Laptop audio feed problem and loop system

[Simon Lewis]

Panzerman, Scenemaster, All,

 

Not wishing to tread on anyone's toes here, but unless the mic feeding a loop amp is pretty close to the sound source, the results are almost always poor. Since the mic is being spoken of in the singular, I presume you have only one to cover any source from the front of the church?

 

Very often, such systems sound fine when a person with normal hearing monitors it with a loop listening device, but under real conditions it could be unintelligible to a loop user.

 

People with hearing loss suffer a loss of hearing acuity. It is often frequency selective - with high frequencies being lost the most. This leads to the inability to hear or distinguish consonants, which carry most of the "meaning" of speech.

 

However, this is just the beginning of the problem, since a simple loss in level could easily be compensated by use of hearing aids.

 

Additional issues include problems with tinnitus, loudness and pitch, sound quality and timbre, the ability to estimate the direction and distance of a source, the recognition and analysis of speech and the ability to attend selectively to sounds of interest in the midst of competing sounds.

 

If the loop system picks up the target sound via a microphone located some distance away, a considerable amount of room noise and probably sound from the reverberent field is added to the signal. Those with normal hearing can use the ear/brain mechanism to filter this out. Those with hearing loss, or listening via hearing aids simply cannot handle even moderate amounts of noise and reverberation.

 

The majority of loop or IR systems that rely on microphones suspended over the stage or on the wall of an auditorium add so much room noise as to make them unusable.

 

To add insult to injury, many installers add an "ambient mic" so that users can "hear the surroundings". This was originally put in the British Standard, to help users know that the system was switched on - should there be no signal going through the loop (e.g. in a cathedral between services). However, leaving this ambient mic on all the time simply degrades the quality of signal made available to users. The original intention was that it should be switched off when the system is in use.

 

So, connecting the loop amp to a post fade auxiliary send on the mixer allows the microphones that are in use to drive the loop directly. Loop users get to hear the microphone that is closest to the person speaking, and they can understand what's going on.

 

Sorry to keep on about loop systems, but having listened to quite a few over the years, and knowing the problems that those in the Deaf Community face, I'm on a mission to improve things ;-)

 

Regards,

 

Simon Lewis

[djw1981]

It may seem strange, but if this is a new install, are the contractors not coming back after a week or so to check it is running ok, and did you spec the PC connection when you arranged the install. I ask only because I know that when my church was spec'ing an install last year, the contractors had a big long list of things they wanted to check if we used. This was based on their previous experience (and ok it was them trying to increase the spec a bit) and in the end we said we were happy with our solution - we just wanted them to reroute the multicore under the floor and sort the rigging for projectors, speakers and plasmas in better locations.

[Panzerman]

It was Australian Monitor 100v mixer amps that gave me some serious problems, perhaps I'll post the pics of the crispy bits one day!

 

Simon, by all means keep on going on about induction loops, they are a seriously misunderstood thing, and whilst I can handle the "what they are, and how they work", I haven't really had any feedback from anyone who actually USES the things because they NEED to. If it helps me, and anyone else, do a better job, then I'm listening (sic). Of course it is always us chaps with good hearing that install them, set them up, then demo them to a client's foreman at handover who also has good hearing. I don't think that I have ever had later feedback, good or bad, from any of the many loops I have installed, which upon reflection, doesn't mean that the jobs have always been 100%, just that they were, and remain functional.

 

The problem is that certainly since October, the only reason that I am putting looooooooooads of loops in places is because construction projects are scared of falling foul of the DDA and spec them everywhere, rather than actually putting them in with a definite goal of making things intelligible for those that need it. Only a person hard-of-hearing can tell exactly what sort of a job has been done, so I hereby resolve to at least find out what the user thinks of some recent installs and see if it makes a difference to how I do future installs.

(Tiny part of your mission accomplished!)

 

PS

To the Original Poster, make sure you tell the install company there are problems! Don't let them go away thinking everything is hunky-dory then complain to yourself that it isn't. If they are any good, they would rather know about it immediately than 2 years down the line when work dries up because someone says "Don't use them, that install they did never worked properly". They probably aren't psychic!

 

Eeh, I remember when I were a lad, there'd just be a vicar and a pipe organ in a church, not a new-fangled pop band!!! (And I know which one sounds best when it is going full pelt, rattling your fillings!)

[Alec]

The auto battery things usually work by sensing if an input is attached. So if you unplug the input cable end of every service you will be fine.

<{POST_SNAPBACK}>

 

NEVER, NEVER, NEVER, NEVER, NEVER get a battery operated DI for church use. However careful you are about unplugging it to turn it of, you can *guarantee* that you or someone else will forget from time to time. And you wil only ever discover it at a critical moment, and when you've no spare batteries - despite your original committment to ensure that you always carry at least 3 spares.

 

I've been there!

 

Phantom powered or passive are the only way to go in this kind of situation. Both have their own benefits/drawbacks, but are far more fit & forget than battery operated DIs (though most phantom powered DIs have a battery option for maximum flexibility).

[lonfire]

hi guys,

the loop system we used to use in our church was setup to run off a post fade aux.. we send the main microphone down the loop and thats it.. we have never had any complaints.. some of the people that used to use it said they only needed the main person speaking at the front, the music they could here ok.. we don't currently have a loop because the old on was run out every week around part of the hall (we meet in a school hall) and the people that used to use it either died or left.. we are looking at leasing the hall soon so are looking at installing a permanent loop system.. but I'm concerned about pickup on foldback amps/guits and such which I've experienced many times in other places..

 

NEVER, NEVER, NEVER, NEVER, NEVER get a battery operated DI for church use

 

I totaly agree.. the guy that used to look after sound years ago didn't really understand phantom power and used to insist on putting batteries in the DI boxes.. I've just took them all out and let them run phantom.. much much less hassle.. and if you have a DI box that has an Auto/On switch like ours, leave it on ON.. I've had weird problems with DI boxes left on Auto..

 

rgds

chris

[mackerr]

We need stereo.  :D

<{POST_SNAPBACK}>

I arrived here quite late, so I apologize if this is old news. You say you need stereo, yet at the beginning of this thread weren't you plugging the laptop into a mic jack? How was this stereo? I am not familiar with the particular gear involved (I'm in the US), but everything you have described sounds like a mono setup. What is it about stereo that you need from the laptop? I would go with a single passive DI wired to the left channel only and call it a day. Your previous setup ran what was essentially an unbalanced line level signal into a mic input. The mic input had way too much gain, so you turned down the output of the laptop, but still had all the noise amplified by the mic preamp in the mixer. You partially solved the noise by turning the mic input to a very low level, and turning up the laptop. Using a DI, passive or active, will balance the line, and lower the level to mic level so you can get better volume control on the mic input. If the DI has 2 phone jacks on it, do not plug both outputs of the latop into the 2 jacks. These will sum the 2 channels together, but laptop sound is notoriously arbitrary as to channel polarity. If you play a sound with out of polarity channels most of the sound will cancel out and you get only low level high frequency sound. It is much safer to just use the left channel unless there are specific sounds hard panned to the right channel. Sorry for running on at the mouth.

 

Mac