Overhead microphone for show relay and induction loop

[Brycie]

I'm looking to reposition and replace a microphone that is used to feed the induction loop and show relay system. At the moment it is some unbranded dynamic vocal mic hanging centrally about 3.5m above the stage from the first LX bar. Due to the mic's position it picks every rumble and squeak of the rigging, so I want to move it FOH.

 

The theatre itself is very small (see here), with the practical stage area being about 5.5m wide and 4m deep, and the auditorium ceiling only 3.2m high. The stage isn't raised, so there is nowhere boundary mics could be laid without the audience stepping on them.

 

I feel that I need to use one or two small shotgun mics, but I've never really played with any before, so I don't know what distances I can get away with. I'm trying to keep the overall cost around £100 (ex-VAT). Here's my two ideas so far:

 

1. 
    
   
2. Hang a pair of Pulse NPCD664 (CPC MP33868) spaced evenly about 2m back from the pros
   
3. Hang one Pulse NPM702 (CPC MP33869) centrally from the FOH LX bar, about 3m back from the pros
   

 

So would either of the two ideas work, or is there something else I should consider? I'll welcome any comments or suggestions.

 

Thanks in advance,

 

Bryce

[boswell]

I would use a single CPC MP33868 either mounted in the centre of the Pros arch on the audience side or maybe 2m back from it.

[paulears]

Personally, I'd keep the mic directly over the action, because for the loop, you want maximum intelligibility. If you move mics further from the sound source, the ratio of wanted to unwanted sound changes - for the worst. If the problem is creaks and noise from the bar it's hung off - why not just decouple the mic in an isolation mount. Loop systems need the cleanest audio source possible - if you take a mic 1.5m from people's faces, and add on an extra 3 m or so to the positions you mention, then the sound will be worse - even with cleverer microphones.

[sleah]

+1 for the CPC MP33868. Cracking little mic for the money. I use two for recording slung above the stage.

I'd suggest above the front of the 'apron' or just forward of the arch. If you wish to keep one above the stage, then as the CPC MP33868's are small and light, could you attach it directly to the ceiling?

Something as simple as a single screw with a large washer would be more than adequate to take the weight of thoses little mics :)

[Brycie]

If the problem is creaks and noise from the bar it's hung off - why not just decouple the mic in an isolation mount.

 

Unfortunately it's not just noise conducted through the bar, but that from various tab tracks that are very close by, and anything else that moves in the rigging (better quality rope is needed). Currently during a show I need to turn down the mic every time there's a scene change, or else there's a deafening roar throughout the building from the show relay as the tabs move, or a roll-drop is raised or lowered - Not ideal. I'd like to be able to largely leave the show relay system alone during a performance.

 

I'm inclined to go with the CPC MP33868, as it has been recommended numerous times within this forum over the last few years. I feel that I'd probably still want a pair of them for better coverage across the width of the stage, as that has also been a problem with the current setup. Looking at a cross sectional plan of the stage, I could probably have the new mics just 1m in front of the pros arch. This would mean that effectively the distance from the mics to the back of the stage would only be increasing from about 5m to just over 6m, plus with these being shotgun mics, I'd hope that I'd be able to get at least a similar level to the current mic.

 

Right, now to rummage through all the CPC special offer catalogues...

 

Thanks all,

 

Bryce

[dwright2104]

iv seen the Behringer B5 (this) used in a few larger theatres. placed at rear above sound mixing position. I dont think the theatres had any problems with it there.

[paulears]

It's not the mic quality it's intelligibility (certain for the loop system) distant mics with the extra reverberation is a backwards step for the hearing impaired. If the cardioid dynamic is hearing things from the rear and sides, then why not try another mic, like the cpcs in the same place. If the noise is bad from air transmission, then I'd expect it must annoy the audience too - are you certain it's not mechanical transmission? We have an SM58 hanging on it's own cable from an LX bat with movers quite close, and the house tabs nearby, and another frequently moved bar next door and the 30cm of cable decouples it so there are no noises?

[Bobbsy]

Paul is spot on when he says intelligibility is the key for hearing loop systems. The biggest enemies to intelligibility are, first, reflections and second, the distance.

 

The big problems with the usual idea of just slinging a mic pointing straight down somewhere above the stage are the fact that most of the pickup is sound reflected off the stage floor and also that a lot of key scenes and dialogue are often blocked to be out on the apron.

 

My preferred position it someplace just in front of the front edge of the stage, using some kind of supporting cable to angle the mic towards the stage. Some manufacturers actually manufacture specialist mounts for angling hanging mics but, frankly, I usually build my own out of coat hanger wire. The exact hanging position will depend on what pipes etc. you have available. I try to sling them as low as aesthetics and lighting considerations will allow and adjust the angle of the mic accordingly.

 

For mics, any cardioid pattern will do...I prefer a small diaphragm condenser but phantom isn't always there so have used dynamics as well. The OP mentioned the possibility of two mics--if space and budget will allow, this always gives better coverage. Just make sure that there isn't too much overlap in the centre or you get nasty comb filter effects when you sum to mono.

 

Bob

[Brycie]

Don't worry I'm bearing intelligibility in mind. The current mic choice and placement is just simply awful, but it's what was setup by the installers several years ago, and never changed. I should mention the control box is behind a window, so the show-relay is the primary method of hearing what's going on, and the current mic placement makes it very difficult to judge levels. I desperately want to loose the window, but that's a battle for another day.

 

The more I think about it, I feel putting a pair of mics over the apron area will be the best bet, since currently whenever anyone does anything in front of closed tabs, hardly anything can be heard. I actually want the opposite, whereby when the tabs are closed, I can't hear anything behind the tabs.

 

Just make sure that there isn't too much overlap in the centre or you get nasty comb filter effects when you sum to mono.

I hadn't thought about comb filtering problems, but I'll bear that in mind. The mics will simply be getting plugged into a Australian Monitor AMIS60 mixer amplifier which drives the show-relays, with its line-out feeding the loop amplifier.

 

So my current plan, as I mentioned previously, is to get a pair of CPC MP33868, and probably mount them as low as possible over the apron area, pointing upstage. I will experiment with the placement before permanently mounting them, as I do really want to get the best out of them.

 

Thanks again to everyone,

 

Bryce

[paulears]

I've got some of those here - the good bit is there are plenty of accessories in the box for all sorts of mounting possibilities. They're not that narrow, so if you need to do it this way, I'd agree they're probably a sensible choice.

[J Pearce]

I've found a spread of rifles on the LX bar/bridge closest to the stage to give excellent intelligibility. Deeper stages may need some upstage cover.

[Simon Lewis]

I've found a spread of rifles on the LX bar/bridge closest to the stage to give excellent intelligibility. Deeper stages may need some upstage cover.

 

However, do bear in mind that in order for speech to be truly intelligible for those with medium to severe hearing loss, an increase in STI in excess of 0.4 above "normal" may be necessary. In some spaces the "required improvement" can be far greater than that which is achievable using the overhead mics.

 

This gives rise to the classic situation where the sound engineer (often a trained listener with good hearing acuity) declares that the mic over the stage picks up speech with "perfect intelligibility". When users of the loop or IR system complain to FOH staff that they cannot understand what is being said, the sound engineer checks the system, and reports back - "it's working fine"...

 

If the show uses radio mics, a sympathetic (I.e predominantly speech only mix) should be fed to the assisted listening system, and the overhead mic not used at all - unless really necessary. Systems which rely solely on overhead mics will simply not provide the necessary intelligibility needed by many ALS users.

 

Simon

[J Pearce]

Totally agree simon, I'll always send the closest mic'd signal I have to the loop/infra red.

 

The rifles work well for drama and shows not using radios.

[paulears]

I'm ashamed to say that the system I installed in my venue has the capability for multiple inputs and outputs, so the overhead mic can be blended with other sources - wired to a desk mix out, and dressing rooms have one mix and the loop system another. I say ashamed because the desk input to it hasn't been connected for two years - because I've only just realised I haven't got it plugged in. I did even see the XLR in the dog box and couldn't remember what it was for - until now. I must make the effort to sort it. I guess I'm guilty of seeing the loop amp led flicker in time with the stage action, and just assuming what was going through it was fine. Not good really.