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Discussion Starter · #1 ·
I am trying to put a 3.5mm stereo plug on an old LT headset cord I have. I have the pin outs for the BMW headset plug (from this site) -
1 - Right Speaker +
2 - Right Speaker -
3 Preamp MIC +
4 Left Speaker -
5 Left Speaker +
6 Shields & Yellow MIC -

Not concerned with the MIC connections just need to hook Left & Right speakers to the 3.5mm plug, but I can't find any info on what + or - should be the hooked to the Ground of the 3.5mm Stereo plug (not being a audiophile) is it the same as the LT + ground?

Thanks
 

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Discussion Starter · #3 ·
Thanks for your input. But no I have the Male LT end of the headset cord & I'm trying to figure which or + or - on Audio circuits would go to the Ground of the 3.5mm (1/8") male plug.

Making a cable up so I can plug it into the SENA SM10 that will feed all audio through to my SENA Bluetooth headsets (SO & Mine listening to the same outputs from the LT audio system).

This is what I'm trying to make as Sena doesn't make one for BMW (only Honda GW & Harley Ultra) Link .

knoticalone said:
 

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Now I understand what you are trying to accomplish. Again this might not be the answer but here is a shot. In Pro Audio dealing with a TRS type plug (in this case a 3.5 mm stereo) we usually see T= one speaker + , Ring = other speaker + and sleeve = speaker neg(s). Just a guess. Not sure how the output levels on the LT compare though to other forms of electronics i.e an MP3, Ipod etc.

If you know the pin outs on the unit you are trying to connect to it would make the task a bit easier.
 

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Discussion Starter · #5 ·
Thanks, I guess I'll try asking on the Sena forum & see if I can get an answer from Sena.

knoticalone said:
Now I understand what you are trying to accomplish. Again this might not be the answer but here is a shot. In Pro Audio dealing with a TRS type plug (in this case a 3.5 mm stereo) we usually see T= one speaker + , Ring = other speaker + and sleeve = speaker neg(s). Just a guess. Not sure how the output levels on the LT compare though to other forms of electronics i.e an MP3, Ipod etc.

If you know the pin outs on the unit you are trying to connect to it would make the task a bit easier.
 

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On almost all MP3 or music players. The tip is one positive, the ring is the other positive and the sleeve is negative. It does not matter left verses right for the positives. Both negatives would go to the sleeve. If you are connecting to an audio input on the Sena it should be wired this way to be compatable.

Some Ipods do use a 4 pin connector especially Iphone and Ipad.

Should be very straight forward. I would start with the lowest possible volume from the K12 though.
 

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Discussion Starter · #7 ·
Ok, that sounds right. I have put the question to Sena anyway. Still waiting for the SM10 to arrive from the eastern US to Western Canada :-(..customs can slow down things bad.

Thanks for your Help.

knoticalone said:
On almost all MP3 or music players. The tip is one positive, the ring is the other positive and the sleeve is negative. It does not matter left verses right for the positives. Both negatives would go to the sleeve. If you are connecting to an audio input on the Sena it should be wired this way to be compatable.

Some Ipods do use a 4 pin connector especially Iphone and Ipad.

Should be very straight forward. I would start with the lowest possible volume from the K12 though.
 

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No problem. I know how customs can be. I sold an FJR a while back and shipped it to Canada. It took a while and a lot of paperwork.
 

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Bighopper, I think I did the same thing that you are trying to do, but I put a 3.5mm (1/8") jack (female) on my BMW intercom cable. I use Cardo Scala BT headsets for my intercom/phone calls, but have my Garmin GPS (with music and XM) plugged into the LT AUX in port so everything comes out the radio speakers. I wanted to listen to it in my helmet instead of blasting it out for the world. I tried tying both speaker grounds to the ground connector on the jack from Radio Shack and the two positives to their respective side, but the audio sounded terrible. I assumed it was my soldering, etc and kept trying to get make it better, but it couldn't.

I found this website http://www.oocities.org/weirsoft/bc1.html which mentions in Note 1 (about a third the way down), that the two grounds need to run through a Capacitor. He used two (4.7uF, 50v) from Radio Shack. Their model # is 272-1012. I tried these on the grounds before tying them together on the jack and it works like a champ. Don't know exactly what or why on this, but very thankful to have found the write-up.

Hope some of this helps you with your endeavor. Let know if I need to describe any of this better.

Sammy
 

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J&M makes an adapter that works like a champ ... might zip them an email ... I forget where I found it on their web sight.
 

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Discussion Starter · #11 ·
Thanks for that info. I am still waiting for my Sena SM10 to arrive to try what I have done. If it has the issue you mention then I will do what you suggested.

Thanks.

sgroover said:
Bighopper, I think I did the same thing that you are trying to do, but I put a 3.5mm (1/8") jack (female) on my BMW intercom cable. I use Cardo Scala BT headsets for my intercom/phone calls, but have my Garmin GPS (with music and XM) plugged into the LT AUX in port so everything comes out the radio speakers. I wanted to listen to it in my helmet instead of blasting it out for the world. I tried tying both speaker grounds to the ground connector on the jack from Radio Shack and the two positives to their respective side, but the audio sounded terrible. I assumed it was my soldering, etc and kept trying to get make it better, but it couldn't.

I found this website http://www.oocities.org/weirsoft/bc1.html which mentions in Note 1 (about a third the way down), that the two grounds need to run through a Capacitor. He used two (4.7uF, 50v) from Radio Shack. Their model # is 272-1012. I tried these on the grounds before tying them together on the jack and it works like a champ. Don't know exactly what or why on this, but very thankful to have found the write-up.

Hope some of this helps you with your endeavor. Let know if I need to describe any of this better.

Sammy
 

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Discussion Starter · #12 ·
Re: LT Headset plug to 3.5mm Stereo Plug - UPDATE

Well the SM10- Dual Bluetooth Stereo Transmitter, arrived this afternoon after spending 2 weeks in the postal system from Eastern US to Western Canada (4 days in customs so they could collect $21.24 in GST).
But I digress I charged up the unit(3hrs) & then went to the LT to hook it up, paired the SMH10 headset easy. Plugged in the cord I made up, turned on the radio..nothing. After investigating found that female plug on the SM10 is recessed & there 3.5mm Stereo plug has ribs on the plastic portion to seal against weather & my 3.5mm plug was too thick to enter properly. Out with the knife & trim the plastic down. Plug it in, Stereo Sound from the radio.
I haven't had a chance to ride yet, but being able to increase the volume on the radio helps with the loudness at the helmet speakers.

I tested the accessory jack, & hooked up my Montana 650 Rugged mount audio out to the accessory jack. Put in a route, had the radio playing & started the route, the radio faded down (does not mute) & I could hear the OZ chick telling me where to go :histerica.

So from what I can see so far I didn't need to do anything else to the plug hook up from the BMW plug to the 3.5mm, just :
1 - Right Speaker + to Tip
2 - Right Speaker - to other - & then to sleeve(ground) on 3.5mm plug

4 Left Speaker - to other - & then to sleeve(ground) on 3.5mm plug
5 Left Speaker + to Ring

I also started the bike to see if I got any feed back but all was good.
 

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Re: LT Headset plug to 3.5mm Stereo Plug - UPDATE

Bighopper said:
But I digress I charged up the unit(3hrs) & then went to the LT to hook it up, paired the SMH10 headset easy. Plugged in the cord I made up, turned on the radio..nothing. After investigating found that female plug on the SM10 is recessed & there 3.5mm Stereo plug has ribs on the plastic portion to seal against weather & my 3.5mm plug was too thick to enter properly. Out with the knife & trim the plastic down. Plug it in, Stereo Sound from the radio.
Have you thought of using a bluetooth dongle instead of the wired solution.
 

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Re: LT Headset plug to 3.5mm Stereo Plug - UPDATE

Bighopper said:
the radio faded down (does not mute) & I could hear the OZ chick telling me where to go :histerica.
was that Kylie or Charlene? :rotf:
 

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Discussion Starter · #15 ·
Re: LT Headset plug to 3.5mm Stereo Plug - UPDATE

cws said:
was that Kylie or Charlene? :rotf:
I think it's Karen....
 

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Discussion Starter · #16 · (Edited)
Re: LT Headset plug to 3.5mm Stereo Plug - UPDATE

johnbaker15 said:
Have you thought of using a bluetooth dongle instead of the wired solution.
That is what the SM10 is, Bluetooth transmitter that allows 2 headsets to hear the same inputs. But you need to connect the LT's output to the input of the SM10.
{Edit} Pictures



 
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