Induction Loop

[IA76]

Hi

 

We want to fit an induction loop.

 

Is it just a case of buying an amp like this http://www.soundsavers.com/shop/audio-equi...er---300m-.html and buying some cable like this http://www.soundsavers.com/shop/audio-equi...s---2-5mm-.html ?

 

What difference does the thickness of induction loop cable available make?

 

Thanks

[handyandi]

Lots of useful info here that should be of help.

[timtheenchanteruk]

I would seriously look at getting a specialist in to at least quote for this, loops are so easy to get wrong, and quite hard to get right, I work in a couple of places where the loop is next to useless in many parts of the hall, although one has improved since doubling the power of the loop amp.

[Simon Lewis]

We want to fit an induction loop.

Good move!

 

Is it just a case of buying an amp like this

Well the online retailers would have you think so, and the basic premise of a loop system is simple so many off the shelf systems do actually work to one extent or another.

 

However, search for posts on loops on Blue Room, or look the Ampetronic link above, and you'll see that there are a number of things that should be done to get it right. Not least of these, is a background electromagnetic survey, and post installation testing in order to comply with the British Standard. Also, the way you get the speech signal into the loop will make the difference between failure and success. Remember - it has to work for the person with hearing loss - not for the installer with golden ears!

 

What difference does the thickness of induction loop cable available make?

It's linked to the amount of current that needs to flow and to the size and shape of the loop (aspect ratio). That should be calculated, taking any building steel present into account as well as the amplifier characteristics.

 

Done well, loops are superb; done badly (and unfortunately many are) they end up just being a sop to those with hearing loss.

 

Simon

[dbuckley]

done badly (and unfortunately many are)

Ats at this point I'm glad I dont have coke in hand, recalling a previous post from Simon on this topic...

[john-sp]

Also it's wise to budget for a receiver such as the Ampetronic ILR3 which you can use to make sure the system is working and providing a sensible signal. I have been to several loops reported as faulty when they haven't been switched on, and nobody on site has any means of verifying that the system is actually working.

 

The other extremely important consideration is that the quality of the signal feeding the loop is of sufficient quality. It's not enough to slap a PZM in the middle of the ceiling of a room and expect it to sound wonderful, depite what many electrical contractors think!

 

Take experienced advice and get a decent system fitted, then you can almost forget about it as they quite happily sit and work for many years. A decent installer will provide you with a certificate to prove that the loop complies with IEC60118-4.

 

I prefer Ampetronic equipment as they come with a 5 year warranty, are built like brick outhouses and will happily provide you with all sorts of advice via their support helpline. They also don't "massage" the specifications of thier amplifiers! Other manufacturers are available.

 

John

 

Edited for my appalling typing - I have fat fingers and that's the excuse I'm sticking with!

[Simon Lewis]

John adds some excellent advice. A loop receiver should be standard kit with a loop system, and the installers who think that a mic on the ceiling is an acceptable form of input signal should have cheap earplugs Araldited to their ear canal fed from an even cheaper PZM placed 20m away from what they want to listen to. Some added reverb, delay and recordings of equipment fan noise, coughs and chair legs scraping on the floor will add to the realism...

 

One point that rarely gets mentioned is that the various manufacturers loop amps sound different. Loops rely on compression and AGC circuits to maintain a relatively narrow dynamic range. This allows quiet sounds to be boosted and prevents loud ones ripping through the poor user's eardrum like a depleted uranium shell.

 

The circuit - and how it is set up - will affect not only the characteristic of the loop signal, but also the noise floor. Many loops have the amp set incorrectly, so that there is constant background hiss and hum, which only briefly disappears when someone speaks near the mic.

 

I too will vouch for Ampetronic loop amps. They are solidly built, and whilst perhaps a little more expensive have good dependability and sound good too. Current Thinking and Signet make good devices, but there are slight niggles with each.

In 25 years of installing loops, I have had perhaps 3 or 4 amps back for repair, and two of those were due to user abuse.

 

For any installers who think I'm being unfair with regards to loop installations, I have initiated or carried out several extensive surveys of area and counter loop systems. Area loops can be made to work very well indeed, but not all do. Counter loop systems can work well, but are very often beset with problems, ranging from incorrect installation, background electromagnetic noise, not actually switched on, not available, lack of training, microphones badly placed, dead batteries etc., to one case where loop stickers had been prominently displayed, but a loop hadn't even been installed. In many cases, money would have been better spent training staff on dDeaf Awareness. Not all dDeaf people benefit from using hearing aids, and simply sticking a loop in doesn't necessarily mean DDA compliance.

 

There are excellent training courses available from Ampetronic and from the Institute of Sound and Communication Engineers. Those who install loops would benefit from attending, and those who buy them should seek an installer who can install it correctly and provide proof of compliance. DIY is possible, but be aware that it isn't a simple plug and play as some would have you think...

 

There... rant over, and Mr Buckley can lift a drink to his lips once more ;-)

 

Simon