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Review and Measurements of HTC Headphone Adapter

amirm

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#1
This is a review and detailed measurements of the HTC USB-C DAC and Headphone "dongle" aimed at mobile phone industry. It is on kind loan from an overseas member. I can only find overseas pricing for it but I think I found one site that listed it at USD $12. In that regard, it falls in the same price category of Google and Apple dongles.

As you can imagine, there is not much to this little adapter:

HTC USB-C Headphone Adapter Review.jpg

Hard to predict if the cable will fail sooner or later than its competitor.

Ghost in the Machine
When I received the HTC dongle, I had a heck of a time getting it to be recognized by Windows. I plugged it into the same USB-3 capable ports I use for testing every DAC. Here though, nothing would happen when I plugged it in. Reboot did not help either, nor would it show up in device manager in any way. I then tried it on my USB 2 front-panel and it worked! This is surprising as with other USB-C adapters, it is the other way around: the USB 3 port works and 2.0 doesn't. That was not all however.

I went to look at my past measurements for Google dongles as a comparison and I remembered that I had gotten inconsistent results there with respect to available power. After some investigation, it seemed that both Google dongles act differently depending on what load you have on them when you plug them in. In other words, if you hook up a 300 ohm headphone/load on it when you plug it in, the output power will be different than if you plugged it in using 33 ohm headphone/load. Highest performance was available when plugging in using high-impedance load and then switching to low impedance.

From what I recall, the HTC was backward yet again. To get the most power out of it, you had to first plug it in with a low load, and then switch to high impedance load.

This is quite troubling as without instrumentation and knowing the above, you have no idea what mode the adapter is in. So your experience may be different/worse than what the measurements show. This also explains why someone had trouble getting as much output out of the Apple dongle as I did in my testing.

Bottom line, like the LG phone I tested, all of these adapters have load sensing and decide how to operate to keep power consumption low as there is no space for them to dissipate any heat. Wish there was an LED or something to indicate operational mode. For now, this is a trade off you have when using such a cheap and light DAC+AMP.

Measurements
As usual we start with our dashboard:
HTC USB-C Headphone Adapter Measurements.png


This is not bad in grand scheme of things with respect to distortion/SINAD. It lands the HTC in our third tier performance bucket:
HTC USB-C Headphone Adapter SINAD Measurements.png


What is bad though is the anemic output voltage of just 0.8 volts. This will naturally hurt the power rating. Here is how much the HTC produces using 300 ohm load:
HTC USB-C Headphone Adapter Power at 300 Ohm Measurements.png


It does better than some of the other dongles like Google version 2 thankfully. At 2 milliwatts though, you can expect anemic response with such headphones.

Here is the performance using 33 ohm load:

HTC USB-C Headphone Adapter Power at 33 Ohm Measurements.png


Note that this has an update graph for Google V2 (in blue) where it now produces more power than earlier measurements showed. As such, the HTC loses to it by a bit, albeit with lower distortion.

Putting this data in context we get this:
HTC USB-C Headphone Adapter Dongle Power Measurements.png


Output impedance is a bit high and the reason it did not do better in 33 ohm test:
HTC USB-C Headphone Adapter Output Impedance Measurements.png


So be careful in using headphones with variable impedance that is below 50 ohm.

Listening Tests
As expected, the experience with high impedance headphone like my Sennheiser HD-650 was not that great. Bass was subdued and overall, there was not enough volume for more than background listening. Switching to lower impedance Hifiman HE-400i made the situation better. Here, at max volume, we had pretty decent sound. Mind you, it won't even come close to competing with desktop products or more powerful dongles but it did OK.

For someone like me who craves power, there is nothing that compels me to recommend the HTC headphone dongle.

------------
As always, questions, comments, recommendations, etc. are welcome.

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#3
I remember that my KEF EGG only works with USB 3.0 port, but the cable is A to Mini B(2.0).
 
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Jimster480

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#4
I have one of these new in box! I just never bothered to mail it to you because I didn't think you would care haha.
Glad to see its finally reviewed now. The performance is really disappointing considering that HTC had top tier audio performance prior to dropping the headphone jack.
 
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#5
Oof, so many people in China claimed that this little dongle is "the one" dongle that kills all other dongle products, the turth hurts...:facepalm:
 

Krunok

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#6
For someone like me who craves power, there is nothing that compels me to recommend the HTC headphone dongle.
I can hardly imagine this product was designed having your listening needs and habits in mind. Taking into consideration this thing costs $12 and was designed to accomodate earbuds as new HTC phones doesn't have the female connector anymore I think you should have try to listen to it with typical earbuds not some hungry power premium headphones.

To make car analogy - if I was to test a SUV but am used to sport coupes I would recommend no SUV. But is that really the idea of a testing?
 

Jimster480

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Oof, so many people in China claimed that this little dongle is "the one" dongle that kills all other dongle products, the turth hurts...:facepalm:
Its probably because HTC slapped so many other companies in audio quality back when they cared.
They have shifted away from being a company that cares and makes innovative products, to a slave for google that really doesn't care about any customers.
I can hardly imagine this product was designed having your listening needs and habits in mind. Taking into consideration this thing costs $12 and was designed to accomodate earbuds as new HTC phones doesn't have the female connector anymore I think you should have try to listen to it with typical earbuds not some hungry power premium headphones.

To make car analogy - if I was to test a SUV but am used to sport coupes I would recommend no SUV. But is that really the idea of a testing?
My HTC 10 has no problem with my Aeons or my PM-2's or my Denon AH-MM400s... nevermind any of my earbuds. The dongle is a move backwards.
 

Krunok

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#8
My HTC 10 has no problem with my Aeons or my PM-2's or my Denon AH-MM400s... nevermind any of my earbuds. The dongle is a move backwards.
Do you have any idea what you are talking about? Amirs Sennheiser HD-650 have impedance of 300 Ohms while your AH-MM400 have impedance of 33 Ohm. :facepalm:

Btw, I do agree that removing headphone socket was a stupid move that some phone manufacturers did, but that is completely another topic.
 

Jimster480

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#9
Do you have any idea what you are talking about? Amirs Sennheiser HD-650 have impedance of 300 Ohms while your AH-MM400 have impedance of 33 Ohm. :facepalm:

Btw, I do agree that removing headphone socket was a stupid move that some phone manufacturers did, but that is completely another topic.
I've tried HD800's in my HTC 10 before and I had 0 issues driving them to quite uncomfortable levels.
The Aeon is a current heavy headphone as is the PM-2. Both of them can struggle easily on small devices (like my iPod touch).

Taking a look at some tests of the HTC 10 by other websites, people show the THD+N around 95-100db and the power output at 0.89-0.98v with many sites showing a flat 0.955v.
 

amirm

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#10
I can hardly imagine this product was designed having your listening needs and habits in mind. Taking into consideration this thing costs $12 and was designed to accomodate earbuds as new HTC phones doesn't have the female connector anymore I think you should have try to listen to it with typical earbuds not some hungry power premium headphones.
Google V1 and Apple dongles also cost the same and have more power. You would also be surprised how many people wear big cans and like to drive them with their phones using these dongles.

Keep in mind that the subjective part of my headphone amp testing is for the benefit of the community. I have standardized on these two headphones so that the results can be compared from review to review. I actually don't use either headphone for everyday listening, nor at such elevated levels.
 

bravomail

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#11
Thx for review, Amir! Another one bites the dust! I more and more think that good built-in DAC is the way to go for mobile devices. So far only Apple's dongle proved good and it is not properly compatible with Android devices.
 

BYRTT

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#12
...When I received the HTC dongle, I had a heck of a time getting it to be recognized by Windows. I plugged it into the same USB-3 capable ports I use for testing every DAC. Here though, nothing would happen when I plugged it in. Reboot did not help either, nor would it show up in device manager in any way. I then tried it on my USB 2 front-panel and it worked! This is surprising as with other USB-C adapters, it is the other way around: the USB 3 port works and 2.0 doesn't...
Hmm that sounds weird but interesting thanks sharing experience, makes one dirty quick conclude then that USB 3 port ain't really backwards compatible as often adverticed for each generation.

...I went to look at my past measurements for Google dongles as a comparison and I remembered that I had gotten inconsistent results there with respect to available power. After some investigation, it seemed that both Google dongles act differently depending on what load you have on them when you plug them in. In other words, if you hook up a 300 ohm headphone/load on it when you plug it in, the output power will be different than if you plugged it in using 33 ohm headphone/load. Highest performance was available when plugging in using high-impedance load and then switching to low impedance.

From what I recall, the HTC was backward yet again. To get the most power out of it, you had to first plug it in with a low load, and then switch to high impedance load.

This is quite troubling as without instrumentation and knowing the above, you have no idea what mode the adapter is in. So your experience may be different/worse than what the measurements show. This also explains why someone had trouble getting as much output out of the Apple dongle as I did in my testing...
Any chance go into Windows active powerplan and change USB selective suspend setting to deactivated will change that variable available power.

A note on above setting is my Khadas TB sounds excellent on Win7 with USB selective suspend activated, never the less while sound is active streaming and monitored over head phones then a change in settings to deactivated will improve sound a tiny bit, a little like when one dial in bias setting for silicon output devices on a power amp in the derection where it reach class A drive. Know this experience is pure subjective and doesn't make any signs in objective graphs but i swear its audiable : ) another note is experience is accurate same using a laptop or desktop and ports used was the standard Intel chipset generation 2.0 ports.
 
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#13
Any chance go into Windows active powerplan and change USB selective suspend setting to deactivated will change that variable available power.
I doubt that will change anything. I also noticed this inconsistent behavior on the Google dongle and discussed it at length in my own review (see the "load sensing behaviour" section), and I was measuring with an Android phone, not Windows. Basically, the Google dongle behaves differently depending on the load impedance it "sees" when either the dongle itself or the jack is plugged in.
 
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