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Topic: Single coil pickups in a church: cautionary tale |
Tim Marcus
From:
San Francisco, CA
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Posted 13 Jan 2012 11:22 pm |
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I figured that I would share an experience I had tonight, in case this happens to you.
I was playing a show at a church, and when I first turned my amp on everything seemed fine. When I pushed the volume pedal down, I heard a terrible feedback. It sounded like my amp was oscillating out of control - did it with my tele too. Then I plugged the bass into the amp and it was mysteriously perfect.
Plugged the guitar back in - horrible feed backing sound even with the volume just barely on.
So I asked them if they had an assisted listening system, and it turns out they did. It was the kind that uses the inductive loops for people with hearing aids - they put a loop around their neck which receives the audio via RF and transmits it to their hearing aids wirelessly.
I went to the back room and pulled the power cord out of the transmitter and tried my steel and telecaster again. Perfect!! No more terrible sound.
That was high current RFI - the bass did not have a magnetic pickup which is why it was clean.
Keep that in mind if this ever happens to you!
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Milkmansound.com |
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Tony Prior
From:
Charlotte NC
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Posted 14 Jan 2012 3:29 am Re: Single coil pickups in a church: cautionary tale
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| Tim Marcus wrote: |
bass did not have a magnetic pickup
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???
Or maybe it had a Humbucker ???
I suspect this is just one more "incident" where Single Coils cannot perform compared to Humbuckers...
_________________
Emmons L-II , Fender Telecasters, B-Benders , Eastman Mandolin ,
Pro Tools 12 on WIN 7 !
jobless- but not homeless- now retired 9 years
CURRENT MUSIC TRACKS AT > https://tprior2241.wixsite.com/website |
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Tim Marcus
From:
San Francisco, CA
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Posted 14 Jan 2012 8:21 am
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It was an upright - I think it had a little microphone inside or a piezo on the bridge
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Milkmansound.com |
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George Macdonald
From:
Vancouver Island BC Canada
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Posted 14 Jan 2012 9:30 am Single coils
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A year ago I played at a banquet at our Church. I had played in the sanctuary before with no problems. But they had strung a couple of hundred feet of tiny Christmas lights all around the banquet hall. First I had no sound at all. The battery in my Freeloader had finally died. [Now I change it every year] I had to run down to a nearby market for another one. After changing the battery, I had lots of sound. The hum was about equal to the music thanks to a single coil and the Cristmas lights. This year I was prepared. A humbucker. No more problems.
Last edited by George Macdonald on 14 Jan 2012 1:55 pm; edited 1 time in total |
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Olli Haavisto
From:
Jarvenpaa,Finland
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Posted 14 Jan 2012 12:31 pm
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I run into this problem with the hearing aid systems from time to time in halls and auditoriums that also host seminars and conferences. I think it is called an induction loop.
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Olli Haavisto
Finland |
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Danny Letz
From:
Old Glory,Texas, USA 79540
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Posted 14 Jan 2012 12:44 pm
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| Another one of my dumb questions and it's probably been discussed before, but is there not some kind of filter that can cure this. If not, paging Ken Fox, Brad Sarno, Keith Hilton, etc. |
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Tim Marcus
From:
San Francisco, CA
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Posted 14 Jan 2012 2:26 pm
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there is a filter that will cure it! Its called the volume pedal 
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Milkmansound.com |
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Jim Smith
From:
Midlothian, TX, USA
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Posted 14 Jan 2012 3:54 pm
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| Tim Marcus wrote: |
| there is a filter that will cure it! Its called the volume pedal |
I played a gig many years ago that was very close to a mega-power AM radio station antenna. No one else in the band had a problem, but every time I pushed my volume pedal, the radio was louder than my guitar. 
I didn't have the knowledge and it never dawned on me at the time to try a different length cable to see if that would have suppressed it. |
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Ken Fox
From:
Nashville GA USA
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Posted 15 Jan 2012 3:51 am
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From the net:
Other equipment within the magnetic field
Audio induction loops create, legitimately, fairly high magnetic field levels. Other equipment must be designed and installed to work properly within this field.
The most common cause of problems is earth loops, where different pieces of equipment are connected together by signal wires, but powered from different power sockets in different parts of the room or building. The combination of the mains earth and signal earth creates a receiving loop that produces an interference signal proportional to the area within the earth loop.[6]
This article contains instructions, advice, or how-to content. The purpose of Wikipedia is to present facts, not to train. Please help improve this article either by rewriting the how-to content or by moving it to Wikiversity or Wikibooks. (October 2011)
Video equipment, such as projectors, commonly displays a horizontal pattern on the screen. The pattern moves with the sound feeding the AFIL. The cure is to avoid earth loops by powering the projector through a mains extension from the same mains supply as the computer, camera or DVD player which provides the video signal.
Audio equipment, such as a keyboard or guitar connected to the main sound system, may be the source of whistles during silent parts of the programme. Again, the cure is to break any possible earth loops. This is often done by the use of "direct injection boxes" which break the earth. The use of balanced audio cables is advised, and is often essential. |
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Ken Fox
From:
Nashville GA USA
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Posted 15 Jan 2012 3:59 am
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more info:
"T-coil", "telecoil", "T" program or even "telephone coil" are all equivalent terms used to describe the induction loop wireless receiver.
The induction loop receiver is housed inside a hearing aid or CI (cochlear implant). The receiver picks up the electromagnetic field from a telephone handset or induction loop system, which is then converted into analog sound.
The T-coil or telecoil is only activated when the, hearing aid or CI, "T" program is selected by the user. Selecting the "T" program automatically disables the hearing aid or CI microphone. This is beneficial because it eliminates "feedback whistling" and reduces distracting background noise.
Some hearing aids have an optional "T+M" program where the T-coil ("T") and microphone ("M") are active simultaneously; this may somewhat negate the benefit of reducing background noise. Another option for hearing impaired users with two hearing aids is to switch one aid to the "T" program, leaving the other to pick-up environmental sounds.
Some newer digital aids offer 'automatic' program selection (as opposed to manual switching). The aid attempts to identify the sound environment and automatically select the most appropriate program. Whether this is successful or not, will depend on the design of the aid and the perceived strength of the induction loop field from the telephone handset or induction loop system.
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Ken Fox
From:
Nashville GA USA
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Posted 15 Jan 2012 4:04 am
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From what I have read it appears that the induction loops are not like the early hard of hearing systems I installed (Williams Sound Corp). Those broadcasted on the upper AM and also FM bands, These new systems are at audio frequency and activate a simple "T" coil. If your guitar is already being amplified thru the system for the hard of hearing program material then feedback is likely to occur, it would seem.
This is a tough one, not sure what the cure would be. Perhaps some others might share there thoughts on this one with us!! |
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Ken Fox
From:
Nashville GA USA
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Tim Marcus
From:
San Francisco, CA
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Posted 16 Jan 2012 9:32 am
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I would be interested to see if a humbucker is even capable of cancelling out the interference.
I may have another gig at the church in April, and by then I will have my Tonealigner installed so I will keep you posted.
The cure was unplugging the transmitter - luckily there were not any people that needed assisted listening.
I am not sure about other states, but in California, any public space with a sound system is required by law to have an ALS system in place. That means churches, museums, theatres... its part of life these days.
There are different types of ALS systems. Some use Infrared, some use high bandwidth RF, and apparently some use RF down in the audible part of the spectrum - those are the ones that may cause trouble. I just wanted to post this so that people will know what to look for in case they encounter this unexpected problem.
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Milkmansound.com |
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