(Unofficial) Review of JCALLY JM20 MAX: USB-C Headphone Dongle with High Unbalanced Output Power

[Count Arthur]

maybe a stupid question but how does this compare to hidizs s9 pro? like that one but if this is comparable I might get it for even smaller dongle

The DACs I have had or have:

HRT Music Streamer II+
Hidizs S9
Ugreen £12 dongle
Moondrop Click
RME ADI-2 DAC FS
JCally JM20 Max

The differences I heard:

 

[delta76]

The DACs I have had or have:

HRT Music Streamer II+
Hidizs S9
Ugreen £12 dongle
Moondrop Click
RME ADI-2 DAC FS
JCally JM20 Max

The differences I heard:

I should be more clear, I was not asking about the audible difference. more like power. As I said main reason for me to buy this one (albeit owning a Hidizs S9 Pro) is size. I wish for something even smaller.

Too bad Amir reviewed Hidizs S9 (not Pro) so there is no direct comparison

 

[goldark]

I should be more clear, I was not asking about the audible difference. more like power. As I said main reason for me to buy this one (albeit owning a Hidizs S9 Pro) is size. I wish for something even smaller.

Too bad Amir reviewed Hidizs S9 (not Pro) so there is no direct comparison

What headphones are you using? S9 has a balanced output which can provide more power for higher impedance loads, but JM20 Max provides more power for unbalanced. Both have more than enough power for most headphones, so I would guess power shouldn't be a problem.

 

[MC_RME]

Did some first measurements which so far confirm the OPs findings. But also made me totally crazy again - my EU iPhone does not put out 2.5V with the JM20 Max, but only 1.4 V (that is still damn loud, 13 dB higher than with the Apple dongle)! So a similar level reduction as with the original Apple dongle is performed in the EU iPhone in the digital domain (yes, simple as that - they lower the digital level fed to the DAC). I did some more checking - my wife's iPhone (not EU) spits out 2.5 V, as does my iPad Pro. So how does Apple know that this dongle is a dongle for headphones and not a standard DAC (where no digital level reduction occurs)?

When connecting the dongle for the first time you can select headphone or others, but that choice is not making a difference. The JM20 Max also does not feature impedance detection, so again that doesn't matter. The answer most probably lies in the USB descriptors, where Jcally has put the same 'headphone' indication as the Apple dongle (bad idea...):

 

[JanL]

Unless you have really hard to drive headphones, what is the point of a dongle that outputs 120dB SPL into your ear at max output? All you are going to do is attenuate it digitally by 40dB and lose that many dB of Signal to Noise ratio, and go from 20 bit resolution to 13.5 bit resolution in the process. I think that a dongle that is matched to your earphones to deliver near full resolution at normal listening levels is a better choice.
I could see using this dongle as a DAC for use with an analog preamp/amp where you attenuate in analog domain and retain the full resolution.

 

[jkim]

Unless you have really hard to drive headphones, what is the point of a dongle that outputs 120dB SPL into your ear at max output? All you are going to do is attenuate it digitally by 40dB and lose that many dB of Signal to Noise ratio, and go from 20 bit resolution to 13.5 bit resolution in the process. I think that a dongle that is matched to your earphones to deliver near full resolution at normal listening levels is a better choice.
I could see using this dongle as a DAC for use with an analog preamp/amp where you attenuate in analog domain and retain the full resolution.

Not at all. Your reasoning would hold only if the JM20 Max achieved its high output power by simply applying more headphone stage gain to an otherwise lower-voltage device. That is not the case here. The gain applied to CS43131 in the JM20 Max is just 1.94 dB (2.5 V / 2.0 V). Its high output power is mostly about its current capability.

For example, the venerable Apple dongle's THD+N at its max volume with 0 dBFS 1 kHz signal (1.03 Vrms) is about -100 dB in its best case. The JM20 Max's THD+N at the same voltage level is about -109 dB, which INCLUES digital attenuation.

 

[iGmole]

Not at all. Your reasoning would hold only if the JM20 Max achieved its high output power by simply applying more headphone stage gain to an otherwise lower-voltage device. That is not the case here. The gain applied to CS43131 in the JM20 Max is just 1.94 dB (2.5 V / 2.0 V). Its high output power is mostly about its current capability.

For example, the venerable Apple dongle's THD+N at its max volume with 0 dBFS 1 kHz signal (1.03 Vrms) is about -100 dB in its best case. The JM20 Max's THD+N at the same voltage level is about -109 dB, which INCLUES digital attenuation.

Also, the JM20 (and the Max) support hardware gain adjustments which I believe is not digital attenuation.

 

[JanL]

Not at all. Your reasoning would hold only if the JM20 Max achieved its high output power by simply applying more headphone stage gain to an otherwise lower-voltage device. That is not the case here. The gain applied to CS43131 in the JM20 Max is just 1.94 dB (2.5 V / 2.0 V). Its high output power is mostly about its current capability.

For example, the venerable Apple dongle's THD+N at its max volume with 0 dBFS 1 kHz signal (1.03 Vrms) is about -100 dB in its best case. The JM20 Max's THD+N at the same voltage level is about -109 dB, which INCLUES digital attenuation.

The volume control attenuation to get 80dB SLP at your ear is in your computer or phone. The signal to noise ratio of 109dB in the dongle is in relation to the maximum possible output signal or 0 dBFS. But if what you are outputting is maxing out at -40 dBFS then your THD+N is at -69dB in relation to your peak signal. The absolute noise floor of the DAC is constant regardless of how loud the signal is and you are sending a very weak signal to it because you are protecting your ears.

EDIT: It's why some manufacturers have that stepped volume when the incoming signal is low.

EDIT2: I read your post again and I now understand. They give you more output capability into higher loads, but the dB gain is relatively low and comparable to other less powerful dongles. So your average IEM will play about as loud as on other dongles with the same volume, but your high impedance headphones will get louder than with other dongles.

 

[JanL]

Also, the JM20 (and the Max) support hardware gain adjustments which I believe is not digital attenuation.

If that's the case that's a good move. I did not see a physical gain switch on it like some of the larger dongles have. It must be a software thing.

 

[iGmole]

If that's the case that's a good move. I did not see a physical gain switch on it like some of the larger dongles have. It must be a software thing.

It works in UAPP - don't know the details or how the dongle handles it internally. But it for sure gives me psychological confidence regarding maximising the dongle performance.

 

[jkim]

EDIT2: I read your post again and I now understand. They give you more output capability into higher loads, but the dB gain is relatively low and comparable to other less powerful dongles. So your average IEM will play about as loud as on other dongles with the same volume, but your high impedance headphones will get louder than with other dongles.

Right. And my reply was on your following point:

I think that a dongle that is matched to your earphones to deliver near full resolution at normal listening levels is a better choice.

There's no such dongle. Why? Because its low-level performance should be dominated by its analog-circuit's noise level. As you said, digital attenuation does not increase a device's noise level but only increases SNR. Most CS43131-based dongles, if properly implemented, have top-notch low-level performance thanks to its extremely low noise.

The signal to noise ratio of 109dB in the dongle is in relation to the maximum possible output signal or 0 dBFS. But if what you are outputting is maxing out at -40 dBFS then your THD+N is at -69dB in relation to your peak signal.

This statement makes some assumptions. In reality, most devices' actual low-level THD+N is usually better than the above principle tells. Two reasons: (1) modern top-tier DACs' real noise levels are lower than analyzers can measure; and (2) harmonic components become substantially lower at such a low level than at its max level where THD+N is measured.

 

[viazniki]

is great i received 2 weeks ago use with my Kiwi Ellipse with DTS X headphones to Senheiser HD650 beautifull sound same have JM28 and now waiting TRN Black Pearl Linsoul sale for 26£ which is great price to see this new product

 

[Aperiodic]

I hope it's better than the 'standard' version I bought that failed after about a week and a half, giving me an 'Accessory drawing too much power' warning which cycled off and on about once per second. It was the third out of three dongles that failed on me, two of which I bought after enthusiastic reviews here, The hardwired cable on my Tanchjin Space Lite (not reveiwed) developed an intermittent in its hardwired cable so, toss. The cable on my TempoTec Sonata developed one also but at least that one had a user-replaceable USBC cable- but replacing it didn't fix the loud POP when plugging it into my phone, so I don't use it anymore. It has a little window with an LED so yuu can see part of the curcuitry though.

On the other hand, my '$9 phone dongle' (as it's referred to around here), has none of the above problems and just keeps working.

IEMs generally don't need the kind of power being discussed here but if someone has higher impedance cans or low impedance. low sensitivity 'phones, this night be a good choice.

 

[iGmole]

I hope it's better than the 'standard' version I bought that failed after about a week and a half, giving me an 'Accessory drawing too much power' warning which cycled off and on about once per second. It was the third out of three dongles that failed on me, two of which I bought after enthusiastic reviews here, The hardwired cable on my Tanchjin Space Lite (not reveiwed) developed an intermittent in its hardwired cable so, toss. The cable on my TempoTec Sonata developed one also but at least that one had a user-replaceable USBC cable- but replacing it didn't fix the loud POP when plugging it into my phone, so I don't use it anymore. It has a little window with an LED so yuu can see part of the curcuitry though.

On the other hand, my '$9 phone dongle' (as it's referred to around here), has none of the above problems and just keeps working.

IEMs generally don't need the kind of power being discussed here but if someone has higher impedance cans or low impedance. low sensitivity 'phones, this night be a good choice.

Given the fact that I have a habit of putting my dongles in the laundry machine and my kid likes to play with them (they are snakes that various dolls hunt and toy cars drive over them and so forth) and I have not broken a single one.. I am amazed you have broken so many.

 

[markanini]

I hope it's better than the 'standard' version I bought that failed after about a week and a half, giving me an 'Accessory drawing too much power' warning which cycled off and on about once per second. It was the third out of three dongles that failed on me, two of which I bought after enthusiastic reviews here, The hardwired cable on my Tanchjin Space Lite (not reveiwed) developed an intermittent in its hardwired cable so, toss. The cable on my TempoTec Sonata developed one also but at least that one had a user-replaceable USBC cable- but replacing it didn't fix the loud POP when plugging it into my phone, so I don't use it anymore. It has a little window with an LED so yuu can see part of the curcuitry though.

On the other hand, my '$9 phone dongle' (as it's referred to around here), has none of the above problems and just keeps working.

IEMs generally don't need the kind of power being discussed here but if someone has higher impedance cans or low impedance. low sensitivity 'phones, this night be a good choice.

Doesn’t surprise me. The strain relief on these dongles is usually poor, and lead-free solder hasn’t helped reliability either, both weaken from real use. I’ve had several dongles fail after just a few months, multiple CX31993 and a JCally JM12. Only the original Samsung dongle has held up. The TempoTec Sonata-style design with a replaceable USB cable is probably the best choice if you care about longevity. Hardwired cables just don’t last.

 

[HissingFree]

I hope it's better than the 'standard' version I bought that failed after about a week and a half, giving me an 'Accessory drawing too much power' warning which cycled off and on about once per second. It was the third out of three dongles that failed on me, two of which I bought after enthusiastic reviews here, The hardwired cable on my Tanchjin Space Lite (not reveiwed) developed an intermittent in its hardwired cable so, toss. The cable on my TempoTec Sonata developed one also but at least that one had a user-replaceable USBC cable- but replacing it didn't fix the loud POP when plugging it into my phone, so I don't use it anymore. It has a little window with an LED so yuu can see part of the curcuitry though.

On the other hand, my '$9 phone dongle' (as it's referred to around here), has none of the above problems and just keeps working.

IEMs generally don't need the kind of power being discussed here but if someone has higher impedance cans or low impedance. low sensitivity 'phones, this night be a good choice.

Why is dongle necessarily associated with IEM? truth is, I value a dongle being powerful a lot, because I don't want to deal with a bigger amplifier if it's not needed, I may be with my Laptop in any place and I just want to plug a very small thing that can power a more power hungry headphone such as AKG K701 and the likes.
Obviously, one will be better with a less powerful dongle if only IEMs are used, because this dongle will probably be more power hungry in terms of batter consumption.

 

[markanini]

Why is dongle necessarily associated with IEM? truth is, I value a dongle being powerful a lot, because I don't want to deal with a bigger amplifier if it's not needed, I may be with my Laptop in any place and I just want to plug a very small thing that can power a more power hungry headphone such as AKG K701 and the likes.
Obviously, one will be better with a less powerful dongle if only IEMs are used, because this dongle will probably be more power hungry in terms of batter consumption.

You're not wrong to want a powerful dongle for full-size headphones, it's valid. @Aperiodic 's point seems more to say that dongles often end up being used with IEMs, and IEMs don't require that much power. There are other concerns that might matter more than output power for a lot of users-like reliability. The issue with powerful dongles producing loud pops on sensitive IEMs makes them unusable to some people. Just today I saw someone report that on Discord with the Blon V1.

 

[Svensson]

New "Record holder" for highest output unbalanced dongle DAC reviewed here (unless I missed one).

Until now, my E1DA 9038D was never being replaced or added to. That had been used so much I got rid of my desktop DAC/amp setup because I wasn't using them, even at my desk. At this price, I'll buy into a couple of these. One for work and one for the car. This is Christmas come early for me.

 

[pioterd]

First up is a 1 kHz sinusoid test under no load (100 kOhm)

Could you please provide results also for maximum line level output (2.5V)?

some recently released Fiio portable DACs adopted it

Also Shanling UA Mini uses the same combination single CS43131 and SGM8262. That amplifier was also used in dual configuration with dual CS43198 in Onix Alpha XI1 dac/amp, Fiio KA15 and probably few others.

Thank you for measurements.

I just want to plug a very small thing that can power a more power hungry headphone such as AKG K701 and the likes

JM20Max, or any other dongle with combination CS43131+SGM8262 will drive AKG K701 / HD650 / DT990 and many many other headphones without any problem to volumes/dynamics/fidelities you will not be able to stand ;-)

 

[Svensson]

Could you please provide results also for maximum line level output (2.5V)?


Also Shanling UA Mini uses the same combination single CS43131 and SGM8262. That amplifier was also used in dual configuration with dual CS43198 in Onix Alpha XI1 dac/amp, Fiio KA15 and probably few others.

Thank you for measurements.



JM20Max, or any other dongle with combination CS43131+SGM8262 will drive AKG K701 / HD650 / DT990 and many many other headphones without any problem to volumes/dynamics/fidelities you will not be able to stand ;-)

Thank you. Do you think that we could anticipate that those dongle DAC's using the same chip and op amp will give similar results, other than just the raw power output?