Macbook Pro USB-C powering from battery

After getting one of the new macbooks, which only had USB-C ports, I initially thought there was a real advantage running the power through this.  The cable’s replaceable and can plug into any USB-C source, potentially making the computer a lot more mobile.

I’m often in situations where I’m away from power sources all day, so being able to use the computer here is very useful.  When working off a cart I use a 12V LiFePO4 battery, so it would be really useful to be able to charge the laptop battery from this.

USB-C Power Delivery

The USB-C power delivery format is actually rather clever.  If the device on the other end is happy, it can up the voltage from 5V in steps up to 20V.  This allows more power to flow along the (usually pretty thin) cable without it getting hot and even melting, as it would by just increasing the current.

However, it seems to be that a number of manufacturers are getting this a bit wrong, and potentially putting out unsafe devices which could blow up your computer or other things attached.   One of the engineers from google has been testing USB-C cables and peripherals to see if they’re up to spec, and a lot of them aren’t.

USB-C Car adapters

It’s pretty easy to do standard USB power from a 12V battery- car USB adaptors are a cheap and easy answer, you just need to attach an XLR4 connector (or whatever you’re using for power distribution), so thought it’d be the case for USB-C.

After doing a bit of research, I only really came up with one adapter which seemed to be able to deliver a reasonable amount of power (45W).  However, that’s still not as much as the laptop can use going full tilt.  This is the Targus APD39EU.  DC input spec is 11-16V so some NP1 type setups may deliver a bit more than 16V.  I expect it’s fine but they may not pay for a replacement if you blow it up.  It’s also quite a lot more expensive than most of the other USB adapters at around £60 (although I managed to snag a reduced one with damaged packaging).

Due to the fact it’s quite an expensive adapter, and a fair bit longer than some other USB adapters, instead of directly attaching an XLR4 I made up a lead from XLR4 to automotive 12V socket.

12 Adapter and cable12V automotive socket on cable

So far the laptop charges off it and nothing has exploded yet…

Anatomy of a Charger box

I’ve seen a few people lately make boxes for all their battery chargers so they can just plug one them in and then have all their chargers set up.  However, most of them relied on using a number of the different power supplies and sometimes running a power strip, which take up a load of weight and space.  I’ve decided to make one but cut it down to be lighter weight and to also have the option of plugging in to a battery or car DC connection in case of being away from mains.

So, first of all I needed to figure out what to was going in and what was required to power it.  I thought about 20 AA batteries is about the maximum I’d go through in a day (I try not to use any other kinds) .  I also use 2054 style SMbus batteries- both the chargers for these are small but require external power supplies, and they take a 24V input.  I also use USB to recharge my Timecode Systems boxes (and some USB batteries, and *everyone* wants a phone charger).

So (according to the manuals/existing power supplies)
2x AA chargers on 12V (1.5A each)
2x SMbus on 24V (2.5A each 5A total)
USB on 5V 2A

and I need something to power all that…

So, basic electricity time:
Power = Voltage x Current
Components will only work within a specific voltage range (otherwise they don’t work or break) and will draw up to a certain current.  So the voltage is the ‘level’ of electricity and the current is the amount it uses.

So 1A of current at 12V = 12W of power
12W divided by 24V = 0.5A of current
so, to provide the same amount of current at twice the voltage requires twice as much power.

So, the SMbus chargers need 100W, AA chargers need 36W and  USB needs 10W.  In all that would need a 150W PSU to run everything at once at max power.

I actually ended up getting 2 under-specced 90W PSU as they were smaller and lighter, had variable voltage, USB built in and a display.   However it may mean it’ll top out (7.5A) if everything’s on at once, which may mean some things won’t charge as quickly.  It’ll also turn off if it gets too hot.  The second can be used too if I need additinal power or even to power my cart

The 5V line is taken care of but what about either the 24V or 12V? Although it’s usually more straightforward to reduce voltage, I decided to run the PSU at 12V and get a 12V to 24V step up converter which will handle 120W.  This way, it gives the option of swapping the PSU out for a 12V battery.  I made all the linking cables up with 4pin XLR connectors, which is fairly standard for DC power distribution, and means the various components can still be used separately.

Here’s all the individual components connected together:

Ends were cut off most of the cables to replace with 4 Pin XLR connectors and the 24V output was soldered directly on.  I also used right angled DC jacks to save space and avoid pressure on the cables when in the box.

For the box I used one of the newer Orca accessory bags made of moulded EVA plastic.  It’s considerably lighter than a Peli case, yet still seems rather durable:


The AA chargers are velcroed to the pockets which contain the PSU, step up converter and USB hub.  It’s a bit top heavy, so I may remove the support straps in the case to let the lid fall back as it falls over if not leaning against something. There’s a channel under the material on the hinge which makes a neat place to run cables too.

The USB cables run to the section to the bottom right, so whatever’s being charged can go there, and the plug can fit there when being transported

Backup rig

Having both the mixer and recorder in one box has really become a standard these days for doco recording.  It’s quite easy to see why, it’s 2 boxes with the size and weight of one.  However, if something goes wrong with it you can be stuffed.  With my old rig, say if there was a problem with either the recorder or mixer it would be possible to either cable to camera and just use the mixer.  Or plug directly into the recorder and just record iso tracks.  Either way, if something bad happened to either box it’d be possible to get something.  If you’ve got one box handling all your mixing and recording and it goes wrong (and it’s a computer!) you need some kind of failsafe.

Since I bought the SX-R4+ I’ve been carrying this rig in the bottom of my bag.  This is partly because I’m only set up to send to camera over wireless or AES3 digital with the R4+ (currently waiting for the XLR5 option board) so it’s had a bit of use, still:



It’s a Sonosax SX-M32 3 channel mixer, Wisycom MCR42 dual channel radio receiver (with standalone back and AA battery compartment) and a Sony PCM-M10 recorder (with remote on the right).

All of it will work for a good 5-6 hours from AA batteries (the recorder runs for about 24!).  So say, I run out of Li-Ion rechargeables, or they’re held up in customs I can at least get a runner to buy a load of AAs from a shop.  I can run a boom and 2 radio mics and be cabled to camera or record independently (with no timecode).  Also a feature the PCM-M10 has which the SX-R4+ doesn’t is recording as MP3 (!).

The whole bag weight about 2kg and I’d probably find I can do a great deal of more basic jobs with this rig

Even when I do get the additional output options for the SX-R4+, I still think I’m going to carry this around, just in case…

Kaoss Pad KP3 DC powering

Just as a note as it doesn’t seem to be anywhere else on the internet (and was quite tricky to find out): the power connector for the Korg Kaoss Pad 3 is JEITA RC-5320A JSBP4 standard:

Outer diameter is 5.5mm
Inner diameter is 3.3mm
Centre diameter pin is 1mm

Plug I used was a Lumberg 1636 04

It’s also nowhere as greedy as the PSU is specified, it’ll boot up with as little as 9V 100mA

This may also be applicable to other Kaoss Pads and other Korg products.

And using alien power supplies may invalidate your warranty etc etc

New DPA concealers

Earlier this week I bought some of the newer style DPA concealers- I’ve found the older style to be really useful for hiding body mounted mics, however they’ve made some changes (very possibly improvements).

Quite a few people seem to be a bit confused about them, so I thought I’d show you how they work:


As you can see, instead of one piece, the new concealer’s made of 4,with one piece being slightly smaller than the original concealer.  The back part can be sewn into clothing or used with the clip, as shown here:


There’s also an extra “space bracket” wire which is removable over the top- both of these should keep fabric away from the mic, reducing the chance of rustle against it.  I also think these may be a good way of mounting wind protection without tape, but may require some further experimentation


Here’s a comparison against the old concealer- the new one’s slightly smaller and the plastic’s more pliable. The new ones are a tighter fit and need to be bent a little to get the mics in. As you can see, there’s a 4071 in the old concealer and a 4061 in the new one.  The old ones need specific concealers for both mics and the new ones will work with either:


Here’s the 4071 in the new concealer:DSC01987

DPA’s part number is DMM0021 for a single concealer or DMM0521 for a pack of 5.

Other versions are available for the heavy duty versions of the 406x and 4071 mics and the new d:screet slim.

Sound Network are the UK distributors


Tascam DR701D and HDMI DSLR Sync

Last month Tascam announced a new recorder, aimed more at DSLR self shooters- the DR701D

Although I’m yet to see one in real life, they have built in a unique feature: an HDMI input and output.  This is by no means a review, but a few thoughts on what impact this could have on workflow.

Why would you put an HDMI input on an audio recorder?
Well, it’s not just video signals which are sent over HDMI.  They need to be synchronised with the source and, in addition to that there are 8 channels of audio and time code.

There are also a number of DSLRs and cheaper cameras which lack professional inputs and outputs for time code and genlock, but do have HDMI outputs.  With a case of a lot of these cameras, it’s simply not possible to synchronise them, so more work is required in the edit (although programs such as Plural Eyes can really help).  In addition to this the inputs for DSLRs are often consumer 3.5mm minijack connections with poor analogue performance.  If they’re sent audio it usually ends up being noisy and adding another cable just adds an additional point of failure to the system.

Single Camera interview
In this situation, a sit down interview- neither the camera or sound recordist are likely to move, so attaching an HDMI cable to the recorder is fine.  This allows the recorder’s clock to synchronise with the camera’s and to receive time code (including remote roll commands).  Here both time code and the clocks are synchronised; these are 2 separate things- time code is only meta data, the clocks which determine the frame rate and sample rate of the camera and recorder require a higher frequency sync signal- genlock or word clock, here the sync signal is in the HDMI stream.  This should mean both files should be perfectly in sync throughout and the files are the same length (never before possible on DSLR shoots).

Vérité shooting (single camera)

Here it’s not really practical to be cabled to camera (especially with something as flimsy as an HDMI cable) , as both camera and sound will be moving.  What’s possible though, is to plug the HDMI into the recorder near the start of the take, then roll separately.  Time code will probably be well within a frame, however the clocks will not be synced so files will be different lengths.  This may be fine for shorter takes, but over longer periods (say, shooting events) the files lengths will differ and may need to be cut and re-synced.

There are some consumer  (and professional) wireless HDMI transmitters, which may work for this, however I think they will have a different clock on the receiver so will not have synchronised clocks.  They will also have a fixed delay time, which will have to be accounted for in the edit.

Multiple cameras

Unfortunately, this is where this workflow totally falls over.  All these cameras only have HDMI outputs, so it’s impossible to get an external time code or clock signal into them.  The only time code and clock output on the DR701D is an HDMI passthrough and I’m not aware of another box which can extract this.  For this another solution may be required, such as sending time code to an audio track on the cameras (which has no clock sync and specialist software is required to decode it), or hiring suitable cameras for the job!  A lot of times DSLRs are used as B-Cams and it’d be good to get a more professional sync solution with them, unfortunately this isn’t it.

However, the DR701D does seem to have a professional level TXCO clock generator, so could be jammed and stay in sync with more professional equipment

Molle radio mic pouch

I’ve been looking for a decent solution for this for a while now.   I’ve been using a few of the hard zip up containers Countryman mics come in for lavelier microphone and wireless transmitter storage, along with mounting accessories.  However I’ve been after something a bit bigger to put belts in so I’ve got an ‘all I need’ radio mic kit for when I need to leave set to get people mic’ed up.

After getting one of the new K-Tek stingray bags it has fabric rings for attaching military standard ‘MOLLE’ accessories.   There’s quite a lot of different kit available which is compatible with this, from army surplus and other places.

I bought a ‘medical pouch’

Inside I can get batteries, 2x countryman pouches with mics, transmitters and belts

Under the countryman pouches:

Inside the pouches:

And here’s how it can be attached to the bag:

I also often carry just one ‘main transmitter pouch’ in the front of the bag- this will just be when I’ve got this bag on its own.  It should also mount onto the waist belt.

I’ll have a look into more MOLLE accessories and see if some are useful…


Sonosax SX-R4+ first impressions

Being an ‘Early Adopter’ is usually a thing I don’t do and warn others away from, especially with products which are heavily software based, however I’ve been a user of the SX-R4 /SX-M32 for some time and have struggled to find another solution which has been able to do quite as much with a similar footprint and weight (despite the numerous workarounds and bodges in my current rig) and have the sound quality I’ve grown accustomed to.  When they offered a discount for pre-orders of the machine I put a deposit down.  Think of this as an ‘initial’ review.  I expect there’s a lot more to come from this machine and the modular system based around it.

The SX-R4+ has been out on 3 separate jobs now, all fairly straightforward corporate /online type things.  It was spared from a trip to Kosovo as it arrived the morning I flew out.

At a first glance the front of the machine and user interface looks pretty bare.  However,  it has a touchscreen interface, I was a bit sceptical about this until I’d used it (especially for a machine this size, it’s only marginally bigger than the SX-R4).  For most menu functions, the screen’s effectively separated into a grid of 9 buttons- all big enough for fingers and there’s a knob to change parameter values.  The menus seem well layered, nothing’s more than 3 layers down.  This allows much faster navigation through menus than on recorders without a touchscreen.   On the main screen there are 3 shortcut sections at the bottom, one to the power menu, one to quickly change scene/slate/take and one to the main menu.  Ideally I’d like a faster way to to the metadata notes screen too, but that’s one click on the web server screen.  Faster hard pan control would also be beneficial.

To add to that, it has a wifi interface which other devices can join or, alternatively it can join a network.  It doesn’t require an app, just a browser window as the machine runs the interface through a web server.  Currently it’s possible to view meters, arm and disarm tracks and add metadata, while almost all parameters on the machine are viewable.  This adds further ease of use to the machine and there’s no reason why a keyboard couldn’t be plugged into your tablet/phone/computer (although there’s no native keyboard port).  Although it’s a small device, it can ‘get big’- there’s no reason why it couldn’t be used effectively for trolley based work with either a mixer in front or with the upcoming control surface.

Webserver screen

Next, what does it sound like?  Lovely. Through the headphone amp, there’s definitely an extra level of cleanness compared to the original R4 and Sound Devices 6 series, this may be just an improvement to the headphone amp, though.  However, it does have an extended dynamic range, due to some kind of dual ADC witchery to give something like 135dB(A) dynamic range- effectively your recordings should be clean without adding any gain to your mics whatsoever (although productions may not understand/like this).  I’m not sure my ears can manage that- it’s from nothing to practically being behind a jet engine and possibly more than any microphone can manage.   There’s some sort of patent wrangling in the US going on with zaxcom’s neverclip which seems to be similar technology meaning the R4+ won’t be sold in the US at this time.

Input-wise it can also take 10 channels of AES3 digital inputs (4 of which can be dual AES42 digial microphone inputs if going though the XLR connectors), 4 microphone inputs and 2 balanced line level.  Using the AES3 inputs make a real difference to the noise floor on the outputs on my Wisycom MCR42 receivers.  All the digital inputs use asynchronous sample rate converters, so clocking is not required.  When switching between analogue and digital on the XLRs, you can hear the mechanical click of a switch inside the machine (in your ears, rather than headphones).  It’s quite satisfying, and I can’t imagine you doing that whilst rolling.  The mechanical record/playback switch is also satisfying, but I think the original R4’s is slightly larger and better.

Outputs are a bit of a sticking point with this machine, as it comes your only outputs (except headphones) are a 2 channel unbalanced output and a 2 channel AES3 output.  This actually worked out fine for a job feeding 2 amiras, with one on wireless but it will require an extra box to run balanced analogue, either an unbalanced-balanced converter or DAC.  There is an empty slot on the left ‘analogue’ side for either a 5pin 2 channel balanced output or RJ45 digital audio connector to run 16 channels I/O over dante, ravenna or AVB- this would really open up the machine to expansion and allow it to be used as a computer audio interface but would still require another box for camera feeds.  Both of these options are currently in development and expected by the end of the year.  Any inputs can be routed to any track or output.  There’s a matrix with each of the 16 tracks and inputs are assignable, while outputs have a 2 track matrix with each pair of channels assignable to either output channel.

The R4+ is a 16 channel recorder, which records to 2x SD cards located on the front at up to 192kHz.  I didn’t receive a cover for these as they’re currently being re-designed.  Sonosax weren’t happy with the initial batch so a new one should be on the way.  Personally I like the front access to the cards- it avoids ferreting around the sides/back with some pliers trying to pull out a CF card . Also the SD cards are considerably cheaper than CF.  A new development is that the R4+ formats the SD cards as UDF- which is the ‘dvd writing format’.  This means file headers are written at the start and the data is added sequentially- if there’s any interruption to recording, say a loss of power then the files stay intact and won’t be lost as a header hasn’t been written.

The power management on the R4+ takes another step up from many other recorders available.  It uses ‘2054’ shape Inspired Energy/RRC/audioroot batteries internally with a runtime of over 8 hours with the machine as-is, and running a RF distributor and 2 wisycom receivers just under 5 hours on one 48W/hr battery.  You can tell this from the smbus interface with the battery- detailed current draw, how many charge cycles the battery has done and accurate runtime are all viewable.  Battery warning alarms can be set at whatever time you like.  It also has a 12V regulated output, and 7W can be drawn from this- this is switchable so peripherals can be turned off through the menu.  There’s also an hot-swappable external DC input which will also receive smbus data over pins 3 and 4 (check your wiring in case DC is going through those pins!).

Finally, the 4 main controller knobs.  First, the good news- these are connected to the DSP and control the ADC input levels of the inputs to each of the 4 corresponding XLRs. Also, the fact they’re offset from each other makes it easier to identify channels without looking. They’re very smooth and totally free of ‘zipper’ noise; sensitivity, gain ranges and whether the knobs mute at zero can all be selected through menu options.  They also have a button which is activated when they are pushed in (this can also be programmed to do number of functions- including something else on a ‘long’ press, although PFL seems to be the most useful).  The issue that they’re currently ‘locked’ to input gain on each XLR, is however an issue at the moment- this means it’s only possible to record post-fader iso tracks, and that each AES3 pair is automatically ganged to one fader, so in AES3 output mode my receivers are effecitively single channel.  This is one of a number of issues which are due to be fixed in the next firmware update, however.  The faders for inputs 5 and 6 correspond only to the analogue line inputs and are pre-adc potentiometers, so if used as faders the iso tracks will be ‘post fade’ (and this can’t be changed in software).

The final missing feature is dedicated comms sends.  I think it’s something Sonosax want to keep for their bigger mixers, however this machine does have plenty of tracks and it certainly has the DSP power to route a mic input to a number of destinations (possibly through programming some of the buttons).  It could also be possible using an external analogue mic switch or through a third party dante/ravenna/AVB compatible box.

In conclusion,  it’s small, this is a very powerful machine, which sounds fantastic and has an excellent user interface.  It should also get very expandable later in the year when the additional mic preamp box, control surface and option cards become available.  There’s also buckets of DSP horsepower in there yet to be used, so it’s still early days on software capability.  However there are a few missing pieces at the moment, which should hopefully be sorted very soon.

For further information, see and the IPS have a detailed interview with Pierre Blanc from Sonosax about the machine here

New battery standard?

For the last few years I’ve been using NP1 batteries (mainly the shorter NP35 format), which seem to have become a standard for most location sound recordists.

However, there are other 14.4V Li-Ion batteries available.  Another type, which I feel may become a new standard are the “2054” format batteries.  They come in 2 sizes, one around the same as an NP1 but packing in up to 98Whr of energy (pretty much the maximum allowable on flights without limitations being imposed) and a half length one at 48-49Whr.  This is compared to a maximum of 84Whr in an NP1 (DSM’s Ultimate NPLU84) and 35Whr in the half length (Hawk-Woods NP35).

Here’s a picture of the various sizes compared to a full size NP1

Both Sonosax and Aaton have recently announced recorders (SX-R4+ and Cantar X3) which use this battery format and Audioroot have been producing both these batteries and the distribution systems for them for a while now.

Also there aren’t really that many sound recordists, we’re not a huge market.  These batteries are used in industrial and medical equipment.  There are two companies who make them (that I know of): Inspired Energy (USA) and RRC (Germany).  I’ve been informed that Audioroot batteries are supplied by Inspired Energy, but programmed with custom firmware in order to communicate with their distribution systems and chargers. RRC only make the smaller format batteries, there’s also a difference in power gauges- RRC have LEDs which light up in sequence when you press a button, while Inspired Energy have an LCD display on the end which always stays on.

I did say communicate then- these batteries have a system called SMBus, which is a standard system which communicates charge info, battery health, temperature etc to either the charger or the equipment it’s plugged into.  This can allow accurate info on how long the battery will last given the load it’s under, not just a voltage.  This means they require extra contacts for data info (so pins 2 and 3 on a hirose connector will be used).  Check your cables first as some may be made connecting pins 1&2 and 3&4, which may damage components on the other end is they’re given 16 or so volts.



HD-SDI video signal transmission

This is really just a few thoughts on running multiple HD-SDI signals along one cable- a number of production sound mixers have historically run multiple analogue sources over CAT5 cable (and even with a balanced audio return), however, the majority of video signals around set are increasingly HD-SDI, which are more fussy over the 75ohm BNC cable they’re distributed through.

My first thoughts were to up the spec of the cable, to CAT6 or CAT7, which have superior shielding, however I found that Muxlab make a passive HD-SDI balun which says it can transfer HD-SDI video over 120m of CAT5e cable.  As it only uses one pair of wires out of 8 in the CAT5e cable, I can’t see a reason why you couldn’t wire 2 (or even 4) of these baluns to run over 1 cable.  There also isn’t much to them, they’re a 75ohm to 100ohm balun transformer, however they need to work at 1.5GHz in order to transfer HD-SDI, and 3GHz for 3G SDI (and finding a suitable transformer is more difficult)

After looking at the 3G-SDI spec (SMPTE424M), I noticed there was a mode (B-DS), which allows 2 independent HD-SDI signals to be transferred in one channel.  So I had a look round for a box that could combine and split the two signals, and came across something even more powerful: Blackmagic’s SDI multiplex 4K mini converter* This allows 4 independent 1.5Gbit HD-SDI signals to be muliplexed into one 6G-SDI signal.  This will also allow for current monitors to work with fancy new 4K signals and it’ll also work as a distribution amplifier if things get a bit congested at video village (although this is not sound dept’s job).  I don’t know whether it’d be possible to run a 6G-SDI balun, CAT6 cable is capable of handling 10Mbit/s networks, however not over long distances (CAT7 would be more appropriate, if a suitable transformer could be found)

Another solution is running a quad split, where the converter box will put up to 4 different images on each quarter of the screen- a single, larger monitor could be a good solution to this, however an advantage could be to be able to get a cheaper HDMI monitor (as some have HDMI out), run the quad split close to that.  Decimator design make a number of suitable boxes for this, depending on your requirements.

*amendment- After contacting both Muxlab and Blackmagic about their 6G multiplexer boxes, they’ve both said they *should* support multiple streams, however they’ll all need to be in sync, however neither company has tested them.  So neither box has sample rate converters (or their video equivalent?) on the inputs.  I’d expect them to work if all the cameras have genlock sources on lockits