Analogue audio over CAT5 cable

Cat5 cable can be cheap, it’s pretty light and thin but surprisingly well shielded with 4 twisted pairs in there which will all resist interference.  It also has 100 ohms impedance, which isn’t far off the AES/EBU standard of 110 ohms, so should be able to carry digital audio a fair distance.

So I’ve done a bit of a make and an experiment to make a lightweight 4 way multicore:

I got a couple of Neutrik NE8-FDY-C6-B connectors- these are fairly easy to assemble, there’s instructions on the site, and don’t even need a soldering iron- just some snips, really.  You could probably prep one with your teeth if in a desperate situation.
On the other end I attached 4 XLRs

As they’re not meant to be cable mounted (and there isn’t an appropriate connector) I had to improvise with sugru and heatshrink

Anyhow, they work and with shielded CAT5 cable (you have to look quite carefully at the specs, most isn’t) they’ll work with phantom power too.

There are also a few commercially available solutions for audio over cat5, the “balun” boxes don’t usually do any more than this.

I’ll hopefully have another make done next week (you wait ages for one…)

4 channel mini line mixer – nearly there

I’ve been working on a design for a small line mixer since January, on and off. I’m getting pretty close now- I’ve got a working circuit and managed to get the enclosure design working. I need to make a few tweaks to the board design, as some components need to be moved in order for it to fit in the box

This particular one is an unbalanced design, with 4 inputs over 2 mini XLR inputs, outputting to a single mini xlr output. The reason for this is to work with my Sonosax recorder and mixer, in order to be able to be able to add the recorder’s 4 XLR inputs to a mix (on the bus in for the mixer) and still record pre-fade ISO tracks.

The holes at the top are for L-C-R panning switches, which will need to be glued into place (one’s actually on the table in the photo above to the left).

I’ve made sure to use high quality components in the circuit- resistors on the inputs are matched within 0.1% tolerance and high quality op-amps have been used. The most expensive parts were the sfernice conductive plastic potentiometers, though.

There’s no internal batteries, but it will run on sources from around 9-16V, with the internal regulator providing +15 and-15V for the op-amps

Here’s how it fits in the bag.

It shouldn’t be too different making a balanced design using 5 pin mini XLRs- I went through one in the design process. There’s also a headphone amp on the board, I’m wondering where I can squeeze a 3.5mm jack and a small level pot in there.

As the boards are being fabricated I may be able to sell some of these as kits, if it’s useful to anyone else

Won something!

I found out last week that a little short film I did, Best directed by William Oldroyd won the Sundance London short film competition. Unfortunately (thanks to the masses of Pink fans at the Millenium Dome) I managed to miss the screening, but got to see some of the other shorts and have a chat with some of the other directors and crew involved.

It was shot really quickly in an afternoon on DSLR with a very small crew, with the actors getting changed in a nearby cafe and, although the church knew we were shooting a film there, they didn’t know what the content was.

Here it is; some people may find it offensive, it might not be safe for viewing at work

BEST from William Oldroyd on Vimeo.

Since then I’ve done another short with William- Wanted: Murderer, where I also did the post mix.

Travel NP1 charger

I’ve been looking for a small NP1 charger for a while- something which came to mind after I’ve had a few jobs where I’ve been away for a few days and didn’t want to take my big 4 bay one.

I think I’ve found quite a neat solution after finding some 14.4V Li-Ion chargers on ebay being sold by Audioroot (French company which makes high-end power distribution systems and portable microphone preamplifiers).

I bought a couple of these (one’s going spare if anyone’s interested) and soldered on a female hirose socket (HR10-7J-4S) so I can just attach an NP1 shoe with a hirose plug.

It also *may* work with the unregulated flying lead on the Hawk Woods battery distributors, but I’ve emailed them to confirm- so I don’t blow something up

Interview setup

I’ve recently invested in a paintball gun bag, which is proving surprisingly useful.  I even managed to carry my entire kit for an interview (with Dame Helen Mirren, no less) in it yesterday.

Inside the main compartment, I’ve got a vdb doco pole, Manfrotto 5001b light stand with boom buddy, magic arm, mic suspension and clip and 3 XLR cables.

In the front I’ve got a Sonosax SX-R4 recorder, headphones, 2x AKG C480 mics with various capsules (in peli case) and my lavelier microphone kit including 2x DPA4071 with hardline adaptors.

When running more complex setups, I’ve got this doubling as my boom case, where the Sennheiser MKH8060 setup can go in the front compartment

As another note, a Rycote WS4 will fit in the front compartment too

Microtech Gefell KEM970 Cardioid Plane mic

After talking to John Willett (Sound-Link Pro Audio) and Elisabeth Kuenhast (Microtech Gefell) at BVE a few weeks ago, after just spotting this mic and saying ‘what’s this?’ I’ve hired one out this week for a couple of days recording a play.

It’s a really interesting design, it effectively works like a line array – essentially meaning it will pick up sound with only a 3dB loss from a doubling of distance, rather than 6dB from an omnidirectional mic.  The pickup pattern’s also interesting- it works like a cardioid in the horizontal plane, but lobar in the vertical.

I decided to give it the cruellest test possible in my flat by recording my voice from the other end of the bathroom, our bathroom’s quite long- it’s about 4m away.


It wasn’t all good though, the internal noise was considerably higher than the Sennheiser MKH and AKG ULS mics I’m used to, 15dB(A) (DIN EN 60 651 scale)- however not surprising, considering there’s 8 capsules in there.  Another thing which is frankly scary is the price to buy it- however, this will probably do the job of 5-6 mics for me this week.

Another thing is it requires mains power for the matrix/powering box, so wouldn’t be suitable most situations I find myself in



I’ve been having a bit of a look round at cases- Most of my jobs are with a reasonably light kit and I’ll get there on public transport.  I’ve been looking at Peli cases, which are made to withstand environmental extremes, but I could probably do with something a bit lighter.  For the last couple of years I’ve made do with a backpack, along with having my sound bag on but there’s the odd time where ‘I could have really done with that’.  Also something where I can use dividers should also help finding things quickly, instead of having to root around at the bottom of the bag for that obscure adapter.

Stuff I’m having a look at:

Lowepro Pro Roller X300  – A self-shooting director I work with bought one of these for his C300.  Being able to use the inside as a backpack’s nice.  It’s got 35L capacity, which is only a bit more than I’ve got now.  Weight 6.1kg

Petrol PA1003 – Really like the 2 layer design, *looks* quite big although the interior specs seem to say otherwise (30L, maybe only counts 1 layer as main compartment?).  It’s also quite heavy (8.1kg) There’s a video up here:

Kata FlyBy-77   – Lightest of the lot (4.1kg) and pushes 40L capacity, although some of that is from being a bit deeper.  Is also good as airline carry-on.  Wonder if reduced weight= less protection, though?

Lighting bags? Petrol PL2003 etc
They’d need extra dividers to cushion stuff, but they’ve certainly got enough space in.  You can also put a whole boompole and/or mic stand in lengthways on the longer ones.

Also as an alternative to Peli cases, I’ve been pointed at B&W cases, they’re made in smaller sizes and are considerably cheaper with dividers.

Anyone used any of these, or have any other ideas?

Here’s a comparison table

int L(cm) W(cm) D(cm) vol (L) Weight (kg) ££ (inc VAT)
Peli 1560 51.6 39 17.8 35.82 9.07 252.91
Peli 1610 56.2 43.1 21.6 52.32 10.2 328.62
Peli 1650 74 46 22 74.89 16.1 373.94
B&W Type 66 53.5 36 19.5 37.56 6.6* 180
B&W Type   70 67.5 42.5 22 63.11 9* 252
Lowepro x300 37 17.5 55.5 35.94 6.6 338
Petrol   PA1003 58 27 20 31.32 8.1 186
Kata FB77 53 33 22 38.48 4.175 215
Petrol   PL2003 (+trolley) 73 35 21 53.66 7.77 238.77
Petrol   PL2004 (+trolley) 88 35 21 64.68 8.6 262.21

*no weight with internal dividers given (expect to be similar to Peli cases)

New Recorder

I’ve just gone and purchased a recorder- a Sonosax SX-R4.  A rare second hand example came up and I thought I couldn’t really miss the chance to get it.

It may be small but can record up to 8 channels on HDD, plus a 2 track mix on CF card.  It’s also got 4 excellent Sonosax preamps (the same as in my 3 channel mixer), although less precise control over LF cutoff points.

I’ll be looking to make some additions to it in time, I still need to make up cables for timecode and the accessory port, so I can use the digital in. And I’d like to use a passive mixer to allow greater control of my mix, feeding that back into the M32 mix bus. I think I’ll look into putting one together myself.  There’s also a serial bus in the accessory port – I’ve sent Sonosax an email to see what that can do (possible remote commands?).

Stuff for sale

Clearout time…  Here’s some stuff I find I just don’t really use, if you don’t think the price is right, feel free to send me an offer:

RME Quadmic, older design front panel, same specs £175

Neurosky Mindset EEG headset- can be used to send brainwave signals to MIDI etc £100

Sony MDR-CD1700 headphones £100 SOLD

Philip Rees MM5 Midi foot controller £75 SOLD

AKG SE300B/CK93 hypercardioid mic  £130 SOLD
CK98 short shotgun capsule (broken)- offers

Yoga EM-268 Stereo mic.  Cheap electret mic for field recorders £5, or a beer

Peavey PC1600 Midi fader controller.  Couple of faders a bit dodgy, no PSU included- offers

Sony BC-1WA NP1  battery charger (NIMH).  Broken.  Take it.

Glyph FW400 Hard Drive (320GB), fan’s a bit noisy. £20

Tascam HD-P2 £300 SOLD

Marian ADCON £100 SOLD

Edirol / Roland R-44 £500

Rycote G3 short boompole £100

and.. although I love it, it doesn’t get used enough so:
Dave Smith Poly Evolver Rack £650 SOLD

Moog MF107 Freqbox £220

Computer Bag setup

Following on from my computer recording post, from a few months back- I’ve started to put a system together.

I’ve managed to sell all my other computers etc and bought a shiny new Sony Vaio Z (other shortlisted models were the Macbook Air 11″ and the Lenovo Thinkpad x230, based on connectivity, weight, battery power and ability to fit in the bottom of a Petrol PS602 sound bag).

For the interface (based on power, size and connectivity options), the computer was limited to USB.  I’m also a bit wary of firewire interfaces as I’ve managed to blow the controller chip in one, possibly by moving the cable moving a small amount while it was plugged in (or looking at it the wrong way?).  This left me with only 2 options, the RME Fireface UC/UCX and the MOTU Ultralite Mk3 Hybrid (I’d actually discounted this before due to lack of word clock for Timecode sync).

Despite being a long term user of RME interfaces, I couldn’t really justify the price difference for a bit of extra niceness and a word clock input.  MOTU interfaces will (according to their documentation) slave their clocks to incoming timecode on an audio input, so I’m hoping that works.

It actually involved quite a bit of pain getting the MOTU to work with the computer.  I found it’s not currently USB3.0 compatible (all the ports on the computer are USB3.0).  I had to switch them to USB2.0 in the BIOS to get it working.

I also got a control surface, after stumbling across the dodgily named iCON i-controls pro.  It’s probably the most compact control surface with 100mm faders I’ve come across and it runs from DC (and even seems to work without the motorised faders from USB power). It weighs just under 2kg. From having a play, the build seems better than the Euphonix/Avid Artist surfaces.  Was dead easy to set up, seems to talk pretty flawlessly to Samplitude and MOTU Cuemix, although I could do with modifying the setup so that the knobs control trim rather than pan.  Motorised faders are endlessly entertaining (although not to be used during takes).  For some reason Cuemix seems to eat about 10% CPU, which seems a tad excessive.

I’m still short of a few cables to truly make it work as a bag setup (right angled everything for the back of the ultralite, but it fits (with Sonosax mixer providing cabled mic ins and RME Quadmic as pre for radios (may not be necessary). I also need to get a VGA cable to output to the small monitor (may get an HDMI one instead, that one really is bad- ok for checking the frame though), seems a bit of a shame considering the laptop’s screen is 1080p.

Here’s a picture (spot the computer):

and here’s with the control surface, I’ll need some way of securing it, it just balances on top: