Induction Loop & Instruments

[cmcculloch]

I have recently taken charge of the sound system at my church, and have run into lots of problems (both with the actual set up and those that use the desk!) that I am trying to sort out. I think I have now made everyone aware of pre-fade and post-fade, but I don't know much about induction loops.

 

Should induction loops be solely for speaking, or can instruments and other music go through? My concern is that, by putting keyboards and guitars thruogh the loop it may cause problems.

 

Any advice would be appreciated.

 

Thanks!

[DanHerbert]

Induction loops should only be used for speech as they are not designed to take instrument signals etc - also you'll probably find that the hard of hearing can hear a full band but struggle to hear a single voice.

 

The loop should be run off a pre-fade aux with separate control over all speech inputs to create a unique mix for this output. You have to remember though that if you mute a channel on the desk say a radio mic, the loop can still hear the person who is using it unless the mute it at the transmitter!

 

Apologies for the rush but I'm about to go out! PM me if you'd like further info!

[handyandi]

A welcome to the BR. In at the deep end with Church PA. Not an easy task getting personnel trained up, especially when some will not have the enthusiasm of BR members. Good luck.

 

On loop systems think of it as putting on an isolated pair of headphones & then listening to your service, since that is what will happen to the listener once their hearing aid is switched form the internal mic to the induction loop coil receiver. Definitely speech is the priority. Maybe a full instrument mix is not completely necessary, maybe the lead vocalist & the piano/keys etc. Problem with guitars is the electric & Bass variety use coils & will if of the cheaper variety & location to the loop (in the loop) feedback the loop signal back into the PA in the same sort of way as a microphone does when turned up too loud. You could put up an ambient mic for congregational singing if well placed & feed that just into the loop if using an AUX send feed to stop the listener feeling so isolated. Saying all this there is still a lot of ignorance in loop system usage even with hearing aid users as how to use them etc (especially the older generation who never get it explained the operation of their aid) & some fail to take up is benefits.

 

Good luck with the training!

 

Hope this helps

 

Andi

 

A concurrent post has been automatically merged from this point on.

 

Induction loops should only be used for speech as they are not designed to take instrument signals etc - also you'll probably find that the hard of hearing can hear a full band but struggle to hear a single voice.

Induction loops can cope with music otherwise there would be no use putting one in a cinema etc, 'sorry but we will only let you listen the speech tracks not the effects or music'!

Agreed a hearing aid maybe tuned more for speech than full range audio frequencies. Most decent model like from Ampetronic etc have compressor on the input etc to cope with changing input signals & to maximize the level send round the loop. Their web site.

[p.k.roberts]

The loop should be run off a pre-fade aux with separate control over all speech inputs to create a unique mix for this output. You have to remember though that if you mute a channel on the desk say a radio mic, the loop can still hear the person who is using it unless the mute it at the transmitter!

 

So why not simply use a post-fader aux for the mix?

[Paul TC]

The loop should be run off a pre-fade aux with separate control over all speech inputs to create a unique mix for this output. You have to remember though that if you mute a channel on the desk say a radio mic, the loop can still hear the person who is using it unless the mute it at the transmitter!

 

I usually feed the induction loop from a post-fade aux for the following reaso.

 

If the input source is set on the desk for normal room levels via the main fader and then the post fade send level is set to feed the correct level to the loop amp then the drive level should be correct for normal use, any change by the operator for a quiet or loud source into the microphone will also then be reflected in the level sent to the loop. (Although the AGC function of the loop should assist in levels).

 

The input source to the loop is then restricted to the micrphone / input source(s) in use, and any pickup by other microphones which may not help in achiving a "clean" feed is reduced.

 

Again, I usually restrict the inputs to speech and recorded sources.

 

 

A method of then introducing an Ambient Mic to this post-fade aux output is to connect the ambient mic to the desk, but not to assign the mixer channel to any output bus if the mixer has this capability. It will then appear in the output with a level set by channel fader and pre-fade aux level.

 

 

A search on the Blue Room should give some info and opinions on the advisability of the use or not of an ambient mic in loop systems.

[studiofile]

I would advise you to feed the loop from a post fade aux send and feed it with all the speech mics, the main vocal mics, and core musical instruments of the folk who lead in the band. So if the worship leader sings and plays guitar that their guitar should be fed into the loop. Also I add the main piano or keyboard to add the depth of melody and harmony but very little else to keep the loop mix from getting too cluttered. Remember that anyone who uses the loop, when they switch to T, on their hearing aid, it turns off the internal mic so all they can hear is what you send them on the post fade aux send. Consequently they can become disconnected from the folk around them. To this end all induction loop systems should have an ambient mic which picks up the sound in the room so that loop users also will hear the sound of those worshipping around them and feel a part of the body. This ambient mic should go direct to the loop amp, NOT via the PA mixing desk, and all good loop amps should have two inputs, a mic input for the ambient mic, and a line input for the post fade aux send. You should have an induction loop listener so you can monitor what the loop is actually radiating. When mixing you should check that the balance of the post fade aux send is working for those using the loop and occasionally check with the loop monitor that the loop is working well.

 

Hope that helps,

 

Mike.

[MrPete]

One thing that you could try is when you've set things up and you believe the mix for the loop to be just right, ask someone who has a hearing aid to judge how it all sounds as they are the ones who are going to be hearing that mix in the end. And depending on the person, they might be able to judge things just right for you!

 

Just a thought ;)

 

E2A: Beaten to it! Heh

[revbobuk]

Good advice so far. We find the ambient mic to be really important - and we feed ours in to the desk, but don't route it to any of the subgroup or main outs, just to the post-fade aux we're using. Actually, we use the same mix for this as we do for recording, but that's not as ideal as a separate mix.

 

I'd just add this. Single coil guitar pickups are really good at picking up loop signals. Even if they don't feed into the loop mix (ours don't) what this will mean is that you often get the loop mix being picked up by the guitars and coming out of the guitarists amp - which can be strange!

 

There are ways to lay the loop out to minimise this. Humbuckers don't suffer from it so much, nor do the piezo pickups used in acoustic guitars. Fender-style pickups can cut this effect down by using one of the 'inbetween' pickup settings.

[Simon Lewis]

I too would argue for use of post fade auxes. There's less likelihood of having unwanted or embarrassing material going into the loop that way.

 

I would argue for mainly speech in the loop mix. If there's a band playing, you can normally hear the rest of the instruments pretty well through vocal mic bleed. Percussive instruments and loud bass sounds will probably cause pumping or fairly aggressive AGC action in the loop amp, which is not nice to listen to.

The comments about putting high levels of instrument through and getting bleed through the instrument pickup are true, and this is best avoided.

 

I'm going to buck the trend and argue against ambient mics, unless (as stated in the British Standard) it is used to show that the system is actually on, and is not used when speech is being listened to.

 

Here's why...

 

Hearing loss isn't just reduced acuity at given frequencies, but includes a loss of discrimination between wanted and unwanted sound. Those with hearing loss are significantly affected by reverberation and background noise. Whereas it is helpful to know that a loop system is on (say at the start of a service), leaving the ambient mic on will degrade speech intelligibility.

 

This fact seems lost on loop installers, who put ambient mics in with gay abandon. I really wish they didn't, because the whole point of a loop is to exclude the ambient noise that makes understanding speech difficult.

 

Loop systems are almost always set up by people with very good hearing, and they'll state that the ambient mics sound great ;-)

 

There... mini rant over!

 

Simon

[revbobuk]

The thing is, it's our hearing-impaired users who tell us that ambient mics are vital. They say that the feeling of isolation they get when mics are cut off is really unnerving, and much prefer to have some idea of what is happening. Our services include a lot of participation from the congregation, and aren't just front-led performances. So do we exclude the hearing-impaired from (for example) open prayer times?

 

Of course, since the only differentiation between 'wanted' and 'unwanted' through the loop system is level, we have to make sure that the ambient feed is quiet. But it really is the users who want it, not the sound desk operators. We regularly check back with our loop users that we're getting levels and mixes right, and they are very quick to tell us if we're not!

[Simon Lewis]

The thing is, it's our hearing-impaired users who tell us that ambient mics are vital. They say that the feeling of isolation they get when mics are cut off is really unnerving, and much prefer to have some idea of what is happening.

 

Do you have to cut mics off? I know that when I'm mixing a service, there will always be a radio mic, lectern mic or worship group mic on, so the loop feed has a signal going through it.

 

Our services include a lot of participation from the congregation, and aren't just front-led performances. So do we exclude the hearing-impaired from (for example) open prayer times?

 

Of course not! But in your case, the audience participation element becomes the 'signal', and needs to be picked up. It would be better if this was via a hand held mic close to the talker, but otherwise an audience mic is needed.

 

Of course, since the only differentiation between 'wanted' and 'unwanted' through the loop system is level, we have to make sure that the ambient feed is quiet.

True to some extent - but do bear in mind that the further away the ambient mic is from the source, the less intelligible the signal will be - irrespective of signal level.

In your situation, it looks like you have a) operators that check the relative levels and b) operators that actually mix for the hearing impaired. It's great to see both activities!

 

Many installations have an ambient mic plugged into the back of a loop amp, and have it permanently turned up so much that even a mouse farting in the vestry causes FSD. Everything that is fed into the loop is then coloured with the room's reverberant response, and intelligibility goes through the floor.

 

Worse still, the installer thinks that putting a boundary mic on a wall behind the talker or on the ceiling is a Good Idea. It isn't.

 

Simon

Getting hot under the collar about loops since 1985

[revbobuk]

Simon - agree completely with that post. Yes, just poking a mic straight into the spare input on the loop amp is not good. For us, the ambient signal really comes into its own during hymns where the organ plays - no other mics up then. When the worship group plays, or a speaker is speaking, then there's no problem.

 

Should have mentioned for the OP that if you want information about loops, especially about loop layouts, then Ampetronic have a superb website with great technical information.