I've noticed something that's got me a bit confused, and I've been doing some experimentation and research. I'd like to see if anyone else can confirm what I'm seeing.

Occasionally I can hear distortion when I'm using certain pairs of headphones. And this isn't distortion caused by the playback amplification, it seems to be entirely in the speakers of the headphones themselves. And the odd thing is that it seems to happen equally at any volume, from whisper-quiet to very loud. Normally, you'd think that frequency-induced distortion of a speaker would decrease with reduced amplitude, but in this particular case it seems to happen even at very low volumes.

I noticed one particular song in my collection which clearly induces this distortion every single time for me. I have posted a 10-second snippet of the song, "Samurai" from The Pretenders' album Viva el Amor, at my web site here.

I'd like to know if anyone else gets distortion when this is played back on their equipment. The distortion clearly happens for me as Chrissy sings the word "champagne". It's not subtle, either, it manifests itself as a clear, plastic-y sounding crackle for almost the entire time she's singing the word.

Here's the odd part. This distortion doesn't show up at all whatsoever on any full-size speaker systems I own. Not on my Altec Lansinc computer speakers, not on my boom box, not on my car system played with the empeg player, etc. It only shows up on headphones, and only on certain pairs of headphones.

I have also ruled out playback amplification, because I can hear it if I plug the headphones straight into the RCA's of the empeg, but not through any full-size speakers driven by the same RCA's. The problem also manifests itself equally whether or not I'm playing the Empeg piped through my soundcard or whether I'm playing it from WinAmp, so it's not the empeg. And again, full-size speakers do not play any distortion, whereas the headphones do. Even a full-size set simultaneously plugged in with a Y-adapter to the same line the headphones are plugged into: Speakers don't distort, headphones do.

All headphones except for one, that is. I own exactly one pair of headphones (out of several) which don't manifest this problem. They are a very old pair (over 15 years old) of walkman-style headphones from a no-name company called "Gemini". They play the music perfectly with no distortion, just like a full-size set of speakers does.

Does anyone know why this is? Even my full-size, around-the-ear, $75.00 big headphones distort this piece of music. What is it about the frequency content of this particular song that makes headphones angry?

And why only headphones? Why don't some full-size speakers distort? If it were just a question of cone size, well, the big over-the-ear headphones have a larger cone than the Gemini headphones which don't distort.

If it was just a question of bass response, I'd understand, but this piece of music has less bass than many pieces of music I play which don't distort the headphones. And the in-ear Fontopia headphones I just got will reproduce incredibly low frequencies quite clearly in my tests (lower than most of my full-size speaker systems), yet they show the distortion on this song.

If it was just a question of volume, I'd understand, but the distortion seems to happen equally at any volume.

I have a guess about this, but I'm not sure if this guess is close to reality. Maybe some of the audio tech people on this BBS can tell me if I'm warm or not... Many (most?) headphones use thin plastic mebranes instead of actual speaker cones to do their job. Maybe there is a certain combination of normal frequencies in this song that, when combined, cause a resonant standing wave at a much lower frequency which this plastic membrane can't handle. Does that sound right?

Can anyone else confirm my findings?

Can anyone else confirm my findings?

Fontopia "ear-bud" style headphones: Very noticeable, primarily in the right channel.

Optimus "walkman" style headphones: Less noticeable but still there.

Car stereo: Not there.

tanstaafl.

iPod neodymium earbuds: very slightly, right before ``champagne''
Sennheiser HD545: no
Cheapass Koss earbud clips: yes, clearly, but not if I press my hands over them

I'm thinking it might have something to do with a resonating frequency in the headphones that are affected. Clearly, there is a very strong tone to that segment.

By the way, I've never heard that song before, but is it all as annoying as that 10 second clip?

You've probably tried this, but...

Have you played the song back from the orginal CD on these same headphones to see what it sounds like? That'd show if it was an empeg problem or a cd mastering problem. It wouldn't prove anything about why it might be happening but it would shift the blame.

Matthew

I know it's not an empeg problem, an MP3 problem, or a CD mastering problem. The track is well-reproduced by the MP3. It's not the song, it's the headphones reacting to a specific frequency combination which just happens to be very strong in that snippet.

By the way, I've never heard that song before, but is it all as annoying as that 10 second clip?

Taken out of context, that clip is rather annoying, I agree.

It's actually an OK song when you hear the whole thing. It's one of the weaker songs on an otherwise excellent album, but it's not as bad as the clip would make it seem to be.

Can anyone else confirm my findings?

No noticable distortion on a pair of Philips SBC HC065 infra red cordless headphones.

Do those headphones use actual speaker cones or do they use the plastic membranes?

I was under the assumption that the RCAs of the Empeg were not designed to drive headphones. Have you tried the problem headphones with one of those headphone amplifiers? I suspect the impedance of the Empeg output is not correct for a headphone (~32ohm I think) and it probably changes wildly over frequency. This would cause distortion in the headphones. Just a guess, slap me if I'm wrong

Speedy

I am not driving the headphones off of the RCAs directly. I am using the line-out of the empeg into the line-in of my PC and using the PC's output to drive the headphones.

But as I said I have already ruled out the empeg as a factor, since the same thing happens when playing the track in WinAmp.

I know the soundcard is not distorting it because I can crank the soundcard output (and the individual soundcard sliders) down to whisper-quiet and it still happens.

And the full-size speakers driven off of the same soundcard output do not distort at all.

And one certain pair of headphones off of the same soundcard output do not distort at all.

And by the way, read the FAQ entry on driving your headphones directly off of the empeg's RCA's. I have tried this with my little headphones and it works fine. Just so happens that it induces the distortion as well, but as I said, the empeg is long since ruled out of the equation.

It's definitely the headphones themselves and not any other component of the system. My question remains: WHY?!?!

What is it about different pairs of headphones that this particular song's frequency combinations messes up?

Try pressing the affected headphones against the sides of your head firmly with your hands and see if you still get the same distortion. When I heard it, this ``solved'' the problem, which would indicate to me that it's a problem with the body of the headphone vibrating on its own, induced by the sound that's supposed to be happening. But damping the headphones with your hands should ``solve'' that vibration. If that works, you know that the problem is with the headphone body, as opposed to the membrane or cone emitting sounds that it's not supposed to, since it's still able to vibrate freely.

Oops, sorry. I misread the part about piping through the soundcard.

I suppose that the intermodulation distortion of the particular sound causes the speakers or housing to resonate at their natural frequency. Or maybe I'm just full of hooey, but it sounds good!

Maybe there is software on the PC to do a spectrum analysis of the sound to determine what frequency(ies) cause(s) this audible distortion. Maybe do a frequency sweep on the headphones and see if a fundamental frequency can produce the effect.

Speedy

Interesting idea. I've can easily create frequency sweeps in my sound editing packages...

I'm afraid I can't tell Tony.They are sealed units and the foam covers don't appear to be removable.

It's possible that the IR part of it drops the problem frequencies, although I have always thought these headphones had a very respectable frequency range.