Floating ground - diff amp intercom systems

My intercom system uses a differential amplifier (floating ground) design. Most aftermarket earbuds/headphones use a 'earth ground' negative and positive polarity system where the ground is always at 0 vdc.

Is it possible to convert a set of Etymotic ER6i earbuds to be compatible with an differential amp (DA) system? My intercom vendor offers a stock set of earbuds that are DA compatible, but I'd really prefer to use the ER6i's as they sound great and offer good noise isolation too. This makes me wonder what the heck is the difference between a 'normal' headset and one that is DA compatible. I'm not an EE, but I think I understand DA op amp design in simple terms. Is it possible to convert a 'normal' set of headphones/earbuds to be compatible with DA designed systems? What would it take to modify them?

I'm purposely being mum about the intercom mfr at this point. Everyone has been working very hard to determine the root cause of this issue which is when it's hot outside, >100F ambient, the audio decreases to inaudible levels; when volume is increased to compensate, the distortion is terrible. Yes, the intercom's temperatures are well under the stated operating range as measured with calibrated digital temp indicators, the audio sources (mp3/cd) are working correctly, the cabling is correct, the various potentiometers are set correctly, the power source is clean and within proper voltages. A new replacement board has the same problem. Reduce the ambient temperature and it works great again. Too bad for me I live where it's HOT. The mfr states that in very limited cases, the impedance imbalance caused by using a earth ground headset/earbud causes the DA system to have difficulties and their solution is to use their specific earbuds, which I may or may not like (they arrive tommorrow).

Any ideas? And if you need to PM me for specific details to help resolve this issue, PLEASE do.

Thanks In Advance

Possibly the use of a floating ground adapter from the car audio world could be wired in? Just a thought.

They come in stereo, so you're halfway there. I'd have to dig into my parts box to find one. Haven't had to use one of those on an install in years.

FJRandy said:

Possibly the use of a floating ground adapter from the car audio world could be wired in? Just a thought.They come in stereo, so you're halfway there. I'd have to dig into my parts box to find one. Haven't had to use one of those on an install in years.

Click to expand...

Randy, Thanks for a response. what is this 'floating ground adapter' you refer to? Does it install in-line with the audio source? Do you know how it works? This would be a very easy solution if still available. Anyone else know of sources for such said device?

dcarver said:

FJRandy said:

Possibly the use of a floating ground adapter from the car audio world could be wired in? Just a thought.They come in stereo, so you're halfway there. I'd have to dig into my parts box to find one. Haven't had to use one of those on an install in years.

Click to expand...

Randy, Thanks for a response. what is this 'floating ground adapter' you refer to? Does it install in-line with the audio source? Do you know how it works? This would be a very easy solution if still available. Anyone else know of sources for such said device?

Click to expand...

See my response on the wretched 'sidestand' thread.

A 'floating ground adapter' (digital bridge rectifier) would probably work, but may introduce noise depending on where in the audio loop you install it. Go with the manufacturer recommendation....

Most of this stuff just isn't made for motorcycle applications where the electronics can cause a current through the frame anyhow--there just isn't much metal to ground to in a motorcycle....

The problem is not with your headphones. It is the ground loop between the audio source and the amp.

You can verify this by setting it up so there is noise (engine will need to be running, headphones in, etc.). Now disconnect the audio source, or make it run on it's battery rather than bike power if it has one. If the noise goes away, installing a ground loop isolator between the source and the amp will do the trick. You can buy these at Radio Shack or online for around ten bucks.

-BD