Headset to mp3 Adapter

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I bought one of those "Y" adapters so I could play my iPod thru my
stereo headset. Your headset plug goes in 1 end, and then it branches
off to a standard headset plug for the intercom and a "mini" plug for
the iPod. The problem is that the plane's radio volume drops to barely
audible, even with the volume turned all the way up. The mp3 player
volume has a nice low to loud range so I can adjust it. But I can
barely pick up ATC calls even with the radio volume turned to max. I
had to disconnect it.

Any explanations and work-arounds? I tossed the bag and receipt so I
can't return it.

Thanks!

--Jeff

[mikem]

wrote:
> I bought one of those "Y" adapters so I could play my iPod thru my
> stereo headset. Your headset plug goes in 1 end, and then it branches
> off to a standard headset plug for the intercom and a "mini" plug for
> the iPod. The problem is that the plane's radio volume drops to barely
> audible, even with the volume turned all the way up. The mp3 player
> volume has a nice low to loud range so I can adjust it. But I can
> barely pick up ATC calls even with the radio volume turned to max. I
> had to disconnect it.
>
> Any explanations and work-arounds? I tossed the bag and receipt so I
> can't return it.

Jeff, you have a classic case of two low-impedance audio outputs
shorted to each other. With the Y, the intercom's audio output is tied
to the iPod's audio amplifier as well as the headset. The output
impedance of the iPod is so low that it overwhelms the ability of the
intercom amplifier to drive it, making the level from the aircraft side
too low (and probably distorted). OTOH, the iPod's output can backdrive
the output impedance of the intercom's audio amps, and it wins out.

The correct solution to this is to use the type of intercom that has a
provision for "Entertainment" input. Internally, such an intercom has a
provision for "summing" the entertainment audio with the aircraft audio
in a way that avoids shorting the two sources to each other. Some use
switching to mute music while there is activity on the aircraft side.

A half-assed solution if your intercom doesn't have an entertainment
input is to put series resistors (one for RIGHT and the another for
LEFT) between the iPod's outputs and the inputs to the Y-adapter. I
would start with 47 Ohms 1/2Watt. If the aircraft level is still too
low, try 100 Ohms. If with 47Ohms, the aircraft side can be made loud
enough, but the iPod level is now too low, try 22 Ohms in series with
each side.

[Newps]

Another option is to wear the ear buds for the Ipod under your headset.



mikem wrote:
> wrote:
>
>>I bought one of those "Y" adapters so I could play my iPod thru my
>>stereo headset. Your headset plug goes in 1 end, and then it branches
>>off to a standard headset plug for the intercom and a "mini" plug for
>>the iPod. The problem is that the plane's radio volume drops to barely
>>audible, even with the volume turned all the way up. The mp3 player
>>volume has a nice low to loud range so I can adjust it. But I can
>>barely pick up ATC calls even with the radio volume turned to max. I
>>had to disconnect it.
>>
>>Any explanations and work-arounds? I tossed the bag and receipt so I
>>can't return it.
>
>
> Jeff, you have a classic case of two low-impedance audio outputs
> shorted to each other. With the Y, the intercom's audio output is tied
> to the iPod's audio amplifier as well as the headset. The output
> impedance of the iPod is so low that it overwhelms the ability of the
> intercom amplifier to drive it, making the level from the aircraft side
> too low (and probably distorted). OTOH, the iPod's output can backdrive
> the output impedance of the intercom's audio amps, and it wins out.
>
> The correct solution to this is to use the type of intercom that has a
> provision for "Entertainment" input. Internally, such an intercom has a
> provision for "summing" the entertainment audio with the aircraft audio
> in a way that avoids shorting the two sources to each other. Some use
> switching to mute music while there is activity on the aircraft side.
>
> A half-assed solution if your intercom doesn't have an entertainment
> input is to put series resistors (one for RIGHT and the another for
> LEFT) between the iPod's outputs and the inputs to the Y-adapter. I
> would start with 47 Ohms 1/2Watt. If the aircraft level is still too
> low, try 100 Ohms. If with 47Ohms, the aircraft side can be made loud
> enough, but the iPod level is now too low, try 22 Ohms in series with
> each side.
>