This is a review and detailed measurements of the JCALLY JM20MAX DAC and portable headphone amplifier. It was sent to me by Crinacle. Cost is anywhere from US $22 to $65 
.
The dongle has a bit of style to it with that logo and such. Otherwise it is well, a dongle. Key thing is how it performs.
If you are not familiar with amplifier measurements, please watch my tutorial on it:
[And subscribe to the channel ]
JCALLY JM20 MAX Measurements
I dialed down the digital input to JM20 MAX to get the voltage to be nominal 2 volts:
This is excellent performance for any DAC, let alone a little dongle:
I should note however that the low frequency noise was changing fair bit, at times dropping SINAD by 10 dB. This *may* indicated more than usual susceptibility to host noise.
Best performance is a bit higher than measured above:
Above wiggles indicates the varying noise I just mentioned.
Letting the dongle fly at max output produces excellent dynamic range:
Shoot, I just realized i did not run the 50mv test. Will do that later.
Filter and frequency response are as they should be:
Multitone shows a bit of weakness in low frequencies relative to superb performance higher up so can easily be forgiven:
Linearity shows a bit of offset but I think we can also forgive that in this class:
EDIT: IMD vs Level:
Jitter is one of the best measured for dongles:
Wideband distortion showed very high levels:
A spectrum analysis shows this is due to ultrasonic noise shaping and some high frequency interference:
Otherwise, peak distortion is below threshold of hearing.
These are appetizers which are for the main meal of how much power the adapter is able to produce. At 300 ohm, it is very good:
At low impedance of 32/33 ohm, it is mind boggling:
This thing can product current! You can see it just as well in my impedance sweeps:
Just remarkable.
Conclusions
It is incredible how far these tiny dongles have come. They are now easily achieving performance of high performance DACs and power that is hard to fathom given their diminutive size. The JM20 MAX further showcases these advancements, producing performance that should be good enough for many people whether you use it for desktop or portable! This is especially so for low impedance headphones. We are in the midst of a great revolution with wonderful IEMs to pair with these dongles!
------------
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 dongle has a bit of style to it with that logo and such. Otherwise it is well, a dongle.
Key thing is how it performs.If you are not familiar with amplifier measurements, please watch my tutorial on it:
[And subscribe to the channel
]JCALLY JM20 MAX Measurements
I dialed down the digital input to JM20 MAX to get the voltage to be nominal 2 volts:
This is excellent performance for any DAC, let alone a little dongle:
I should note however that the low frequency noise was changing fair bit, at times dropping SINAD by 10 dB. This *may* indicated more than usual susceptibility to host noise.
Best performance is a bit higher than measured above:
Above wiggles indicates the varying noise I just mentioned.
Letting the dongle fly at max output produces excellent dynamic range:
Shoot, I just realized i did not run the 50mv test. Will do that later.
Filter and frequency response are as they should be:
Multitone shows a bit of weakness in low frequencies relative to superb performance higher up so can easily be forgiven:
Linearity shows a bit of offset but I think we can also forgive that in this class:
EDIT: IMD vs Level:
Jitter is one of the best measured for dongles:
Wideband distortion showed very high levels:
A spectrum analysis shows this is due to ultrasonic noise shaping and some high frequency interference:
Otherwise, peak distortion is below threshold of hearing.
These are appetizers which are for the main meal of how much power the adapter is able to produce. At 300 ohm, it is very good:
At low impedance of 32/33 ohm, it is mind boggling:
This thing can product current! You can see it just as well in my impedance sweeps:
Just remarkable.
Conclusions
It is incredible how far these tiny dongles have come. They are now easily achieving performance of high performance DACs and power that is hard to fathom given their diminutive size. The JM20 MAX further showcases these advancements, producing performance that should be good enough for many people whether you use it for desktop or portable! This is especially so for low impedance headphones. We are in the midst of a great revolution with wonderful IEMs to pair with these dongles!
------------
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/
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