Audio-gd NFB-5.2 DAC/Amp

For a while now I’ve been using a Creative X-Fi USB soundcard as my quality DAC and amplifier and it’s done an amazing job, but as a USB-powered amp, it was never going to shine with any truly high quality headphones. And so it came to pass that I decided on my first step into the realm of dedicated headphone amplifiers – the Audio-gd NFB-5.2

I decided on the NFB-5.2 because it is a combination digital-to-analogue converter (DAC) and headphone amplifier. Reviews I read seemed good and it was available from the great crew at Addicted to Audio where I buy a bunch of my stuff (often with their wise advice).

Specifications

Signal to noise ratio:  119dB
Output power:  3500mW @ 25 ohm – 150mW @ 600 ohm
Output impedance:  2 ohm (headphone out)
Sampling support: 44.1kHz – 192kHz (16-bit or 24-bit)
Inputs:  Optical, Coaxial, USB

I’ll review the NFB-5.2 in 3 stages: first a quick overview, then the DAC, and then the amp.

Overview

The front panel of the Audio-gd NFB-5.2The NFB-5.2 is quite simple and that’s good. On the front of the unit is:

  • A power button (left)
  • Volume control (right)
  • 6mm stereo headphone socket with a securing system to keep the plug in place
  • Simple, 4 character, blue display
  • 4 control switches (under the display)

All of the buttons and the volume knob are brushed metal and the case of the unit is also all metal. It’s not super heavy, but seems very well built.

The 4 buttons under the display allow you to select different options.

Button 1: Filter

The “Filter” button lets you select from a number of filters used to remove unnecessary frequencies from the DAC output. It’s generally not something that you’ll notice in the sound and is used more to remove subtle digital artefacts and noise from the signal. I played around a bit and now leave my NFB-5.2 set to filter #6 which has creates an output that looks like this:

A graph showing the effect of filter #6

Filter #6 frequency response chart

As you can see, it only starts to affect the sound at around 20kHz and above – all frequencies which are beyond normal human hearing limits, but it should help to clean up the overall signal.

There’s a full listing of the possible filter options here.

Button 2: DAC/HP

This button has 4 options. Options 1 & 2 activate the headphone amplifier output either without (option 1) or with (option 2) the OP amp. Options 3 & 4 activate the RCA line outs on the back of the NFB-5.2 and allow you to use it as just a DAC with a separate dedicated amplifier. Once again the two options are for the OP amp being used or not used.

The OP Amp

The OP amp (OPA) is modular circuit that can colour the sound to suit individual tastes. Audio-gd supply the NFB-5.2 with their OPA-2134 model, but you can buy 3 different options as aftermarket (or custom) options. The 3 other OPAs offer neutral sound, warm sound, or dynamic sound. I hope to review the OPAs separately in the future.

In relation to the OPA-2134 that comes standard, my feeling is that it’s better left switched off. Engaging the OPA using setting 2 or 4 of the DAC/HP switch results in a flatter sound with less depth and a weaker sound stage. There’s really no improvement that I can discern.

Button 3: Gain

A very simple option here: “high” or “low”. The “high” option apparently adds a 12dB boost across the range (from the DAC, not the amp). When I’ve used high gain, the sound seems to become a bit edgy when compared to the equivalent volume on low gain. I’m sticking to the low gain option, but others might like the extra energy delivered by the high gain.

Button 4: Input

3 options here: USB, Optical or Coaxial. Very simple.

All work the same although I have read claims of slight sound variations between the 3 inputs. As I don’t have a source with all three outputs I can’t do a fair comparison.

NFB-5.2 DAC Stage

The DAC in the NFB-5.2 is really nice. I’ve run my Bang & Olufsen BeoLab 3 speakers using the line out of the NFB-5.2 and the sound is beautifully clean, well-layered with plenty of separation between instruments and creates a stunning sound stage through the BeoLab 3’s acoustic lenses.

As I’ve already explained, the filter system is a nice feature for those who are more technically inclined, but once it’s set you’ll probably not think about it ever again so essentially the NFB-5.2 DAC stage is a set-and-forget affair and it does a fine job.

The TE8802 Chip

The NFB-5.2 is an upgraded version of the NFB-5. The only difference (according to what I’ve read) is the inclusion of the TE8802 USB chip. The TE8802 allows for asynchronous transfer… yeah, I didn’t understand either!

What all this really means is that the NFB-5.2 should be less susceptible to minor issues with errors created by the USB chip in your computer slowing down or running inconsistently. In short, it’s a minor upgrade that’s nice to have, but likely won’t be a game changer.

Compatibility

The NFB-5.2 worked perfectly with my laptop running Windows 7 (64-bit) and MediaMonkey as my media player. The Audio-gd drivers, combined with the TE8802 chip allow the NFB-5.2 to work all the way up to 192kHz/24-bit. After doing some reading, I believe there’s no real benefit (and possibly some disadvantages) to using 192kHz output sampling so after testing that it worked, I reverted to 96kHz sound and it’s brilliant!

It’s worth noting that ASIO drivers seem to give the best sound and best compatibility with the NFB-5.2. I started out using WASAPI drivers, but they created some nasty cracks and pops from the computer (not the NFB-5.2’s error) and the sound seemed better when using ASIO.

NFB-5.2 Amp Stage

The amplifier in the NFB-5.2 is probably slightly weaker than the DAC. Where the DAC seems to be beautifully clean and crisp, the amp strikes me as just a touch soft around the edges. Perhaps it’s just a warm sound signature when I prefer a more analytical sound in general. There is also a hum that’s audible through my Shure SE535 LE in-ear monitors, but read on because that’s not necessarily a bad sign.

Power

The NFB-5.2 has plenty of grunt. I’ve just received my new Sennheiser HD650s (thanks Gavin!!) and the NFB-5.2 volume control only just clears 50% (on low gain) to drive the 300ohm HD650s. There are very few (if any) conventional headphones that the NFB-5.2 couldn’t drive. Obviously there will be much more expensive amps that will sound better, but it’s got the power.

Noise

This is a tricky one. With the 300ohm HD650s, the NFB-5.2 sounds pitch black – no noticeable noise. On more sensitive cans like the Audio Technica AD900s, there is some hiss when you turn the volume right up (>75%), but none at normal listening volumes. From this perspective, the NFB-5.2 is nice and clean.

What put me off slightly here is the noise I heard when I connected my Shure SE535 LEs. The Shures are hyper sensitive (119dB SPL/mW) and this showed up a background hum from the amplifier. The NFB-5.2 is listed with a 119dB signal to noise ratio so there’s a good chance the SE535 is picking up the end of the NFB-5.2’s quality control limits and that’s OK – it’s not meant for driving hyper-sensitive IEMs. The main reason for my concern was that the hum isn’t balanced – it is louder in the left channel. That might not mean anything, but I look forward to testing the SE535s on another NFB-5.2 next time I visit Addicted to Audio. Maybe the right channel on my unit is just slightly cleaner than Audio-gd’s quality control standards, but I’m keen to make sure there’s not an error somewhere in the circuitry of my amp.

NOTE: It’s important to note again here that an amp like the NFB-5.2 is not really designed to drive super sensitive, low impedance monitors like the SE535s so this isn’t a major flaw, but until I can test a few other similar amps, the unbalanced hum leaves a tiny doubt in my mind.

Control

The NFB-5.2 amp is really well controlled. My Ultrasone HFI-680s can be quite bassy and that can cause them to lose clarity and control if not well driven. The NFB-5.2 does a great job of tightening the bass and keeping it punchy and full.

I mentioned earlier that the NFB-5.2 amp seems slightly soft around the edges and while that is definitely the case, there is no doubt that it does an amazing job for the cost. It’s an incredibly good amp for the cost (especially when you get a great DAC built-in).

Overall Conclusion

Would I buy the NFB-5.2 again if I had my time over?

Absolutely!!

For less than US$400 plus shipping costs (about AU$480 here in Australia) you get a really nice DAC with a solid, powerful amp that will drive anything very well. The amp may tend towards being slightly warm, but it reveals detail well and definitely won’t create fatiguing edginess in the sound. Being able to bypass the amp in the future while maintaining the really nice DAC stage of the NFB-5.2 is a massive bonus!

The high gain mode seems to bring some unwanted distortion or edginess to the sound, but there’s so much power on tap that you don’t need to use it if you don’t want to.

Of course, there’s also the fact that you can buy different OP amps for around $40 each and modify the sound to your tastes. I look forward to trying these out and sharing some thoughts in a future blog post.

If you’re looking for a nice entry point into DACs and amps, the NFB-5.2 is an excellent option – well priced, clean, powerful and simple to use – I’d recommend it.

Super Sounding IEM Shootout

Today’s post is about 2 very different in-ear monitors (IEMs) (i.e. canal phones or earphones that go inside your ear like an earplug). They are very different in technology, slightly different in sound style, very different in looks, extremely different in price, but very similar in quality. So which one’s better for you? Let’s find out…

Our contestants are the Shure SE535 Limited Edition and the HiFiMan Re272

Dressed in red, the Shure SE535 Limited Edition

Dressed in black, the HiFiMan Re272

Both of these IEMs are recognised as offering brilliant sound quality, but they do it very differently. The Shures use 3 drivers per earphone. Yes, there are 3 tiny speakers in each of those red casings! The drivers are a balanced armature type. Don’t worry if you don’t know what that means – I didn’t either until I spent some quality time with Google. In essence, the balanced armatures are a delicate and sensitive system to push the air that makes sound. They are very good at picking up subtle details in sound, but can sound a bit thin at times and without the warmth of the alternative system. The alternative system is dynamic drivers. These are exactly what we’re all used to seeing in our home theatre systems or car stereos. They have good presence and warmth, but are sometimes less sensitive. The Re272s use just 1 dynamic driver per ear, but don’t be fooled by the 1 vs 3 matchup – dynamics and balanced armatures bring very different characteristics so it’s not won or loss based on this matchup.

I want you to know that I have not planned the order or results of this shootout – I am writing, reviewing and scoring as I go so you are experiencing the comparison exactly as I am and the results will be as much a surprise to me as to you! I’ll score each section out of a possible 10 points for each phone.

Let’s look at the all-important dollar…

The Shure Se535s will set you back around AU$400-500. That places them right up near the top of the pile for non-custom IEMs. There are only a few mainstream brands (e.g. Westone) that charge more for an IEM that doesn’t require an audiologist to make moulds of your ear.

At nearly $500, the 535s may be instantly knocked out of contention for some, but read on because you might find some good news waiting for you.

The Re272s are much more affordable at around AU$250 making them still expensive compared to some alternatives, but there is very little (if anything) for less money that will sound as good.

So far it’s Re272: 8, SE535: 5

Usability & Comfort

Both headphones can be worn with the cords going over the ear, but only the 272s can have the cord straight down. Although it’s fiddly to get used to running the cord over your ear, I find the benefits definitely worthwhile. Wearing the cord over your ear means little or no noise is transmitted through the cable to your ear and it also means that if you snag the cable on something, it doesn’t put pressure directly on the fragile joints where the cable meets the earphone.

Both earphones come with a range of tips, but the 535s have a few more options (including foam tips). In the end, I’m using non-standard tips with both: Comply foams on the 535s and Sony Hybrid tips on the 272s. The range of options supplied with the 535s is offset by the small size tube which can make using aftermarket tips a bit tricky. The 272s are slightly larger than some others, but seem to fit most standard tips I’ve tried.

Both earphones are really comfortable so it’s a draw here… Still Re272: 8 + 8 = 16, SE535: 5 + 8 = 13

Isolation

One of the key benefits of IEMs is their ability to block outside noise. The 535s excel here because of their use of balanced armature technology which is happy in a completely sealed shell. The dynamic drivers in the Re272s need a small vent and therefore allow a tiny bit of sound to come in. I also find that the fit of the 535s helps to keep them snug and keep a secure seal. Using both on a noisy train or airplane, you can definitely hear the difference and it means you either have to go louder with the 272s or lose details in the sound so it’s a win to the 535s for isolation.

Running score: Re272: 16 + 6 = 22, SE535: 13 + 9 = 22

Flexibility

The SE535s are crazily sensitive. While this gives them the ability to delivery incredible details, it also makes them susceptible to poor source quality. They often produce background hiss from poor source units (i.e. amplifiers and players) and can be quite uncomfortable to use for listening to low quality sound such as radio and podcasts. The Re272s are still very revealing and can border on uncomfortable for my favourite podcasts, but they’re a step ahead of the 535s here and are my earphone of choice for low quality sources.

Re272: 22 + 8 = 30, SE535: 22 + 6 = 28

Build Quality

Both IEMs appear well-built and are both made from plastic so no major advantage there. The 535s have a slightly better feel to them and look sexy whereas the 272s could be cheap plastic painted to look nice – it’s hard to know. I definitely trust the 535s more than the 272s based on the feel of them alone, but only time will tell. If I have to choose to give an edge to one over the other, I have to choose the 535s not just for their look and feel, but also for their detachable cable and quality of cable (although that opens a whole other topic which I’ll need to cover shortly).

Re272: 30 + 8 = 38, SE535: 28 +9 = 37

Sound Quality

The all important question! In a case like this where it’s hard to separate the 2 options (except by price), sound becomes everything. It’s not like one of them is ridiculously uncomfortable or brings some fatal flaw so sound is the deciding factor.

The Re272s jump to mind first so let’s discuss their sound. The sound from the 272s is almost flawless – they do nothing wrong, but they also don’t excel anywhere. The sound is neutral without any specific emphasis and instruments are clearly spread out and placed clearly in the soundstage. There is texture to the sound and some energy to the sound, but the bass lacks some fullness and punch. Without EQing (which I’m avoiding purely to keep this shootout a consistent approach), the 272s occasionally leave me wanting more oomph.

The SE535s bring better bass impact and slightly better layering and texturing of sound. You can get lost in the sound of the 535s more so than the 272s, but the placement of the sound is slightly clumsy because of a slight emphasis on mid-range frequencies. On some tracks, you can hear the whole band perfectly laid out before you, but on other tracks it can sound like the band is all clustered together when it shouldn’t be (i.e. the issue is the earphones, not the recording).

So, based on the sound qualities, it is very hard to split the 2, but I think the seductive qualities of the 535s and being able to get lost in the sound leads me to reach for the 535s first (unless it’s for poor quality sources).

Re272: 38 + 8 = 46, SE535: 37 + 8 = 45

There’s one final thing to mention before I give an overall final score. The detachable cable supplied with the SE535s means that you can replace it with a range of aftermarket options. I was fortunate to have a friend in Hong Kong send me an aftermarket cable to try out (thanks Gavin!!) Despite having good results with hifi cables, I was sceptical of the power of a cable change on headphones, but was SO wrong!! The cable completely transformed the SE535s (you can read about it in my review of the SE535s). With the Baldur Mk2 cable attached, the SE535s move head and shoulders above the Re272s, but the total price increases by about AU$140 for the cable so I have to update the price scoring too.

Price adjusted scores with aftermarket cable for SE535:

Re272: 46, SE535: 35 + 1045

So the Re272s win the shootout when we consider all different characteristics and even the aftermarket cable… but part of me is unsatisfied with the result because I know that I always reach for the SE535s first. The reason I’m not satisfied is that I own both now so the price is no longer an issue and that changes everything. Let’s look at the scores again without the price element…

Final, money-no-object scores:

Re272: 46 – 8 = 38, SE535: 45 – 3 = 42

Conclusions

If you’re on a budget that won’t allow $500+ for IEMs (including aftermarket cable) then the Re272s are exceptional value and quality, but may need a slight dose of bass from your EQ. You’ll need to go a long way and spend a decent amount more money to get equivalent or better sound quality.

If budget isn’t such a concern and you can save up the $$$ or consider purchasing the aftermarket cable later, then the SE535s are simply amazing. They’re probably not perfect, but they are one of the most amazing audio experiences I’ve had for less than $30,000 and that’s saying a lot!!

One final note…

I forgot to write this before publishing, hence why it’s tacked on at the end.

The Re272s are able to run in a fully balanced setup. This means finding an amp that I can test them on which is why I can’t comment now. It also means that most people will use them with a standard common ground setup (i.e. both earphones have a signal cable and an earth wire going to them. The earth wires join up into one before they connect to the source unit) which makes the above comparison more relevant to the majority.

In theory (and from what I’ve read), the balanced configuration does significantly improve the sound, but will also require the purchase of a high quality amplifier which will increase the total cost to equal or more than the Shure SE535s with aftermarket cable so it’ll be an interesting comparison. I’ll post more when I can test the 272s with a balanced setup.

Shure SE535 Limited Edition

I have owned the HiFiMan Re0 earphones for about 2-3 years, but they recently succumbed to a broken connection inside one of the earphones so I decided it was time for an upgrade. It’s been quite a journey…

After much research, I had decided on a few potential options, but my decision came down to a question of availability. The fact that I could buy the 535s from my favourite audio shop made it a simple decision. Thanks as always to George and the team at Addicted to Audio for their assistance with advice, comparisons and of course selling me all these wonderful goodies!!

The contents of the SE535-SE box

The 535 LEs come with all the same accessories as the standard 535s, but they DO sound different. The key difference is a slightly stronger top end and that improves the staging produced by the earphones, but back to the accessories…

The 535 LEs come with a grey, detachable cable (more on that later), an airline plug adapter, an inline volume control for loud sources that need attenuation (e.g. airoplanes), 3 different sizes of foam tips, 3 different sizes of silicon tips, a tri-flange silicon tip and a yellow foam tip. There’s also a small, hard carry case just big enough for the phones themselves, and a 3.5mm to 6mm adapter for plugging the phones into amplifiers.

Read the rest of this review over at the new Passion for Sound site. It’s sexier and has lots of great new content coming soon.

 

$300 Headphones at a Glance

I had a great afternoon today, courtesy of the team at Addicted to Audio (www.addictedtoaudio.com.au) I spent about an hour and a half in their audition room checking out a bunch of closed style headphones for around $300. I’m not going to try to give you a full-blown review for all of them, but thought a little description of each pair might be helpful. Here goes…

Shure SRH840 (approx. $200)

Shure SRH840

Having read lots of good things about the 840s, I came in with them high on my shortlist and they didn’t disappoint. The 840s have a warm, but detailed and balanced sound. They’re very easy to listen too, but not boring. Of all the phones I listened to today, the 840s probably had the sweetest midrange. The sound of rim-shots (when the drum stick is used against the metal rim of a drum) sound very warm and woody – just like they should.

Pros: The 840s are easy to drive and ran perfectly from iPod and laptop. They’re also comfortable on the head and have good padding all around.

Cons: My only real issue with these phones is the small cable running outside of the body of the headphones. Just about each cup, a small cable comes out of the housing and then loops back into the cup. This is obviously to allow for adjustment, but leaves a potentially fragile piece of the headphones exposed to accidental damage.

Verdict: These are still very much on my mind and may yet be my final choice given they are so easy to drive. They’re not as exciting to listen to as the Ultrasones, but they are more comfortable and have a beautiful smooth sound signature while still being detailed and crisp. They’re also a great deal at just under $200.

Ultrasone HFI 580 (approx. $250)

Ultrasone HFI 580

I knew nothing about the 580s going into this afternoon, but considered them because of their price and the fact that they’re easier to drive than the 680s. I was told that they are more bass oriented than the 680s, but can’t say that I was overly aware of that.

Having already listened to some other headphones, the 580s weren’t as good and therefore left the shortlist fairly quickly. That said, they’re a very capable headphone and would definitely suit a lot of people, but I like a bit of extra high-end sparkle and detail. It’s a very subtle gap in the 580’s sound signature and it took direct comparisons to realise that the 680s gave me the sparkle that the 580s lacked – it’s very minor and those who prefer a slightly warmer sound will definitely like the 580s.

Pros: The soundstage is huge (for closed headphones) and the sound is lively, detailed and exciting.

Cons: Although solid, the construction is a bit plastic and they’re not as comfortable as some comparable headphones.

Verdict: The HFI 580s are off my shortlist, but only because they were outdone by their senior sibling, the 680s and that was only by a hair. They’re a great headphone with balanced sound, solid bass and a smooth, slightly less bright signature than some others.

Ultrasone HFI 680 (approx. $300)

Ultrasone HFI 680

The 680s were high on my shortlist after reading plenty of good things. They didn’t dissapoint. Plenty of punch, plenty of detail and that awesome Ultrasone soundstage. It’s important to note that the 680s really do need amplification. I listened to the Shure SRH840 and the Ultrasone HFI 680 side-by-side and alternated between them across a variety of music. Initially, I was listening through a dedicated headphone amp, but soon moved over to my iPod and then laptop so I could hear some music I was more familiar with. I wasn’t using amplification at this stage and started to be amazed at the difference between the SRH840s and the HFI 680s. At first I put it down to the music selection, but soon realised it was amplification. Once an amp was added, the 680s once again edged ahead of the 840s in terms of their lively detail and punchy presence.

Pros: Punchy, lively sound in a great big soundstage.

Cons:
As per the whole HFI range, the comfort isn’t as good as some alternatives and the build quality isn’t spectacular. Also, the significant difference between amped and un-amped performance means an amp is a must.

Verdict:
A great headphone for the dollars. I listened to some $1000+ phones today and kept coming back to the fact that I couldn’t justify the extra for the type of listening I do and for the minimal difference in sound. I’m not suggesting the more expensive headphones aren’t better, but the 680s do such a great job across the board that they’re ahead of most other closed cans in terms of bang-for-buck.
I’d highly recommend a listen to these if you have a device that will drive them effectively. I’m personally looking at something like a Nu Force uDAC-2 (approx. $200), but it takes the 680s up to around $500.

Audio Technica ATH-A900
(approx. $250)

Audio Technica ATH-A900

As a massive fan of the open style ATH-AD900s, it made sense to listen to their closed equivalent, the A900s. I’d heard that they have a “darker” sound, but didn’t yet know exactly what that meant – I had my theories, but it’s a very subjective term. I know understand exactly what those people meant. The top-end and bottom-end are just like the AD900s – crisp, detailed and awesome, but then came vocals… The closed design of the A900s make the mid-range sound very closed-in. The mid-range and vocals were muffled and crowded – not very enjoyable.

Pros: Beautifully made and insanely comfortable (like all similar style Audio Technicas with their 3D fitting system)

Cons:
The mid-range is so muffled and crowded that it completely smothers the rest of the sound – such a shame.

Verdict:
There are much better options out there for the price. I would take the Shure SRH840s anytime over the A900s.

Beyer-Dynamic T50p
(approx. $300)

Beyer-Dynamic T50p

I had seen these online, but knew little about them other than funky looks and a good, reliable brand. Straight out of the box they were the most impressive in terms of build quality and style of all the phones listed in this “At a Glance”. The only comparable quality of build is the Audio Technicas, but the T50ps are funkier in style (but that’s also a matter of taste).

Before talking about the sound of these it’s important to note that they were straight out of the box with no burn-in or general play time whatsoever so the following description needs to be taken with a grain of salt as it were…

The T50ps had an interesting sound signature. While detailed and neutral, there was something I couldn’t put my finger on at first, but after a few tracks I think the mid-range is a bit too forward and the top-end not quite forward enough. The bass is sublime for a small on-ear headphone. It’s tight, but with plenty of mass and presence and this continues up into the mids, but somewhere that outstanding start falls away. The T50ps reminded me of the AKG Q460 headphones which I’ll be reviewing very soon. They’re probably a touch better than the Q460s, but still lack a little sparkle at the top-end.

Pros:
They’re sexy, made of metal (i.e. high quality) and have a quality sound if you like warm, mellow signatures.

Cons:
The lack of sparkle at the top-end was a deal-breaker for me, but that was the only issue I could find so if you like the sound signature you’ll love these phones!

Verdict:
Probably a great option for some depending on your music and sound tastes. I’d love to own a pair from a design and quality point of view, but just not sure if I can justify it when I don’t like the sound style. That said, I haven’t had a chance to try them with slightly boosted treble.

At a Glance Overview

After plenty of listening and switching between sources and music tracks, I definitely gravitated towards 2 options. The Shure SRH840s and the Ultrasone HFI 680s were clearly the best of the bunch. For non-amplified use I think the Shures are a winner. For amplified use, the Ultrasones take a slight lead. The tricky thing now is that I haven’t yet auditioned the Ultrasone HFI 780s, but will do so before purchasing because they’re easier to drive from a non-amplified source. I’ll keep you posted…