I decided to test the output of the headphone amplifier in my older surround receiver (the Yamaha).
Here's what I did.
I wired a stereo headphone jack to the left and right surround speaker outputs of the receiver and tested that against the actual headphone jack of the receiver.
I was already aware that the speaker outputs would have more noise than the headphone output because they did not need to be that quiet for the average speaker (90dB/1w sensitivity).
The Testing
With the headphones plugged into the headphone jack of the receiver, I popped in my bass test CD.
I turned it up until it distorted on one of the tracks and it wasn't very loud. I thought it was the headphone drivers hitting their limits.
Then I plugged it in to the speaker outputs.
Well...what do you know? It was clipping after all.
I was able to turn it up way louder AND it sounded much better. I had about 15dB more headroom before the drivers hit their limits and about 25dB more until clipping (higher frequency tests).
Ya'know, Andre, "testing" doesn't mean working anything until it surpasses it physical limitations. I'm not at all sure what you were "testing" in this case.
What did you expect to learn?
That a 1/2 watt IC meant to work into a 100 Ohm load won't play as loud as a 90 watt transistor output meant to work into an eight Ohm load? You didn't need to try to break your headphones to figure that one out.
Other than "that's why they make headphone amps" did you learn anything? How did you come up with 15dB and 25dB levels? Just a guess? So that means what in terms of your "test"?
Andre, you are a curious soul. That's often good but sometimes it's just plain weird.
I didn't learn anything besides the fact that clipping can sound like bottoming. :P I was testing whether or not the headphones were limited by the chip.. They were!
The receiver has a dB volume rating relative to reference level (as you know) and so I gauged it to that. I don't feel like calculating how much more voltage that is.
I like to be able to turn it up more to pressurize my ear canals with bass.
Andre, you need a good meter to start notarizing some of your values. Do you knowe how to use a meter? Fluke make a very nice scopemeter for around $600
Explain it to me, hurry. Hurry before I say it's when you have your receiver calibrated for a reference volume to base every other volume level off of (relative to 0dB on the dial) and make myself look stupid.
