[poffy74]

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I've also been struggling a bit with headsets and adding a CB.

1. Headsets -Even though I have broken down and purchased some headsets for the bike I still want to figure out the system. Currently I have audio into my homemade headset working fine. I'm just having an issue with the mic portion.

I've tested the mic on a CB (off the bike) and it works fine. When I wire it into the 5 pin din wire I get a squeal. So I added a 1/4 w 1k resister inline on the positive side. This got rid of the squeal but I get nothing off the microphone.

Does anyone know what resistor is needed? Does it need to be inline or parallel.

2. CB Interfaces -- I'd love to just build my own so here are the questions.

a. Where can you get a pin out for the CB interface into the radio system. All the pictures I find are of Gen 3. But isn't the GL1500 Gen4????

b. I've narrowed it down to the Kennedy FRS2set and the AirRider "add a radio". Kennedy is now saying they have a feedback problem. Anyone have experience with either of these? I'm not willing to shell out the over $500 for the J&M unit and Stuart doesn't sell interfaces and his whole system again is too much money.

thanks
Steve
90 GL1500
Boston, MA

 

[BRowan]

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Have a look at this page that deals with how to make headsets, it may help;

http://www.goldwingfacts.com/DIYintercom.htm

 

[Dave Campbell]

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poffy74 wrote:

I've tested the mic on a CB (off the bike) and it works fine. When I wire it into the 5 pin din wire I get a squeal. So I added a 1/4 w 1k resister inline on the positive side. This got rid of the squeal but I get nothing off the microphone.

Does anyone know what resistor is needed? Does it need to be inline or parallel.

2. CB Interfaces -- I'd love to just build my own so here are the questions.

a. Where can you get a pin out for the CB interface into the radio system. All the pictures I find are of Gen 3. But isn't the GL1500 Gen4????

b. Kennedy is now saying they have a feedback problem. Anyone have experience with either of these?

There is nothing about the mic squeala resistor will fix, its RF feedback. It can squeal loud enough in your headsets to cause severe pain and possible permanent hearing damage.

Yes, I know everything there is to know about these problems.Im an electrical engineer and Federal Radiotelephone Operator (expert in radio licensed to run broadcast stations) and this was so hard a problem I spent 4 years working almost day and night to solve those problems (mostly the mic squeal problem) AND had to consult with a Federal research lab for help.

Youve picked one of teh hardest physics problems on the face of the earth to tackle.

J&N had the squeal problem in the mid 1990s and admitted they could not fix it. Neither will anyone else that comes along, as Kennedy admits.


The equation is "is permanent hearing loss = $1000?"

 

[Brojees]

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Your squeal can be encountered with J&M headsets as well. I have found judicious adjustment of the various gains involved can eliminate the squeal.

It is quite diminished in open face vs. closed face configuration. This leads me to believe it is more likely AF feedback vs RF as Dave believes. Cable sheilding is also not quite as effective as audio shielding which supports the AF theory, Dave have you ever gotten a scope on the feed back?

One interesting development in my playing with the headset issue, (My testing is by no means complete....But then my nature is such that I will happily experiment for years, so don't look for any results from me soon.), is something my wife did just last week.

I built a tailout that I can come from the 5 pin din on the bike to my bench and plug in various elements to test with simple phone plugs. The wife is sitting there crocheting and listening to her CD player on her fancy headphones. I look over and notice she has plugged her headset into my bike and is listening in. When I ask her, she responds that the sound is so much better, (She has the real J&M set in her fullface.), So I said why not? I popped the earpieces off her head band, pulled the J&M earpieces out and slipped hers in, (I have wee pockets in the ear cavities of our helmets now, copied the idea from Bell). Her considered opinion? Best sound she has heard to date!

Now before Dave jumps, I also have the wee bit of electronic training and Yes I do understand impedance matching. I do know the earpieces should be 32 ohms and I have no idea what impedance this headset is. Plain garden variety Panasonic, black headband, grey highlights on the earpieces. The earpieces readily pop out of their swivels and that is how you would replace the felt covers. (Dave you have any idea? I do have one in my junk box that I could send you a earset to measure impedance since you have the equipment? LOLOL!! I envy you your lab access, wish we could have one here.)

 

[Dave Campbell]

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Brojees wrote:

It is quite diminished in open face vs. closed face configuration. This leads me to believe it is more likely AF feedback vs RF as Dave believes. Cable sheilding is also not quite as effective as audio shielding which supports the AF theory, Dave have you ever gotten a scope on the feed back?

be 32 ohms and I have no idea what impedance this headset is.

Was hoping Brojees would jump in here. Hes also a "sparky." There are others, but they are in hiding.

There are both AF and RF feedback, the AF is much easier to identify because on can hear it. It is triggered by too high gain, and a audio loop between mic and headset. The RF loops will take an eternity to sort out. Both can cause serious pain.

The odd thing about headsets is that closer to the ear they are, the better the sound, especially the bass.

Not sure on the impedance, whatever the audio system demands, but in my experience, the thing about "proper impedance of speakers" is so much nonsense. Ive tried deliberately mis-matching them to little effect. Has as much to do with the amplifier as anything. In the old days, impedance was critical but the new (since mid 1970's) amplifiers can handle most anything you throw at them. Mostly because fools like me would throw on odd impedance speakers!:gunhead:

The J&N headsets have poor quality speakers, going about $0.30 each, although the headsets are very good mechanically (good plastics and cables etc) The speaker pods will come apart with proper persuasion. The next best thing are the commercial sets (Clark, Telex etc.) but they are not made for motorcycles that I know of.

 

[axelwik]

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If a system could be designed that isolated the headset from the mic, it might work... such as using earplug-type headsets or some type of earcups. This would prevent any sound from the headsets from getting into the mic.

Of course with a system like this, safety would become an issue. You wouldn't be able to hear the outside world.

 

[Dave Campbell]

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The mic can be used as an "outside world" monitor provided its left on. My personal favorite ear-pieces were the high quality "ear bods" which fit inside the ear. They were a real annoyance to put in place, then slide a helmet on, but sound is incredible. That is, what sound is left to reproduce after the stero system loses freq response.



poffy74 - I didnt mean to say that youd have an impossible time sorting out the audio feedback, but the radio feedback youll encounter when adding the CB. The problem goes from annoying to impossible at that stage.

 

[poffy74]

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my first hurdle is the squeal just using the intercom. This does not seem like an audio squeal. If I didn't have the mic connected and crossed the wires for the mic (ground and positive) I get the same squeal. So that leads me to theorize it is not actual feedback.

After I sort this out then I will add the CB. However, to avoid the feedback problems I'm going to only put the mono sound into one ear in the helmet. I'm going to use a timer and relay to shut offall audio when I key the mic for the CB. I'm working this out with parts I already have to interface a Radar Detector.

Yes I will ground isolate both the CB and Radar detector when I connect it in.

As for the DIY link: I've looked at it and he's using a condensor mic and I'm using a dynamic. Reading his post is what lead me to try the 1k resistor. However, I tried it inline instead of parallel yesterday. I'm going to parallel today. I shouldn't need the battery has a dynamic mic has nothing to power. However, if nothing is working I may add it in just to see what happens.

Although I'm not an EE person (although I interviewed a Masters Degree EE person from MIT the other day) this is not my first adventure in motorcycling electronics or fabrications. Before the wing I rode an ST1100 and I had everything that the goldwing offers except for the intercom on the ST. It was all home made based off a cheap amplifier off a cheap pair of computer speakers.

I had XM Radio, CD and radar going to both myself and my passenger. However, on the ST I chose to use a throat mic that went straight to the CB. I chose this for versitility as I didn't use the CB much on the ST.

However, my last LD trip from boston to montana and back last summerwith others that had CB showed me its value.

thanks for the info. After I get through these I will start fabricating aux light brackets. Because there is no way I'm paying over 100 bucks for some aux lights.

As for the posibility hearing loss. I'm not really worried about that as years ago I realized that without ear plugs I would be really run down after 8+ hours on the bike. By wearing ear plugs I not only stay more alert but I also save myself from the road noise. I already have some tinitus from my days standing next to amplifiers and cranking toons in my car.

Steve

 

[Dave Campbell]

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It's audio squeal because you can hear it. Squeal cannot occur without feedback. Its not a matter of resistance, its impedance.

I hate to be a wet blanket when someone is making a good attept to DIY, but this job is like throwing 10 cats in a sack, shaking it up,then trying to get a certain one out. May not get the one you want and all 10 will try to tear your arm off...:shock:

 

[Brojees]

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Before we get carried away, it is actually both.

Impedance is measured and calculated as a resistance in ohms. It is an AC element and can be empirically calculated by determining the inductive and capacitive components of your circuitry. The Inductive component would be XL=2*Pi*f*L And the capacitive would be Xc=1/(2*Pi*f*C).

The point for impedance matching was to prenvent an amplifiers power form being reflected back at it, very critical in the old tube days, but as Dave says modern circuitry is quite tolerant. The concept of the reflected waves can be visualized by dropping a pebble into an infinited calm pond. The ripples continue traveling outward until the finally decay to nothing....Matched Impedance. Where as dropping the same pebble into a tub will cause the ripples to reflect back of the tub walls adding and subtrating from the the original ripple source.

As to the feed back, once again let's not get hung on semantics. The audio looping is a possible cause. Basically the loop sees an original tone, (Mic) and the received tone, (Speakers) sightly out of phase and with a slight doppler shift of the frequency. Now when you have two different frequencies they hetrodyne and produce 4 frequencies, (Ignoring 1st second etc. order harmonics). Thise four frequencies are the two oroginals, the sum of the two and the difference amongst the two. Hehe he all this of course runs out abnd hetrodynes with everything else all over again LOLOL And after all this boring musing, you get a unpleasant squeal in your ears.

My squeal appears to be audio, but it could have a number of other causes as well.

It does though create a rather distinctive "Ping" when I transmit on the CB which makes me quite easy to pick out of the crowd as long as I wait to modulate after the Ping and not during it.

Oh look at me, I am supposed to be cleaning up my shop now that I found another place to store the "Police Vespa"!!

And I do want to polish that Ping Wing!

 

[kevinb2u]

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Hi all,

New member Kevin from Maine, USA..This forum has been very interesting and quite helpful..Found it while searching for info on headsets last Spring..I (& family) have 3 Gold Wings: 88 & 89 GL1500's on the road,and a 1983 GL1100 w/sidecar under restoration.. Also we havea restored 1981 GL500 Silver Wing Int(beautiful, but too tall for the Lady, for sale),a 1986 Rebel CMX250 (cute, but too small for the Lady) and a new 2004 FSC600 Silver Wing scooter (pretty, no shifting, just right for the Lady)..I've had3 otherGold Wing 4'sin the past..Throw ina couple ofHarleys owned by in-laws,and we've got quite a little fleet to keep busy...Great reading on this forum, it's nice that people can share their knowledge, experience,and humor with others..Being a master auto tech, I can appreciate thefolks that have a real passion for what they do, and for the striving to learn more through testing, research, and sharing..I try to share what Iknow also......Anyway enough intros for now, don't want to be too awfully boring...

I've been experimenting also with different headsets, and have read through many articles on this wonderful site, and others on the Web..I just have a few questions about the differences in microphones..I have 2 sets of J&M headsets, which do not fit the half helmets we prefer to use..Experimenting with computer style stereo headset/microphones..I have one that goes behind the neck, can be used with the helmet or without, very lightweight and inexpensive..The headphones sound great, but the mic causes the dreaded loud, squealing feedback sound to be transmittedwhen the CB is keyed..Seems like does not work at all for intercom..A "radio" friend has me almostbelieving that my obstacle is not so much the difference in microphones, but the lack of shielding on the cheaper headset cables..I'm not so convinced, the computer headset has a level and mute control halfway up the mic line..I don't get the squeal when it's muted,and thelevel control makes no difference..I've also experimented with the separate grounds in the DIN, noted the resistance differences between mics (J&M: 240 ohm ; Staples: 630 ohm)..Here's my questions for you electronic "sparkys"::

Dynamic vs Condensor: Reading here that Gold Wing mics are dynamic..Talked to a guy from J&M, was told their mics are "powered type", he may have been mistaken??

Which type of microphone are usually used in cheaper headsets or earbuds, like ones for a computer or cellphone?? I thought they were condensor electret before learning thatthis typemust be powered, do not think that cellphones or sound cards supply power on mic line??

You guys mention a shunt across the mic circuit when unplugged..What's the difference, where it does not seem to matter how many (or if any)headsets are plugged in??

Also hearing about "throat" microphones and other types of mics that may work better than what I've been playing with..Though it would be nice to use an out of the box headset w/mic..Justneed to use CB occasionally, like when riding with Gold Wing friends, don't really care about the intercom part, she likes the quiet anyway..What do you say???

Thanks so much for your time, and again thanks for the great website and forum

Kevin in Maine

ASE, GWRRA, iATN, anda fewother obscure acronyms

 

[exavid]

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:waving::waving:Welcome to the Best Goldwing Site on the Internet Kevin!:waving::waving:

As for mikes, most cheap units tend to be crystal or piezo mikes, self generating, high output but lesser quality audio. Dynamic mikes mostly have a coil moved by the audio sound waves in the presence of a magnet, basically a speaker used in reverse. The condenser mike is sensitive but has to be in a powered circuit, basically it is a variable capacitor whose capacitance is varied by the incoming audio. High quality but if used on an audio system designed for a different type must have a powered preamp. Often the preamp is built into the mike. Throat mikes originally were designed for aviation, they were carbon mikes that are a variable resistor type. The main purpose was to be able to work in a very high noise environment. There may be other than carbon versions available now, but typically these mikes have poor audio quality.

The idea of having a shunt resistor on the input of an audio amplifier circuit is to dampen any voltages that might be induced in the input wiring. It there is a totally open circuit in the input these voltages have a tendency to set off the feedback oscillation which results in a nasty howl or buzz. They are usually wired across contacts on the back of phone jacks that close when the plug is removed. Not normally used with other types of connectors.

Computers usually use cheap piezo mikes, no power needed. Cellphones easily could use a condenser mike since it's all internal anyway.

Your radio buddy could be right, unshielded wires in a cable can induce feedback from the audio output to the mike input. An impedance mismatch between the mike and the bike's input can also do it. Measuring with an ohm meter only measures the DC resistance which is not directly related to the AC impedance.The muting control on your mike cord may simply short across the mike leads to silence it. If that's the case you wouldn't get feedback then. Have you tested your bike's system with a head set designed for the bike? Before getting too deep in, you might want to verify the bike's system works correctly. If it does it's your headsets, and most likely the mike.

 

[gaswing]

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Steve, you might find the following "making your own headsets" article interesting, its elsewhere her on the same site;

http://www.goldwingfacts.com/DIYintercom.htm

 

[Kendas]

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Okay, time to put my two cents in people... Is anyone old enough to remember when CB was the big thing (like pre-cell phone young'ens :})?

We where always trying to get more "power" out of the radios to talk "farther" than your buddy. One of the things we'd do was go to a "power mic". These were both hand and stand mics with pre-amps in them and if you bought the really good ones (IE. Turner +2) it didn't come with a plug on the end of the mic. You had to go to Radioshack (when they used to be a real electronics store, unlike today) to get a connector to fit your radio. You then had to figure the pin-out of the mic connector (unless lucky enough to have the schematic, not all radios had one in the box), and wire in the new mic... A lot of times we had to put a .001 microfarad capacitor in the mic circuit because the mic would squeal on transmit.

Seems like this is a similar problem.

Electronic gurus want to comment... I'm just an electronics "tinkerer", but I like looking at the pretty lines in an O-scope until I get dizzy.:gunhead:

 

[exavid]

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Yep, around 1973 the CB boom was in full swing. It had been available for years before that but the advent of cheaper smaller units and the adoption by truck drivers make a real hot market. The low capacity capacitor (.001uf or so) across the mike was to short out any RF that got picked up by the microphone circuit, the RF could cause all kinds of odd things to happen usually resulting in feedback or poor modulation. I'm afraid it's not that simple in Kevin's case. Getting a reasonable impedance match and proper ioutput level from the mike to the bike'sinput. Decent shielding is important too, the ignition system, and wiring on the bike will generate a lot of noise.

As for looking at the lines on a 'scope I sure spent a lot hours looking at that great old instrument, the Tektronics 545. Before that it was a lot of old crummy 'scopes that didn't even have a calibrated time base. It's amazing to me how small the modern oscilloscopes are now, and how high frequency response they have. I also remember how a lot of 'outlaw CBers' would buy 10 meter ham linear amps and operate around 700W instead of the legal 5W. Ah the grand old days when the electronics were tempermental, bulky, heavy, and expensive!

 

[Kendas]

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exavid wrote:

...I also remember how a lot of 'outlaw CBers' would buy 10 meter ham linear amps and operate around 700W instead of the legal 5W. Ah the grand old days when the electronics were tempermental, bulky, heavy, and expensive!

Some of us even added "extra" crystal banks (we're talking 23 channel days) to our radios to get into the "guard" bands where it was empty of all the noise and we could talk. We won't talk about "expanded" clarifiers and the other things you can do with SSB today.


Ahhh!!! Someone else that knows what "Heathkit" was. I'll bet you even know the meaning of V=IxR too.

I know... "Off topic" but it's good to know someone here can answer electronics questions too as more and more bikes have electronic "everything".

 

[exavid]

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P=IE E=IR Norton Thevenin Ohms Mhos VTVM Simpson Triplett B&K Fluke HP

Yes, I used to be fluent in the language.