• WANTED: Happy members who like to discuss audio and other topics related to our interest. Desire to learn and share knowledge of science required as is 20 years of participation in forums (not all true). Come here to have fun, be ready to be teased and not take online life too seriously. We now measure and review equipment for free! Click here for details.

JDS Atom Amp+ Review (Headphone Amplifier)

amirm

Founder/Admin
Staff Member
CFO (Chief Fun Officer)
Joined
Feb 13, 2016
Messages
35,336
Likes
135,205
Location
Seattle Area
This is a review and detailed measurements of the JDS Labs Atom Amp+ headphone amplifier. It was sent to me by the company and costs US $99. It was announced today.

The Amp+ follows the same recent industrial design in JDS amps and dacs:

JDS Labs Atom Amp+ Review Headphone Amplifier.jpg


It is light but functional. Dual gains are provided and single 1/4 headphone jack. The input selector chooses between 3.5 mm and RCA connectors in the back:

JDS Labs Atom Amp+ Review back panel Headphone Amplifier.jpg


As you see power is provided through an external AC transformer.

JDS Labs Atom Amp+ Measurements
As usual we start with our "unity gain" setting which means the same input voltage is produced at the output. In the case of unbalanced amplifiers, I use 2 volts which is the nominal maximum output of desktop DACs:
JDS Labs Atom Amp+ Measurements Headphone Amplifier.png


I would expect stellar performance from JDS and that is exactly what we see. Distortion is incredibly low at -130 dB (15 dB better than threshold of hearing). A 60 Hz tone is also visible but it is ordinarily buried in the broadband noise level as you see in a bit. For now, SINAD which characterizes noise+distortion is near top of the class:

Best desktop headphone amp review 2021.png


Signal to noise ratio at unit gain and 50 mv are excellent:

JDS Labs Atom Amp+ SNR Measurements Headphone Amplifier.png


As you see the noise floor is at -121 dB which is higher than the mains noise I indicated above. Still, this is extremely good performance with 20+ bits of dynamic range at 2 volt out, and 15 bits with just 50 mv out (adjusted by turning down the volume):

best headphone amp.png


Frequency response is one of the widest and flattest I have measured:

JDS Labs Atom Amp+ frequency response Measurements Headphone Amplifier.png


Power into 300 ohm is healthy 248 milliwatts (my threshold is 100 mw):

JDS Labs Atom Amp+ Power into 300 ohm Measurements Headphone Amplifier.png


In either gain, there is no clipping so if you hear some, it is your headphone!

Switching to 32 ohm load, there is clipping now in high gain:

JDS Labs Atom Amp+ Power into 32 ohm Measurements Headphone Amplifier.png


Distortion rises a bit with lower impedance which you can see better when I sweep from 600 down to 12 ohm:

JDS Labs Atom Amp+ THD vs frequency vs power Measurements Headphone Amplifier.png


Channel balance is specified at 0.6 dB. My testing shows even better results:

JDS Labs Atom Amp+ Channel Balance Measurements Headphone Amplifier.png


JDS Atom Amp+ Listening Tests
The Amp+ had no trouble driving my Sennheiser HD650 to hearing loss territory with incredible dynamics, bass and lack of distortion. Switching to much lower impedance Ether CX showed a bit of limit at the highest outputs with a touch of distortion. By then though, I could only tolerate the sound for a few seconds so for any "normal" listening, there is excellent fidelity there.

Conclusions
JDS Labs targets 99% of the state of the art in headphone performance and delivers. It is a breath of fresh air to check my measurements against their specs and see them very closely match with no weasel words used to get better numbers. Company has impeccable reputation for excellent customer service which when combined with such a low cost, means a winner in my book.

It is my pleasure to put JDS Labs Atom Amp+ on my recommendation list.


-----------
As always, questions, comments, recommendations, etc. are welcome.

Any donations are much appreciated using: https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/
 

acbarn

Major Contributor
Forum Donor
Joined
Mar 11, 2020
Messages
1,344
Likes
3,164
Location
California
What's the difference between this and the last Atom amp?
From the JDS blog:

Aside from subtle fit and finish improvements since release, we’re tagging “Atom Amp+” because we’ve boosted performance using the same analog IC employed in the matching Atom DAC+. More importantly, every Atom Amp+ is built with hand matched potentiometers for superior low volume imaging, up to 20dB better than the originally spec’ed Alps pots.

More here: https://blog.jdslabs.com/2021/07/jds-labs-atom-amp-is-now-atom-amp-plus/
 

raif71

Major Contributor
Joined
Sep 7, 2019
Messages
1,563
Likes
1,433
I almost gave this thread a miss...thought it was the older jds atom thread. Luckily I saw, "today" at the date. What did jds lab do differently in the design or selection of components to improve the atom?
 
OP
amirm

amirm

Founder/Admin
Staff Member
CFO (Chief Fun Officer)
Joined
Feb 13, 2016
Messages
35,336
Likes
135,205
Location
Seattle Area
How is the volume knob and the chassis? They were horribly plastic and cheap in the normal previous version.
Basically the same although I think the feet are larger/stickier.
 

phoenixsong

Addicted to Fun and Learning
Joined
Nov 17, 2018
Messages
657
Likes
529
I like how they've always paid attention to the channel balance of their amps. My o2 amp from them was clearly better in this regard compared o the one from Massdrop
 

filo97s

Active Member
Joined
Feb 17, 2019
Messages
105
Likes
199
Location
Sestri Levante
Is still LME49600-based like the old atom right?
From the JDS blog, it seems they've changed only the input stage
 

JohnYang1997

Master Contributor
Technical Expert
Manufacturer
Joined
Dec 28, 2018
Messages
7,005
Likes
15,776
Location
China
Is still LME49600-based like the old atom right?
From the JDS blog, it seems they've changed only the input stage
It sounds like they changed the opamps to lm4562/lme49720. Just like their EL series.
One dual opamp per channel. Each opamp has half for gain stage and half for controlling lme49600.
 

Helicopter

Major Contributor
Forum Donor
Joined
Aug 13, 2020
Messages
2,491
Likes
3,465
Location
Michigan
Thanks Amir. This is really impressive, beating Heresy on SINAD and the aesthetic is better than their old products. Topping and Schiit are still better looking but no complaints about the look of this at $99. Does this have protection like IEMagni?
 
Top Bottom