Review: Mixcder MS301 Bluetooth V4.2 Wireless Headset with aptX

Whenever I’m out and about, especially when commuting on public transport, I’m often listening to music or watching a video on my phone. Having a set of headphones over my head is my way of making the commute more bearable by “tuning out” the outside world. When I look around, it’s something a lot of people do. It’s rare to see people not fully absorbed into their smartphones with a set of headphones or earphones on.

But as technology advances, the frustrations of tangled, snagged or broken cables are something users often wish they didn’t have to contend with. Likewise, manufacturers are slowly following Apple’s lead in removing the “legacy” 3.5mm headphone socket. The result is clear – a preference for Bluetooth wireless audio devices.

While there is a big market for Bluetooth stereo headsets, they have never quite met everyone’s expectations. For one, the Bluetooth connection is limited in bitrate and thus audio quality is compromised due to the use of compression. Most headsets on the market use the “standard” SBC (sub-band coding) codec, which is adequate but not “hi-fi”. It’s often likened to 128kbit/s MP3 encoding with some audible artifacts especially in treble and stereo imaging. There is also a 200-250ms delay due to encoding/buffering which can result in synchronization issues. It is one reason why I still very much prefer a cabled solution.

However, when I was approached by Mixcder about reviewing their MS301 which features aptX low-latency support, I decided it was worth giving it a go – after all, I did have an aptX capable Bluetooth dongle. This review of the MS301 was made possible thanks to their generosity, and is performed with their agreement to the review challenge terms.

What is aptX? Why does it matter?

As mentioned in the introduction, traditional Bluetooth A2DP (stereo audio) devices typically use the Bluetooth SIG’s standard sub-band coding (SBC) codec. This is a computationally inexpensive codec with no additional licensing requirements, and is thus the most popular amongst devices. Unfortunately, it has limitations when it comes to quality which can result in audible artifacts. Thankfully, the Bluetooth SIG also allows for third-party codecs which can provide better quality, of which MP3, AAC and aptX are options. In the market, very few to no devices are known to use MP3 due to licensing issues, and AAC appears to be used by Apple products primarily.

aptX was introduced to Bluetooth headsets by Cambridge Silicon Radio (CSR for short, now part of Qualcomm). This codec operates at a higher bit-rate of 352kbit/s and offers higher quality than SBC (which runs up to 328kbit/s at best quality, often less and with a less efficient algorithm). There are several variations of aptX, including low-latency which runs at just 40ms latency making delay imperceptible, and high definition/lossless which offers a “near lossless” experience with higher sample rates and bit-depths. For these functions to operate, you must have both sender and receiver aptX-compatible, which normally means of a “compatible” chipset and with licensing fees paid. Otherwise, devices will revert to a “basic” SBC mode.

The Mixcder MS301 supports the “regular” flavour of aptX as well as aptX low-latency mode. Failing this, it should fall-back to regular SBC mode for other devices. Note that some others have confused aptX-LL as meaning lossless – it does not mean lossless, but merely low-latency.

Support for aptX is listed on Qualcomm’s site, of which there are a fair number of devices supporting aptX, but much fewer supporting aptX-LL or aptX-HD. However, some Android devices can be hacked to enable aptX even if not officially supported (at your own risk). When it comes to PCs, only those using CSR Bluetooth chipsets with the Harmony stack support aptX. Of note is that no Apple devices support aptX, thus using an aptX device with an Apple device will result in an regular SBC connection.

As a result, it might pay to do some research beforehand to see if your devices support aptX before buying a headset. However, even if your device does not support aptX, it should still work with your device albeit without the benefits that aptX brings.

The Package

The unit comes packaged in a black coloured cardboard box. The front side has a iridescent gold-coloured print sporting a line-art drawing of the headphones themselves, along with the aptX logo. It lists some features including 10m transmission distance, 20 hour talk/play time, last-call redialling and 2200 hours standby.

The rear of the box provides the specifications – the key specifications are a 40mm driver, 32 ohm impedance, 20Hz – 20kHz frequency response, 90+/-3dB sensitivity, 500mAh rechargeable lithium battery.

The headphone is supported on a black plastic tray with a box including some accessories.

The included accessories include a thin microUSB charging lead, a 3.5mm to 3.5mm stereo lead for wired usage, and a multi-lingual instruction manual booklet.

The headphones themselves feel moderately weighty due to the use of metal parts and construction, with padded surfaces covered in a soft pleather material. The headband has the brand embossed into it.

A closer look at the stitching of the material on the headband seems to show some waviness.

The branding is also on each of the metal earcups, which is not as discreet as it could be, but isn’t too conspicuous. The headband is internally a stainless steel band, which connects to a metal hinge section.

The hinge itself feels fairly durable as a result. The metal hinge is connected to the metal earcup through a plastic grommet to allow the earcups to swivel in one dimension. This arrangement was smooth on one side, but slightly tight on the left which resulted in some creaking noises when adjusted.

The internal plastic backing of the headband has a number of click detents allowing for the headband to adjust in length to suit various sizes and shapes of head.

On one side of the interior face of the headband, the model number is printed. The other side has a label with regulatory approval numbers on it.

Removing it reveals the aptX logo.

A closer look at the rear of the earcup shows that only the rear portion is metal, with a small vented “gap” between the rear and front plastic portion. This gap is intentional, and provides the ability for the earcup to pivot up and down to ensure a comfortable fit. The front plastic portion does have a slight amount of “creak” to it on one side.

Each earcup is externally covered with a generous amount of pleather. The foam inside is not quite filling, resulting in a bit of a “baggy” look. The inner surface of the ear cushions is covered with a plastic-like material of a different texture and some fabric. The left and right orientations are printed on the fabric inside the cups for easy reference.

The right side earcup houses the main controls which include a power button, power LED (which shines through a hole in the casing), volume up and down buttons, a 3.5mm jack for “emergency” wired operation and a microphone. There is an extra hole at the top which does not seem to have a specific function.

The left-side earcup provides access to the microUSB charging port and a hole is provided to show the charging status.

The hinges allow the unit to swivel with the cups laying flat for transport.

It is also possible to contort it into a more compact shape, although as pressure seems to be applied onto the earpads, this is not recommended.

Teardown

Disassembly starts by removing the ear cushions, which are fitted with a bayonet mechanism. This is done by rotating and then unclipping the whole assembly – if you attempt to peel the cushions off, you are likely to damage the cushion. Undoing four screws lets us gain access to the driver.

The driver is unmarked, and its make is unknown. There is a piece of felt wadding inside the chamber to provide damping. This being the right earcup, there is a piece of self-adhesive tape which is metallized and acts as the antenna for the unit. Notice how it is torn – this was how it was received.

After carefully peeling it away to try and prevent any further damage, we can see the metallized pattern on the rear. I don’t believe the design intended for the antenna to be torn, as it seems this basically breaks one of the elements of the antenna and disconnects it. This may adversely affect the performance of the unit, and demonstrates poor manufacturing QC or a design problem, especially when the stiffness of the soldered coaxial lead is taken into consideration.

The active side shows the use of a module featuring a CSR A64215 chipset. A look at the datasheet shows this particular chipset as being capable of Bluetooth v4.2, 9dBm transmit power and -90.5dBm receiver sensitivity, AVRCP v1.6, wideband speech support with HSF v.1.6 with mSBC, cVc technology with wind noise reduction, multi-point A2DP support, aptX/aptX low latency/SBC and AAC support and wired audio support. While the chip itself is capable of these features, not all of them will be available in end products.

The module’s antenna output is connected to a socket where a coax lead brings the signal to the torn printed flexible antenna. Aside from that, there are a few wires which come from the other ear-cup that bring power and driver connections from that side. A single microphone capsule is seen as well as a few switches, a 3.5mm socket and indicator LEDs.

Removing the screws allows for the underside of the PCB to be examined. There are no components mounted on the underside, but there appears to be many provisions for ESD protection diodes which have not been fitted. These may not be entirely necessary, but their absence implies a cost-reduction measure. The PCB manufacture date is 3rd week of 2017, and the project itself is dated 23rd November 2016, making this a pretty fresh product. Its project name appears to be B032P or BT15215.

Opening the other earcup, I realize I’ve forgotten to show the intermediate disassembly step where the plastic pivot hinges are removed. These are screwed in, however, are plastic so it would not be advisable to place too much stress on the front portion of the earcups themselves.

As promised, there is a BYT Li-Polymer 3.7v 500mAh cell. This one was manufactured 7th February 2017, making it very fresh as well. The board features charge regulation for the battery, which is itself protected with its own protection PCB.

The underside of this PCB does not have any components either. So that’s all the internals covered – it’s definitely using the “right stuff” to have aptX capabilities, and it seems to have proved itself to be honest in regards to the battery capacity. However, the lack of ESD protective components on the PCB, the torn flexible antenna and the plastic pivot hinges seem to be some negative points on the construction.

Set-Up

Regular users of Bluetooth devices will find set-up simple and familiar. Pressing and holding the power button puts the unit into pairing mode, and Bluetooth Secure Simple Pairing means that in most cases, entering a PIN code is unnecessary. The unit makes things somewhat easier by featuring voice feedback in the form of voice prompts so looking at the LEDs is not necessary.

Android with aptX-compatible Qualcomm Bluetooth Stack

Pairing with my Mi Max was easily achieved by scanning for the device while in pairing mode, and clicking on the device name.

Once connected, the device also shows its battery status in the status bar of the phone. This is a feature of some, but not all, Bluetooth headsets.

To verify the ability of the unit to connect in aptX mode requires CatLog and root access. Once some music is played, the log should display the codec selected as aptX. A quick check of the OUI shows that the internal module is a Shenzhen Boomtech Industry Co. Ltd module.

In the case your device does not support aptX, or you are using a headset without aptX support, you will see SBC instead (like the screenshot below).

Windows 7 with CSR Bluecore-based USB Bluetooth & aptX-compatible Harmony Stack

Adding the device follows the same basic routine of placing the device into pairing mode and adding a new device.

Pairing is established quickly with no PIN code required.

When properly completed, the unit should connect automatically and the aptX banner should display to confirm the presence of aptX connection.

The device will also come up in the sound devices, and can be set to default to route audio through it.

While it was possible to get it to work, it wasn’t always quite this easy. In fact, initially, I ran along a few issues which are due to the no-longer-maintained CSR Harmony Bluetooth Stack being just plain buggy.

The first time I tried, I could pair the device, but the Bluetooth Audio Renderer for Bluetooth Stereo Audio came up as “Not plugged in”. The aptX banner also did not appear.

Manually attempting to connect to A2DP (Sink) resulted in a time-out after a minute of waiting. No audio aside from the “telephone quality” handsfree was achieved under this situation. Rather interestingly, this unit also claims to do A2DP (Source) and Serial Port connectivity too.

In order to resolve this issue, I had to go to device manager and remove the two Bluetooth Audio devices.

Then I had to unpair the device by removing it within CSR Harmony.

Then, I set the headset to pairing mode, and paired the device. At this time, the drivers should re-install. Then, turn the headset off, and then back on so it auto reconnects. At this time, you should see the banner indicating success.

Unfortunately, this seems to be a temporary fix. Once the device is unpaired or the computer is restarted, the same symptoms will re-occur and following this procedure is required to restore connectivity. This seems to be the fault of the Harmony stack software which was last updated about five years ago, but sadly, is the only Bluetooth stack that allows aptX connection on a PC at this time to my knowledge.

Note that this is not a problem with the Mixcder MS301, but more a problem with the CSR Harmony software. However, if you do use the CSR Harmony stack, you may have problems connecting even in SBC mode.

Windows 10 with Broadcom-based Bluetooth Solution

Unfortunately, when using non-Qualcomm/CSR Bluetooth solutions, it is not possible to achieve aptX compatibility. However, pairing and using the headset is still just as simple and completed with no issues.

Once Bluetooth was turned on, the device placed into pairing mode, and a scan initiated, the device could be paired. No PIN code entry was required.

A short wait was necessary as Windows configured the drivers for the device.

Once ready, connection was established and audio routed through the device just fine.

Apple iOS 9.3.5

Unfortunately, I don’t use Apple devices primarily, so the “latest” device I use is an iPad 3rd-generation. Of course, we won’t get aptX capability, but pairing was easily completed and audio worked just fine, although presumably in SBC mode.

The battery indicator is also available under iOS.

Subjective Opinions

When it comes to audio products, opinions often differ widely. In this section, I’ll describe my experiences and feelings about the products, which some people may disagree upon. However, I won’t be drawn into arguments about it. For reference, I currently prefer the Audio-Technica M50x headphones as the “standard day-to-day reference”, and have listened to a good number of other wired headphone products ranging from AU$20 through to AU$350. While it may feel a little unfair to compare the product with a much more expensive product of a different category, this is the only way to adequately understand the strengths and limitations of a product.

That being said, everyone has a different idea of what “sounds” right or what sounds good, so feel free to ignore my opinions and form your own. That being said, I will remind you that I’m reviewing the product independently, with no financial incentive.

Ergonomics and Fit

The unit itself feels fairly good with a heft that implies some level of quality. It has good balance between the earcups, so as not to feel lopsided. The soft pleather also feels plush and sufficiently durable for everyday use. The headband has sufficient adjustment range to cater for larger heads, and the metal accents help improve the appearance and durability of the product.

When wearing the unit for extended listening sessions however, some discomfort can be felt. The clamping pressure feels slightly higher than other products. The wide and “baggy” pleather earcups form a positive seal to help improve isolation, however, the design is a hybrid supra-aural and circum-aural design with the pad both applying pressure to your ears and its surrounds. These two factors combined results in reduced breathability and “warm” stuffy ears. At least it does somewhat mitigate the risk of the unit falling off your head due to the amount of contact.

Isolation is average to fair. While the design of the earpads definitely help isolation, the vented rear plastic earcup defeats this to some extent, allowing some sound leakage in and out of the unit.

The design of the unit appears to deliberately ignore the inbuilt charging capabilities of the CSR chip and opt for a standalone charger IC. This design choice results in the possibility to use the unit to listen to audio while charging, which some people may find handy. The charging LED is easy to interpret and separate from the main Bluetooth LEDs – a red LED lights to indicate charging and turns off when fully charged.

All of the interface buttons are on the right side earcup, which makes it easy for one-handed operation. Like other CSR based devices, just three buttons are provided, which is easy to navigate by feel but results in the need to double-click the power button for redial, or long-click the volume keys for next/previous. To avoid the need to reference the LEDs, voice prompts are provided through the headset, but the voice prompts and tones are fairly loud. This may ensure that all users can clearly hear it, but is also very disconcerting to those with more sensitive ears as the “end of volume range” beep and battery low beep can be loud enough to startle. There doesn’t seem to be any way to change this, unfortunately. The LED on the right side earcup does indicate status, and when connected, shines a solid blue which is less distracting than the flashing blue of many other headsets.

The unit does offer battery status monitoring over Bluetooth so that your phone can display the battery status. However, in testing, this was found to be very approximate. In one case, it showed about half-full and dropped into the red after merely a minute or two of playback. As a result, it cannot be relied upon as an accurate gauge of remaining power.

As the device is wireless, it is expected that users might choose to take the unit around. The hinges do have extra articulation to allow the unit to be contorted into a shape which minimises its space requirements, however, it does not come with any protective bag or casing thus leaving its pleather surfaces at risk of damage.

Bluetooth Sound Quality

I first started by auditioning the unit connected via aptX using FLAC files of music I was familiar with. I spent at least 60 hours throughout two weeks listening to the headphones in aptX mode, and then several hours afterward listening to it in SBC mode paired to devices which did not offer aptX.

The character of the headphones seem to have a slightly veiled and laid back treble, offering a warmer presentation. This is not unexpected, since my reference M50x are sometimes criticized for being a bit too clinical and “sharp”. The upper midrange seemed a bit resonant and boosted, which reduced the clarity of the audio slightly. The unit was not especially bassy, offering a good balanced bass although one which does not extend very deeply, thus some basslines are almost completely lost. If I had to summarize the sound quality in general, it would be more balanced to warm, but very “average” in the clarity department and something like a AU$40 wired set of headphones.

Unfortunately, this does not make them audiophile quality. This is particularly problematic, as people who specifically look for aptX on Bluetooth products tend to be those who look for higher fidelity products, and this one seems to fall a short of my expectations.

My frustrations were amplified somewhat by the fact when switching over to SBC-only devices, it was extremely difficult to distinguish the difference in quality between SBC and aptX mode due to the limitations in the sound quality of the unit. I could not be certain, but it seemed SBC didn’t have as well defined treble, but I could not confirm it definitively. I think this illustrates clearly just how limiting the quality of the drivers and earcup design is.

Unfortunately, there was another drawback which seems common to many Bluetooth products. During idle connected periods prior to being commanded to standby, the unit does have a noticeable amount of background white noise hiss. This is somewhat distracting during quiet portions of music, and persisted regardless of which codec was used. When commanded to standby, the unit drops to dead silence with a quiet “tick”, but this merely makes it more apparent just how noisy the module is when in operation. However, one positive is the maximum volume is more than adequately loud.

Directly-Connected Sound Quality

In a rather surprising twist of fate, when directly connected to my Soundblaster X-Fi Xtrememusic, the headphone has a slightly different quality. The treble was more prominent and stronger, verging on tinny but still lacking in fine detail. The bass was still somewhat limited. The upper midrange seemed more recessed and lacking in comparison. Unfortunately, I’d have to say the directly connected sound quality sounds extremely average, which probably stems from the design of the headphones and the driver units in use. While it certainly is not bad for casual listening, it’s not commendable in any particular way.

As a result of this result, it seems to suggest the CSR-based module while capable of directly driving speakers, may not be optimized to do so. Higher end aptX headsets may use its I2S capability and use that to drive an external DAC or buffer the output with an opamp rather than use direct connection.

Having the option of direct connection is a good thing, especially if users remember to bring their cables, so that they can use it with devices without Bluetooth capabilities or when the battery is depleted.

Testing

Battery Charging

I first depleted the headset by running a run-time test until it shut down on its own. Using my Keysight U1461A as a data-logger and my USB current shunt, it was found that the unit charged in 2 hours and 1 minute – pretty much right on time. The delivered charge was 510mAh from the USB, and due to the linear regulator, all of this would have been delivered to the cell minus a little bit to light up the status LED. As a result, the onboard battery is an honest battery with a capacity of 500mAh. Charge tapered and terminated as expected, and thus indicates it is safe to leave this unit plugged and charging.

Battery Runtime

Battery run-time was assessed by setting the unit to my preferred listening volume in a quiet room and running a song on loop with the audio recorded by a microphone. Total running time was found to be 25 hours and 56 minutes, exceeding the 20 hours claimed. This was with aptX audio, although run-time is likely to vary depending on the loudness, RF signal level, codec and playing material.

The claimed 2200 hours of standby is about three months and is a big claim, but what type of standby was not specified. When connected but idle in standby, the LED indicator shines a continuous blue – with this drain on the battery, I find it unlikely that 2200 hours of standby can be achieved. Instead, I suspect they mean on a soft-off state, or maybe even a disconnected standby state.

Microphone Voice Quality

I checked the quality of the microphone by recording a sample with myself speaking inside my quiet room environment. The resulting audio has a bass-heavy character lacking in treble detail. This was intelligible for the most part, although when tested “on call” with several people, they did note that it was difficult to understand when I was speaking quickly. This is likely due to the fact that there is no microphone boom – the mic merely sits inside the earcup and thus gets less-than-ideal sound.

This is no major issue, as most users will probably be using it to listen to music more than to make calls with, however should still be considered.

Transmission Range

I tested the range of the unit paired with my Class 1 (50m) CSR USB dongle, and my Mi Max mobile phone. With the Mi Max, I could easily reach 10m with clear audio despite the torn antenna, which may have been due to a good antenna design on the Mi Max.

However, with the Class 1 (50m) CSR USB dongle, I did have difficulties at around 4-5m, with occasional audio stuttering. At 10m, the unit was stuck in a continuous connect/disconnect loop. I suspect that if the antenna was not torn, the performance may have been improved.

The use of metal earcups and metal hinges makes adequate RF design difficult due to the potential for shielding or multipath reflections to arise due to the close proximity of the metal.

Conclusion

The Mixcder MS301 is a Bluetooth headset with a bit of an identity crisis. On the one hand, it offers an aesthetically pleasing metal-accented construction with lush black pleather earpads and premium aptX low-latency codec support. On the other, it targets a low price to give value for money. In the end, the result seems somewhat of a compromise.

For those specifically looking for aptX support and high-fidelity audio, they will be somewhat disappointed by the recessed treble, resonant upper-mid range and limited depth of bass. They might also be distracted by the background hiss that pervades every quiet section. If you’re specifically looking for high quality audio, you’re probably looking at much pricier products from major brands anyway.

For those looking for a Bluetooth headset with a decent build quality and better quality than the average “cheapy” plastic unit, then this unit does have merit as a step-up, offering more definition and better build quality. It is suitable for casual listening, and feels sturdy enough for everyday use. In this case, aptX is probably not on your priority list, but it doesn’t do you any harm so you might as well have it. It will connect as regular headsets do, in SBC mode. Given its retail price of about US$90, it does command a premium over a wired headphone of similar characteristics, but isn’t as expensive as (the few) other aptX capable options.

However, there was some observed build quality issues, mainly with the torn flexible antenna which may compromise performance slightly, and slightly creaky hinge and plastic cup on one side. The semi-open design also means that isolation isn’t as good as it could be. The hybrid supra-aural and circum-aural earcups with higher clamping pressure also isn’t as comfortable or breathable as some other products.

At no fault of the product itself, aptX support itself is also patchy due to the issue of licensing. Only a limited number of products support aptX which should bring better audio quality, of which no Apple products support it. Even fewer support low-latency. As a result, most users will never experience any latency advantage. Even if you do have aptX support, it seems doubtful that this particular set of headphones will let you experience it fully. I certainly found it difficult to discern any advantage from aptX over SBC, so I suppose if you’re considering buying this particular unit, it shouldn’t be because of the advertised aptX support.

Thanks to Mixcder for providing this unit for review.

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Teardown: Motorola CableComm Series II Cable Access Unit (MM1012A)

I remember when I was very young, peering outside the window and seeing a bunch of workmen and trucks pull up in front of the house. In a short time, they rigged a steel wire between the power poles, then pulled up a thick insulated cable, and used some rotating machinery to wrap a wire to bind the cable to the support cable. Not before long, I would hear on the news that this was the roll-out of the hybrid fibre-coax network, known as HFC for short, that was to carry pay TV to consumers. This was around the mid-90s, and there was a frantic competition between Telstra and Optus to build the largest HFC network.

Not before long, I remember there were consumer complaints about the large number of unsightly cables in the air and damage to trees which had holes cut through them to let the wires pass through. In the end, I believe it was agreed that Optus and Telstra would not overbuild each others’ coverage footprint. With that, it seemed that HFC technology was to be relegated as a technology for the privileged few. In a way, just like how Galaxy TV (a pay TV microwave broadcaster) was for the privileged few as well.

I never had any pay TV service myself, so things were simple and unchanged. The phone ran from copper lines from Telstra (although resold as Optus). Internet, which came later, was via dial-up access. Nothing complicated.

But when I passed by some of my friend’s houses, I noticed something high up on their wall near the eaves. We didn’t have one of these – it looks a bit like a kick-board from swim school but had cables running in and out of the bottom. I took the time to ask and the answers I got ranged from “I don’t know”, to a less-than-satisfactory answer of “that’s our telephone line”. For years, I just assumed it was an oversized demarcation box, but then I noticed some units had a second square grey box next to it … that could also have been a demarcation box. In which case, why two boxes?

This mystery has been in the back of my mind since I entered primary school, and was not resolved for me until just recently. Just the other week, our local area council had its final scheduled clean-up, which meant one last chance to go salvaging. To my luck, I found one of these units sitting kerbside. It was quite covered in dust, grout, spiderwebs and even came complete with some live beetles inside. I took it home, cleaned it up, and that’s what is pictured above.

Up close we could see the Motorola branding, so it was probably going to be a piece of radio equipment. Aha, HFC is RF based. On the rear we see it’s an SII/CAU 1LN 65MHZ with a model number of MM1012A. This unit appears to be refurbished September 2003, which isn’t that long ago. The unit was secured by security Torx which took a lot of work to remove, which I did, to remove the scraps of cut wire and clean out the wildlife.

With that information alone, I didn’t find too much information on it. I couldn’t even find a picture of it online, even when every third house down some streets around here still have them hanging on their wall. I was still left somewhat in doubt as to what it was – so only once I opened it up did I fully realize what this unit was.

HFC Cable Telephony

After a bit of looking around, I resolved the mystery box to be a Motorola CableComm Series II Cable Access Unit. The product code seems to indicate it is a one-line telephony interface, with an operating frequency of 65Mhz (likely a 6Mhz wide cable channel). But lets take a step back and recognize this for what it is.

In the early 1990s, competition in the telephony market was difficult. Telecom Australia (later Telstra) owned the copper line infrastructure which every reseller used. It was hard to offer more competitive prices when your minimum costs are set by your rival. Optus pinned its hope on HFC to break this deadlock.

Over in the USA, where HFC is the primary telecommunications media in some areas, the desire to perform “triple-play” services over HFC resulted in the production of cable modems of various proprietary protocols. Systems designed to provide a voice port over HFC included Motorola’s CableComm, Tellabs CableSpan 2300, Unisys DCSS, ADC HomeWorx, General Instrument’s Mediaspan, Scientific-Atlanta’s CoAxiom and Arris Cornerstone.

Motorola was a late entrant into this rather crowded market, but using their expertise in trunked radio systems, they announced the CableComm system in 1994. Early trials were named with TCI and Teleport Communications Group in Arlington Heights, Illinois with some tests between the houses of 25 selected employees. Full-scale commercial roll-out was planned for the first quarter of 1996 with a per-line cost of US$350 to US$550. The system is claimed to use TDMA, allowing between 500-1000 calls in a 6Mhz channel.

In November 1996, Coherent Communications Systems provided an echo canceller solution for Motorola CableComm, which appears to operate in the digital domain. This article seems to suggest that aggressive expansion would commence “during the remainder of 1996.” This suggests that things took a little longer to get off the ground than expected.

But Motorola definitely did bet big on it at chipping away the grip that phone companies had on telephony – in the article by Chicago Business, the boxes are described as “looking like paper towel dispensers”. Apparently, Motorola rented the Lake Zurch factory for four years to produce these devices.

In early 1996, Optus chose the CableComm system to provide its competing telephone service. Even in 2002, they proudly claimed to have secured a long term supply of this equipment. Note that they misspelled CableComm in the press release! A search for CableComm online shows that some people were locally employed to keep these units going past their discontinuance by Motorola.

However, as with all technology, it has a lifetime. The time was up for Motorola CableComm even before 2008 had hit, as an expert report from Michael G. Harris of Harris Communications Consulting LLC points out. In this report, Optus is criticised for severe underinvestment in their HFC network with oversubscription. They are also criticised for relying on Motorola CableComm – a discontinued proprietary system for which a multi-dwelling unit compatible telephony adapter was never developed. The older circuit switched nature of the system was also not contemporary with the technology used in the US which had or was in the process of being replaced with packet switched solutions. The report seems to point to Optus’ own lack of confidence in their own network – preferring not to hook up customers where other providers would have done so, and avoiding investment in the belief that HFC is an inferior technology. This apparently stemmed from Telstra’s disagreement with Optus in regards to how customers were not connected to their own networks even when it was available, instead opting to use Telstra’s copper network instead.

In fact, as CableComm itself is a proprietary standard used by their early internet cable modems, it was soon supplanted by the Data Over Cable Service Interface Specification (DOCSIS) industry standard which involved a large number of industry players. As IP-converged technologies became more popular, services were run over the “internet” data connection rather than occupying its own discrete channel spectrum, hence the move from circuit switched to packet switched networking.

In 2011, NBN Co cut a deal with Optus to shutter its HFC network and noted it may use sections of it to run the NBN network. By 2012, Optus had publicly announced it will be turning off its HFC network in 2014 with complete dismantling by 2018. Customers would be migrated to NBN. Unfortunately, and not unexpectedly in light of the previous critiques, the network was not up to scratch, with underinvestment meaning having equipment reaching end-of-life and a rather complicated network architecture. To ensure quality service would have required overbuilding. In the end, it appears they abandoned the cable instead, so the whole network had a lifetime of about 20 years. Despite the NBN choosing a mixed technology mix which should have accelerated the deployment of the NBN and reduced the cost, the use of HFC seems to have caused its own headaches.

Telephony Thoughts

In researching this, I have now come to understand a lot more about HFC telephony. What I discovered was somewhat fascinating to me, since it seems that some customers may not have had cable TV, and the HFC was solely used to provide telephony service to customers.

Unfortunately, as I was not ever served by the CableComm system, I don’t know what it’s characteristics were. Did it really provide carrier-grade service indistinguishable from a POTS line? Did data services work reliably? Even V.90? I have no idea. But it’s important to recognize that in some way, these “early” HFC telephony services were a first step towards competing against traditional telecommunications companies and were the “step” in-between POTS and full-blown packet-switched VoIP (whether through a softphone or ATA) or even VoLTE.

That being said, as cable is a shared medium, security would have been a potential issue. While it is already presumed to be a fully digital codec system, did it utilize encryption? Was there the potential for calls to be “eavesdropped on” by others served by the same node? Was there any encryption on system metadata? Were there actual vulnerabilities in the system which might allow others to place calls on other subscriber’s accounts? In modern SIP VoIP telephony, we made a big step backward, with most calls going out in the clear using G.711/729a. Now that we have a security focus, maybe such old systems would not mass muster anymore.

Even on the RF side, it would be fascinating to know – did it really operate at 65Mhz on the cable x 6Mhz bandwidth? How was the TDMA and return channel achieved? What was the physical layer coding? Was FEC involved? Is it still operating for the last few people that might need it before NBN comes in?

To be honest, circuit switched technology may be outmoded, but it does have a more consistent guaranteed quality as compared to packet switched technology which can be affected by latency, jitter, packet loss and contention which established circuit switched calls do not have to worry about. When it comes to running voice-band modem data services, circuit switched technology generally works better.

Unfortunately, information seems to be scant. It’s probably moot anyway, but it’s always intriguing to know. Unfortunately as I don’t have any equipment to use this unit with, it’s not something which I can determine.

However, one disadvantage is already apparent – as it’s not a traditional copper line, you can’t get ADSL2+ unless you reconnect a traditional copper line. With a “CableComm” provided line, you can only get cable internet at the price Optus charges you. Cable internet competition is pretty low compared to ADSL, thus it can be more expensive as a result. Maybe this was “built in inertia” to stop bundled Optus customers from going back to a copper-line. At least their newer Optus Cable services use modems with integrated VoIP packet-switched service instead.

Teardown

We saw the unit front and back earlier on, so continuing on, we see there is a mounting hole at the top.

At the bottom, there are three cable entry positions, with two spring-loaded security Torx screws securing the covers. The covers can be slid down to reveal the connection terminal area. There is a recessed area next to the “Manufactured by Motorola” text which may have been used by service providers to apply their branding – but I’ve never seen it used around here.

The larger outer cover uncovers the parts which are “customer responsibility” – namely their own internal telephone wiring pair and an F-connector for the cable “loop-out”. This is terminated with a 75-ohm terminator, suggesting this subscriber may not have had a pay TV or cable internet service. The cable entry boot was inverted in the photo after I cleaned it.

A test jack is supplied to allow testing of the line output from the CAU without interrupting the wiring.

The wiring attaches into a plastic block which is snapped down into IDC fingers.

Removing the service provider cover reveals the F-connector for the incoming HFC feeder line. This is where power is derived, up to 100V. A grounding bar is also provided. The connection on the left appears to provide an alternative power connection, a covered diagnostic port and a socket which may allow for a failover service.

The port is similar to a LAN 8p8c connector.

The IDC blocks and test jacks themselves are a module that can be removed. The part number is 0104080X10, with this unit being Revision B, made Week 44 of 1999. Vendor is 912, Made in the USA.

On the inside, the CAU is further identified with its MSN/ESN. Apparently it was Assembled in Singapore. Given the numbers, I wonder if it is somehow related to GSM just running over coax, in which case encryption is part of the standard. Maybe it also runs voice compression?

 

The top cover is surrounded by a rubber gasket and is supposed to stay nice and “dry” as that’s where the brains are. This board showed only very slight signs of corrosion at some points. We’ll take a more detailed look at the board once it’s freed from the base.

The line interface module, however, once removed was found to be potted entirely, and thus not serviceable. Is it just a bunch of wires? Or are there some surge protective elements inside?

In the interests of complete disassembly, I removed the screw holding the can over the radio section of the CAU. Internally, part numbers of 2604550X03/2604550X04 are printed, along with Issue A Vendor 912. Date is coded as 2228 and 1758 respectively. The cans were Made in Mexico.

The top side of the board is where most of the action happens. We will break it down into sections, but overall, the board has a code of 8404629X01 Issue-0. Printed in white is 21399-03-8 with a date of 12th March 1998. It clearly identifies as Made in USA, Motorola CableComm and CAU Series 2. The barcoded label in the centre has the text “MMLN5061B 606VLW 01/11/99 MM1012A” which seems to suggest a factory alignment date of 11th January 1999 along with the product code of MM1012A. The board is a fairly complex six layer PCB. It definitely looks like Motorola quality at a glance.

Starting in the lower-left side, we can see two symmetrical line interfaces. The left side is Line 1 and is populated, with Line 2 unpopulated as this is a single line unit. Lines are protected by fuses on both tip and ring. The line interface is handled by an Ericsson PBL 387 10/1 SLIC. This takes the place of a traditional hybrid transformer. The inductors may be responsible for ring voltage generation. The resultant audio is handled by a Motorola MC14LC5480DW PCM CODEC-Filter. A row of test pads is bought out as well. The fingers at the bottom connect to the potted module to make connections to outside lines.

The right half of the image is the power conditioning portion of the unit consisting of an assortment of solid electrolytic capacitors (good choice), inductors and transformers. A 2A fuse appears to protect the unit. The power is controlled by a TOP224G with feedback via an MOC8106 optoisolator.

The top left corner has a large Motorola 5104545X01 IC, which may be an ASIC, along with a 4.608Mhz crystal. The firmware is stored on a pair of flash chips.

The left one has a Motorola label with 5170806C07 120398 printed on it. Assuming they’re both identical, the chips are AMD AM29F200AB 2Mbit Flash chips, thus the unit contains at most 512kiB of firmware. Complementing this is two Samsung Electronic Corporation KM62256DLGI-7 32k x 8 SRAM chips for a total of 64kiB RAM. A Motorola XC68LC302CPU20B 50Mhz 68k CPU is seen in the top corner. Interestingly, the CPU is pretty beefy – a relative to the 68k CPUs that powered whole Macintosh LC desktop computers. The top corner has some edge contact fingers probably used for factory alignment use.

The radio section has some Motorola custom ICs, a filter, a few capacitors, an adjustable oscillator and a bypass relay (RK1-L2-4.5V-H33). The filter networks are pretty elegant to behold, but way above my ability to design or comprehend.

The underside of the board has fewer components in comparison.

The radio section predominantly features small surface mount components. U203 is an RF MicroDevices RF2317 Linear CATV Amplifier (DC to 3Ghz). Aside from that, the other components are not very notable, with the exception of C441 which appears to be a discoloured tantalum surface mount capacitor. This unit may have suffered some damage at some point and may not be functional (e.g. surge? reverse polarity?).

The remainder is not particularly notable. But at least, now I know what the unit is for, and what’s inside.

Optus’ HFC Network

Prior to all of this, on a previous salvage walk, I decided to look at the HFC cables in my neighbourhood just out of interest. I had an expectation that Optus’ HFC network would not be usable at the time just based on observations of the equipment in the air – but since we’re discussing HFC, I might as well put up some images. I’ll first say that I’m not an expert in HFC technology by any means, nor am I familiar with the equipment used, but I present my observations even if incorrect.

At this time, I’m living in a townhouse complex with something like 28 units. Our HFC feed is this cable that crosses the road. It’s not well bound to its support wire, thus the snaky appearance, but it has just a two-way splitter at the end. No way will it serve the “population” especially if all users are connected – such equipment has to be re-planned/replaced.

The splitter itself is Scientific Atlanta branded. This brand had been acquired by Cisco in 2005. As this the pre-acquisition logo, the equipment is at least 12 years old now. At a good estimation, such equipment has useful lives of about 15 years (roughly speaking), so I suspect equipment replacement is not unexpected.

The nearest trunk amplifier seems to be this unit, with the incoming trunk passing through a Regal combiner with surge protection. It definitely looks dated, but the cabling itself is slightly confusing. It seems there are two trunks coming in on the left, with the combiner used to split the signal so the trunk continues through to the right along with other trunk, and one output from the amplifier making the three cables on the right. But two of the trunk cables have an end-to-end join under shrink-wrap. Maybe it’s the opposite direction, but I’m not familiar enough with the equipment to know.

That being said, the physical condition of the aerial cabling “needs attention” – the fine wrapping wire that secures the lines to the support wire has come free and “unwrapped” along a section.

The support wire is held to the poles with simple hardware – interestingly, in our area, there is support wiring with no HFC cables bound to it. It may have been initially planned to be rolled out, but then due to a lack of potential customers, abandoned.

Not knowing much about the specification of the cables used, I noticed that some of the cables in the area seem to be a darker colour, whereas others are more “grey”. Maybe it’s related to sun exposure, or different batches of cables, but here’s another set of joints with some “cable tie” bundling.

Sometimes, along the road, we will see such boxes and sometimes they even hum loudly to signal their presence. I don’t think this is a HFC node, but more likely a power injector as it has a mains input, and its output goes up the pole into a coupler.

The couplers/splitters in question all seem to be Regal branded in my area. The marked frequency response is 5-1000Mhz, and the model is RDLC10-12S290V.

The splitters in the area also come in some other varieties – in the case of larger splits, it seems that it is a powered splitter, but where the two core power comes from is not obvious to me. It’s not just mains is it?

We can see the varying penetration levels, but rarely are all existing ports taken, as the popularity of pay TV is relatively limited. The second splitter seems to have one port where a former customer’s drop was merely “cut off”. The improperly terminated F-connector port may well result in signal reflections and distortions, or noise ingress into the cable network as well as potential damage to the splitter from having water enter through the stub of cabling, helped by capillary action of the coax braid.

There are un-powered variants as well, which seem more “expected”.

This is an anchor point that’s attached to the support wire to secure the drop to the customer.

As for amplifiers, around our area, there’s the occasional “flat” one that looks like this. From what I can gather, this appears to be a line extension amplifier, to help push the signal further down the line. I’m not sure the customers connected at the end of this would enjoy the best signal-to-noise ratios.

The other amplifiers look as above, with a varying port position configurations and number of cables leading in and out. Just looking at the PDF about related units from Cisco’s website seems to show that they’re pretty complex.

While it does seem somewhat complicated, this is relatively anemic compared to the complexity of the networks I witnessed overseas in South Korea and Taiwan where HFC is one of their core technologies for delivering high speed broadband. I might comment more on this once I get some holiday photos up – but needless to say, HFC outages and service trucks were constantly attending to the network in South Korea, and customers were being migrated to FTTH services, so the lifetime of HFC is limited at best.

Conclusion

At long last, a question I had from childhood has been resolved – namely, what’s that box on the wall? In examining this, I learned a lot about the history of telephony over HFC in terms of the alternative technologies available, the hopes of the companies, and its ultimate fate.

Looking at the Motorola CableComm CAU, I’ve managed to get some good shots of its internals which I couldn’t find online, so that’s a pretty unique opportunity in my eyes. While I’m not able to ascertain the operational status of the unit, or run it, it was still good to know what was used internally.

It also gave me a chance to share some of the photos of the Optus Vision Cable HFC network equipment in my area. In the end, it seems I’m still left waiting for NBN, but it looks like it will be VDSL2 when it arrives … late and underwhelming.

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Tested: “Compatible” Nikon EN-EL14 Batteries vs Genuine

Amongst the published articles on the site, it seems there is a fair amount of interest in the ones dealing with “compatible” and “fake” camera accessories, specifically Nikon EN-EL14 and EN-EL14a batteries.

Having just recently returned from my first extended holiday, and now armed with the B&K Precision Model 8600 DC Electronic Load, I thought it would be a good idea to see just what the capacity of my genuine and compatible surviving EN-EL14/a series batteries were, just to see if it is even worth bringing them with me. After all, luggage allowances are like gold.

Methodology

I rounded up all of my surviving EN-EL14/a series batteries of which there were five. Two of the batteries are genuine batteries as supplied with a Nikon D3200 and D3300 body. The remainder were “compatible” aftermarket batteries. Their characteristics are noted in the table below along with their weights.

Specifically, the compatible EN-EL14a is identical to this prior teardown of a failed unit. The first compatible EN-EL14 is the surviving “brother” of this failed unit. The second EN-EL14 has not yet otherwise featured on the site. Unfortunately, no living samples of this particular variant were available.

The batteries were connected to the tester using a short length of AWG18 wire and a spade crimp which was “compressed” using the crimp tool as to fit within genuine Nikon battery sockets. It was noted that this was not necessary for the counterfeit batteries, which had wider terminals that could accommodate the spade terminal without modification.

The “compatible” battery is on the left, with a genuine battery on the right. The wider terminal shroud seems to be a common factor amongst all compatible batteries tested to date.

Regardless, testing using such spade terminals is not recommended for end users as they risk causing contact fatigue or damage to the plating, as it was not designed for mating with the terminal block. I decided the risk was worth the reward (for me), and have completed the testing this way with no ill effect. However, if you choose to replicate this set-up, you do so at your own risk.

Testing was simplified to a 300mA constant current load, despite the camera load profile being more “peaky” in nature due to the mechanical nature of a DSLR. The obtained results may not perfectly reflect the true “in-service” capacity of the battery as a result, especially if live view or the pop-up flash are used. The loading was chosen as a “safe” value below the (anticipated) 1C rating of the worst battery which should not cause any dangerous situations to arise. Test termination voltage was set to 5V for 2.5V per cell as to reduce the risk of any permanent cell damage.

As the batteries are not obtained new and are actually significantly aged, the results are not representative of fresh batteries. Of note is that failed samples of the compatible batteries have been excluded by the nature of their failure, and thus one cannot infer the reliability of the batteries from the fact that a certain capacity remains after a number of years of use.

Results

If you haven’t read the methodology section, please do so to ensure you are aware of the caveats of the testing involved and significance of the results.

A summary of the results is presented in the table above. Both Nikon genuine batteries achieved just above 90% of their claimed mAh capacity, with above 88% of their claimed energy capacity. As a result, the EN-EL14 achieved 930mAh and the EN-EL14a achieved 1116.9mAh which are fairly good results considering their age of 4.5 and 2 years respectively.

The compatible cells varied somewhat. The compatible EN-EL14a which should boast a greater capacity than the older EN-EL14 reported a result of 709.7mAh which is 57.7% of the claimed capacity.

The first compatible EN-EL14 bested this by offering 837.3mAh which is within 100mAh of the result of the genuine cell. However, it boasts an inflated capacity claim on the unit, as such can only achieve 59.8% of its claimed capacity. In terms of energy capacity, it achieved 59.7% of its inflated energy capacity claim.

The second compatible EN-EL14 only had 220.8mAh capacity in this test, just 21.4% of its claimed mAh capacity. It fared no better in the energy department with 20.2% of its claim. This battery appears to be showing signs of impending failure, which was observed to be gross cell capacity imbalance in previous failures.

Looking at the voltage trends, most of the batteries (with the exception of the final one) show a reasonably traditional Li-Ion discharge characteristic. The results had some noteworthy characteristics. Neither of the genuine Nikon batteries cut-out at 5V, and instead, the test software stopped the testing as the voltage was at 5V during discharge. This implies the cell protection cut-off voltage threshold of genuine cells are likely to be less than 2.5V per cell to maximise capacity and reduce the risk of inadvertent power-down during a card write and may put more onus on the camera software to finish its tasks before battery depletion and prevent user operations to prevent stress to the battery.

The other compatible batteries “dropped out” at voltages above 5V, although the threshold is not constant which implies one of the two cells in the battery have hit their minimum voltage and the battery is “disconnected” to protect the cell from damage. This behaviour could (in the worst case) result in removal of power to the camera in an unexpected way.

The failing battery seems to have a discharge curve that is just linear, which appears unusual but may indicate internal resistance issues along with cell capacity imbalance. This battery is almost worthless to me, and thus, it now participates in a teardown in the name of science.

Teardown

This “failing” specimen is black in colour with laser-etched text on one side and the top near the battery terminal. No other distinguishing features appear on the casing. It is very well sealed, and opening it required snipping at the case with side-cutters.

Inside, double-sided adhesive tape and foam rubber strips are used to position the cells. The cells are unmarked.

On the reverse, white silicone adhesive is used to secure the battery to its shell. As is common with other clones, the mid-point cell connection is provided for cell balancing.

The board proves to be identical to this earlier failed compatible battery, with the same markings but different cells used.

As I was curious as to the state of the batteries, I charged this EN-EL14 to full. This took a normal amount of time (~2hrs) despite its reduced capacity, potentially because the BMS is balancing the cells at the top of charge or due to internal resistance issues. I then repeated the CC 300mA discharge, but addressing each cell individually with a cut-off of 2.5V.

A gross capacity imbalance is seen with one cell registering almost twice the capacity of the other under the same test condition. This suggests that Cell 1 was limiting the battery capacity. But even more significant is the shape of the graph that does not have a traditional sharp “drop” at the end of discharge.

While the discharge terminated at an on-load voltage of 2.5V, after 12 hours unloaded, the voltage rose to 3.6V for Cell 1 and 3.7V for Cell 2. I suspect this is proof that the battery may indeed have more capacity but cannot deliver it at the requested current due to internal resistance.

This is relevant, as one observation I have made is that the compatible cells rarely achieve the same level of performance in live view mode, which is demanding current-wise. Engaging live-view for non-trivial amounts of time quickly shows the low-battery indication more quickly than would be suggested by the capacity figures alone.

Conclusion

Compatible batteries have been a bit of a mixed bag especially recently. They seem to feature inflated ratings at times, but almost all are now built with low quality domestically produced Li-Ion cells which result in gross cell imbalances and battery failures within a relatively short time. The ones that have not failed still do not match the genuine cells nor meet their ratings by any stretch, however, may not be completely worthless.

Unfortunately, this is not a simple pickle to resolve as the cost of compatible batteries is much lower than the genuine batteries and for most people, do not cause any damage and come with only a small level of risk. Unfortunately, if you end up with a bad batch, replacing them time and time again, queueing them for charge and waiting, along with the increase in bulk carried is also a “cost”. To date, while the clones haven’t cost me any photos, they have limited live-view video opportunities and occasionally caused a shutter error to appear (which is resolved by pressing the shutter button again). I suspect this is because of internal resistance issues resulting in a voltage “dip”.

Genuine batteries are not that easy to come by, and can be difficult to differentiate as well. That being said, it seems all compatible EN-EL14/a batteries have wider terminal shroud spacing and cut-off before 5V under load, thus could be simple characteristics to differentiate “counterfeit” batteries from genuine ones.

Regardless, a compatible battery in the process of failure was torn down and examined – which brings the number of different EN-EL14/a batteries torn down to four different types with two families of PCBs.

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