I have a Samsung TV with only an optical output for audio and have tried the optical to RCA converters but would like to not have all the extra wires to deal with. I tried taking signal from the TV's speakers using a simple voltage divider to a RCA jack I installed in the TV's rear panel and it worked kinda.. I'm getting noise that kind of sounds like a ground loop mixed with interference. I figured my next step would be to try some ground loop isolation transformers or swap the 2 prong TV plug for a 3 prong cord and attach the ground to the TV's circuit board. I have a Yamaha AVR that I did that to and it solved a bad ground loop I got when connecting an external amplifier via the RCA audio out jack on the AVR. Does this sound feasible or am I wasting my time? The biggest reason I want this to work is so I can control the volume using the remote.
A ground loop isolator shoud be all that is necessary to solve your interference problem.
https://www.monacor.com/products/pa-technology/signal-processing/signal-optimisation/fga-40hq/
https://www.monacor.com/products/pa-technology/signal-processing/signal-optimisation/fga-40hq/
Trying to install a LOC (line out converter) instead of a voltage divider may solve your ground loop noise problem. It has built-in isolation transformers per channel to isolate the TV speakers from the RCA amplifier line outputs.
Scosche-LOC80
Scosche-LOC80
Last edited:
You're wasting your time, to put it mildly. Buy a decent DAC with TOSLINK input and plug it into the amp. Apart from the incomparably better sound, you got rid of all the interference and the potential ground loop.
And don't try to ground the TV if the manufacturer didn't provide it.
And don't try to ground the TV if the manufacturer didn't provide it.
Are you able to access the PCB where the amp is located? Do you know what IC is powering the speakers? There's a good chance it's running in BTL mode, in which case the signal on the speaker negative leads are not ground but a polarity inverted replica of the positive lead signal. So you'd have to find a different approach, such as differential output or a transformer as mentioned by others
Last edited:
Sorry dkfan9 I just saw your post now! I can take the back off the TV again and investigate. I put this project to the side for now because of the Holidays and family in town visiting. I thought this may work because I did the exact same thing using the same resistors tapped off the output of a tpa3116d2 amp and it works flawlessly as far as I can tell. I have a few passive subwoofers that I am struggling to power around the house and have been using 3116 mono boards taking input from another 2.1 3116 board to utilize the LPF on the 2.1 amp. I find myself constantly doing unconventional things that require odd implementation. Most people say to buy this or that instead but I already own this gear and want to be able to use it vs throwing it away and buying new.
I did the same thing on a TV years ago to get a line level signal with adjustable volume via the remote. Needed both a resistor voltage divider to get the signal down to line level and the transformer or isolator as mentioned by Galu in post #2 because the TVs amp chip had a BTL output. It did work good but, as for sound quailty you are still dealing with the TVs invariably low-end DAC, an uneccessary amp stage, and a transformer in the signal path. Later I did compare it with an outboard DAC (ES9038) which sounded much better.
BEWARE DANGER: your speaker wires can very well be electrically HOT. Very probably your CHASSIS is LIVE
There is a reason they don't offer speaker or headphone out, it may shock you or worse.
There is a reason why they only offer an optical output.
Do not repeat not tap speaker out to get a line out for an external amp.
There is a reason they don't offer speaker or headphone out, it may shock you or worse.
There is a reason why they only offer an optical output.
Do not repeat not tap speaker out to get a line out for an external amp.
I appreciate the warning but I tested the wires first with my multimeter before touching anything. I'm a beginner with PCB layouts and components but know enough to look at the overall design and at least make a general assumption whether or not something may be high voltage. I've worked doing remodeling for 20yrs and have wired up countless 110v and 220v corcuits so I'm very familiar with how dangerous and scary electricity can be! I wouldn't attempt a modification like this if I wasn't somewhat confident about the wiring/danger. I knew going in that it would likely cause issues with noise or ground loops. I've read other posts where it's been done successfully but most posts advise against even trying it. I figured it can't cause any harm to try.. besides I like to take risks. Lol
I have some 1:1 isolation transformers from a ground loop isolator I bought for car audio awhile ago but it blocked a lot of the low frequencies. Seeing as how I purchased it for a truck with a subwoofer it didn't do me any good to use it! I ended up finding and fixing my ground loop the right way so it worked out. That experience has left me wondering if that's a common trait of isolation transformers or just of cheap crappy ones?
The isolation transformer will have a frequency response of it's own, and probably poor at the low end. There may be a data sheet for the transformer with those specs. Google the part number if it's marked.
They came out of a $15 ground loop isolator and don't have a single marking on them anywhere. They were soldered onto a PCB with 2 pairs of RCAs in and out for a 4ch system. I guess I'll hold onto them in case I need to isolate a tweeter one day.. lol
It's clear now that my efforts to control volume from my TV remote is futile. I'll look into getting a DAC that has a remote. I have dabbled in way more hobbies than the average person and audio is one the most challenging ones to conquer.
It's clear now that my efforts to control volume from my TV remote is futile. I'll look into getting a DAC that has a remote. I have dabbled in way more hobbies than the average person and audio is one the most challenging ones to conquer.
Last edited:
Completely understand the holiday bustle--busy week for me as well. What model is your TV? There may be some info or a service manual online. Also, even if you don't end up finding a way to do this per your initial plan, you may be able to use a control signal from the TV so you can use the TV remote.
I'm surprised the Samsung doesn't have a headphone output you can use for remote controlled audio. I think the optical out would be a fixed level and not variable.
I am still guessing a live chassis.
≥>>>>>> but know enough to look at the overall design and at least make a general assumption whether or not something may be high voltage. I've worked doing remodeling for 20yrs and have wired up countless 110v and 220v corcuits so I'm very familiar with how dangerous and scary electricity can be! I wouldn't attempt a modification like this if I wasn't somewhat confident about the wiring/danger.<<<<<<<<
True enough, but all those mains circuits are floating/isolated.
No chance you touch live or mains with your bare hands..
But here you WILL connect speaker derived signal to audio Ground, where you will touch connectors, chassis, circuit ground.
In fact, I guess THAT is behind your ground/buzz problems; it goes way deeper than a humble ground loop problem.
More than a multimeter, I suggest you use a neon bulb screwdriver, touching everywhere, specially speaker terminals but also any device you connected to the resistive attenuator.
It never hurts, takes all of 1 minute, and will dispel doubts for good.