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Author
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Topic: Cell Phones and Amplifiers
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Darrell Owens
Member From: Norco, California, USA
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posted 13 November 2005 08:05 PM
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Has anyone experienced a problem with cell phones causing a problem near your amp? I have a new Webb amp and it has been making a noise. Today I relaized it seems to happen when my cell phone is near it. I am not sure if I have a problem with the amp, or if there is some reason a cell phone would interfere with the amp. Can anyone help me figure this out?------------------
Darrell Owens
www.darrellowens.com |
Tom Campbell
Member From: Houston, Texas, USA
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posted 13 November 2005 08:40 PM
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I've had the same problem. Had visitors at a band rehersal that were sitting near my amp. Their cell phone went off and caused all sorts of interference with my amp. I was using a vintage (1980's) Peavey Musician head. I don't think the design of that era was meant to filter out our current cell phone signals. |
John Macy
Member From: Denver, CO USA
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posted 13 November 2005 08:59 PM
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If it's freaking your amp out that bad, I wonder what it's doing to your brain while talking on it  ... |
Michael Garnett
Member From: Fort Worth, TX
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posted 13 November 2005 09:38 PM
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Or other parts of your body while it's in your pocket.....Anyway, yeah, that's the cellphone's signal inducing a current somewhere in your signal path. It happens all the time when I play and forget to turn my cell off. It only happens when your phone is transmitting to the tower, so it'll start up every time the phone checks in with the tower, or right before your phone rings. It does a doozy on my computer speakers as well. To diagnose the problem, dial a number (like your voicemail) and hold the phone close to the amp. If it's the same sound you're hearing, that's it. Just make it a habit to either leave your phone in the truck when you're playing, or turn it off. Hope this helps, -MG |
Jack Stoner
Sysop From: Inverness, Florida
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posted 14 November 2005 03:05 AM
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If it's from a cell phone transmitting then it's "RFI" and anything from the guitar's pickup, volume pedal, an effects unit, bad cord, amp, reverb pan - anything can pick that up.But, with the very low transmitter power of a cell phone, any close transmitter - police, CB, radio station, cell phone tower - all with much higher power - should also be interferring. |
Ray Minich
Member From: Limestone, New York, USA
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posted 14 November 2005 04:42 AM
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quote:
If it's freaking your amp out that bad, I wonder what it's doing to your brain while talking on it
It's the little secret of this communications medium that your head is part of the "radiator" (i.e. antenna). |
Gaylon Mathews
Member From: Jasper, Georgia
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posted 14 November 2005 05:31 AM
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When I'm in the studio working, I can lay my cellphone(Verizon Wireless)right beside my computer and never have any sort of problem. My son, who uses Cigular Wireless has to turn his phone off when he walks in the door or my computer and any guitar amp that happens to be on will go crazy when his phone rings or transmits to the tower.------------------
Gaylon's Homepage
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www.gretchenwilson.com GFI Ultra D-10, Fender Steel King, GHS Strings, SteelSeat.com
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Brad Sarno
Member From: St. Louis, MO USA
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posted 14 November 2005 06:20 AM
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I can't have a cell phone anywhere near my studio gear. When they are on and connected to a call or do their periodic tower-check (Big Brother locator beacon) they give off a series of pulses that is clearly powerful enough to radiate across a room and interfere with the analog audio gear. If anyone is familiar with the inverse square law, it doesn't take much calculation to see how horribly dangerous these things probably are when they're held close to the head or body. I rarely use my cell phone and if my conversation is longer than a couple of minutes, I use the headset cable thingy and keep the phone a couple of feet away. If anyone has a line sniffer device like phone repairmen use, check out the strength of the cell phones transmission. It's very scary how strong that little microwave transmitter is and how cloesly people hold them near their brains. I feel very sorry for these people who use them all day. No thanks.Brad |
Jack Stoner
Sysop From: Inverness, Florida
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posted 14 November 2005 09:32 AM
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Brad, an "RF Field Strength Meter" is what is needed to determine radiation. Telco uses an audio frequency signal tracerHaving worked in high powered transmitter sites (e.g. 45KW HF transmitters) where there is radiation all around, there have not been any documented cases, that I know of, of any affects. I wouild work on my Ham Radio transmitters with the covers off, etc. There are 'wives tale" stories about RF making people "sterile" but I know a Radar Tech, that was around Radar Transmitters and there were 7 children in his family - didn't affect him. |
Tyler Hall
Member From: Alabama, USA
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posted 14 November 2005 01:42 PM
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I have Cingular, and if I get my phone near an amp, it makes noise. If the phone rings it's a mess. All kinds of awful noise. This happens with my Nashville 112 AND my old Session.D-10 Fessenden, Nashville 112, Session 500, Goodrich LDR |
Donny Hinson
Member From: Balto., Md. U.S.A.
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posted 14 November 2005 01:46 PM
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Yes, cell phone, computer, and Blackberry interference is very common. Almost any amplified audio device (including a regular corded speaker phone) will pick up the interference that these units generate.Keeping the cell phone at least 10 feet from the amplified device usually eliminates the problem.[This message was edited by Donny Hinson on 14 November 2005 at 01:49 PM.] |
Mike Wheeler
Member From: Columbus, Ohio, USA
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posted 14 November 2005 04:08 PM
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Yeah, the tales about RF causing medical problems are exagerated. On the other hand, there is a very real danger and plenty of documented cases where a focused beam (as in a microwave dish transmitter, or radar set) caused a person who stepped into it serious problems.The transmission power of a cell phone is quite small and has negligible affect on humans. We are actually already bathed in tons RF transmissions constantly, all day, by radios, TV, and various electronic devices. I don't worry about that little, old cell phone.....then again, I smoke!!! |
jim milewski
Member From: stowe, vermont
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posted 14 November 2005 04:28 PM
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just don't fall asleep near a satelite transmitter, the world will be able too see your dreams |
Brad Sarno
Member From: St. Louis, MO USA
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posted 14 November 2005 06:30 PM
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Yea, it just seems to me that holding the little thing an inch from your brain can't be good. Just creeps me out. I know we're bathed in RF, but being that close to the source there is a concentration of energy. I swear my head feels weird and hot after using a cell phone. Psychological, maybe. Still creeps me out. Brad
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Darrell Owens
Member From: Norco, California, USA
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posted 14 November 2005 07:59 PM
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Thanks to everyone for the replies. I have a new cingular phone, so that's the problem. I had laid it too near the amp on a couple of occasions. I was about to take the amp in for service, so thanks again.Regarding what it is doing to my head, my brain is an all tube vintage model with no transistors and my wife says my head is thick enough to filter out any interference. In fact she says I don't hear half of what she says to me, and none of it if I am playing my guitar. ------------------
Darrell Owens
www.darrellowens.com |
Keith Hilton
Member From: 248 Laurel Road Ozark, Missouri 65721
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posted 14 November 2005 09:51 PM
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Let's talk about the solution. Radio Frequency being amplified can easily be eliminated. On the input,signal line, install a 39pf capacitor to ground. This grounds all RF signas and does not allow them to be amplified. Because audio signals do not go beyond the range of 20K, the 39pf capacitor does not cut frequencies below 20K.
RF protection goes into all the products I make. Hope this information helps. |
Keith Hilton
Member From: 248 Laurel Road Ozark, Missouri 65721
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posted 14 November 2005 10:02 PM
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Also, don't forget a cell phone has a coil in it that can cause EMF. To understand what I mean, get a wall wart transformer. A wall wart transformer is nothing more than a coil. Power the wall wart and lay it on the strings above your pickup. You will get lots of noise. You can also get noise if the wall wart is laying on a guitar cord. Many times you can get noise if the coil is laying on your effect unit, or on top of your amp. This is not radio frequency noise. It is electro-motive-force noise from a coil. Hope this information helps. |
Michael Garnett
Member From: Fort Worth, TX
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posted 15 November 2005 06:38 AM
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Also to add to what Keith said, when I was fixing the reverb on my NV400, I had the can pulled out and laying on top of the amp. This causes a very nasty hum in the reverb circuit, because the reverb springs act like a pickup and magnify the noise in the power supply and transformer.-MG |
Ron Randall
Member From: Dallas, Texas, USA
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posted 15 November 2005 09:13 PM
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Really messes with my powered monitors (aka amplifiers) Messes with my guitar amps. There is a distance of about 20 feet that kinda cures it. That's as far as I can throw it!  Ron |
John Daugherty
Member From: Rolla, Missouri, USA
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posted 16 November 2005 02:17 PM
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Keith, you are correct about a capacitor on the input of an amplifier eliminating RF. Sometimes the RF gets into the circuit after the input stage. As Donny mentioned, I have heard radio signals coming through a speaker when the electronics was turned off. This could possibly be caused by the speaker cable length being a submultible of the transmitter wave length. In that case, changing the length of the speaker cable by a few inches may solve the problem.
If the input capacitor to ground doesn't cure the problem,it may be necessary to put a capacitor to ground on the second,third or later stages in the preamp circuit.
Another cause for RF pickup is poor solder joints which act as diode detectors.
Before doing any of the above,you should make sure you have good cables and the jacks are making good ground contact. .... JD------------------
www.phelpscountychoppers.com/steelguitar
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Dave Ristrim
Member From: Whites Creek, TN
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posted 17 November 2005 04:25 AM
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Cingular cell phone, Webb amp... NOT GOOD! I've had problems too. I hate cell phones anyway. I waited until the year 2000 to get one, now sometimes I wish I never did. Oh I know, they can be great, but I also think they will be the downfall of Western Civilization.It's too early in the morning.
Dave |
T. C. Furlong
Member From: Vernon Hills, Illinois, USA
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posted 17 November 2005 06:29 AM
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In my business, I provide sound systems and wireless microphones to Motorola for business meetings. About five years ago, I got the report that there were hand-made signs outside of all of the meetings that said NO NEXTEL PHONES ALLOWED. Apparently, Nextels (manufactured by Motorola) were inducing a "motorboat" sound into the wireless microphone receivers. So I called the manufacturer of the wireless mics, Sony, to ask if they knew anything about this phenomenon. They said they had never heard of it and immediately sent a team of technicians from Japan to my shop where they spent two days with all kinds of measurement equipment, Nextel phones, audio mixers, wireless systems etc. At the end of the two days, they determined that these phones were not only operating outside of their approved part of the spectrum, but were emmitting spikes of energy that were riding up and down the waveform of their carrier. That same energy emmision was getting into the mixer, cables, connections, etc. if the proximity was close enough. After all of this was documented, the team went right from my shop to the FCC in Washington to register a formal notice of what they had discovered only to find out that the FCC did not even recognize wireless microphones as a product that used radio frequencies. I think that in the end, Nextel was notified that they needed to address this spurious emmision problem. So it is likely this raw energy that is being emmited, and not so much RFI that is causing the noise in our steel guitar rigs.
Also, I know an RF engineer who sits on an FCC Board of Standards and Practices. He said that they have spent enormous amounts of time and resources trying to correlate the use of cellphones with any biological health issues. To date, there is nothing conclusive and he said it really looks like there is no correlation. On the other hand, I recently heard about a brain surgeon who specializes in tumor removal reporting that he had more patients than he could ever have imagined and he couldn't help but think that the dramatic increase in the use of cell phones as being a big part of the reason. There is a direct correlation in the increased use of cellphones and the increase in traffic accidents, loss of productivity in the workplace and a rise in my bloodpressure when rude teenagers talk on their cute litte phones at a movie theatre during the movie!!! I'm with Brad, these things creep me out too!
TC |
Ray Minich
Member From: Limestone, New York, USA
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posted 17 November 2005 02:07 PM
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One of the things I learned in grad school was that the correlation coefficient doesn't have to be 0.999 for there to be a correlation. In engineering we like a nice perfect 1.0, but, it can be around 0.2 and people get interested in further research. Unfortunately a 0.2 correllation coefficient doesn't get you very far in court.[This message was edited by Ray Minich on 17 November 2005 at 02:09 PM.] |
Michael Garnett
Member From: Fort Worth, TX
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posted 17 November 2005 04:43 PM
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Ray, that's a good point. The problem is that people often confuse correlation with causation. And T.C, you're sounding quite curmudgeonly by the end of that post. Us kids aren't so bad when you get to know us. Whadda ya think the folks born in the 1800s were saying about you with your fancy electricity and television and auto-motive buggies? -MG |
T. C. Furlong
Member From: Vernon Hills, Illinois, USA
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posted 17 November 2005 05:52 PM
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MG,
I've never been accused of sounding curmudgeonly before. So thanks! As a rule, I tend to really like younger people, but I must admit that as I get older I do notice that I have less in common with a few of them, specifically manners. I'll work on better tolerance. You have an excellent point about what my generation may have done to contribute to what we fossils used to call the generation gap. I think my grandmother (born in 1888) would have been pretty ticked if I flashed the lights and beeped the horn on my auto-motive buggy while she was trying to enjoy a silent film.
TC |
Darrell Owens
Member From: Norco, California, USA
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posted 24 November 2005 10:33 PM
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I am not sure I understand all that has been posted in this thread regarding the use of cell phones, but one thing is sure, You cannot talk on a cell phone and play a PSG at the same time!My Webb still has a problem - even with no cell phone in the building, so I am going to need a tech. It "chirps" at the most annoying moment. great amp, great sound, just hate that "chirping" noise. I hope the warranty is still good on my Webb.
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Darrell Owens
www.darrellowens.com |
Todd Pertll
Member From: Austin, Texas, USA
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posted 25 November 2005 07:06 AM
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Cell phones have opened up a whole new world of joking with friends. I leave my cell phone on silent and sitting next on my guitar next to my extra picks, bar, etc. I have a group of friends that find it funny to text message each other while on the band stand. Next time you go watch a buddy play, text message "Your 4th string is out of tune". Its funny to see the look on his/her face when he reads it. OR when the band is between songs and its quiet call your buddies phone to see if he remembered to turn the ringer off. It's realy emberassing for him, but his fault for not turning the phone off. |
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