Spent many an hour in the forums and can barely keep up with you technowizards, but I'm at a standstill here. And this is my first post, so I'm sure to violate some forum policy--just let me know what it is.
After buying a Samsung UN22D5003, I am noticing a trend of about a year or more that many new (and inexpensive) HDTVs don't have audio out. I obviously learned the hard way.
You'll notice the white 4 pin plug at the end of the blue and yellow wires that goes into the TV circuit board and, on the other end, two female quick disconnects of different widths per speaker.
QUESTION: Is there any way to use the existing 4 pin receptor or quick disconnects to convert to Left and Right RCA male plugs to then plug into my Lepai mini amplifier to drive the in-ceiling speakers?
A long time ago, strictly back in the analog days I did something similar. I soldered extensions to the wires that went to the built-in speakers and then put RCA type plugs on the extensions. I am sure this is not quite proper as far as the measure of ohms and such, but it did work to a degree. You would have to experiment with how loud to turn the volume on the TV and the amplifier so as to not cause distortions. I also never could eliminate some "hum" but of course all of this was inches from a 25 inch CRT.
If you have a digital audio out, and most new TVs do, that would be a more proper way of getting audio out of the TV and into a separate amplifier. There have been a number of threads on that subject lately. Try to search something like "headphones to digital out" on our forum if you had rather go that route. Of course that will involve buying some equipment.
Surprisingly, there is no digital audio out, optical or other. I keep looking just to be sure my eyes aren't messing with me. Every port and plug is for an input (Component, HDMI, USB, Service port). Hard to believe when small TVs are known to be sound quality limited. Must be a money saver for circuit boards. In any case, I'll check out those other threads for any leads. Thanks, Mister B!
It might be as easy as paralleling a pair of RCA type cables across the speaker wire pairs....
BUT there is a lot that can go WRONG. The input impedance of an external Amplifier won't load down the internal amp so no problem there....HOWEVER, depending on the design of the internal amp, the GROUND wire in the new RCA wires might SHORT-OUT the internal amp if it happens to be a Push-Pull type (very common)....cuz NEITHER of the internal speaker wires is at Ground level...they're out of phase with each other and BOTH ARE ACTIVE. To overcome this problem, use a pair of audio isolation transformers. This will also protect against Ground Loop (Hum) and (if needed) "Hot Chassis" designs...which used to be quite common many years ago. Because you are in essence connecting an external antenna wire to the TV's internal circuitry, external interfering signals have an easy path into the TV....and the set will probably no longer meet FCC Emissions requirements that prevent interference to other appliances and overflying aircraft. Since you don't KNOW whether going through the audio transformer is adequate to prevent this problem, IDEALLY you should also route the audio signals through RF EMI Filters which need to also be located as close as possible to the wire exit point and are also connected to the TV's Chassis Shield Ground point.
Yes, I knew even then (about 1982) that it was not the proper way to connect an external amplifier, but it was better than nothing for a while. Actually, within the year I bought my first Beta-max and it was so nice to have that RCA type audio out on the back of it. All I had to do is run a cable to my receiver and hit the "mono" switch so it would come out of both speakers.
I tried live chat with Samsung. I was told that the RCA audio connectors could be used for audio out as well as audio in, with fixed level. I don't know if this is correct or not. If true, this would require your exteral amp with volume control. They also told me that the remote control can switch to external speakers, but you don't have external speaker jacks. They also told me that you could use the digital audio out, which you don't have.
If you can't do audio out with the RCA connectors, the only other way I can think of is to connect an isolation transformer (for safety) to each speaker and connect to an external amp. If you only want to use the external speakers, the primary of the isolation transformer should have about the same impedance as the internal speakers. If your audio isolation transformer has a high impedance primary for bridging, then the outputs of the TV amp should have a load resistor equal to the impedance of the internal speakers. If you want to switch from internal to external speakers, that gets more complicated.
An alternative would be a load resistor on each TV amp output with a tap for line level for your Lepai amp, but you still need isolation transformers for safety. If you are using the Lepai 2020 these are the specs:
Specifications: • Power output: 2 x 20 watts RMS • Input impedance: 47k ohms • Frequency response: 20 Hz - 20 kHz • Input sensitivity: 200 mV • Minimum THD: <0.05% • Dimensions (D x W x H): 120 x 147 x 42 mm. http://www.audiokarma.org/forums/showthread.php?t=464404
Secondly... :Live Chat with Samsung? LOL! You may as well ask your Grandmother what the features are and how to operate:They'll tell you anything to take your call and get you off the phone to take the next call.
Yes, I got a good laugh too from the Samsung chat exchange. Thanks for that, rabbit73, and I do have a Lepai 2020. Good guess.
And thanks for the info on the need for isolation transformers and all the other warnings about going inside the TV. Never realized all that. Safety first. Or, it woulda been safety second in my case without this advice!
I'll visit the local Radio Shack and look into these options a little more... before probably deciding to just get another TV with audio out! and give this one to my Dad for his birthday!
...oh btw, I would only use the external speakers and do not want to use the TV's speakers.
The Input Impedance of the Isolation Transformer (with Input:Output winding ratio of Ni:No)
will be Ni/No times the Input Impedance of the Preamp (typical 47K ohm). The "impedance"
of the transformer can be ignored, although Ni/No=Zi/Zo. A simple 1:1 Isolation Transformer
would result in a (typical) 47K ohm load across each speaker...this is a GOOD THING, cuz
it doesn't load down the internal TV Amp with yet another low impedance paralleled across
the (typ.) 3.2 ohm internal speaker impedance. I would use transformers intended for use
on high impedance interfaces and avoid those with very low (e.g. 2-16 ohms) impedances,
because they will have a very low DC resistance, which can cause problems.
Note that the TV's internal Amp puts out about 5-10 Watts/channel, which corresponds to less
than 6 volts across each 3.2 ohm speaker. This is the same max voltage range that would
appear on the output of a 1:1 Isolation Transformer, which should allow the TV to drive the
external Amp to full power with low to moderate sound levels out of the internal speakers.
The Input Impedance of the Isolation Transformer (with Input:Output winding ratio of Ni:No) will be Ni/No times the Input Impedance of the Preamp (typical 47K ohm). The "impedance"of the transformer can be ignored, although Ni/No=Zi/Zo.
Holl_ands, unless physics has changed (or I've forgotten more than I think I have), impedance ratio is the square of turns ratio. That doesn't detract from your otherwise excellent information.