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USB Headphones hack - Soldering a 3.5mm plug instead of the headphones



 
 
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  #1  
Old September 15th 07, 07:19 PM posted to rec.audio.tech
[email protected]
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Posts: 5
Default USB Headphones hack - Soldering a 3.5mm plug instead of the headphones

I have a cell phone with a mini-usb plug on it.. the camera also came
with a set of earphones that plug into this usb connector, however, I
would like to go from this mini-usb to a 3.5 mm plug instead of the
headphones (my car has an aux plug input). The earphone/usb cable has
a little 3/4" case that has a microphone and Im guessing a amplifier.


So..

I opened the the little case, and sure enough where there are 3 wires
"L", "R", and ground that are going to the earbuds. The ground and
"R" wires were both going to the right earbud. So I desoldered these 3
wires from the board, and soldered the 2 wires coming from the 3.5 mm
plug.

The problem is, Im getting tons of noise, and at VERY low volume. Im
guessing this is because the ground on the plug isnt connected to the
ground of the amplifier/microphone board. However, the 3.5 mm plug
doesnt have a 3rd (ground) conductor to connect.. it only has a white
and red wire, nothing else.

If my post above, wasnt confusing enough, here's a totally blurry
picture that I took with the cell. Its hard to see anything on it,
but the red and white wires on the right are going to the plug.

http://i6.tinypic.com/5xe5fth.jpg

Im probably missing something obvious, but what am I doing wrong? How
can I connect a plug to where the headphones used to go?

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  #2  
Old September 15th 07, 10:18 PM posted to rec.audio.tech
Richard Crowley
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Posts: 4,172
Default USB Headphones hack - Soldering a 3.5mm plug instead of the headphones

> wrote ...
>I have a cell phone with a mini-usb plug on it.. the camera also came
> with a set of earphones that plug into this usb connector, however, I
> would like to go from this mini-usb to a 3.5 mm plug instead of the
> headphones (my car has an aux plug input). The earphone/usb cable has
> a little 3/4" case that has a microphone and Im guessing a amplifier.
>
>
> So..
>
> I opened the the little case, and sure enough where there are 3 wires
> "L", "R", and ground that are going to the earbuds. The ground and
> "R" wires were both going to the right earbud. So I desoldered these 3
> wires from the board, and soldered the 2 wires coming from the 3.5 mm
> plug.
>
> The problem is, Im getting tons of noise, and at VERY low volume. Im
> guessing this is because the ground on the plug isnt connected to the
> ground of the amplifier/microphone board. However, the 3.5 mm plug
> doesnt have a 3rd (ground) conductor to connect.. it only has a white
> and red wire, nothing else.
>
> If my post above, wasnt confusing enough, here's a totally blurry
> picture that I took with the cell. Its hard to see anything on it,
> but the red and white wires on the right are going to the plug.
>
> http://i6.tinypic.com/5xe5fth.jpg
>
> Im probably missing something obvious, but what am I doing wrong? How
> can I connect a plug to where the headphones used to go?


What cell phone?
What camera?
What does the camera have to do with anything?
Are you trying to connect the output of your cell phone
to the aux input of your car radio?
Did you try your two wires connected the other way
around?
Is your 3.5mm connector stereo (tip-ring-sleve)?
If so, why does it have only 2 wires?
Is the wire to your 3.5mm connector shielded?

I would have left the earbud wire as it was and
chopped it in half to install the 3.5mm connector.
That way you know what is what out of your little
case. And you can install a plug on the remaining
earbud wire to be able to use your lash-up either
way.

  #3  
Old September 16th 07, 01:06 AM posted to rec.audio.tech
[email protected]
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Posts: 5
Default USB Headphones hack - Soldering a 3.5mm plug instead of the headphones

The cell phone that has the camera and a usb headphone is the Philips
Xenium [email protected] cell phone.
Yes, I am trying to connect it's usb output to a aux 3.5mm input of my
car radio. The cell phone came with a set of ear phones that plugs
into the cell's usb connector, but I want to drive a 3.5mm plug
instead of the headphones.

The 3.5mm plug Im using has 3 conductive areas (sleeve, ring, right,
ring, and left (tip)), yet the cable only has 2 wires (left and
tip)! Im not sure where this cable came from, but it had a 3.5mm
plug on both ends, so I just chopped off one end so that I could
solder it in place of the headphones. Perhaps this is an oddball
cable? If I find and cut open another audio cable (with 3.5mm plugs
on both ends) is it likely it will have 3 wires?

The little board in the case, has silkscreen that shows "L", "R" and
"GND", which is where the earbud wires were connected to, so Im pretty
sure thats correct. My only guess on why this isnt working is is that
plug's ground needs to be grounded with the board's ground. Is there
any other explanation?

Even if the Left and Right were reversed, what that cause issues?


  #4  
Old September 16th 07, 03:54 AM posted to rec.audio.tech
JANA
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Posts: 52
Default USB Headphones hack - Soldering a 3.5mm plug instead of the headphones

That picture is too out of focus to see what is really there! Do you have a
camera with a macro lens?

I am thinking that there is a severe impedance mismatch, and at the same
time, there may be an active DC voltage on the earphone output. The
earphones on some of these mobile phones are using active circuitry, and
require a few volts to operate.

You would have to use a scope and a DVM and spend some time to figure out
the characteristics especially before doing any moods.

--

JANA
_____


> wrote in message
ups.com...
I have a cell phone with a mini-usb plug on it.. the camera also came
with a set of earphones that plug into this usb connector, however, I
would like to go from this mini-usb to a 3.5 mm plug instead of the
headphones (my car has an aux plug input). The earphone/usb cable has
a little 3/4" case that has a microphone and Im guessing a amplifier.


So..

I opened the the little case, and sure enough where there are 3 wires
"L", "R", and ground that are going to the earbuds. The ground and
"R" wires were both going to the right earbud. So I desoldered these 3
wires from the board, and soldered the 2 wires coming from the 3.5 mm
plug.

The problem is, Im getting tons of noise, and at VERY low volume. Im
guessing this is because the ground on the plug isnt connected to the
ground of the amplifier/microphone board. However, the 3.5 mm plug
doesnt have a 3rd (ground) conductor to connect.. it only has a white
and red wire, nothing else.

If my post above, wasnt confusing enough, here's a totally blurry
picture that I took with the cell. Its hard to see anything on it,
but the red and white wires on the right are going to the plug.

http://i6.tinypic.com/5xe5fth.jpg

Im probably missing something obvious, but what am I doing wrong? How
can I connect a plug to where the headphones used to go?


  #5  
Old September 16th 07, 05:36 AM posted to rec.audio.tech
Richard Crowley
external usenet poster
 
Posts: 4,172
Default USB Headphones hack - Soldering a 3.5mm plug instead of the headphones

> wrote ...
> The cell phone that has the camera and a usb headphone is the Philips
> Xenium [email protected] cell phone.
> Yes, I am trying to connect it's usb output to a aux 3.5mm input of my
> car radio. The cell phone came with a set of ear phones that plugs
> into the cell's usb connector, but I want to drive a 3.5mm plug
> instead of the headphones.
>
> The 3.5mm plug Im using has 3 conductive areas (sleeve, ring, right,
> ring, and left (tip)), yet the cable only has 2 wires (left and
> tip)! Im not sure where this cable came from, but it had a 3.5mm
> plug on both ends, so I just chopped off one end so that I could
> solder it in place of the headphones. Perhaps this is an oddball
> cable? If I find and cut open another audio cable (with 3.5mm plugs
> on both ends) is it likely it will have 3 wires?
>
> The little board in the case, has silkscreen that shows "L", "R" and
> "GND", which is where the earbud wires were connected to, so Im pretty
> sure thats correct. My only guess on why this isnt working is is that
> plug's ground needs to be grounded with the board's ground. Is there
> any other explanation?
>
> Even if the Left and Right were reversed, what that cause issues?


So, to review the bidding:
1) you have a cable with a stereo 3.5m connector,
but only two wires in the cable.
2) You don't know which two parts (tip, ring, sleeve)
of the connector your two wires go to.
3) You connected your two unknown wires to L & R
and with the ground unconnected.

1) You almost certainly don't have the cable you need.
2) You must establish how your cable is wired if you
want to use it. (NOTE: If you get any other pre-wired
cable you will need to do the same thing.)
3) Wiring anything to just the "L" and "R" is almost
guaranteed to produce your "tons of noise and very
low volume" Reason: you are only hearing the
*difference* between the "L" and "R" audio signals
because they are both referenced to ground which
you left disconnected.

Connect the "GND" to the sleeve of the 3.5mm stereo
mini-phone cable. Connect the "L" and "R" to the
tip and ring of the mini phone connector. Some of
your noise may also be coming from the problem
of not using a shielded wire, as well.

Note that if you are trying to turn your phone into
some sort of hands-free device in your car, prepare
to be disappointed because it is rarely that simple.

  #6  
Old September 16th 07, 11:53 PM posted to rec.audio.tech
[email protected]
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Posts: 5
Default USB Headphones hack - Soldering a 3.5mm plug instead of the headphones

> So, to review the bidding:
> 1) you have a cable with a stereo 3.5m connector,
> but only two wires in the cable.
> 2) You don't know which two parts (tip, ring, sleeve)
> of the connector your two wires go to.
> 3) You connected your two unknown wires to L & R
> and with the ground unconnected.


1) Yes,
2) The white wire from the cable is going to the tip, while the red
wire is going to the center. The plug itself has a sleeve portion
(ground), but there is no additional wire connected to it, only 2.
3) I soldered the white wire (tip) to the pcb where it says "L" and
the red to "R". The pcb shows a "G" but the stereo cable doesnt have
any other wire. Do audio stereo cables (with 3.5m plugs) normally have
3 conductor wires all the way through?


I'll try to connect the ground to the sleeve with just some alligator
clips to see if that fixes the issue... as for the active voltage,
Im assuming that the usb connector is providing the power, but the
earbuds that Im replacing only had the L, R, and Ground wires going to
them so Im guessing in theory, those are the only signals I need to
get it on a 3.5mm plug, no?

  #7  
Old September 17th 07, 02:06 PM posted to rec.audio.tech
Richard Crowley
external usenet poster
 
Posts: 4,172
Default USB Headphones hack - Soldering a 3.5mm plug instead of the headphones

> wrote...
>> So, to review the bidding:
>> 1) you have a cable with a stereo 3.5m connector,
>> but only two wires in the cable.
>> 2) You don't know which two parts (tip, ring, sleeve)
>> of the connector your two wires go to.
>> 3) You connected your two unknown wires to L & R
>> and with the ground unconnected.

>
> 1) Yes,
> 2) The white wire from the cable is going to the tip, while the red
> wire is going to the center. The plug itself has a sleeve portion
> (ground), but there is no additional wire connected to it, only 2.


Then it will never work for what you need. You need a
cable with all three wires, one each to the tip, ring, and sleeve.

> 3) I soldered the white wire (tip) to the pcb where it says "L" and
> the red to "R". The pcb shows a "G" but the stereo cable doesnt have
> any other wire. Do audio stereo cables (with 3.5m plugs) normally have
> 3 conductor wires all the way through?


Yes you need all three connections. You cable is an oddball
that will not work for your application.

> I'll try to connect the ground to the sleeve with just some alligator
> clips to see if that fixes the issue... as for the active voltage,
> Im assuming that the usb connector is providing the power, but the
> earbuds that Im replacing only had the L, R, and Ground wires going to
> them so Im guessing in theory, those are the only signals I need to
> get it on a 3.5mm plug, no?


Correct.

  #8  
Old September 17th 07, 05:38 PM posted to rec.audio.tech
Gareth Magennis
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Posts: 589
Default USB Headphones hack - Soldering a 3.5mm plug instead of the headphones


> wrote in message
ups.com...
>> So, to review the bidding:
>> 1) you have a cable with a stereo 3.5m connector,
>> but only two wires in the cable.
>> 2) You don't know which two parts (tip, ring, sleeve)
>> of the connector your two wires go to.
>> 3) You connected your two unknown wires to L & R
>> and with the ground unconnected.

>
> 1) Yes,
> 2) The white wire from the cable is going to the tip, while the red
> wire is going to the center. The plug itself has a sleeve portion
> (ground), but there is no additional wire connected to it, only 2.
> 3) I soldered the white wire (tip) to the pcb where it says "L" and
> the red to "R". The pcb shows a "G" but the stereo cable doesnt have
> any other wire. Do audio stereo cables (with 3.5m plugs) normally have
> 3 conductor wires all the way through?
>



Your cable will have a ground connection, you probably inadvertantly chopped
it off while removing the outer sleeving. Go back and very carefully try to
remove the outer sleeving until you find a fine braid or otherwise that is
the earth connection. You may have to do this several times before the
ground connection reveals itself.


Gareth.


  #9  
Old September 17th 07, 11:15 PM posted to rec.audio.tech
[email protected]
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Posts: 5
Default USB Headphones hack - Soldering a 3.5mm plug instead of the headphones

On Sep 17, 9:38 am, "Gareth Magennis" >
wrote:
> > wrote in message
>
> ups.com...
>
>
>
>
>
> >> So, to review the bidding:
> >> 1) you have a cable with a stereo 3.5m connector,
> >> but only two wires in the cable.
> >> 2) You don't know which two parts (tip, ring, sleeve)
> >> of the connector your two wires go to.
> >> 3) You connected your two unknown wires to L & R
> >> and with the ground unconnected.

>
> > 1) Yes,
> > 2) The white wire from the cable is going to the tip, while the red
> > wire is going to the center. The plug itself has a sleeve portion
> > (ground), but there is no additional wire connected to it, only 2.
> > 3) I soldered the white wire (tip) to the pcb where it says "L" and
> > the red to "R". The pcb shows a "G" but the stereo cable doesnt have
> > any other wire. Do audio stereo cables (with 3.5m plugs) normally have
> > 3 conductor wires all the way through?

>
> Your cable will have a ground connection, you probably inadvertantly chopped
> it off while removing the outer sleeving. Go back and very carefully try to
> remove the outer sleeving until you find a fine braid or otherwise that is
> the earth connection. You may have to do this several times before the
> ground connection reveals itself.
>
> Gareth.- Hide quoted text -
>
> - Show quoted text -


doh! You are right, I cant believe it, the ground wire appeared about
3 inches away from where I had made the cut! How the heck did it
break from there??!

Anyhoot, I connected the ground wire, and everything sounds great!

Thanks!!




  #10  
Old September 17th 07, 11:18 PM posted to rec.audio.tech
[email protected]
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Posts: 5
Default USB Headphones hack - Soldering a 3.5mm plug instead of the headphones

On Sep 17, 9:38 am, "Gareth Magennis" >
wrote:
> > wrote in message
>
> ups.com...
>
>
>
>
>
> >> So, to review the bidding:
> >> 1) you have a cable with a stereo 3.5m connector,
> >> but only two wires in the cable.
> >> 2) You don't know which two parts (tip, ring, sleeve)
> >> of the connector your two wires go to.
> >> 3) You connected your two unknown wires to L & R
> >> and with the ground unconnected.

>
> > 1) Yes,
> > 2) The white wire from the cable is going to the tip, while the red
> > wire is going to the center. The plug itself has a sleeve portion
> > (ground), but there is no additional wire connected to it, only 2.
> > 3) I soldered the white wire (tip) to the pcb where it says "L" and
> > the red to "R". The pcb shows a "G" but the stereo cable doesnt have
> > any other wire. Do audio stereo cables (with 3.5m plugs) normally have
> > 3 conductor wires all the way through?

>
> Your cable will have a ground connection, you probably inadvertantly chopped
> it off while removing the outer sleeving. Go back and very carefully try to
> remove the outer sleeving until you find a fine braid or otherwise that is
> the earth connection. You may have to do this several times before the
> ground connection reveals itself.
>
> Gareth.- Hide quoted text -
>
> - Show quoted text -


BTW, do you think I'll have any noise / impedance matching issues, if
I were to connect the headphones AND the 3.5mm cable? I figure it
might be nice to keep the originally earbuds soldered to the board in
additon to the stereo cable but not if I'll low volume / noise.

Thanks!

 




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