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Topic: Headphone out vs. line out on my TV, impedance problem? (Read 7045 times) previous topic - next topic
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Headphone out vs. line out on my TV, impedance problem?

hi,
I recently tried out connecting the audio output (of the AV out) from the SONY 21" crt, to the Phillips 2.1 amplifier. But the audio quality was very poor. Then i connected the headphone output of the TV to the Phillips amplifier and now it was pretty good. In the former case the frequency response was bad in all the ranges, but in the later case almost all the frequency range was audible.
Anybody has any thoughts to share,
What exactly would be the impedance of the headphone and the A/V out put connectors may have ?

Regards,
abhayadev s

Headphone out vs. line out on my TV, impedance problem?

Reply #1 –
I don't know what the problem is, but unless there something unusual about your amplifier it's NOT an impedance problem...  Do you have any information/specs on the amplifier?  What's the input labeled?  Is this amplifier designed for a hi-fi system, or for a computer system?

The rule (for audio connections*) is that you want a low source/output impedance and a high (higher) input/load impedance.

It's generally a bad idea to connect headphones to a line output, but it's OK to connect a line-input to a headphone output.

You may be getting a higher (signal) voltage from the headphone output, and this is generally a good thing, unless you're also getting more noise.

The line input to your amplifier is probably 10k ohms or more.  The line output from your TV is probably 1k ohms or less.    Line-out to line-in should always work  (unless you're mixing pro & home equipment).

Headphones are typically 32 ohms or more.  The headphone output probably has a source impedance of a couple of ohms. 


* The rules are different for RF connections or for transformer connections (where you need a true inpedance match).