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Thread: Inductive Loop Success

  1. #1
    Join Date
    Aug 2010
    Location
    Central California
    Posts
    25

    Default Inductive Loop Success

    While waiting for my new Bernafon Versa 9 CT hearing aids to arrive at Costco, I've been passing the time experimenting with home made loop systems. Yesterday I made a small, square loop, 12 turns of #28 copper wire, 2 feet on a side on a piece of peg board. The d.c resistance of the loop measured 6.75 ohms.

    The only amplifier I had to play with was a 10 watt guitar practice amp which logic told me would be woefully inadequate. Undaunted, I fed an audio signal from a a small FM radio to the mic input of the amp. I connected the loop to the headphone output jack of the amp, primarily to mute the speaker. Lo and behold, when I switched my antique Rexton canal aids over the the T-coil mode I could hear the radio perfectly from the loop. With the small amp the range was only about 3-4 feet but that was enough to convince me the system would work.

    Late last night I was cruising around Craig's List on my laptop and just for the fun of it I did a search for "UniVox." I was very surprised to find an older UniVox loop amplifier (Model 2A+) for sale about ten miles from home. The price was $10 which was absolutely unheard of. I picked it up this morning, hooked it to my loop this afternoon and was blown away with the performance. My next project is to build a larger loop, perhaps 10' x 10' to put in my attic.

    If you've ever considered playing with inductance loops, my suggestion is to go for it. They really work. When those Bernafons arrive I'm going to be in loop heaven.

  2. #2
    Join Date
    Sep 2009
    Location
    NY Metro area
    Posts
    281

    Default

    Glad to hear "you've been thrown for a loop". I've used T-coils since the '50's and only wish them fluorescent lamps along with car engine ignitions were a lot quieter in their EMI department....
    Last edited by kretsh; 08-21-2010 at 08:56 PM.
    Hz..250.....500...1K.....2K......3K......4K.....6K ......8K
    L&R....-15....-15....-15....-15.....-15.....-15.....-15....-15 (with Cochlear Implants)

    Audiogram BEFORE CI's
    L&R....-95....-85....-95...-120...-120....-120...-105...-105

    Cochlear Freedom Implanted 11/30/11, Activated 12/21/11 N6
    Cochlear Freedom Implanted 6/11/15 Activated 7/1/15 N6

    Formerly Phonak Naida's

  3. #3

    Default

    OldGeezer.

    Hi, any update? Does the loop work with your Bernafon instruments?

    The Costco fitter told me that the telephone "program" on the Verite was not exactly a T-coil, but could not explain how it was different. Gave me a magnet to stick on the telephone receiver to trip the hearing aid into the "telephone mode", works, sort of.

    I'm very interested in your experience with the loop and Bernafon, and congratulate you on experimenting and building something that works!

    Regards,
    Andrew
    Right:
    125 HZ -60
    250 HZ -60
    500 HZ -60
    750 HZ -75
    1kHZ -80
    1.75k HZ -80
    2kHZ -60
    4kHZ -75
    5kHZ -85

  4. #4
    Join Date
    May 2010
    Location
    trenton, NJ
    Posts
    120

    Default

    I just installed my new Univox DLS-50 room loop amplifier and WOW! It is nice. I still miss a word here and there but it works much better than my Sennheiser FM wireless headphones. The problem I had with the headphones is that they amplified all frequencies. I don't need amplification of the lower frequencies.The beauty of this system is that the TV audio is sent directly to the HA's that are programed for your loss so there's no over amplification of any frequencies.

    It's nice to just walk into the TV room,sit down,switch to t-coil mode and hear 99% of everything! No headphones, TV ears or neck loops. Only 179.00 too Plus 16.00 for 100' of 18 Gauge speaker wire to make the loop with.
    If you have t-coils in your HA's, you've just got to try this system. They give you two weeks to try it and you can then send it back for a full refund if you don't like it. Your only loss would be the shipping.


    Don
    250hz - 15
    500hz - 15
    750hz - 30
    1Khz - 45
    2Khz - 65
    4Khz - 60
    8Khz - 50

    Both ears are the same

  5. #5

    Default

    I'm currently using a compact amp to drive my Aux. speakers from my TV. The spec are 15Wx2 with a max power of 150w. Could I run a loop off of this amp to power a small system? 100 Sq feet.

  6. #6
    Join Date
    May 2010
    Location
    trenton, NJ
    Posts
    120

    Default

    Here's where I bought mine. http://hearinglosshelp.com/articles/loopamplifiers.htm

    On this page, they tell you how to make one using a Radio Shack PA amplifier. There's a lot of good loop system info on this site.

    Here's another link from a guy who made a loop system from a 7 watt stereo amplifier. http://marcspages.co.uk/tech/deafloop.htm

    Here's an inexpensive 20 watt amp that would probably be perfect.

    http://www.parts-express.com/pe/show...number=310-300

    Hmm... Looks like I could have made one myself and saved 150.00
    Last edited by bigbeck; 11-13-2010 at 08:38 AM.
    250hz - 15
    500hz - 15
    750hz - 30
    1Khz - 45
    2Khz - 65
    4Khz - 60
    8Khz - 50

    Both ears are the same

  7. #7
    Join Date
    Aug 2010
    Location
    Central California
    Posts
    25

    Default Bernafon Versa CP update with loop system

    I am sorry to take so long to get an update on my HA/Loop system. The Versa 9 CP's work extremely well with my small (home made) couch loop. My next project is to expand the physical dimensions of the actual loop to make it 'room sized.' As it stands now with the couch loop, moving about five feet away from the couch causes the audio from the television to disappear as expected.

    For those of you contemplating building your own loop system with a standard audio amplifier, be sure to pay attention to electrical charistics of the physical loop itself. A typical audio amplifier needs to "see" a characteristic load (4-10 Ohms resistance) to operate safely. For a bit of an explanation, go here:
    http://www.mreilly.com/WebPages/loop/loop.html

    Loop systems are not difficult to build and install. As bigbeck pointed out, the audio from a loop system is absolutely wonderful.
    Frequency...Left......Right
    250 Hz.......35 dB....50 dB
    500 Hz.......55 dB....60 dB
    1,000 Hz....65 dB....70 dB
    2,000 Hz....70 dB....75 dB
    4,000 Hz....75 dB....70 dB
    8,000 Hz....90 dB....70 dB

  8. #8
    Join Date
    May 2010
    Location
    trenton, NJ
    Posts
    120

    Default

    Geezer, I'm stoked now! I removed the 3 watt amplifier from one of my old computer speakers and hooked it up to my loop. It worked! I had to turn it up to full volume for it to be loud enough. The sound quality was as good as the Univox loop amp. That surprised me because they use cheapest components known to man in building budget computer speakers.

    My 12' x 14' double loop is installed in the attic.

    I'm amazed by how simple and inexpensive these loop systems are. They can be assembled by the average handyman for 50.00 or less and the sound quality is better than a 3,000.00 hearing aid! Go figure. Heck,you can find an old bookshelf stereo unit on the side of the road and build a top notch system for just the cost of the wire!

    What really perplexes me is that more people don't know about and discuss the advantages of these systems - not even the professionals.

    Don
    250hz - 15
    500hz - 15
    750hz - 30
    1Khz - 45
    2Khz - 65
    4Khz - 60
    8Khz - 50

    Both ears are the same

  9. #9
    Join Date
    Aug 2010
    Location
    Central California
    Posts
    25

    Default

    Like bigbeck, I was amazed at just how cheaply a loop system can be. My ten-watt guitar practice amp was enough to get me started. Finding a UniVox 2A+ for $10 on Craig's List (see my original post) was a gift from God. Some pretty good public address amplifiers in the 20-30 watt range can be found on eBay for very little money. This is not rocket science although it may seem that way once you hear the difference in television sound with a loop.
    Frequency...Left......Right
    250 Hz.......35 dB....50 dB
    500 Hz.......55 dB....60 dB
    1,000 Hz....65 dB....70 dB
    2,000 Hz....70 dB....75 dB
    4,000 Hz....75 dB....70 dB
    8,000 Hz....90 dB....70 dB

  10. #10
    Join Date
    May 2010
    Location
    trenton, NJ
    Posts
    120

    Default

    Quote Originally Posted by OldGeezer View Post
    This is not rocket science although it may seem that way once you hear the difference in television sound with a loop.
    Yes, it is old technology. Most circuits hearing aid related are just old technology that's just been miniaturized. The only thing that's "state of the art" on an 8,000.00 pair of aids is the marketing BS. LOL!

    Don
    250hz - 15
    500hz - 15
    750hz - 30
    1Khz - 45
    2Khz - 65
    4Khz - 60
    8Khz - 50

    Both ears are the same

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