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:
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:
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:
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:
Signal to noise ratio at unit gain and 50 mv are excellent:
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):
Frequency response is one of the widest and flattest I have measured:
Power into 300 ohm is healthy 248 milliwatts (my threshold is 100 mw):
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:
Distortion rises a bit with lower impedance which you can see better when I sweep from 600 down to 12 ohm:
Channel balance is specified at 0.6 dB. My testing shows even better results:
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/
The Amp+ follows the same recent industrial design in JDS amps and dacs:
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:
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:
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:
Signal to noise ratio at unit gain and 50 mv are excellent:
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):
Frequency response is one of the widest and flattest I have measured:
Power into 300 ohm is healthy 248 milliwatts (my threshold is 100 mw):
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:
Distortion rises a bit with lower impedance which you can see better when I sweep from 600 down to 12 ohm:
Channel balance is specified at 0.6 dB. My testing shows even better results:
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/
