JDS Labs Atom Amp – Official Release & Benchmarks

JDS Labs Atom Amp

JDS Labs has been the face of Objective audio throughout the decade. To us, making headphone listening enjoyable starts with honest designs in which measurements come first. Make no mistake: We do not create to be another car on a hype train, or for the sake of a predictable release schedule, or for revenue targets. Worthwhile releases must bring more to the table than specifications.

We’re proud to share that Atom Amp is our new best amplifier. We built it to outperform Objective2 in every way: better specifications, greater power, higher reliability, and more input and output flexibility. Atom Amp ships standard with a 1/4in headphone jack, an integrated dual-input preamp (selectable RCA and 3.5mm inputs), and RCA preamp outputs. All controls are front mounted, and the knob is backlit so Atom Amp looks awesome on your desk. It’s only $99 USD.

Hardware Overview
PCB Layout

Atom Amp adopts a new JDS Labs board layout philosophy. I ran into a wall with respect to noise performance of several prototypes last year. New circuits were measuring no better than older circuits using our standard PCB stackup.

To push performance to the next level, Atom Amp’s AC rectification stage is physically isolated from its amplifier stage at the PCB level, like two boards in one. Linear DC rails and ground connect to the amplifier in a star fashion, improving noise performance by more than 10dB relative to ordinary 4-layer stackups.

Amplification Stage

Atom Amp is DC coupled throughout. It’s been a long time since I encountered a source with DC offset. Consumer audio players are often AC coupled, and all JDS Labs DACs are DC coupled with insignificant DC offset.

The amplifier is powered by +/-15VDC rails derived from internal AC rectification. Our standard 15VAC 500mA transformer was suitable for most listening, but we’re shipping Atom Amp with our larger 16VAC 1000mA supplies. The extra transformer capacity helps drive demanding sets.

Atom Amp’s gain stage accepts up to 2.1VRMS input at high gain of 4.5x, or you may listen at unity gain (1.0x) with sensitive headphones. A custom Alps 9mm potentiometer with 15A taper ensures excellent channel balance. Clean output buffers deliver more power than a vast majority of listeners will ever need.

Relay Muting

Hardware relay muting enables audio output after a one second delay, to avoid startup pops and thumps. Muting applies to both the headphone output and preamp outputs.

Integrated Preamp

Atom Amp essentially replaces the need for pairing OL Switcher with Objective2. The Input button selects between RCA or 3.5mm input, so you can connect two different audio sources and switch between them as needed.

The RCA preamp outputs mute while headphones are connected. Output volume is controlled by Atom Amp’s knob.

Benchmarks

Measurements were taken using RCA-to-BNC and TRS-to-BNC cables to a Prism dScope Series III Audio Analyzer. Atom Amp was powered by a JDS Labs 16VAC 1000mA transformer. Test load for all screenshots below is 150 ohms at 1.0x gain. We also conducted all measurements at 32 ohms and 600 ohms. As results are remarkably similar to look at, we’ll leave further analysis to the community. Maximum output power is observed at high gain, of course.

Measurement Unit
Frequency Response (20-20kHz) +/- 0.01 dB
THD+N (20-20kHz) 32 Ohms < 0.0012 %
THD 1kHz 32 Ohms 0.0008 %
IMD CCIF 19/20kHz <0.0002 %
IMD SMPTE < 0.0005 %
Noise (A-Weighted) -114 dBu
Max Output @ 32 Ohms 1001 mW
Max Output @ 150 Ohms 502 mW
Max Output @ 600 Ohm 126 mW
Output Impedance 0.7 ohm
Crosstalk (1kHz, 150 ohms) -87 dBu
Channel Balance (50% volume) < 0.6 dBu
THD+N at 1kHz, 2VRMS input.
THD+N vs Frequency, 2VRMS input
Noise (A Weighted)
Frequency Response
Crosstalk @ 1kHz
THD+N Level Sweep, 20-20kHz
IMD SMPTE
IMD CCIF 19/20kHz

Production Banter

Atom Amp is our first all injection molded assembly. Because we primarily create aluminum enclosures at JDS Labs, we proceeded with caution, meaning one design at at time. Fortunately, Atom Amp fit together smoothly thanks to our production partners and the power of 3D printing.

OL DAC and EL DAC stack well with Atom Amp for now. As always, we’re listening to your feedback!

Engineering samples of Atom Amp were sent to customers and insiders throughout the year for feedback. As we wrapped up testing and initiated v1.00 production, I handed a first-article board to our intern for a listen. A few minutes later, he reported reversed L/R channels via 3.5mm input. I listened. Yep, left and right channels were backwards. How had industry experts and I missed this?! Easy: We all use RCA input. Our team spent a week manually correcting pinout of the 3.5mm input on the entire batch of production boards. Performance, appearance, and functionality are all the same. I only share, as anyone who performs a detailed teardown may ask.

Being injection molded, Atom Amp weighs about 9 ounces. We added internal weights in the corners to better balance the chassis on your desk. Early reviewers enjoy the amp’s feel. That said, weight can be customized as needed and we’ll listen to your feedback.

Reviews

Atom Amp is in the hands of several reviewers and we look forward to seeing more community feedback in the coming days.

Links will be added and updated as they become available at:

Don’t see your favorite outlet? Ask your favorite reviewer!

Availability

Atom Amp is IN STOCK at the time of this posting. We will ship upon arrival of packaging on Wednesday, November 21.

Quantities are limited by the number of 16VAC power adapters in our inventory, and we expect Atom Amp to sell out rapidly. More AC adapters will arrive early December. Inventory status will be updated here as well as on the Atom Amp product page.

Let us know if you have any questions!


Availability Updates

  • Friday, Nov 16 Update: Wow, we’re blown away! Thank you to all who adopted Atom Amp within the first 24 hours. Your order will ship by Wednesday, Nov 21.Atom Amp will remain listed as “Backorder” until our next batch of AC adapters arrive in early December. Orders placed with Australian (AU) [AU sold out Dec 6] or British (UK) power adapters may ship sooner, while most US and EU orders will be fulfilled early December.
  • Tuesday, Nov 27 Update: Many thanks to everyone who has supported Atom Amp thus far. We’re off to a crazy start! Production of a second batch began yesterday. We’re actively working with our partners to keep the supply chain running smoothly.AC power adapters are scheduled for shipment to JDS Labs on Thursday, Nov 29th. Freight shipments typically arrive in about 1 week. Barring any freight delays, Atom Amps will continue shipping in early December.
  • Tuesday, Dec 4 Update: US and EU Power adapters arrived ahead of schedule and we’re on schedule to ship all backorders within the next 1-2 days. Atom Amp stock is quickly vanishing due to high demand, and may be sold out by late December!
  • Monday, Dec 10 Update: The first batch of Atom Amp boards have sold out (thank you!). Batch #2 is being assembled this week, and we hope to resume shipping by December 20th.

24 thoughts to “JDS Labs Atom Amp – Official Release & Benchmarks”

  1. This looks brilliant! Any chance of getting a DAC in a matching case for nice stacking?

    The only change I’d want is a power button. I switch between speakers and headphones a few times a day and a button to select headphone out VS rca out would be perfect. Having to hold the amp with one hand and pull the cable with the other is just a tiny aesthetic annoyance. First world problems eh.

  2. Performance-wise this Atom Amp is perfect!
    Given its size and weight it can be still regarded as very transportable. If it can be used without the need of an AC plug (e.g. with internal rechargeable battery or being able to use USB power) this will be a big plus. I am willing to pay more if it has a nice metal body like the Element as well.

  3. Looks fantastic, John! What colour is the LED behind the volume knob? Would there be any way to add an engraving like with the Element?

    1. Good questions! Atom Amp’s backlighting is cool white.

      Engraving requires anodized aluminum, so custom artwork must remain exclusive to our aluminum amps and DACs.

      1. Hopefully soon enough a DAC with the Atom design language is released and it being equal or better than the Schiit Modi 3 which showed exceptional performance for a $99 device as did the Atom on Amp territory. Also I suggest the DAC to be named Neutron as it should be neutral and is also part of the nucleus of and atom, so hopefully I get a cookie or better still a free DAC when available!

    1. @Jimmy: Preamp outputs are active, and require the power supply. Use the 1.0x gain position when using preamp output; this eliminates gain.

  4. Given this is DC coupled – is there any DC offset protection? Or any protection circuits beyond the muting relay to protect headphones from damage?

    1. None present; we have shipped thousands of DC coupled amplifiers in the past similarly.

      You can detect DC offset of any amp by listening for a large pop when changing gain, or severe noise when turning the volume potentiometer. If either happens, it’s a good idea to check your source for offset. We’ll add these suggestions to the Instructions guide. Thanks for your thoughts.

    1. Element is in transparent territory, so while Atom sets record measurable performance, I see no reason to swap. Enjoy what you have!

      Element’s larger PCB surface area gives it an edge in thermal disspation over long duration high power listening (read: ear damage). Atom reaches 1W easily, but does not compete with the 1.5W bursts I was able to hit with Element. Probably lucky for us, as Element v1.53 remains relevant for this reason. That being said, I have reservations advocating more power. Check our Power is Volume article from 2015. Headphone manufacturers are increasingly releasing more efficient drivers, so the case for more power is declining.

  5. The new Atom Amp looks great!

    Like @Cory Nelson suggested, any chance you guys could just put the current OL DAC into a matching case? They would look great stacked together, and I’d definitely get a pair.

  6. Could you please explain the meaning of dBu in the measurements of crosstalk and channel balance? Why is it referenced to 0.775V? Usually this is just a relative ratio measured in dBr (or simply dB).
    Is crosstalk measured from left to right or from right to left? Or is it measured in both directions and you state the average or the better or the worse value?
    Is it worse at higher (up to 20 kHz) or lower (down to 20 Hz) frequencies? A sweep would be nice!
    Besides that, I’m really astonished about Amir’s APx555 measurements. This amp is of incredible high objective measurable quality, especially for its price. How is this possible?
    An Atom DAC would be the icing on the cake…

  7. I would love to see a blog post on some of the design process including a discussion of the various prototypes and the process involved to select an optimal design. All of that knowledge is of course your proprietary intellectual property but I think it would be a great resource for the audio community about how audio quality is objectively quantified and how great performance is achieved through good design practices instead of expensive and exotic components. The legendary NwAvGuy post on the O2 amp design has a lot of fantastic information about spec’ing components and layout considerations, but he doesn’t go into much detail about his process for prototyping and his design iterations.

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