calling all stereo experts...using cabin stereo speakers with a 12V TV....

[CliffA]

i recently installed a 22" LED TV/DVD combo which is 12V powered....it works great but the stock TV speakers leave a lot to be desired regarding sound quality and volume level...i want to use the Clarion 6.5" stereo speakers that are already mounted beside the TV in the cabin when we are watching the TV....i have wired up a DPDT switch that allows me to use two different source inputs to power the same set of speakers...i can switch between the stereo and the TV as being the input for the cabin speakers and that works well....the 'audio out' from the TV is only 2 watts which is not enough power to drive the Clarion speakers...so i purchased and installed a TA2020 digital 'T amp' like the one below that is rated at 20W RMS X 2 channels at 4 ohms to push more power to the Clarion speakers from the TV input.....i am using standard red and white RCA analog audio cables between the TV and amp......it works well enough but there is 'speaker hum' from the Clarions when i turn the volume on the amp up past about 1/2 way...i have tried adjusting the volume on the TV up and down and also tried all the different sound settings for the TV but i still get the speaker hum....i have also tried to use the treble and bass controls on the amp....turning the treble control all the way down does lessen the hum but does not eliminate it...turning the bass control has no affect on the hum....when i turun the built-in equalizer off to bypass the treble/bass controls the hum gets worse....the amp does have a mini plug input port to use the TV headphone output as the source for the amp, but when i tried this connection method the speaker hum got much worse than using the RCA cables....i have insured the speaker wires are not running close to any power wires and have even tried a 'ground loop isolator' to remove the speaker hum but no luck so far...i have read that using the same power and ground wires that are used for the TV's power source may help but i have not tried that yet...right now i am using two different sets of wires for the power/ground for the TV power and the amp power just because the desired mounting location of the amp is a few feet from the TV....i have also insured the polarity of the speakers wires is correct....

does anyone have any ideas what to check to get rid of the speaker hum?....i suppose the amp could be bad as i have read some internet posts about quality concerns associated with this company and this amp...it is a cheap amp but there are numerous positive reviews on the net concerning the amp...i though about just installing a regular small car amp without a built-in volume control but not sure if the TV would control the volume well enough...

any other suggested methods to add power to the cabin Clarion speakers that won't suck down the house battery charge too much and not be overly expensive would be appreciated.....my experience in these kind of things is limited but i do have a good basic understanding how a stereo speaker system works...

thanks....

cliff

[MonacoMike]

Do you have an AUX to connect the TV direct to the Clarion?

MM

[EarmarkMarine]

Ouch! That is one cheesy piece of electronics and you get what you pay for. But in this application it may get you by.
First, disconnect the input from the amplifier. You do not need a substitute source. Once the amplifier is 'On' if you have the hum then it is an issue with the amplifier or downstream from the amplifier.
Hopefully you have switched the negative speaker wires as well as the positives. An amplifier could have a speaker ground common with the supply ground, an 'above ground' common with the RCA shield ground or no ground at all being a push-pull arrangement (like bridged). So with different topologies you may need more poles on those switches for total isolation.
If the noise is only present with a source you can try an ipod as a substitute source for confirmation. A supply or ground loop can be caused by having different supply points for two pieces of electronics in the signal path. Any voltage potential difference will seek to level via any available circumventing interconnect which happens to be the audio cable ground shield....which is actually supposed to shield radiated noise rather than induce noise. So a common 12 V supply and common ground point are often essential. Once resolving this you still may or may not require the ground loop isolator. It all depends on what the common 3.5mm ground on the TV references internally.
Then you have the option of inputing the TV audio through the radio/cd player auxilary input. If you have more than one auxilary source, JL Audio makes a 3-in/1-out electronic selector. If no auxilary is available then you can use a hardwired FM modulator. A quality version of this will be far superior to a wireless modulator.

David
Earmark Marine

[Pyrojodge]

I purchased an FM transmitter that I plug into the headphone jack on the TV. Works well for $14 and no hum...I just select the speakers through the CD player

[CliffA]

Thanks for the replies....

Mike,
my stereo head unit is actually a Kenwood marine unit...the PO must have installed it before i bought the boat....it does hav an AUX port on the back of the unit but i have not been able to get it work....i bought the adapter cable from Kenwood but for some reason it still won't work...i just use the modulator built into the Sirius head unit to listen to satellite music.....

David,
you are absolutely right in that the amp is just a cheap POS, but it had so many positive reviews i decided to take a gamble on it...normally i don't cheap out on stuff like this as i am also a firm believer in 'you get what you pay for.....when i disconnect the red RCA cable the hum stops....connecting or disconnecting the white RCA cable makes no diference....i have tried switching the pos and neg speaker wires to insure the polarity is correct but that made no difference....in the specs for the amp i believe there is a 'floating ground' and that the two channels are independant from each other...i was surprised that the metal amp itself does not have a ground wire like other car amps i have installed...i have tried to using independant speaker negative grounding as well as a common speaker negative grounding and no noticeable difference between each method.....i will try to connect another source such as an mp3 player to see if that makes a difference....i will also try to use the same power/ground wires to power both the TV and the amp to see if that helps....

Jason,
i had not thought off using a modulator to connect the TV to the Kenwood stereo head unit....that is a great idea and may end up being the easiest and most cost effective...the only disadvantage is i would have to control the volume at the head unit but that's not a big deal....where did you get the modulator you used?

thanks again for the replies...

cliff

[Pyrojodge]

I got mine at The evil empire (Walmart) in the car radio department. It works well with the TV and the laptop not so good with my DROID phone.

[JimFromMD]

I purchased an FM transmitter that I plug into the headphone jack on the TV. Works well for $14 and no hum...I just select the speakers through the CD player

+1 on the FM Transmitter. The one I use is in the link... Have had really good luck with it. Works from up in the cockpit with ipod, tranmitting to stereo head unit in the cabin... also use it for the tv in the cabin or laptop/movies up in the cockpit with the laptop.

http://clubsearay.com/showthread.php...129#post576129

[CliffA]

+1 on the FM Transmitter. The one I use is in the link... Have had really good luck with it. Works from up in the cockpit with ipod, tranmitting to stereo head unit in the cabin... also use it for the tv in the cabin or laptop/movies up in the cockpit with the laptop.

http://clubsearay.com/showthread.php...129#post576129

as a follow-up post, this w/e i tried to use an FM modulator to connect my TV speaker output to my Kenwood head unit... i bought a 'iTrip' modulator from Walmart at around $50....it has a nice feature that automatically scans for the best stations in the area to use as a transmitting station.....it had a lot of positive reviews on-line so i decided to give it a shot....the modulator did work but not very well....i still had some static coming through the speakers at mid to higher volume levels....i tried numerous transmitting stations and could not eliminate the static...i also tried using the headphone output on the TV as well as the RCA output on the TV....when listening to music a certain level of static is not bad as the static will be overpowered by the music....but when watching a movie and there is just dialogue going on between the actors the static can be heard....this is too annoying for me and unacceptable.....for now i will just settle for the sound from the built-in TV speakers when watching a movie unless i can figure a way to get my AUX input port to work on my Kenwood head unit....i did order a new 13 pin cable adapter from Kenwood on the outside chance that the cable i have now may be bad....the new cable is supposed to be delivered today so i'll try it this evening....if the new cable does not work i will eventually change out the Kenwood head unit for a new model with AUX input....

what is odd is that the FM modulator that is built in my Sirius satellite radio head unit produces clear sound through the Kenwood head unit...perhaps the Sirius modulator is just better quality and more powerful than the iTrip modulator i tried....

cliff

[JimFromMD]

as a follow-up post, this w/e i tried to use an FM modulator to connect my TV speaker output to my Kenwood head unit... i bought a 'iTrip' modulator from Walmart at around $50....it has a nice feature that automatically scans for the best stations in the area to use as a transmitting station.....it had a lot of positive reviews on-line so i decided to give it a shot....the modulator did work but not very well....i still had some static coming through the speakers at mid to higher volume levels....i tried numerous transmitting stations and could not eliminate the static...i also tried using the headphone output on the TV as well as the RCA output on the TV....when listening to music a certain level of static is not bad as the static will be overpowered by the music....but when watching a movie and there is just dialogue going on between the actors the static can be heard....this is too annoying for me and unacceptable.....for now i will just settle for the sound from the built-in TV speakers when watching a movie unless i can figure a way to get my AUX input port to work on my Kenwood head unit....i did order a new 13 pin cable adapter from Kenwood on the outside chance that the cable i have now may be bad....the new cable is supposed to be delivered today so i'll try it this evening....if the new cable does not work i will eventually change out the Kenwood head unit for a new model with AUX input....

what is odd is that the FM modulator that is built in my Sirius satellite radio head unit produces clear sound through the Kenwood head unit...perhaps the Sirius modulator is just better quality and more powerful than the iTrip modulator i tried....

cliff

Cliff,
I'm guessing it was the iTrip modulator. I typically dont believe in paying extra for the Monster-branded stuff like cables etc, but this was one time where I made the exception just because i knew someone with one and it worked well for him under pretty much all circumstances. With the monster, I dont have the static that you experienced. The one time I did have static was when a friend plugged in his ipod to the transmitter and cranked the stereo volume way up. Once I realized that volume on the ipod was very low, and the stereo was way up, reversing the two (middle/upper-middle level volume setting on ipod, and "normal" range on the stereo) it sounded fine again. Otherwise it's worked very well. I'll keep an eye out for additional posts and see how things work out for you with the head unit.

[CliffA]

Cliff,
I'm guessing it was the iTrip modulator. I typically dont believe in paying extra for the Monster-branded stuff like cables etc, but this was one time where I made the exception just because i knew someone with one and it worked well for him under pretty much all circumstances. With the monster, I dont have the static that you experienced. The one time I did have static was when a friend plugged in his ipod to the transmitter and cranked the stereo volume way up. Once I realized that volume on the ipod was very low, and the stereo was way up, reversing the two (middle/upper-middle level volume setting on ipod, and "normal" range on the stereo) it sounded fine again. Otherwise it's worked very well. I'll keep an eye out for additional posts and see how things work out for you with the head unit.

thanks for the info on the Monster modulator....i may give it a shot....this is really not as big of a deal as i am making it....we only camp several times a year so its not like we are watching movies every w/e on the boat.....but i get anal about stuff like this and want things to work as they are designed....when they don't work as designed i do my best to determine why or figure a work around....i tried the new Kenwood adapter cable last night and there's 'no joy in whoville'...it did not work either....the head unit is actually supposed to be a pretty good unit...it is a Kenwood KDC-232MR....back when it was new several years ago it was considered to be one of the more popular marine units....but it is several years old and showing its age...it will not play mp3 discs which i find to be weird short coming.....i may replace it as a winter project this year....

cliff