HA INFO NG27, another DAC Headamp
Jul 20, 2009 at 6:31 AM Thread Starter Post #1 of 30

acetate

New Head-Fier
Joined
Jul 20, 2009
Posts
13
Likes
10
Prequel

There are many DAC Headphones amp combo on the market now. The famous ones should be ZERO DAC, Compass DAC and the smaller ibasso. The Compass offers fabulous sound quality but comes with a price, while ibasso offers the portability at somewhat similar price range. Both are great products, but seems like it is always a tradeoff between size and sound quality. You can only have one of them.

For the price reason, ZERO DAC became the all time favorite for such DAC headphones amp set up. Priced lower than USD200, the ZERO provides fairly good performance but housed in bulky and flimsy chassis. That is something I dislike about ZERO, thus I am hunting for more similar product on the market.

First thought that came into my mind was: all 3 products mentioned above are Chinese brand; I should continue to search in the Land of Dragon for some reasons: The products are priced too high for Chinese local consumption, the ability for other Chinese brands to copy, the technology used in the products are not unique to one company. There should be more similar products undiscovered by foreigners, as the Chinese are beginning to be like the Japanese, local consumption is all it takes to feed a company.

Introduction

Thus my journey began, and true enough, I have found a few great DAC AMP combos, and will do a series of sharing about them. My last review was the Compass/ZERO’s rival, the USB Mini DAC. Now, I am going to introduce a low cost option, the HA INFO NG 27 USB DAC + Headphones Amp.

Priced at only RMB380 in Chinese retail market, the NG27 is based on a very simple and trust-worthy design. It is as if the combination of Alien DAC and META42 amp. The DAC section of NG27 actually implemented in the simplest way to get the PCM2702 working; purist concept. The amplifier section is very similar to the META amp, using opamp to amplify the audio signal and buffer to supply the current to drive the headphones. The NG27 uses opa2134 and BUF634.

In my opinion and experience in audio DIY, simple circuitry sounds best with exotic components, because only those are only few parts that affect the sound signal. With this reason, I threw away the opa2134 and replace it with dual opa627 (the opamp and buffers are user replaceable).

Build Quality

Although it does not feature the thick brush aluminum faceplate as the Mini USB DAC, the NG27 definitely not shy in term of sturdiness as it is constructed using fairly thick aluminum alloy. The black paint is done professionally, and it does not look or feel cheap, or even as good as the ibasso’s.

The connectors both at the front or back are of high quality, tight and grip the connector well. The headphone jack is a clone neutrik jack. Although it is not as good as the real thing, it is definitely much better than normal headphone jacks.

The PCB is populated with mostly audio grade components, the nichicon and WIMA audio grade capacitors.

The Sound

(The tested unit is using best audio opamp opa627)

First impression after 10 hours burn-in:

Test track: Fields of Gold by Emi Fujita, PCM WAV format, uncompressed.

The texture of the sound is good, very good; “full body” and warm, delivered to the eardrums with weight. I have never heard Emi’s voice in real, but I heard this track on speaker set up before, gosh, it has those “British sound”, warm mids. Taste like thick, dark coffee. (Something which I am not very used to, I like Jap sound) The amplifier is not as powerful as the Mini’s, and less dynamic, but nevertheless still sound big thanks to the opa627.

Sound Imaging:

Test track: March F The King of Laois by the Chieftains, PCM WAV format, uncompressed.

Live recording is always the best for sound imaging test. The track started with a round of applause, and due to rich lows and lower mids, the clapping sounds real. Next, the soundstage is ok, not very wide, sounds like in a theater or a hall, definitely not stadium. Throughout the track, the Chieftains are crazy and shout here and there, “ohh” here and “woh” there. That is the best time to catch the positioning. Instrument separation is good; I can hear the violin, the pipes, and the drums in rather accurate positioning and depth. However, compared to the Mini USB DAC, the NG27 still lose out in the soundstage and airiness.

Sound Detail:

Test track: Barrio san Miguel [Bulerias] in Guno D’Auri, PCM WAV format, uncompressed.

This track is a flamenco kind of guitar music, coupled with percussions. The plucking of strings could be heard, but not very clear as it is overwhelmed by the rich guitar sound itself. The drums and percussions too, not much reverb could be heard, the drum and percussion itself already slam hard, and cover those detailed. Overall, musicality is very good, without those details, it might make music listening less fatiguing and more enjoyable.

Conclusion:

Overall a very good value for money piece of DAC amp, going for RMB380, and extra RMB80 for the dual opa627, it is definitely a good buy for entry level PC HiFi enthusiasts. The NG27 comes with another function which is not tested yet; it accepts analog line in and can function as standalone headphone amplifier. Compared to the USB Mini DAC, I would say it is at least 70% to 80% as good.

The original text:
HA Info NG27 Review | IsnoopyU.com

The product website official url:
HA INFO Audio Studio


snc10001_0.jpg


snc10007.jpg


snc10008.jpg
 
Jul 21, 2009 at 3:05 PM Post #2 of 30
Hi,
and thank you for your impressions!
smily_headphones1.gif
Can you say something about hiss and gain? Could you please test it with sensitive IEMs to see wether or not it's hissing?

best regards,
bearmann
 
Jul 28, 2009 at 5:53 AM Post #3 of 30
Quote:

Originally Posted by bearmann /img/forum/go_quote.gif
Hi,
and thank you for your impressions!
smily_headphones1.gif
Can you say something about hiss and gain? Could you please test it with sensitive IEMs to see wether or not it's hissing?

best regards,
bearmann



I am sorry, I don't have good IEMs to test. The closest to IEM would be 16ohm earbud and the Vsonic R02. Other test phones are HD600 and Bayer DT880, of course there's no hiss on this high impedance phones.
 
Jun 12, 2010 at 9:26 PM Post #4 of 30
You can now get the MK II version of the HA NG27 from the Chinese company HA INFO on eBay for $72USD ($75CAD) shipped. That’s cheaper than the $80-$85 for the original. This model was apparently launched in May 2010. The same DAC is used but there are major changes to the amp and DC power sections. The 1/8” line-in has also been traded for RCA line-outs. The changes are hopefully improvements as the people behind HA INFO gain more experience.
 
Looks:
- same black painted aluminum alloy case 
- new brushed aluminum end plates, black option
- different aluminum volume knob
- added small feet instead of resting on the face plate
 
Front and Back:
- added power switch on front
- different non-locking 1/4" jack on front
- added RCA DAC outputs on back
- removed 1/8" line in from back
- power LED on front, removed the other LED
 
Original HA NG27

 
 
HA NG27 MKII

 
So on the outside the DAC section changed as now you can use it as a standalone DAC while the internal DAC stayed the same. From the outside the amp still functions the same way (minus the analog inputs) but on the inside it has been completely revamped to use a transistor push-pull design with a new opamp.
 
 
Features:
- changed to a transistor push-pull amp design
- rated for 32Ω - 250Ω vs. old 32Ω - 300Ω rating
- same 16bit 48khz max DAC section
- same USB-B input, shielded cable included
- same plug and play windows 2K and up
- same 12V DC power, adapter included
 
Audio Components:
- same Texas Instruments PCM2702E DAC
- changed opamp to Burr-Brown OPA2604AP from BB OPA2134
- removed the BUF634 buffers
- added BD139 and BD149 transistors which were not on the original
- 1/4" jack is now soldered instead of using a pin connector and wire leads
- same stereo pot
- removed large cap near the DC input
- added a coil and a large 5 pin chip near the DC input
 
Original HA NG27 PCB

 
HA NG27 MKII PCB
 

 
Leeperry has commented that his friend preferred the original model over the Asus STX and sold his STX. That is the only other review I have found besides this one from acetate(Huangyong). Using Google and following a link from leeperry on another forum I only found one other review. Fred86`s impression was positive with Yuin PK3 though that is to be expected. On the same forum [Top-Gun] said the original powered DT990 250Ω fine in his FS post but didn't give any comparison other than saying it sounded great.
 
A will be buying this unit after I have used my new DT880 250Ω for a couple of weeks on my current gear. I just wanted to let everyone know that the new version is out and ask about the new changes. Are there any pros or cons to the new amp section design from a components/basic principals standpoint? I`ll get the MKII unless someone completely rips apart the new opamp/transistor amp design as being inferior for high impedance cans or something.
 
The amp section in this unit should be better than a uDAC and similar to the Musiland Monitor 02 for 250Ω cans as far as power goes. The Musiland Monitor 02 I`m sure has a better sounding DAC but feature wise all that is added is 24/192, a low gain 1/4" jack and optical out. For me none of these things are useful as I don`t have a private tracker membership or the equipment to rip vinyl, my motherboard has optical/coax out and I don`t use IEMs at my desk. There is also the "disadvantage" of custom drivers and software instead of plug and play and a simple volume pot that you can adjust without leaving your movie etc. At this level the extra $55-$65 for the Moniter 02 is a major difference when the NG27 MKII is only $75.
 
Jun 13, 2010 at 12:10 AM Post #6 of 30
About the diff between the older/newer models, an italian friend of mine(who's quite an opamp rolling nutcase) said: "The new model has a better headphone amp, with much higher-current output transistors (in place of the 250 mA buffers, which despite the current spec. will struggle a little with 32 ohm or less). Also I prefer the RCA line out of the new version."
 
I've had the newer model shipped to me earlier this week, I might make a thread in the "dedicated source" forum w/ pics+impressions. A friend of mine wants me find an optimal opamp for his MDR-CD850. I don't think LT1363 will work(too much DC offset?) so maybe I'll use AD797BR/OPA132U...not sure yet
popcorn.gif

 
Jun 13, 2010 at 1:11 AM Post #7 of 30
Oh great, I was thinking I was going to be first. If what your saying is that the new output transistors are able to drive higher impedance loads better than the old buffers than I'm getting the MKII for sure. I think I might not even read your review of the unit for at least a month after I get mine so I can do my own mental mini review and compare my experience to yours without bias.
 
Jun 13, 2010 at 2:40 PM Post #8 of 30
I wouldn't touch HA-info myself.
http://www.head-fi.org/forum/thread/474294/ha-info-ng94-mkii
 
Sloppy build quality, their claim for the ridiculously overpowered output is "to raise snr" - in other words, a trick.. A 2 vrms dac can easily reach 124db snr/dynamic range, so why the F use an output so strong that it can overdrive or even fry gear? Over 124db snr is really quite unnecessary, and 3vrms is like using a tank's cannon to blow away a fly.
 
Not to mention if you have a defective unit, you'll have to repair it yourself unless you want to spend $40 to ship it to china. Jesus christ.
 
Jun 13, 2010 at 10:28 PM Post #9 of 30
Oh great, I was thinking I was going to be first.


Several friends of mine have the older version and the only thing they complained about is the crappy pot...but well, even the uDAC has one too. You can't get a high quality pot for so cheap
rolleyes.gif

 
The new unit has a RCA out, and my friend's CD850 is dead easy to drive so I'll be using one of those adapters w/ digital volume attenuation: http://www.buyincoins.com/gallery/pc/3.5mm-female-2rca-adapter-0.jpg
 
Jun 13, 2010 at 11:28 PM Post #10 of 30
That's one advantage to overpowered lineouts. Your bypassing the headamp to avoid the pot? What opamp is used to drive the headphones then?
 
Are there good pots with the right resistance that you can get of ebay for <$10? I guess if I hate the pot I can always just set it high and adjust digitally or open it up and bypass the pot by adding a few short wires. It looks like the exact same pot which is too bad. I guess the designer might always control the level of the lineouts digitally to match the amp so that is why it is possible to hit 3V with a full level digital signal. I guess you loose bit perfect data, I don't know how much that affects the signal quality though.
 
Jun 13, 2010 at 11:51 PM Post #11 of 30
most DAC's output 2Vrms on their line-out AFAIK.. HA-Info's site down and my ebay seller listing doesn't mention it for the NG27 MK2.
 
a good stepless pot costs 10X the price of the NG27, and I'll take digital attenuation over a crappy stepless pot w/ major stereo imbalance <9 o'clock anytime. If most serious amps use a stepped attenuator, there's a very good reason
wink_face.gif

 
I don't know what the stock opamp is, but I'll replace it anyway.
 
Jun 14, 2010 at 12:22 AM Post #12 of 30


Quote:
That's one advantage to overpowered lineouts. Your bypassing the headamp to avoid the pot? What opamp is used to drive the headphones then?
 
Are there good pots with the right resistance that you can get of ebay for <$10? I guess if I hate the pot I can always just set it high and adjust digitally or open it up and bypass the pot by adding a few short wires. It looks like the exact same pot which is too bad. I guess the designer might always control the level of the lineouts digitally to match the amp so that is why it is possible to hit 3V with a full level digital signal. I guess you loose bit perfect data, I don't know how much that affects the signal quality though.


Lowering the digital signal pushes the noise floor up.
 
Jun 14, 2010 at 12:58 AM Post #13 of 30
 
Using google translate with the HA INFO site it does say the unit has "6.35 output and RCA stereo headphone stereo output" which sounds like the RCA could be driven of some non-standard way. Latter though it says "connections are suitable for multimedia speaker, external amplifier, etc." It may be the high output is only with the NG94 MKII anyways. Do you know what opamps or circuits connect the dac to the lineouts leeperry? 
 
Quote:
Lowering the digital signal pushes the noise floor up.



 
Oh yeah. It shouldn't be noticeable with 250Ω but good point. That may be an issue with easy to drive cans.
 
It sounds like the problem is only with the pot at < 9 o'clock so I probably wont notice any imbalance.
 
Do you mean that amps with proper stepless pots cost $750 or that the actual pots cost hundreds of dollars? I never really realized so many amps used stepless knobs. I was reading through the higher end amp reviews looking at their volume control and now I really want a Matrix M-Stage. I was going to stop at $100 ATH-M50 with my receiver, then I found a pair of $150 DT880, now I want a better source that can push them to their full potential. I think that whatever the NG27 can do with a little eq is where I'm going to draw the line.
 
^^ that is supposed to be under the quote bellow but the editor is broken
 


Quote:
a good stepless pot costs 10X the price of the NG27, and I'll take digital attenuation over a crappy stepless pot w/ major stereo imbalance <9 o'clock anytime. If most serious amps use a stepped attenuator, there's a very good reason
wink_face.gif

 
 
 

 
Jun 14, 2010 at 1:08 AM Post #14 of 30
quoting at the bottom instead of the top is confusing...anyways, when you listen at low volume you're merely using 10bit. And a high quality media player does very accurate attenuation(53bit float in Reclock, 64bit float in foobar/ulilith). As long as the SNR is >100dB on the line-out, it'll sound far better than a crappy pot ever will 
wink_face.gif

 
I dunno what opamps are used, but I'll swap them anyway...prolly some crappy OPA2604/2134 or so.
 
a bootcamp on why cheapo pots suck: http://www.bursonaudio.com/hp_volume_control.htm
 
but I find stepped pots not accurate enough when you like to listen at low volume on highly sensitive phones...digital attenuation adresses all those problems, and a Griffin Powermate is just awesome to use!
 

Users who are viewing this thread

Back
Top