Apparently, Im not allowed to use active speakers on LCD TV via the headphone output?

[Marcos]

Just discussed with an engineer that a TV whose' headphone output has failed isnt covered by warranty when it was used with Active speakers (in this case, Audio Engine A2)

I'd like your advice/input?

How can laptops be completely fine with having active speakers plugged into them, but TVs can't?

He said the impedance is the issue and the headphone ports are only designed for headphones. :-/

[TheAnimus]

how old where these TV's?

I can't imagine the impedance of say a wireless headphone basestation being different to the impedance of some active speakers.

[peterb]

You need to look at the detailed specs to find the output impedance of the TV and the input impedance of the active speakers... but sounds like a bit of bull to me.

[Biscuit]

You need to look at the detailed specs to find the output impedance of the TV and the input impedance of the active speakers... but sounds like a bit of bull to me.

This...

[Marcos]

how old where these TV's?

I can't imagine the impedance of say a wireless headphone basestation being different to the impedance of some active speakers.

This is the Samsung LE40C580 from about a year and a half ago. He reckoned the TV was about 8ohms and the spaeakers would be 32 or something like that, but I would understand if these were passive speakers drawing power from the TV, but they're active??

[Marcos]

You need to look at the detailed specs to find the output impedance of the TV and the input impedance of the active speakers... but sounds like a bit of bull to me.

Lol, tried to look up specs and noticed Amazon's page says no headphone socket...whoops

http://www.amazon.co.uk/Samsung-LE40.../ref=de_a_smtd

But there definitely is one, will try and find the manual

[peterb]

8 Ohms output impedance would be pretty typical for driving headphones or (conventional/passive) speakers. Connecting to a higher impedance load would not cause damage, and a most monolithic/integrated amplifier chips (which is usually what TVs use) should tolerate even a short cct on the headphone socket, as short ccts can happen momentarily on inserting/removing a jack plug.

So again, I reckon horse manure!

If you want to put the repair technician on the spot, ask him how/why an impedance mismatch caused the failure.

[Marcos]

8 Ohms output impedance would be pretty typical for driving headphones or (conventional/passive) speakers. Connecting to a higher impedance load would not cause damage, and a most monolithic/integrated amplifier chips (which is usually what TVs use) should tolerate even a short cct on the headphone socket, as short ccts can happen momentarily on inserting/removing a jack plug.

So again, I reckon horse manure!

If you want to put the repair technician on the spot, ask him how/why an impedance mismatch caused the failure.

I sort of tried to grill him a bit on it :-p, he was trying to explain to me that, like voltage, if you tried to connect to circuits of different impedance it would cause damage. He's an older, bossy chap and stood his ground on this theory pretty good so i couldnt disprove it at the time. I'm gonna shoot AudioEngine and email.

PS, I bought these speakers from Item Audio, just been on the phone to them and they are super helpful, they never heard of it either though, but did recommend I just buy a DAC anyway to get better sound out of my sources and avoid any future headphone port drama.

[peterb]

If you run a high impedance source to a low impedance load, you can generate higher voltages (caused by standing waves set up at the boundary. (Why a valve amplifier should not be run open cct, as it is an intrinsically high impedance source, with an impedance matching transformer at the output) the other way round is unlikely to cause problems, the ultimate high impedance load is an open cct - is he saying that running the TV with no load connected would cause damage?

[Barakka]

As said by others he's talking drivel, yes to get best performance you should have the impedance matched, but headphones can be anything from 8Ohms to 200Ohms+.

16Ohms is typical for consumer headphones and 32Ohms for studio headphones, using a higher impedance will give a quieter output and need driving harder.

There is a voltage difference though, in that consumer headphone outputs run around 2.5V and consumer line in will be expecting around 5v, again will need driving harder and potentially introduce distortion.

If you're concerned you have a line out, just no connector, get a SCART to phono adaptor like this.. SCART Adaptor which will give you a pair of RCA line-out connections and just don't use the yellow

[dave87]

Only problem with using the line out is you then lose the ability to use the TV remote to control the volume, you'd need a separate remote or to get up each time you want to change it.


I'd challenge the engineer's assessment with Samsung(?) who sent the engineer to you. Explain he was talking rubbish (and that you know this) and that you'd like an engineer to have another look. If that fails, written complaint time/SOGA challenge against the retailer.


If you can't be bothered with that lot, how much would a private repair be?