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Review and Measurements of New JDS Labs Atom Headphone Amp

amirm

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#1
This is a review and detailed measurements of JDS Labs Atom Headphone Amplifier. It was kindly sent on loan by JDS Labs in advance of its formal announcement and availability this week. It retails for USD $99. As such, I will be comparing its performance to other $99 amplifiers such as Schiit Magni 3 and Monoprice Liquid Spark.

The Atom is a nice departure from the JDS O2 in having proper RCA connectors in the back and 1/4 headphone jack in front (and 3.5mm in the back):

JDS Labs Atom Headphone Amplifier Review.jpg


The enclosure is plastic and lightweight but is stable enough to not move around with the weight of cables.

As you see in the comparison above, it is about 10% wider and deeper than O2. The volume control feels slightly less good than the O2 with the latter having more of a "hydraulic" feel.

There is not much else to say about it so let's get into the measurements and see how she does.

Measurements
I started my measurements with a dashboard view of unity gain with 2 volts in, and nearly 2 volts out:

JDS Labs Atom Headphone Amplifier Measurement.png


Are you seeing what I am seeing? SINAD of 114 dB??? In a $99 device? Are you kidding me? Running the same test on Monoprice Liquid Spark struggled to get to 100 dB. This is a good 15 dB better performance.

With our best case hearing dynamic range of 116 dB, this is provably audibly transparent.

At lower output levels of say 1 volt (not shown), the distortion goes so far down that the mains spike at 60 Hz dominates. Since our hearing sensitivity there is some 50 dB higher, this device becomes essentially distortionless.

This is in low gain by the way. High gain was not quite as good.

Since some of you have been asking, I also added the phase information. As we see, the differential of 0.003 degree means there is nothing there to worry about.

Signal to noise ratio is likewise exceptional:
JDS Labs Atom Headphone Amplifier Power Signal to Noise Ratio Measurement.png


123 dB in high gain! Wow.

Yes, this is Massdrop THX AAA 789 territory. And no, the Atom does not use THX technology:

1542249059882.png


Output impedance is comfortably low at 0.7 ohm:
JDS Labs Atom Headphone Amplifier output impedance Measurement.png


Frequency response is dead flat to 40 kHz:
JDS Labs Atom Headphone Amplifier frequency response Measurement.png


Let's see how much power there is compared to Monoprice Liquid Spark and Schiit Magni 3. Note that I have refined these tests and used better setup to get the best performance (Monoprice performance improved but not Schiit Magni 3 compared to my previous review):

JDS Labs Atom Headphone Amplifier Power at 300 Ohm Compared Schiit Magni 3 Monoprice Liquid Sp...png


We get 250 milliwatts of power with essentially no distortion or clipping. At max power, distortion is incredibly low 0.0005% (SINAD 106 db). This is an order of magnitude better than Schiiit Magni 3. And is more power than Liquid Spark manages.

Switching to 33 ohm load we get:
JDS Labs Atom Headphone Amplifier Power at 33 Ohm Compared Schiit Magni 3 Monoprice Liquid Spa...png


Similar picture emerges. We have slightly less power output but much, much lower distortion and noise. You get one full watt of power at just 0.0009% distortion. Incredible.

Here is the intermodulation distortion versus level:
JDS Labs Atom Headphone Amplifier Power IMD Measurement.png


Finally, here is the channel imbalance versus volume position:

JDS Labs Atom Headphone Amplifier Channel Imbalance Measurement.png


Worst case error occurs as usual close to the end of the range. The above is in high gain mode. Switching to low gain should reduce the impact here.

Listening Tests
There was no shortage of power driving my Sennheiser HD-650s. Comfortable level as 11:00 to 12:00 o'clock. As shown in measurements, there is no rise in distortion up to max volume at 5:00 at which time, you are hearing thundering bass and control of the drivers.

Switching to Hifiman HE-400i was the same, resulting in some of the cleanest, best bass I have heard on these headphones.

Playing my audiophile track list brings joy and satisfaction with every detail audible. It is so nice to be free of amplification distortion even during the loudest segments.

Channel imbalance was only audible with my headphones at almost zero volume level.

Conclusions
We have arrived at the golden age of headphone amplification folks. What JDS Labs Atom delivers for just $99 is astonishing. Performance is without fault. Plenty of power is available for even high impedance headphones like Sennheiser HD-650. We are talking clean, clean, power.

During this testing I asked John from JDS Labs how he had achieved this level of performance. His answer: "just many prototypes and lessons learned throughout the year." In other words, good engineering. Use a closed loop measurement system as JDS does and you are golden as we see here.

Official announcement of product is tomorrow (11/15). Shipment is shortly after (not sure if I have permission to say when).

Needless to say, JDS Labs Atom gets one of my highest recommendations. Given their excellent support, activity in forums, and bargain $99 price, every audiophile with a headphone needs to get one of these.

As always, all questions, comments and criticism is welcome.

-----
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amirm

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#7
Hey, Amir. Can you show us a picture of the rear of the JDS Atom? Thank you.
Sure. Anticipating the next request :), I also included a picture of the AC transformer:

JDS Labs Atom Headphone Amplifier Back Panel.png.jpg
 

amirm

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#8
Here is a zoomed shot of the power supply:

1542253556023.png


Using an AC transformer allows the amp to create positive and negative supplies from the same source.

If a dc switching supply is used, then the negative output needs to be created which can cause performance degradation if not done well.
 

maxxevv

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#12
Exceptional performance for an excellent pricepoint!

I wonder how it would pair with an excellent sub US$100/- DAC though ? Was thinking hooking it up with a Sabaj Da3 and use its balanced 2.5mm output to the Atom's RCA inputs.

It would make for a really nice budget headphone setup, thats actually very much "transportable" between home and office for example.

@amirm , would it be possible to test such a setup ? ( if you still have the Sabaj Da3). Or plug a D50 into this !
 
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#13
Oui! Nice, I got one of those in today for review as well. But I was told to wait till tomorrow to "talk about it" :3

Didn't even know it was $99!!!!! Man that's awesome to seem them reach this level of performance!!!! Anyways, let me at least upload my pics here and give you guys my subjective thoughts
 
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#14
i'm new to this but this atom seems like a no brainer for someone looking to get into higher fidelity . will the plastic case cause any issues ? i'm from the school of thought that metal provides shielding from RF and such that could become audible and/or cause noise issues . is that something that doesn't have to be considered these days or with this particular unit ?
 
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#16
Wow JDS labs knocked it out the park! Happy to see it, I have been a fan for a long time. Glad to see the Magni 3 clearly dethroned.

I have heard they are making a new 99 dollar dac to go with it, lets hope that rumor is true and we will finally have the ultimate 200 dollar stack. Perhaps using that new AKM 4493 chip.

Its a good thing I actually need the power of the THX amp I just bought or I would be real salty right about now lol.

I am guessing they still allow you to engrave the case too, might end up getting one of the new stacks if the DAC comes out just to have a spare amp/dac.
 
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#18
A new JDS Labs Dac for $99 yes please!


Also this unit's no joke. Guys that's a K240 M the 700 Ohm Variant that I run exclusively balanced due to it's 88 dB/mW sensitivity and I'm down right blown away at how clean and powerful this little guy is.

Pulling out my LCD 2 next lol, wish I still had my HE 4 though!!
 

helloworld

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#19
I just bought the massdrop 789, otherwise I will definitely buy this. Hopefully they are going to design a preamp based on this design.
 
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