Thursday, June 20, 2013

Knitting with cables...

Or Macrame for sound technicians


We've had a couple of customers lately have problems with hired loop intercoms and sales microphone cables - one of them ended up using hand signals whilst the other was inadvertently doing Norman Collier impressions.

It was only when the sales customer bought his cable back to be repaired (he'd only had it a few weeks anyway) that the cause of his misery became apparent - he produced from a carrier bag a tangle of cable that was only just recognisable for its newness. Just looking at the cable we could see a couple of bulges in the outer and because we took pity on him (he had just spent several hundred pounds with us) we replaced the cable with a gentle admonishment to coil it properly and it would last longer.

The Hire customer

Our hire customer came back to us having used our cables to run the intercom he hired from us and then suffered low volume on one leg of his loop and intermittent contact on the other. We refunded his hire as a gesture of goodwill (he's a nice loyal customer and he's referred other customers to us) with a promise to check the system and repair it. He was adamant that the beltpacks were faulty, his rudimentary fault finding pointed at them - politely I suggested that it was a cable problem, 98% of comms problems are.

I tested the system the next day, sure enough - the beltpacks, headsets and masterstation worked but when we tested the cables we found two faulty. One was a broken connection inside the XLR, the inner core had been overstripped and held on by a whisker which finally gave up. The other cable had an intermittent break partway down - it showed as OK some of the time on our basic tester but when the cable was twisted it failed. Close inspection showed the sheath from one of the inner cores had split and the copper was protruding when twisted and shorting to the screen.

It's not just sound cables

We hire out a lot of cables over the course of a year and all of them go out neatly rope coiled - they're easy to count and easy to guesstimate their length if the ID sleeve gets damaged. When the cables return to us it's always a different story - cables are wrapped around each other, coiled like a skein of rope, coiled and secured with masking tape or sellotape. Don't get us started on the cables that come back covered in gaffa tape residue or brown parcel tape gunk... Of course, we're going to unwrap the cables and recoil them anyway but the point of concern from my point of view is the unseen damage that can occur from badly returned cable - it may not be readily apparent until it's too late. Our visual check of mains cables as we coil them catches damage to the outer sheath and the plug/ socket but anything happening internally won't come to light until it fails - perhaps during your show. If the cable is coiled nicely, then there's a lot less chance of it failing and with a mains cable there's a chance that something nasty could happen when it fails.

What to do?

It's quite simple when you think about it - any cables you have (not just ours but yours too) should be rope coiled before you store or transport them. Not sure what I mean by rope coiled - then have a look at this video?
 
Once they're coiled - secure them tightly with PVC Electricians tape - not Gaffa, sellotape, glittery pink tape or masking tape. If you don't have any PVC tape - we always have it on the shelf and it's not expensive to buy or keep in your box of bits.
 
Not sure whether your cables are ok or not? Buy a cable tester, they're not expensive and could save a heap of woe - from experience it's mostly sound cables and control cables that cause the most aggro, especially the sound cable that gets used to connect the lighting desk to the dimmers. 
 
I bought myself one of these - it tests XLRs, speakons, DMX cables, 8pin DIN cables and gives a visual indication of which pin is connected where.
 
Mains extension cables are easy to check - pop the cover off the plug and socket and check terminals and wire are tight - if still faulty then use another but this isn't so easy to do with XLR cables if it's Saturday night and B&Q is closed.
 
Still not sure how to rope coil a cable? Ask us to show you when you next visit us to collect or return a hire - we'll be glad to show you how, ultimately it will save you and us some aggro.

Wednesday, June 05, 2013

Are Radio mikes really that difficult to use?

We've reached the point in the academic year when lots of schools up and down the country are in the process of rehearsing for their end of term show. Some are relatively well prepared and have already begun to talk to us about hiring equipment from us, whereas others are only just realising that they need stuff. More often than anything, the one issue that raises its head is that of actually being able to hear the performers onstage. For drama, it's not too much of an issue - a little bit of work doing exercises to enhance 'projection' can perhaps be enough, the issues generally arise when the production is a musical and some childrens voices struggle to get over the music.

Invariably, someone suggests hiring radio mikes - one per child and the problem is solved - easy eh? Well, not really as there are two things working against you - one of them is cost (and we're not going to talk over the why's and wherefores of that here - you can ring us when you're sat down in a comfy chair!) the other is the simple practicalities. Radio mikes being operated using electricity (in simple terms) are governed mostly by the pesky laws of physics and radio waves - yes there are digital systems available but not in the practical price range we're working in - which dictate how many microphones can be used simultaneously. Alongside the laws of physics sit the laws of the land which dictate where in the radio frequencies you can legally use radio microphones - it's all changed over the last 2 years to make room for mobile broadband (and rumour has it - is going to change again)  which has had some impact on what you can use.

The Hardware

Central Theatre Supplies is a longstanding Audio Technica user and dealer - we install a lot of their microphones (wired and wireless) and also use their equipment for our hire stock. The AT3000 series is sturdy and reliable kit and priced at the point where we can hire it out sensibly and still make some money from the hires. There are other makes of radio mikes available which we do use and install - JTS mostly and some makes that we have hired in from elsewhere to cover busy periods.  The make of the radio microphone determines how many you can actually use simultaneously, it's to do with design of the circuits inside the transmitters and receivers that help the manufacturer reach the performance criteria they set themselves. The AT3000 series working in Channel 38 (the licensed frequency in the UK) generally allows us to use 10 units simultaneously - so if you have 8 performers that you can't hear it's quite simple or even if you find a couple more that are just on the edge of being intelligible. The problems arise when you suddenly realise that you have 12 performers who can't be heard - what do you do then?

The Plot thickens

The first reaction when usually being faced with performers that can't be heard is "Oh - put a radio mike on them..." and for 3 or 4 that works as an approach (there may still be issues that even with a radio mike the performer may still not be heard - if they're not trying to 'project' the microphone won't pick up much of a signal). As we noted above, if you think you need more than 10 performers with mikes - then there are issues to be confronted.

  • Is everyone on stage simultaneously? Whilst you may have 18 performers that can't be heard clearly - are they all onstage together? It might be that with some thought, you could share 6 microphones (or less) between them by having a member of staff backstage helping the performers to swap microphones with each other.
  • How long are they onstage? This is linked to the previous question - if the performer is singing one song and can't be heard, does it make sense to put a microphone on them? Does the blocking of the show allow them to be placed onstage in a position where they could be picked up with a conventional (and cheaper) corded microphone? Would it not be possible to do that over more of the show - use some radio microphones and some strategically placed corded microphones? Not sure about how to handle teaching projection? Have a look here
  • Will your sound system handle 8 more microphones? This is (believe it or not) the most common stumbling block that we come across. Most schools nowadays have a projector and screen in the hall with some means of plugging in a laptop to play music - some schools have an actual sound system, whilst some (and it's shrinking) still have a Coomber Portable PA. To use radio microphones, you need one input channel per microphone so for 10 - that's 10 channels of mixing AND someone who can sit with the mixer during the performance fading microphones up and down. Don't listen to the folk who say "Oh no - we just turn them on and leave them..." - they've never heard the apocryphal story about Barbara Windsor in the first West End show to use Radio Microphones!!

It all sounds horribly complicated

Perhaps it does seem complicated and on one level - yes it is (and we've not even covered things like batteries and the different types of microphones), but don't let that deter you from considering radio microphones for your show. We're always happy to talk around your show either by phone, in our shop or (if it suits your timetable) we may be able to come to you. We often find that a simple 5 minute conversation by telephone can make you think about the show slightly differently and sometimes even save you some money. It's harder to cover everything here - it's not really interactive and eMail has a lag to it which doesn't help (but we'll certainly start a conversation by eMail) but hopefully we've given you some food for thought. If we've inspired you to pick up the telephone and call us then good - but honestly don't leave it too much longer before you make the call if your show is soon.