JCALLY JM20 Headphone Dongle Review

[jkim]

Hi there. Long time reader/lurker, first time writing. Thanks ASR and you all to be my no.1 reality check place to go.

I just purchased a JM20Pro from Ali and I am kind on the situation where I fired first and asking later

My main use case for this dongle is to plug it to a Macbook and feed the 2V out to a Topping L30 II. Basically an ultra compact desktop DAC.
Has anybody here tried it as a DAC only?
If I got it right, volume control here is something purely demanded to the input source - if I max the Macbook volume I get the full 2V out, am I right?
I am amazed how this tiny thing measured so well. Do you see any hidden drawback to use it purely as a DAC? What can be "different" (in audible terms) compared to a dedicated AC powered DAC?

Welcome to the forum!

Exactly what model did you purchase? The JM20Pro or JM20? If it's JM20Pro, unfortunately it is different from the JM20 and produces the "Cirrus Hump" distortion as reported here. You may want to return it and purchase the JM20 or JM20 Max.

The JM20 or JM20 Max will serve your purpose with no problem. No difference from a desktop-size DAC that adopts the same DAC chip.

 

[patoulol]

Welcome to the forum!

Exactly what model did you purchase? The JM20Pro or JM20? If it's JM20Pro, unfortunately it is different from the JM20 and produces the "Cirrus Hump" distortion as reported here. You may want to return it and purchase the JM20 or JM20 Max.

The JM20 or JM20 Max will serve your purpose with no problem. No difference from a desktop-size DAC that adopts the same DAC chip.

Hello

I bought the PRO but it doesn't work (it only works on PC and not on my iphone and ipad)

What do you advise me? take a MAX?

thanks

 

[haivanjv]

Thanks @jkim for the pointer at your new research. Impressive read!

Although I am not that technical to grasp every bit of it, I have some scientific bases to at least try to have a read at the charts.
As I said, unfortunately I already pulled the trigger and the JM20Pro is on its way to me. Maybe not the easiest now to ask for a return from Ali Express.
Nonetheless, I think it might still be fine for my main use case which is feeding a 0db line signal to it. If I did not get it all wrong, the Cirrus hump distortion should go to normal levels from around -15 to 0 dbfs. If I max all volumes on my input source (Macbook vol at max + Spotify or Tidal in exclusive mode), I should set the JM20Pro to play at 0dbfs where there should be no "hump". Can you please help me confirm this? This was connected to my volume control question above: I assume this is purely controlled at the input source.

I don't plan to use it on-the-go as a dongle. For that I have a Qudelix 5k with full feature set and I am very satisfied with it.
My itch was more to have a simple laptop setup when I am listening with the Topping amp.

 

[jkim]

Hello

I bought the PRO but it doesn't work (it only works on PC and not on my iphone and ipad)

What do you advise me? take a MAX?

thanks

Not sure if the Max works on ios correctly. Search in its thread.

 

[jkim]

Thanks @jkim for the pointer at your new research. Impressive read!

Although I am not that technical to grasp every bit of it, I have some scientific bases to at least try to have a read at the charts.
As I said, unfortunately I already pulled the trigger and the JM20Pro is on its way to me. Maybe not the easiest now to ask for a return from Ali Express.
Nonetheless, I think it might still be fine for my main use case which is feeding a 0db line signal to it. If I did not get it all wrong, the Cirrus hump distortion should go to normal levels from around -15 to 0 dbfs. If I max all volumes on my input source (Macbook vol at max + Spotify or Tidal in exclusive mode), I should set the JM20Pro to play at 0dbfs where there should be no "hump". Can you please help me confirm this? This was connected to my volume control question above: I assume this is purely controlled at the input source.

I don't plan to use it on-the-go as a dongle. For that I have a Qudelix 5k with full feature set and I am very satisfied with it.
My itch was more to have a simple laptop setup when I am listening with the Topping amp.

You won't listen to it at 0 dbFS, anyway. It WILL be affected by the distortion.

 

[fws]

Hi there. Long time reader/lurker, first time writing. Thanks ASR and you all to be my no.1 reality check place to go.

I just purchased a JM20Pro from Ali and I am kind on the situation where I fired first and asking later

My main use case for this dongle is to plug it to a Macbook and feed the 2V out to a Topping L30 II. Basically an ultra compact desktop DAC.
Has anybody here tried it as a DAC only?
If I got it right, volume control here is something purely demanded to the input source - if I max the Macbook volume I get the full 2V out, am I right?
I am amazed how this tiny thing measured so well. Do you see any hidden drawback to use it purely as a DAC? What can be "different" (in audible terms) compared to a dedicated AC powered DAC?

I've just ran JM20 with L30 II on Windows, it is not the same dongle, but seemed fine aside the click/pop on start shenanigans which honestly it is better just not to think about. Ye 100% is right, some people will make it 98% out of a habit just to be sure there, which is not an issue as L30 II will still output heaps of power, and the SiNAD will be high enough anyway. I don't count it as a proper 1:1 comparison, because in my setup switching the cable between the sources just takes too long, but JM20 sounds properly ok vs using PCI-e SoundBlaster Z as DAC (102dB SiNAD).

External USB desktop DACs are often still using USB for power, for example a highly popular SMSL SU-1 or the newer, also measured by Amirm, PS200. It is generally assumed that a desktop DAC will have a more robust filtering than a dongle, however it is not like you can't run into a case where some bad designed desktop DAC will have issues despite using a dedicated power supply, while a mere USB dongle runs fine.

 

[Ahmonge]

Not sure if the Max works on ios correctly. Search in its thread

Listening to Jcally JM20 Max on my iPad Air M2 driving my Senns HD 620s: seems to be fully compatible with iPad OS

 

[Billy Budapest]

Not sure if the Max works on ios correctly. Search in its thread.

It works fine.

 

[Aster]

Hi, I bought jm20 max and I have issue with it, when audio is playing I hear static noise on my phone (nothing phone 2) tested it with Fiio ft1 and truthear hexa, on other phone (pixel 8 a) everything is fine. Is it possible to fix?

 

[staticV3]

Hi, I bought jm20 max and I have issue with it, when audio is playing I hear static noise on my phone (nothing phone 2) tested it with Fiio ft1 and truthear hexa, on other phone (pixel 8 a) everything is fine. Is it possible to fix?

It's still unclear if the phone is at fault or the dongle. Do you have another dongle DAC that you could try?

Another thing that you can try is:

Install USB Audio Player Pro
Plug the dongle into your phone
Wait for "Use USB Audio Player Pro to open JM20" message, tap OK
UAPP launches->tap the three bars at the bottom->Hardware Volume control->Turn down the Master slider
Burger menu top left corner->Scroll down->Exit UAPP

Now you should be able to turn up the default Android volume more than before, which may remove the static noise.

 

[Aster]

It's still unclear if the phone is at fault or the dongle. Do you have another dongle DAC that you could try?

Another thing that you can try is:

Install USB Audio Player Pro
Plug the dongle into your phone
Wait for "Use USB Audio Player Pro to open JM20" message, tap OK
UAPP launches->tap the three bars at the bottom->Hardware Volume control->Turn down the Master slider
Burger menu top left corner->Scroll down->Exit UAPP

Now you should be able to turn up the default Android volume more than before, which may remove the static noise.

Don't have other dongles, I can hear noise at maximum android volume, used poweramp EQ and reduced gain for this, don't have UAPP, so can't test with it.

 

[boogerlad]

Is there any reason to get this over the jm20 max?

 

[iGmole]

Is there any reason to get this over the jm20 max?

Yes.

Sensitive IEMs and such will blow your eardrums instantly with the Max if you're not careful. You'll perhaps find even the lowest volume setting in your Windroid too loud.

Headroom is great but.. yeah.

 

[fws]

Is there any reason to get this over the jm20 max?

For use as a DAC to drive an Amp, assuming the amp would be designed for 2Vrms input. In such case you just crank it to 100% (but leaving a few % just in case is never a bad idea) for your setup to work optimally. With JM20 Max you would need to measure the output level on various volume settings to be sure that you aren't either overdriving the amp's input, or leaving some output power on the table. Not a big deal, but a bit of a hassle for an average consumer.

Given the CS431xx issues though, despite those 2 dongles actually not being affected by the Cirrus Hump (and if they were, JM20 would avoid the issue since it would be run cranked all up), I would rather just get FiiO KA1 for the job instead.

Additionally as mentioned in the comment above, for some earphones people might prefer to have dongle's output limited by the impedance sensing which JM20 is a subject to. Not to mention, that since we are talking about portable devices, for some thermals and power drain might be important.

 

[boogerlad]

Oh interesting. I can avoid the cirrus distortion issue if the volume is at 100%?

I'm planning on driving a yu9 u556. It's sensitivity is 96.5dB/100mV@1kHz and has an impedance of 116Ω@1kHz. How can I calculate if this dac will be sufficient?

 

[jkim]

Oh interesting. I can avoid the cirrus distortion issue if the volume is at 100%?

I'm planning on driving a yu9 u556. It's sensitivity is 96.5dB/100mV@1kHz and has an impedance of 116Ω@1kHz. How can I calculate if this dac will be sufficient?

Either the JM20 or JM20 Max is way more than powerful enough to drive the IEM. As for the Cirrus distortion, refer to my reply to your question asked in the other thread: https://audiosciencereview.com/foru...vices-a-comparative-review.63038/post-2353180

But note that by setting the dongle's volume to 100% and controlling volume on an external amp, you may lower the audibility and likelihood of the distortion, but still cannot eliminate its occurrence completely. Why? Because real audio content can go below the level that triggers the distortion at any time.

 

[Freezak]

So seeing how this dongle is apparently not affected by the "cirrus distortion" would it be a good dongle with low power consumption for driving Truthear Novas? main usage would be Pixel 9 on the go, so i'm looking for something that doesn't consume a lot of power - Apple dongle would be a good idea here, though i'm from the EU and it's a smartphone so i'm thinking the volume could be too low. Which dongles should i be considering here? thanks in advance.

 

[mc.god]

So seeing how this dongle is apparently not affected by the "cirrus distortion" would it be a good dongle with low power consumption for driving Truthear Novas? main usage would be Pixel 9 on the go, so i'm looking for something that doesn't consume a lot of power - Apple dongle would be a good idea here, though i'm from the EU and it's a smartphone so i'm thinking the volume could be too low. Which dongles should i be considering here? thanks in advance.

JM20 is more than what you'll need with almost any IEM, and it is not fully immune to the CS Hump issue. Nova is pretty sensitive at 123 dbV, so you may want to consider a CX-31993 dongle, they are super cheap on aliexpress, measure decently, output 1Vrms and drains much less power than CS43131 dongles. They also support mic input for calls should you need it.

 

[Freezak]

JM20 is more than what you'll need with almost any IEM, and it is not fully immune to the CS Hump issue. Nova is pretty sensitive at 123 dbV, so you may want to consider a CX-31993 dongle, they are super cheap on aliexpress, measure decently, output 1Vrms and drains much less power than CS43131 dongles. They also support mic input for calls should you need it.

Thank you, going with a CX31993 dongle then

 

[toine512]

Hi. Long fan of the YouTube channel, this is my first post here. I'm very thankful someone is doing measurements on these things.

First, I'd like to confirm that the JM20 is loud enough for HD 650s. But that's when it works.

On my part, it's unusable with Android (Samsung Tab S9). As soon as the audio stream closes (Spotify paused for some time, switch YouTube video...) it's game over: the dongle will never work again until it is unplugged and plugged back in again. I have a noname-Amazon dongle that doesn't show this behavior, which rules out (for once..) a bug of audio routing in Samsung's OS. I'm returning the JM20.
(And if someone has a replacement suggestion, with a different USB interface, I'll be happy to hear about it.)