Partha P ChakrabarttySep 13, 2019 08:55:24 IST
Editor's note: This is part 6 of a series on getting started as an audiophile comprising reviews and explainers on audio gear and the tech that makes it tick:
In my article about the basics of great headphones, I had mentioned that Bluetooth headphones are still lagging behind wired ones when it comes to sound quality. Are we then condemned to choose between either the convenience of wireless or great sound quality? Why can't we have both?
A new breed of gadgets promises to solve this dilemma. To understand why wired is better requires us to understand some basics of sound. When we listen to music, we start from a ‘source’, which contains the recording of the music. This could be a CD, a vinyl record, or, as is more popular today, streaming service like Spotify or Saavn.
For wireless audio, the data from the source is converted into a digital signal via a codec (in this case, an algorithm for more efficiently packaging an audio signal), and transmitted wirelessly to a receiver. The receiver decodes the signal, converts it into an analogue electrical signal (via a DAC) and then amplifies it.
Efficiently transmitting and decoding a wireless signal while maintaining high fidelity, however, especially over Bluetooth, isn't very easy. The problem is that the Bluetooth standard wasn't designed for audiophiles to begin with, it was developed as a short-range wireless communication standard and nothing more. Usually, the result is a significant degradation in audio quality.
While Bluetooth codecs designed for higher quality audio transmission have existed for nearly a decade now, the adoption of said standards only started picking up pace recently. Today, dedicated hardware like Apple's W1 chip and codecs like aptX are finally bridging that perceivable gap in quality.
But this brings us to another dilemma. What do we do with all our expensive, wired headphones that we just couldn't give up on? Do we sacrifice them on the altar of convenience and shell out an inordinate amount on good, wireless audio gear?
This is where Bluetooth DACs/Amps come in. Bluetooth DACs/amps take over the task of receiving data via Bluetooth, converting the digital data to analogue electrical signals and amplifying them, and then transmitting these signals via a short wire to our headphones.
Since they are small, they can easily clip on to the headband of our headphones. With them, one can convert any wired headphone into a convenient, wireless one. Today, we will review two Bluetooth DAC/amps you can buy right now to elevate your music experience.
To learn more about the difference a dedicated DAC/amp can make to your listening experience, please click here. If you want to learn the basics of Bluetooth audio, including information about codecs and why Bluetooth has a bad reputation in audio, click here for a later section on the same page.
Two Great Choices for entry-level Bluetooth DAC/Amps
The devices under review are the Fiio BTR3, and the EarStudio ES100. Both devices can turn any headphones into Bluetooth headphones so long as you have a short cable for connecting your headphones to the unit. Both units come with pre-installed clips to attach the device to your headphones, or your shirt collar or pocket.
Even if you don’t want to use this method, I’ve found having a Bluetooth DAC/amp with a set of long-wired headphones is also more convenient than connecting them directly to a phone. First, the sound quality is often better than a direct connection to a phone because of the dedicated DAC/amp. Second, you are free to use your phone as a phone, instead of having it tethered to your headphones.
The ES100 is made of plastic, and is very light; the BTR3 is made of metal and glass and has a more premium feel. However, I’ve experienced a few signal drops on the BTR3 while the ES100 has had great connectivity. For the most part, however, neither unit gave me problems walking around my flat with my phone in another room, or walking on the street with my phone in my pocket or in a bag. Each one also has a mic for calls, and these do a pretty solid job as well.
The BTR3 lasted about nine hours on average for me, with the power-hungry LDAC codec whittling it down to just over eight hours. The ES100 exceeded 12 hours on its 3.5 mm output, and clocked in excess of 12 hours even on the balanced port, on LDAC throughout (more on the balanced out later). This is outstanding battery performance. The BTR3, however, has a USB C connection, which is more convenient and fast becoming more ubiquitous. The ES100 has a Micro USB port.
Both the BTR3 and the ES100 can handle most major Bluetooth Codecs, including AAC, aptX, aptX HD, and LDAC (requires a quick software update on the ES100). The BTR3, however, also supports aptX LL and Huawei’s new codec LHDC, which claims to deliver high quality sound files with low latency. This makes the BTR3 a better choice for watching movies, though keep in mind that neither Windows nor Apple support aptX LL just yet, and you need to check if your smartphone supports the codecs as well.
The ES100 has dual AK4375A chipsets. This is to fully support both a single-ended and a balanced output, which are represented by two output jacks on the ES100. As per conventions, the regular 3.5 mm jack (on the left of the ES100) is the single-ended output, while the 2.5 mm jack is for a balanced output. We need to get a little technical to understand balanced connections.
A single-ended connection uses a single wire to transmit the signal, along with one ground wire – a simple set up. A balanced connection, however, has two wires to transmit the signal, along with a ground wire. One signal wire transmits a copy of the signal, while the extra signal wire transmits a copy, only with the polarity reversed. Think of it as one wire sending a ‘positive’ signal, with the other sending the same signal, only this time turned ‘negative’.
When these ‘positive’ and ‘negative’ signals are summed, the two cancel each other and leave you with silence. Therefore, to hear the signal, the ‘negative’ signal is once more flipped into a ‘positive’ one. But what is the point of turning this copy of the signal ‘negative’, only to flip it back to ‘positive’? The answer lies in noise. When a cable picks up noise, it registers as ‘positive’ on both the ‘positive’ signal and the ‘negative’ signal: so you get positive signal+positive noise, and negative signal+positive noise. When this is re-reversed, you get positive signal+positive noise, with the other wire’s output being positive signal+negative noise. This negative noise cancels out the positive noise, giving you a noise-free connection.
This was primarily done for long cable runs at concerts, where the chance of picking up noise from an environment cluttered with equipment was high. Theoretically, a balanced system should not make much difference in sound quality in headphones, where the cable runs are short.
Balanced systems are also typically more expensive — a balanced cable costs about thrice as much as a single-ended one. They can also be more uncertain, as a balanced connection implies more complexity, and more scope for errors to creep in. However, if a balanced connection is well-implemented, audiophiles on internet forums have reported an improvement in sound quality — scroll down to the sound review below to see if it makes a difference in the ES100.
At any rate, the ES100’s ‘Dual Drive’, two-chip technology claims benefits over single-chip implementations of balanced outputs, which require a ‘switch’ between the single-ended and balanced outputs. This switch can have a negative effect on the signal.
With the BTR3, we get a single AK4376 chipset, which is slightly more advanced than the chips in the ES100. There is also no balanced output. An advanced chipset, however, does not mean a noticeable improvement in sound quality. Both chips are equally capable of handling the data from the highest quality Bluetooth codecs on offer.
Both the BTR3 and the ES100 can be used in USB DAC mode. This happens when you connect them to a source using a cable instead of Bluetooth. This turns off the amplifier and uses just the DAC.
However, if your device’s amp is crappy (and they often are), both the ES100 and the BTR3 also have self-powered modes. To use them, you have to use their smartphone apps to turn off charging entirely. The charging is automatically turned back on once battery gets low, or if you switch off and switch on the unit. This protects you from permanently disabling the charging function of your own device!
One significant annoyance with the BTR3 is the location of the headphone jack right next to the USB C charging port. They are so close to each other that having a wire and a headphone connected simultaneously proved very difficult, and with some headphones, impossible. This affected DAC-only functionality. However, this shouldn’t be a problem with most IEMs, which tend to have less bulky plugs.
In terms of the power output, both can drive headphones with an impedance rating of up to 100 ohms. The balanced out of the ES100 pumps out more power (2.2 Vp @ 16 ohms) because it uses both DAC/amps housed in the unit. The smartphone app also allows you to use 2x power on the single-ended output.
Using this mode on the single out of the ES100, I was able to achieve a really loud volume for a quiet track like Alexandre Desplat’s “Prologue” from his Birth OST on my 150-ohm Sennheiser HD58x. The BTR3 has lesser power, barely reaching listening levels at max volume, and only just exceeding on the 70 ohm HD 25 (review here), though more usual tracks get plenty loud. However, the music got as loud as safety allows on the 64-ohm HD 280 Pro (review here), the 32-ohm CB-1 and the 38-ohm M50x (reviews here).
Other than all this, each unit also comes with a dedicated app. The ES100’s app has more options, with Fiio yet to even provide a 10-band equaliser. App updates, however, are easier, and we should see parity in this regard soon. Both allow you to choose from a series of software filters which make a very slight difference in the sound. Primarily, the ‘slow roll-off’ option sounds a bit warmer, while the ‘sharp roll-off’ option sounds more analytical, with a sharper attack for instruments like Kenny Dorham’s trumpet in ‘Sao Paulo’ (Remastered 2014).
I primarily compared the sound of these Bluetooth DAC/amps with respect to a Samsung Galaxy S8 (Review), because the primary application is likely to be with phones. The Samsung Galaxy line, while not being the worst in terms of sound implementation, is not of the calibre of an LG V-series or an Apple device and should be a good proxy for most other popular brands. The advantages of each DAC/amp over the Samsung should be even greater than other, less-expensive brands.
Right off the bat, let me say that both units made a massive difference to sound quality. Listening to pink noise on the S8, I was subjected to a significant amount of hiss, and random treble spikes. Pink noise on either unit was a much tighter ball, with the mid frequencies enjoying pride of place. If you are starting out as an Audiophile, either of these will be a great way to deliver better sound.
The BTR3’s sound is a touch on the bright side, but there is a satisfying increase in bass and percussive force on the Sennheiser HD 25. The sound is cleaner, with an improvement in instrument separation as well as a slight increase in the width of the soundstage. All in all, I was pleasantly surprised by how much of a difference this small, inexpensive device made to my listening experience, and I can easily see myself using it to permanently convert one of my favourite headphones into a wireless device.
The ES100 also immediately improved bass response, clarity and soundstage over the S8’s native sound. However, there were also significant differences between its 3.5 mm and 2.5 mm jacks, even when I equalised the volume. This surprised me, as everything I’d read had suggested there should not be much difference. I’m not sure it is just the balanced connection that is making the difference in sound — but the difference is substantial.
The 3.5 mm jack seemed to have very faithful and uncoloured mids to me, though I found it a little less resolving than the BTR3. Bass was very satisfying, but there was something off with the treble: there are spikes in the upper treble region, and that gets really piercing at times.
This was particularly noticeable in ‘The Wind’ from Jamey Haddad et al’s album, Explorations in Time and Space. Switching between the S8, the BTR3, and the 3.5 mm out of the ES100 made it very stark: where the former two had the bells chiming gently in the distance, the 3.5 mm of the ES100 had them playing loudly. This seemed enough of a problem to me to reach for the cheaper BTR3.
However, the 2.5 mm balanced out was a revelation. I did feel that it coloured the mids a touch, about as much as the BTR3, hyping the upper mids just enough to affect the timbre. But everything else was outstanding. Instrument separation was so much better that it felt like I was more awake when listening to the same tracks. There was a noticeable improvement in soundstage, over even the 3.5 mm jack and the BTR3. The track was very clean, and I felt the dynamics (the difference between louder and quieter sounds) had improved — Wes Montgomery’s subtle changes in the volume of the notes of his guitar just shone through.
Of course, this required a balanced cable, which cost half as much as the ES100 itself. If, however, you are a more advanced audiophile, or happen to already have a balanced headphone — the ES100, for its convenience and its sound, could just be an indispensable accompaniment.
If you feel you want to buy something you can upgrade to a balanced setup, then the ES100 is also a good choice. If you are happy with the versatility and universal availability of the 3.5 mm jack, I’d recommend the BTR3 over the single-ended output of the ES100.
Both Fiio and EarStudio sent me review units for this review. My opinions, however, remain unbiased and true to my experience with these products.
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