Super fast review of the past few months.

Foolishly, perhaps, we thought this year would be a quiet one.
A couple months on the ship at the start, then back in the UK until August, Teenstreet in Germany, and then back home for the rest of the year.

There’s a quote regarding the fallibility of apparently structurally sound plans of humans and rodents which might be appropriate around here.

When we finished our time on Logos Hope, we were in Bangkok.  Our organisation was holding a conference there at that time, so we helped out with the A/V techie arrangements for that.  When that was over, Becky headed home to Carlisle, and I went North for a week or so as cameraman, filming and visiting with one of our teams in the region.

After I got back two weeks later to the UK, We had a couple of weeks ‘normal work’, before I had to go to Ireland to run sound for an Event in Cork, as one of our other Sound Engineers needed to go back to Korea for surgery.

After getting back to Carlisle, we had about two weeks before we’d scheduled a couple of weeks in Cyprus, to take the Christmas break we’d missed on the ship, and take some time off, in lieu.

Two days before we were due to leave Cyprus, my Grandmother in Birmingham passed away, quite suddenly – although not totally unexpectedly – and so we returned to the UK with my parents and brother for her funeral.

We were then in back to Carlisle for a few weeks, before travelling over to Germany for Teenstreet.

While we were at Teenstreet, the arrangments came together for a filming project my Dad has been planning for a while in Cyprus, so instead of coming back to the UK, we headed over to Cyprus again to help with that, myself doing the sound recording and Becky the shoot documenting and general assisting.

We’ve since been back in the UK for just about three weeks, and so wondering what’s going to happen next.

Right now we have our friend Ant, staying with us, and he inspired me to start blogging again.  This may not be the most exciting post in the world, but it at least starts to cover the great gap of the last several months.

You should check Ant’s Thoughts About Job.

Documentation, and how balanced audio cables work.

I finally had a bit more time this morning to write a bit more in the A/V manual.  There’s lots of bits and pieces of documentation on board, but no comprehensive single getting started manual.  So I’m writing one, bring together bits and pieces from all over the place, sorting out what documentation there is, updating schematics, etc.

Anyway, here’s the rough version on the article I just wrote about how balanced sound cables work.  It’s pretty much my standard explanation of Balanced Audio, and aimed at people coming to A/V from a non-techy musical background, rather than for Electronics Engineers.
You may find it interesting.  Then again, you may not.


Sound is basically vibrations in the air.
TODO: more details, pingpong ball analogy? 

Inside an (SM57) Microphone head.
That is the bit of plastic and the coils!

This translates really easily into an analogue electrical signal: you simply turn the air vibrations into voltage vibrations.  A Dynamic microphone does this by having a small bit of paper (or plastic) which vibrates with the air around it, and pushes against a very small copper coil which, moving inside a magnetic coil itself, generates a very-very-very small amount of electrical current.

 TODO: more pictures.
This gets dumped down a wire, which gets amplified by (you guessed it) an amplifier into a very big amount of electrical current, which then drives a big electromagnet inside a speaker, which pushes another copper coil around, which is attached to another big bit of paper (the speaker cone), which causes the air around the speaker to vibrate – with the same vibrations that the microphone vibrated with, just bigger.
Simple, isn’t it? (well. Kind of.)

Balanced Audio Cabling

The trouble with simply dumping an audio signal down a cable, and picking it up at the other end is that your signal line, and return (usually ground) will pick up noise (say from A/C mains electricity, fluorescent lights, dimmers, mobile phones, etc)  along the way.

Here’s an original signal:

And here’s some noise:


 And the result:

This is a Bad Thing™.
So some clever engineers, back in the deep recesses of time figured out the following:  You could take a signal, and before sending down the wire where it could pick up noise, invert it:

If we add the signal to the inverse, you get a grand result of nothing (e.g. -3 + 3 = 0).
Now, if we throw these two signals down a pair of very similar cables twisted round and round each other like crazy, then they’ll both pick up noise pretty much the same as each other:

Note that 3 (the original) + 1 noise = 4,
while -3 (the inverse) + 1 noise = -2. NOT -4!
This is really cool, because if we add these two signals together, we don’t get 0 anymore, we get no original signal, but you do get the noise (doubled).


So we’ll use our amazing maths skills again, and divide this doubled noise in half. (2/2 = 1).

And we can subtract this 1 noise from the noisy original signal (4-1=3)

Voila! The original clean signal is back again.

  This is (roughly speaking) how balanced audio works.  And since almost all professional audio equipment runs with balanced circuitry, all we need to do is make sure the cables are in good shape, and then everything works magically with hardly any noise.

This is why for balanced cables (XLR/Mic, or TRS jack) you have 3 pins: +, -, and ground.  The ground is connected to a wire-mesh sheath around the other two, to try and keep as much noise away as possible.
(Technically, you don’t need to invert the signal, you could just use an empty zero, but for various impedance, op-amp, techy reasons, it works better if you do.)
Sometimes the ground wire will pick up noise itself, or due to being connected to different grounds at both ends of the circuit (say a piano on stage, and the A/V room sound desk) it will end up with a bit of random leaked current running down itself.  This can show up as noise, so you often use a Ground-Lift switch to disconnect the ground at one end or the other, which can sometimes help.
A DI box takes an unbalanced signal, and turns it into a balanced one, which means you can send a signal a long way without noise.
Remember how the two wires have to be twisted together like crazy?  This is so that if there is some noisy thing (like a flurescent light) nearby, both wires will be equally effected.  This is so important, that for broadcast audio, sometimes cables with 4 or more wires are used.  The + signal on 1 & 3, the – signal on 2 and 4, and then all of these are twisted together.  There are brand names of these cables such as QuadStar, etc.  Usually this is somewhat overkill for regular live sound though, as the cabling is much stiffer and harder to use day to day.

So, what do you think?

Back in the UK – for a while.

Hello Blog.
Hello everyone who reads this blog.
Hello google-bot.
Hello world.

It’s me. Daniel. Back again. Exciting, wot?

So, we’re back in the UK. I arrived back here literally 4 hours before getting on to a bus to go to TeenStreet in Germany, which we (OMNIvision) were doing video and some sound and lights and so on for. After two weeks of running this event, which I will tell you all about – later, which was very cool, we came back to the UK.

10 days later, Adam, Becky and myself went across to the Nederlands for our friends Jurgens and Eleanor’s wedding. Which was lots of fun. We came back after that to the the UK again.

(from that biggish place near New Zealand… um, forgottern what it’s called. Aus something? Something with trailers? or something?) also came with us back to the UK, and was here with us for about a month, hanging out, working at OMNIvision, and so on.

Then 10 days ago (or so) Bridget took us over to Malta, so see the Logos Hope for a few days, and also Becky’s dad and church there. I’d never been to Malta before, but Becky grew up there, so that was VERY cool. Malta is beautiful.

I’ll be posting more detailed stuff and photos later.. This is just to catch y’all up to date, you know.

So. We then came back to the UK, last week.

Now for the next scattered layer of events in between those all.

Yesterday we ran the video and lights for the Northern Women’s Convention, which we’ve been doing for the best part of a decade every year now, I believe.

On friday morning, we set up our whole smaller OB unit (the bus – aka “The Tardis”) at the main office for devotions, we filmed a bunch of stories people were telling. We hadn’t set up the unit in a while, so this was good to check everything was working before the Women’s convention… one bad camera cable, one missing focus adaptor, not much else actually wrong.

Two weeks ago, just before going off to Malta I ran sound and we did a spill-over room for the local Baptist church – as they had a new minister arriving (for the first time in decades) and so there were a few hundred people along. I’m in the middle of overhauling our sound equipment / side-racks stuff, so it’s good as well getting these smaller gigs to test things on.

I also went down to the Quinta and ran sound for them for their big 30 years Quinta+OM celebration a few weeks ago.

I do enjoy doing live sound stuff. I still wonder quite frequently if I should somehow go and do some more official training for it…

Oh well.

So, that’s the grand scope of my last few months, I’ll post more details soon.

Travelling again…

This evening we’ll be heading down to catch a ferry to Spain.

Exotic holiday time? Um, no.

Eloping? Um, also no.

Work? Yes. My name’s Daniel, and I’m a workaholic. I know.

So, there’s a conference in Spain, which our team here is covering the audio/visual side of. So we’ll take the Outside Broadcast bus down by ferry, stuffed to the gunwhales (if busses have gunwhales, but anyway. Stuffed…) with equipment, and also a blue van equally stuffed full of equipment. Due to ferry time-tables, we arrive a bit earlier than we need to, so Becky and I can visit her mum for a day or so en route – which is pretty cool! Then we’ll arrive at the hotel, and set up. The reason for the whole bus is that they also want everything videod and recorded, so we’ll be doing a 3 camera shoot, and producing DVDs of it.

Becky will be running a camera, while I’ll be in the bus operating the Camera Control Units, routing, recording, graphics and so on. I’m quite new at this – and while I got to do some last time I was with the team 2 years ago, I’m also quite glad that it’s the usual chief engineer directing, so I can learn from him.

Anyway. Time to go and pack…

So… Blogging.

Today marks 2 months of Becky and me being at OMNIvision, up in Carlisle. Time… is weird. It has gone so fast, and yet it seems like we’ve been here for only a few weeks, and yet Doulos is like another world away in the past.

I guess there will be another 200 odd people around the globe feeling the same way right now… and about 300 people every year have been feeling that for the last 30 years.

Our work is a bit random – we hardly know what we’ll be doing, one day to the next. We spent a lot of time in our first week or two pulling wires out of a big OB truck, then about 10 days sorting out books, inventorying, etc, then a few days moving a server rack across the building, including making and crimping all the new cables/extensions. Then a bunch of random small editing projects, a live concert in Manchester (me on a camera, Becky as my “cable monkey”), Becky is working a lot on admin stuff – figuring out some of the shipping arrangements for equipment, and writing the OMNIvision manual, and I’ve been doing some cleaning, sorting, lighting design, editing, fixing stuff, inventorying equipment, measuring cables, pulling electric cables through ceiling spaces, writing 30 second advert clips, and so on…

Yes. Quite busy.

And yet, not… it feels in some ways a lot more relaxed and slow than Doulos… yet also it feels a bit like I have less free time.

Becky and I live about 20 minutes walk apart, and neither of us have cars. The Office – where we go 2 mornings a week – is 15 minutes one direction, and the Studio – where we work the rest of the time – is 20 minutes the other direction. Busses are slow, somewhat irregular, and expensive, so we’re spending a LOT of time travelling. Also all the regular domestic stuff – cleaning, cooking, washing up, etc, takes time. On Doulos, I’d frequently be working until 6.15, pop down to the dining room, grab a plate of food, and the continue working while eating my meal. Same for lunch, and often Breakfast. Here, a meal can take over an hour. I guess it’s good, helping me to slow down… but BOY is it frustrating.

Like yesterday, I hoped to get a video project edited and finished… but then after Prayer Breakfast at the Office, I got a lift to the Shed (where we keep the vechicals), and picked up some equipment there, then got a lift to the Studio, and it was already 12.30. At lunch, there were a whole bunch of announcements and talking… and then with computers taking a long time to work, and Final Cut Server being a pain, I didn’t actually get to editing until 2.30pm!! And then Final Cut Pro decided to act stupid and to forget half the work I did with the Multi-Camera Editing tool (which otherwise is VERY cool…)…. So I only really got about 2 hours work done. Still, I’d done enough prep work with the lighting to make the keying and stuff a fairly easy job. I spent most of today editing too, and so that’s another piece basically finished.

I’m not sure if I like editing and that or not… in some ways it’s a lot of fun, and I do enjoy it. Yet I also miss “live” theatre.

So. That’s a bit about what we’ve been up to. I’ll blog more about future plans… in the future.

Long time no update…

So I guess I’d better try and get back into the swing of things.

Well, it finally happened. Doulos is officially ending. In just under 3 weeks time.

Surprised? Well, I wasn’t. We’d known that many issues were coming to light during the drydock, and it turned out the issues were more than were worth trying to sort out, for an increasingly short possible length of time.

You can read more about it on if you hadn’t already heard…

It’s been public for about a month now, I guess… and so my girlfriend and I will be leaving Doulos in exactly 2 weeks.

We’ll be going to work with OMNIvision for a few months, hoping to get a clearer notion as to whether we should go back there for a few years longer, later next year.

Right now, I’m pretty tired. I’m officially not AV any more, but working in training department, but still with many AV commitments, and jobs. I’ve not been able to hand over some of the last bits to my friend and replacement, as too many bits were caught up in the whole drydock thing, which didn’t really end solidly, so stuff just dragged out.

I’m getting bits of my new jobs kind of messed up to – down to forgetting to organize someone to lead music this morning at the “Tuesday Morning Devotions”.

I’m horribly behind with email, blog, newletters, packing and preparing to leave here soon, I’m behind on days-off, I have large projects I don’t even know where to start on, and so on.

I’m writing this at 5am, after having stayed up all night working with the videographer on finishing an “End of Doulos” presentation video which is needed later today. I was mainly doing audio engineering / cleaning up work. We still need one shot, and so a couple of guys are heading out at in half an hour to go shoot it – us sailing Doulos into Vivo City in Singapore for the final time. Then it’ll be rendering all day until getting shown this evening.

I also need to rig up an amplifier for some speakers in the bookshop this morning, and then I’m going out off the ship with the other Training Department people for the day.

It’s busy.

AV updates, mid drydock.


I think it looks a little better. Still messy, but at least understandable. Pretty much everything is plugged in now, and from preliminary tests, we appear to have somewhat better clarity in EVERYTHING, and some of the video signals are visibly higher signal-to-noise with much less interference.
We bought two new audio patch panels too, Behringer ones. Strangely, Behringer also seem to do unbalanced patch panels. Fortunately, the shop had both, and I noticed. What on earth would anyone want unbalanced patch panels for?!

I also had to butcher the two panels which we were replacing to get enough parts to fix a third panel which was very glitchy. Here are some of the internals which are slightly broken.

You can see a bit of corrosion on the top contact – even with jackplug cleaners and everything, the equipment is just plain old.

Today, hopefully, I can do the full system tests (need to borrow a oscilliscope and reference signal generators…), and then get the whole thing boxed up and leave it until the end of drydock. Then I can work on more fun projects. Videos, song composition, etc.

That’s all for now, I’ll post more shorter posts later, with more pictures.

Bolts and other bits and bobs

Ever wonder what a stainless steel bolt looks like when it completely rusts into oblivion?

Well. Now you know. This fell off one of our lifeboats. Makes you feel very secure, right?

This is the latest addition to the AV room:

It’s getting quite full, these days. Well, it has been for YEARS now. Any time we want to change anything, it gets quite major and complicated, trying to shuffle things around. Basically, I was fed up of having our stationary drawer jam because of too many tools inside it, so had the carpenters make us this. Makes me feel all reminiscent of the keyshop. *sigh* good old days.

Here it is, in place. As you can tell, the room isn’t all that tidy, still. Just SO MUCH STUFF! Other additions, the mug hooks on the wall, the per-day form hooks too, and also a removable wall-mount for the fan (which always used to just sit on the floor and get kicked…)

and lastly, we’ve FINALLY got the slot on the door for request forms!

exciting! I’ll post pictures of the opposite side of this amazing slot soon. It’s small, subtle, elegantly engineered and discreet. You’ll love it.