connecting wireless headphones to an optical audio out

[jakesdilemma]

hi All,

About 2 months ago i wanted to hook up headphones to my LG TV, which doesn’t have a headphone jack, only a digital optical audio out. Spent ages on the internet researching all this and then went out and bought the digital analog converter and Toslink cable. The set up works perfectly with wired headphones, but does not work with my wireless headphones. the wireless headphones work perfectly on another TV where the associated base station transmitter connects directly via a 3.5mm headphone jack, and they also work in the room in which i have the tv that i now wish to connect to, as i tested them by connecting to a portable cd player, hence there isn’t any interference from anything else in the room in question. However, the wireless headphones emit a loud buzzing noise when the base station transmitter is connected to the converter. Does anyone have any suggestions as to why the converter is causing such interference? is it electrical power interference?"

i've since done further research, and it's saying that wireless headphones should work with a D/A converter. However, i've come across something else. it appears that wireless headphones come in basically 2 "flavours", analog ones which operate in the FM frequency at 86mhz (as mine are) , and digital ones that operate in UHF at 2.4ghz. Could it be that those that have got this working have 2.4ghz wireless headphones?

[DB83]

Don't know about the frequency issue of the headphones but the D/A converter will only function when the audio output of the device is set to PCM not ac3 or any compressed output.

[Cornucopia]

Maybe a ground loop is allowing the D->A converter's timing clock signal to leak into the circuitry of the xmitter.

Scott

[jakesdilemma]

Don't know about the frequency issue of the headphones but the D/A converter will only function when the audio output of the device is set to PCM not ac3 or any compressed output.

hi DB83, thanks for your reply. i havent adjusted any settings on the TV. it only has PCM anyway. the converter works fine with the wired headphones

[jakesdilemma]

Maybe a ground loop is allowing the D->A converter's timing clock signal to leak into the circuitry of the xmitter.

Scott

hi Scott, very interesting reply. My thinking has been that there is some incompatability between the wireless transmitter and the converter. the ground loop concept is another angle. any way i can test that?

[jakesdilemma]

ooops, sorry, forgot to say thanks Scott

[jakesdilemma]

Hi again, I think I’ve found the problem. It’s electrical interference, not aproblem with the converter. I had tested the wireless headphones in the roomwhere my TV is with a separate (portable) audio device unrelated to the TV, andit worked ok, but today I connected the base transmitter again to the same unrelateddevice and moved around my apartment. Sure enough, whenever I was close to an electricalsource the same loud buzzing noise started again. Clearly it would seem I’vepurchased inferior wireless headphones, or maybe it’s the 86mhz, but either waythey do not function when near any electrical connection. Even just connectingthe base transmitter to the converter with the converter disconnected from thepower, starts the buzzing noise. I guess the question remains then, is itpossible to eliminate the electrical interference in any way?

[Cornucopia]

All analog audio ciruits are susceptable to EMI/RFI. The good/pro ones use higher levels, lower impedance, and balanced (i.e. noise-cancelling) circuitry to minimize this interference. Regardless, the LONGER a line is, the more opportunity. Plus, things like badly soldered points and jack-plug contacts that don't make good connections will allow more interference.

What to do? Troubleshooting is all about breaking things down to knowing just what link(s) in the chain are responsible and then working around them.

If it was a ground loop (which it could still be), you could try a "ground lift" (which basically disconnects one of the ground/return lines from the loop). You can buy these or make them yourself (info on various websites).
There are also ways to externally ISOLATE/SHIELD a line/circuit with certain mu-metal ferro-magnetic beads & sleeves, etc. But they aren't perfect, plus we still don't know if this is really what's going on here.

For other possibilities, we would have to know more info. Particularly, what the actual chain of connection is, type of connection(s), make & model of all devices involved, etc.

Scott

[Verify]

There are a great variety of 'wireless' earphones. they include FM band , 900 MHz, etc. plus infrared, etc.
Some that I evaluated for a non-line of site application (which of course excludes the IR units):

900 MHz: http://www.walmart.com/ip/JVC-HAW600RF-900MHz-Wireless-Stereo-Headphones-with-Location...ature/13241382
900 MHz http://www.tigerdirect.com/applications/searchtools/item-details.asp?EdpNo=4252359&SRC...Ma.kKwVlSC.ZyQ
900 MHz: http://www.4homespeakers.com/rowesusowihe.html
FM: http://www.pyleaudio.com/sku/PHPW2

The FM units were eliminated because of the almost universal bad reviews - noise, intermittent operation, etc.

The Sony product was eventually used because it had the combination of features that were needed, including a volume control, rechargeable batteries, convenient charging stand, and the use of one transmitter with multiple headsets.

Hope that this helps.

[jakesdilemma]

thanks Scott. i'm fast beginning to think it's the FM frequency. might just wait til i have a few more pennies and buy a better set of headphones

[jakesdilemma]

thanks Verify. yes, i am thinking now it's the FM frequency. need to save some pennies up

[DB83]

While I am sure you know your equipment, Scott did ask you to advise us of the make/model of each item - tv, d/a converter and headphones.

I do find it hard to believe that you do not have right/left audio out jacks on the tv. Also, eliminating other possibilities, does the wireless transmitter have alternative 'channel' selectors since a different channel may eliminate the interference.

[jakesdilemma]

hi DB83, the TV is an LG, but i don't think there's any problem with the TV, nor the converter, as they work fine with the wired headphones. Yes, surprisingly, it seems many later model TVs don't have headphone jacks nor audio out jacks. They have coax or digital optical audio outs. i've probably read over 100+ threads and web page adverts etc to confirm this, and almost all popular brands of TVs have been mentioned. Hence the market for the D/A converters and Toslink cables i guess. it seems my problem is a combination of the 86mhz FM frequency and the electrical interference. The headphones will only connect to the transmitter at 86mhz. the transmitter does not have a channel adjuster. i bought both the converter and wireless headsets from ebay. they are generic China manufactured brands

[DB83]

We know it is an LG. You said that in the first post. But if you are unable to give this info no one can explore the equipment to check if you have missed anything. Hmmn. China + Ebay. Words that go well together. There is an addage here. "You get what you pay for"

As for 'many later models', my Sony Bravia 32" is quite recent and that has a full compliment of input and outpur connectors.

[thambirk]

I had the same problem with busing sound in my LG smart and I thought exactly like the frequency of the head phone. mine is 88.3 MGz.I tried more than an hour and repacked every thing. Finally I found a new option 3 popped up in the input list.
1. TV speakerto
2. Optical/HDMI
3. Optical Sync


Then I tried the 3rd option, it worked pretty normal like any other device. No more busing sound in my wireless head phone, which I connected through "Dynex digital audio to analog audio converter.


Try, you don't need to buy another wireless headphone.