 production to run to build two more boards. Atom DAC v6 finally passed all testing and was released for PCB manufacturing on Dec 23, 2019.

When all materials are available, PCB production runs can be pulled together in under two weeks. Atom DAC relies on some relatively obscure parts, with lead times of 8-14 weeks. I conservatively withheld ordering three components in bulk until the last minute, due to their direct impact on radiated emissions. These parts can be substituted or customized to balance performance and emissions compliance, and must not be changed once a design is locked in.

Electronics are globally sourced. As the ship date neared for the critical parts, our US distributor issued a notice of extended lead times due to COVID-19. Likewise, lead time of AC transformers doubled. Just as we were ready to announce Atom DAC, the pandemic forced the majority of our staff to work from home. Fortunately, we had not announced a firm date or taken preorders, so the only harm done was to our patience.

Thank you all for waiting. Atom DAC is here, and we hope you enjoy!

Availability

Atom DAC is In Stock exclusively at jdslabs.com today.


Reviews

50 thoughts to “JDS Labs Atom DAC — Official Release & Benchmarks”

    1. Will there be a version with optical/coaxial in? Or maybe another usb input? I think it would be nice to have two digital inputs.

  1. Hi! It looks awesome, congrats! Just wanted to know, does automatic standby kick in after 15 minutes of inactivity from the source, or from the output? Maybe this question doesn’t make sense, but if I turn the amp off, will that suffice, or do I need to make sure my source isn’t transmitting sound via the USB? Thanks.

    1. Uhhh what? Theyre in completely difference classes of performance. Im not sure the Atom lineup is bad, I actually love it, its just the RME is significantly better in every way. In terms of audible differences to human hearing, probably wont notice between Atom and RME though, so you do you haha.

    1. @Caleb – I wanted to see TOSLINK support in this design, and chose not to copy and paste this area from our previous work after finding a better way. Your feedback will be forwarded along!

      1. Do you have an ETA on when the batch will be available? Would love to buy a matching stack, but prefer to have the fonts match as well.

        BTW, congratulations on bring this DAC to market given all the turmoil.

          1. “106dB is 100x cleaner than the previously agreed point of transparency. ”
            woah! thx for giving us this perspective. 🙂

      1. Hmm as I can see that KTB it is measuring perfect on ASR review. I have the device in combo with my JDS Labs Atom AMP and no single issue. Maybe because I am using it just with an AMP? No active preamp or external system

        Can’t wait to see ASR results of JDS Atom DAC. It would stack nicely with my Atom AMP. 😀

  2. Hi John,

    Have you had a chance to test this DAC with PS4 Pro using its USB output?

    Just thinking ahead as no one is sure whether the PS5 will have an optical out. In case it only supports audio over USB, I will need an extra DAC with USB input only.

    1. @Boris: PS4 only supports UAC1, so no UAC2 can connect. We can provide custom UAC1 firmware upon request, but there is a caveat: Forcing UAC1 disables the DFU device. In other words, it’s a one way change.

      There is a UAC2-to-UAC1 fallback option in the XMOS codebase. I have not tested this, but will do so if there is sufficient interest.

  3. Are internal weights needed for the Atom amp to stay flush when stacked? You mention the weights aren’t necessary when used with the JDS Labs Stack RCA cables, but in the photo it looks like the pull of the cables is causing the front of the Atom amp to pop up.

    1. @Matt: Atom DAC and Atom Amp are designed with a slight front uptilt; they do not rest at 0 degrees. This is why the front appears to be lifted, and has no relationship to the device weight. The default build is just fine!

  4. would love to see a combo device similar to the element.
    it would bring the total cost down, as only one ac adaptor, one pcb and one case areneed.
    It also avoids the possibility of ground loops as the dac and amp would have the same ground.

    1. Thanks for the feedback!

      Use of AC transformers also avoids ground loops; this is the primary reason Atom DAC was designed to require an AC transformer. You are correct that an amp+DAC is more cost efficient; it is slightly more challenging to design both onto one board while maintaining incredible performance.

      On that note, Atom DAC and Element II share the same DAC circuitry, yet, SINAD of Atom DAC is slightly higher from Atom DAC because of fewer components involved impacting the noise floor. At today’s high performance levels, even small changes to firmware like LED intensity can degrade benchmarks. With this in mind, we need to ask ourselves what is most important to improve the listening experience. I’m not sure pushing benchmarks higher is the answer.

      1. Oh I believe the performance of JDS products (atom, element, etc) is good enough for 99% of the people. To me they’re all perfect. I would rather see manufacturers like you spending time on the user experience side.

        For instance, not having two adapters make the desktop wires less cluttered (you know how messy year 2020’s cable management is. turning it to 1 device eliminate 3 wires, 2 rca and one power). It also allows the user to turn off both devices with one single push button (currently it’s a mess — amp has a button on the front, and the dac’s button is on extension cable).

        Also very importantly, I’d like to see a -10 or -15 db gain on HP amps, which is not only useful for IEM users, but also solves the channel imbalance issues for people like me who listen with low volume (so no need to turn their pot before 10 o’clock).

        I don’t mind the final product a little bit bigger, if you need extra space for isolation.

        1. Great thoughts to consider. So basically, you would like to see an affordable amp+DAC with extra attenuation at the frontend?

          Effective late May 2020, all Atom Amps are now built with hand matched volume pots. Channel balance is better than ever.

          1. > you would like to see an affordable amp+DAC with extra attenuation at the frontend?

            exactly. Massdrop THX AAA has -9db attenuation. RME ADI-2 DAC has a IEM port, at 0.55V ( -11.2db gain compared to 2V Line out). I assume with just a few extra resistors, JDS amps could have the same feature.

            > Effective late May 2020, all Atom Amps are now built with hand matched volume pots. Channel balance is better than ever.

            We have email conversation on this last year (you were also inviting me for testing at planning stage but probably forgot about it later on when working on the product… ). Nice to hear that this has been improved significantly.

            I still believe a minus gain is useful. Making the pot perform well at low volume would cost manufacturer significantly more. With extra -10 ~ -15db gain available you may be able to achieve better result, while reduce the cost of the customized pot.

            in addition to channel balance improvement, minus gain in certain situations can also reduce the noise (for instance, when most of the noise come from the DAC rather than the amp side). Useful for IEM users.

  5. John, what would happen if I use a barrel jack splitter to run both an Atom Amp and an Atom DAC off same the 16V 1000 mA transformer? i) this would be fine? ii) some sort of ground loop? iii) immaterially impacted performance? iv) very poor performance? v) good performance but less power available?

    1. @Paul: This will result in ground loop, as you would bypass AC transformer isolation between the two devices. The separate linear regulators driven by a single AC outlet would create ground loop, likely audible. Strongly discouraged.

      1. Thanks John,

        Second question: why the 15 minute standby timer? If the DAC is on whenever the USB uplink is available, couldn’t you make the timer ~5 seconds and the amp will be on essentially any time the computer or streamer is on and turn off pretty much immediately upon PC shutdown?

        1. @Paul – Soft muting, or soft powerdowns in any DAC implementation are likely to produce a small transient when unmuting. This is difficult to avoid without a physical relay. In other words, a 15 minute delay reduces the occurrence of potentially audible transients.

          1. Hey John, would that explain the audible pop that occurs when powering on the unit or when the unit wakes up from sleep mode? Is this normal behaviour and nothing to be afraid of?

          2. Correct, this small transient is normal and safe. Startup transients are common to many entry-level DACs. The wakeup transient is rather small in most instances. We use a muting relay in EL DAC II and in all JDS Labs amplifiers.

            It’s good practice with any system to power up DAC/EQs/preamps first, and apply power to the final amplifier in the chain last. This will bypass any unexpected noises from equipment earlier in the chain.

  6. Coming back to the question from Matt about the pop on start up and the response from John allaying any concerns about this trainsient effect. I also had a seperate email exchange with John about whether to leave the equipment permanently powered on as my JDS DAC came with an inline power switch but it also has the 15 minute standby function. I am using the JDS stack in my home office as I am currently working from home for obvious reasons. I normally have music playing while I work (typically streamed though the IDAGIO, which I really enjoy), if I need to answer a call I tend to pause the stream with the mouse as that is most convenient, which often means the DAC goes into standby before I restart the stream and I then get the pop on restart. While not painfully loud, it does make anybody else in the room jump and to be honest just sounds clunky. I get John’s point that powering up the AMP as the last component in the stream is good practice, as would be turning the volume knob down on the front of the AMP, but I am as lazy as the next person so I guess that the best solution would be to download the permanently on DAC software and skip the standby. This is not a showstopper as I am otherwise very impressed with the JDS equipment – AMP and DAC for $200 is great value – just wondering if anybody else has a similar experince and/or has come up with a better solution.

    1. @Graham: Installing Atom DAC’s optional Sleepless firmware will prevent the mute/unmute transitions. Easy solution!

    1. All of our DACs are balanced internally. They happen to have a balanced-to-unbalanced stage on the end 😉

      Going fully balanced necessitates a matching amplifier with balanced inputs. We haven’t ruled out the idea.

  7. hi John,

    Have both the JADS Labs ATOM Dac & Amp, they work very well with Audio-Technica ATH-MSR7b closed headphones.

    My Question is, is there any point in upgrading USB Cable or extra power supply filtes using IFI products, or is there no point?

Leave a Reply to Stephen Tranter Cancel reply

Your email address will not be published. Required fields are marked *

This site uses Akismet to reduce spam. Learn how your comment data is processed.