JCALLY JM20 MAX Headphone Dongle Review

[TheEverydayNightmare]

That's the price you pay for 200mW @32Ω in such a small package.

Same deal with the FiiO KA11. Both use the SGM8262 Amp. Both run hot, even at idle.

is this an indication of inefficient/poor electronics? Or nonexistent software limiters?

 

[staticV3]

is this an indication of inefficient/poor electronics? Or nonexistent software limiters?

It is no fault of the JM20Max itself as far as I'm concerned.

Just the reality of squeezing comparatively powerful headphone amplification inside a tiny USB-C plug.

 

[TheEverydayNightmare]

It is no fault of the JM20Max itself as far as I'm concerned.

Just the reality of squeezing comparatively powerful headphone amplification inside a tiny USB-C plug.

I see... while on that note, the other guy who weighed in, @Somafunk, recommended the HiBy Digital D1 for me at 65mW @ 32ohms. I pretty much exclusively use this dongle with my new Verum 2's, (94 dB/mW & 12 ohms), I'm mostly concerned about the current draw(which is why I paired this jcally at like, 1 amps? 2 amps?? @ 12 ohms if I remember correctly), so does a power increase necessarily relate to an increase in current? Do manufacturers always try to balance voltage and current, so more power means more voltage and current? Like, if a manufacturer didn't provide current figures, using the Power formula, P=V^2/R, I get a voltage of 1.44 V, and 45mA @ 32 ohms. Are these accurate estimates? When impedance decreases and such, and power and current increase(or vice versa) then would it follow ohm's law perfectly? Or are there some physical or software things that might change this a bit unintentionally? What would typically be the current limit for this kind of dongle? Sorry for all the questions lol. Thanks!

 

[staticV3]

I paired this jcally at like, 1 amps? 2 amps?? @ 12 ohms if I remember correctly

At 12Ω, the JM20Max clips at 1.5Vrms, so that's 0.125A:

so does a power increase necessarily relate to an increase in current?

Yes.

using the Power formula, P=V^2/R, I get a voltage of 1.44 V, and 45mA @ 32 ohms. Are these accurate estimates?

At 32Ω, Amir measured 186mW so that's sqrt(.186*32)=2.44Vrms and 2.44/32=76mA

When impedance decreases and such, and power and current increase(or vice versa) then would it follow ohm's law perfectly?

Yes. Ohm's Law is not optional.

What would typically be the current limit for this kind of dongle?

Hard to say with the available data.

For the SGM8262 (Amp used inside the JM20Max and KA11), SGMicro specify a peak current of .31A at 32Ω, but that's with 24V/±12V supply voltage which dongles cannot afford.

 

[CedarX]

I see... while on that note, the other guy who weighed in, @Somafunk, recommended the HiBy Digital D1 for me at 65mW @ 32ohms. I pretty much exclusively use this dongle with my new Verum 2's, (94 dB/mW & 12 ohms), I'm mostly concerned about the current draw(which is why I paired this jcally at like, 1 amps? 2 amps?? @ 12 ohms if I remember correctly), so does a power increase necessarily relate to an increase in current? Do manufacturers always try to balance voltage and current, so more power means more voltage and current? Like, if a manufacturer didn't provide current figures, using the Power formula, P=V^2/R, I get a voltage of 1.44 V, and 45mA @ 32 ohms. Are these accurate estimates? When impedance decreases and such, and power and current increase(or vice versa) then would it follow ohm's law perfectly? Or are there some physical or software things that might change this a bit unintentionally? What would typically be the current limit for this kind of dongle? Sorry for all the questions lol. Thanks!

Note that if current draw is your main concern, you should not forget the HP/IEMs: selecting efficient ones (high dB/mW) helps as much, if not more, than selecting an efficient dongle.

You may also consider those dongles with an onboard battery (e.g. Qudelix 5K) which solve the current draw problem and come with many more features. But, that’s off-topic!

 

[jkim]

I see... while on that note, the other guy who weighed in, @Somafunk, recommended the HiBy Digital D1 for me at 65mW @ 32ohms. I pretty much exclusively use this dongle with my new Verum 2's, (94 dB/mW & 12 ohms), I'm mostly concerned about the current draw(which is why I paired this jcally at like, 1 amps? 2 amps?? @ 12 ohms if I remember correctly), so does a power increase necessarily relate to an increase in current? Do manufacturers always try to balance voltage and current, so more power means more voltage and current? Like, if a manufacturer didn't provide current figures, using the Power formula, P=V^2/R, I get a voltage of 1.44 V, and 45mA @ 32 ohms. Are these accurate estimates? When impedance decreases and such, and power and current increase(or vice versa) then would it follow ohm's law perfectly? Or are there some physical or software things that might change this a bit unintentionally? What would typically be the current limit for this kind of dongle? Sorry for all the questions lol. Thanks!

At 12Ω, the JM20Max clips at 1.5Vrms, so that's 0.125A:
View attachment 467382


Yes.


At 32Ω, Amir measured 186mW so that's sqrt(.186*32)=2.44Vrms and 2.44/32=76mA
View attachment 467383


Yes. Ohm's Law is not optional.


Hard to say with the available data.

For the SGM8262 (Amp used inside the JM20Max and KA11), SGMicro specify a peak current of .31A at 32Ω, but that's with 24V/±12V supply voltage which dongles cannot afford.

Note that if current draw is your main concern, you should not forget the HP/IEMs: selecting efficient ones (high dB/mW) helps as much, if not more, than selecting an efficient dongle.

You may also consider those dongles with an onboard battery (e.g. Qudelix 5K) which solve the current draw problem and come with many more features. But, that’s off-topic!

As for the JM20 MAX (and a variant like FiiO KA11 or Shanling UA Mini), here's a proper view IMO. It is one of a kind: single CS43131 + SGM8262-5 in a tiny form factor. AFAIK, the current supply capability of the SGM8262-5 is as good as it gets for a single, small op-amp. No wonder it generates heat. Actually the fact that it is hot to the touch means heat dissipates well through its metal housing. I like the design of the JM20 Max more than other variants.

By the way, I would not consider Hiby D1. It must produce DRE-induced distortion just as all Cirrus Logic DAC chips do. But it may do even more than CS431xx---it may have adopted more aggressive DRE parameters to compensate for greater thermal noise of the chip. Apparently the CS431xx has higher-quality analog circuitry of all their DAC chips.

 

[Ahmonge]

@TheEverydayNightmare
Mine doesn't heat too much; just warm to the touch. No noticeable battery drainage, but I'm using it connected to an iPad Air 13", whicih has a big battery.

 

[lucian]

the SGM8262 draws 10mA per channel constantly. thats 100mW constant power disipation just for beeing there.

 

[PiedroPieretto]

I really don't know if anyone else has this sort of issue, but I feel as if it gets very hot. I'm not sure if this is even supposed to happen lol. Is this normal? It get hot just plugged in without sending any signal :/

I've noticed this. It also is eating my iPhone's battery life like crazy even when not playing any music (but having it plugged in).

After having it plugged into my iPhone for 2 hours with maybe 30 minutes of actual music playback and not using my iPhone much for anything else during that time, battery drained from 100% to 60%.

I did expect battery drain to be more substantial with this dongle compared to the Apple Dongle, but 40% after 2 hours with 90 minutes of staying idle?

Again, makes me think that I very well got a faulty unit. Can't imagine this is normal, but anyone more knowledgeable, please challenge me on that.

I noticed similar with my JM20max along with battery drain so I now use a HiBy D1 with only 65mW of power which is more than enough for anything i own/use (in signature), it comes with the added bonus of having volume up/down buttons

HiBy Digital D1

The HiBy Digital D1 is a miniature USB audio dongle that may be connected to smartphones and computers alike! Best match: HiBy Digital D1 + HiBy Yves 6mm Micro-dynamic Ti-plated HiFi Earphones

store.hiby.com

How does the HiBy D1 compare to the US Apple Dongle in terms of power-to-performance?

 

[Somafunk]

How does the HiBy D1 compare to the US Apple Dongle in terms of power-to-performance?

No idea?, but it has plenty of power for anything I own (in sig). Just been listening to my xenns tea pro iem’s and only at 50/100 volume on low gain through Roon/tidal and I “could” go up to 60/100 but there’s no need

 

[VoidXero]

Mine failed after less than an hour of usage. Was playing music off an Android phone when it suddenly went silent. I thought I pulled the plug out or something but it was still connected. Tried it on other phones, laptops and even a desktop PC. Not a single one recognize it as a USB DAC. Don't bother paying more than $30 for one of these as they are a QC crap shoot. Sound was perfect while it lasted, though...

Just wanted to provide an update:

I got a replacement from good people at The Hangout by Crinacle and the new DAC has been working fine for many hours of use. It runs cool powering IEMs but does heat up quite a bit powering my Hifiman Edition XS or Focal Clear. I don't really see that as a problem since I only intend use it with IEMs on a regular basis. If you can get a good sample, this thing is great bang for the buck.

 

[PiedroPieretto]

I too got a replacement unit and can confirm that my previous unit was most likely faulty. It now connects seamlessly to my iPhone and stays connected even when I keep it plugged in for hours.

However, keeping it plugged in is still not something I want to do. There is absolutely a very, very noticeable drain on my phone's battery. It also does not appear to ever go into stand-by while having it plugged in as the plug is consistently warm to the touch even when no music is playing.

Even if this is due to this unit being broken as well (which I doubt), it would still be enough that I wouldn't buy one again. The lacking power regulation is absolutely an issue. Having the phone's battery drained by almost 20% after 30 mins of (screen off) music listening is just not acceptable for me.

Too bad. I really, really want to like it. ALAS, the Apple Dongle just is a better compromise between power and performance. As ist the Qudelix 5k which has almost no in-active drain on my iPhone's battery while connected via USB-C.

 

[CedarX]

As ist the Qudelix 5k which has almost no in-active drain on my iPhone's battery while connected via USB-C.

The Q5K has its own battery: not a fair comparison... The only reason to use the JM20-Max over, say the Apple dongle, or the non-MAX JM20 is if you need power. If you don't need that much power—as for the vast majority of IEM's—then yes, there are better choices.

 

[Ahmonge]

I too got a replacement unit and can confirm that my previous unit was most likely faulty. It now connects seamlessly to my iPhone and stays connected even when I keep it plugged in for hours.

However, keeping it plugged in is still not something I want to do. There is absolutely a very, very noticeable drain on my phone's battery. It also does not appear to ever go into stand-by while having it plugged in as the plug is consistently warm to the touch even when no music is playing.

Even if this is due to this unit being broken as well (which I doubt), it would still be enough that I wouldn't buy one again. The lacking power regulation is absolutely an issue. Having the phone's battery drained by almost 20% after 30 mins of (screen off) music listening is just not acceptable for me.

Too bad. I really, really want to like it. ALAS, the Apple Dongle just is a better compromise between power and performance. As ist the Qudelix 5k which has almost no in-active drain on my iPhone's battery while connected via USB-C.

I ran some tests with my unit connected to an iPhone 15 Pro Max. When running with no headphones connected and no audio playing, the battery drained at a rate of 3% per hour. In a second test, playing music (source: Qobuz, headphones: Hifiman Ananda), the battery drained at 7% per hour. The battery level was 67% at the start of both tests. During the second test, the unit became noticeably warm to the touch, but still comfortably manageable.

 

[PiedroPieretto]

And mine drained 10% per hour without music playing on the latest version of iOS.

Which likely means I’ve got yet another faulty unit. Call it a “fool me twice” situation.

I’m glad for anyone who has a great experience with this dongle. My experience has been soured by a questionable quality control.

 

[staticV3]

And mine drained 10% per hour without music playing on the latest version of iOS.

Which likely means I’ve got yet another faulty unit. Call it a “fool me twice” situation.

I’m glad for anyone who has a great experience with this dongle. My experience has been soured by a questionable quality control.

Have you tried actually measuring the current draw with an inexpensive USB power meter?

Battery percentage loss per hour is in no way a reliable metric that could determine if your dongle is faulty. Current draw is.

 

[markanini]

...Ideally with airplane mode enabled. Ampere is good app for Android. I don't know if there's something equivalent for iOS.

 

[Ahmonge]

And mine drained 10% per hour without music playing on the latest version of iOS.

Why do you need to let the unit connected if not using it? Just curious.

 

[HissingFree]

Why do you need to let the unit connected if not using it? Just curious.

A good use case for me is I will hear a podcast or something like that before sleeping, so the unit will be connected for like 8 hours.

 

[Ciobi69]

hey guys i should get a j20 max or the pro version? cost is about the same, will use the timeless 2 in ear on my iphone