Maximum allowable headphone amp output impedance.

[AUDIODH]

Right on, I so agree with everything you said!

[RocketScientist]

Originally Posted by AUDIODH

Let's remember most electro-mechanical transducers are at or near 1% THD. So if a tube design introduces a little of it's own, doesn't necessarily mean it's bad. Just Sayin'Attachment 220424

That's a common myth, but it's not true. Most headphones someone is likely to use with a headphone amp have THD around 0.1% or even less at typical listening levels. There are plenty of tests that demonstrate that. I've even seen 0.01% midrange distortion on headphones.

There are also plenty of studies that have shown even 0.1% can be audible. It depends on the source, type of distortion, duration of the distortion, listener, volume, etc. But tests have shown the 3rd and higher order harmonics can be heard down to 0.05%.

And, finally, there's the "cocktail party effect" that's also been proven in studies. Much like picking out someone's relatively quieter voice across a crowded room, the ear and brain do the same thing with distortion. The studies have shown we can hear distortion down to about 1/10th the masking distortion. So even if a speaker has 1% THD, if you add another 0.1% THD of a different kind of distortion, it can be audible.

[AUDIODH]

Tell where you get a Calibrated microphone that has <~0.1%.
Also, I would like to see the part number and THD vs frequency calibration chart!

[jcx]

Search is broken in your browser?

basically just back off in SPL and microphone distortion reduces at least proportionately

0.1% @ 120 dB SPL is no probelm for a mic speced at 3% distortion @ 160+ dB

http://www.acopacific.com/chart.html

[AUDIODH]

Search is broken in your browser?

basically just back off in SPL and microphone distortion reduces at least proportionately

jcx, No actually, I find no microphone that has that kind of distortion across the audible range.
I can't agree with your statement....distortion isn't linear problem with respect to SPL...it's more about the electro-acoustics and the limitations incurred.
Even LinearX and Earthworks do not specify a distortion in those area's.
One can play games with numbers, but I doubt your Google can find a microphone with less than or equal to 0.01% THD across the audio range. Maybe your browser is more powerful than mine.....
Additionally, those that state very low THD are likely at 1 KHz and not across the audio band. Lastly I'm not sure what the fencing is about with these numbers...what music do you listen too that has distortion that low????

Have you ever mixed in Pro recording studio?? Do you think the very source of the material passed from input to medium with those astronomical numbers? If your lucky a guitar amp is around 10% at the source. Most all studio microphones will not pass the 1% test....again, what are we fencing about here - numbers?

[RocketScientist]

For the HD650 discussed here, the highest peak in the distortion spectrum at HeadRoom is at -93 dB. That's less than 0.003%!

http://graphs.headphone.com/graphCompare.php?graphType=1&graphID[]=853

A tube amp cranking out a typical 1% THD has overall distortion of -40 dB. That's a whopping 50+ dB louder grunge than the Sennheiser's produce by themselves.

And if you think the above graph is somehow wrong, here's another test made on very different equipment that also shows the HD 650's distortion down near zero (2nd graph down):

Sound Quality - Sennheiser HD 650 Headphones Review - Over-Ear

Both of these were made with the microphones you claim cannot have low distortion. Distortion is distortion. If the sine wave is altered by ANYTHING in the signal path it shows up in the spectrum and a THD measurement. In this case both the mic and the headphones are essentially distortion free.

Like I said earlier, it's a common MYTH but that doesn't make it fact. If you have evidence to the contrary, please present it?

[AUDIODH]

Phenomenalism!
I bet if when cryo-cooled the numbers actually go negative. like -0.0001%

[davidsrsb]

Microphones rarely have to capture all of the instruments at once, so intermodulation is largely eliminated.