People are always telling me that I should blog about things everyone wants to read about.
So, I thought about it and I came up with the subject of microphonics, so-called cable microphonics specifically. Those of you who read (over and over, I’m sure) Wires, Baby! know I’ve recently slipped the bounds of the 21st century and gone back to wired earbuds because for the most part they simply sound better.
Now, oddly, inexplicably I’ve found that a good number of wired earbuds suffer from what’s been called in many corners microphonics.
When people say this they referring to hearing extraneous bass coming through their earbuds, such as the sound of their own footsteps, as they walk.
It can be damned annoying and some decent buds are let down by this. The problem is that it’s not actually microphonics. As pretty much all of you know, microphonics are when a mechanical/acoustic object generates an unintended electrical signal that’s amplified and heard during playback.
The oldest example of this is in relatively high gain small signal phono tubes. The 12AU7/ECC82 was notorious for this, but any small-signal tube that is part of a circuit with enough gain could suffer from this effect. And, as an aside to you tube guys, the 12AU7 is really not appropriate for use in a phono circuit when there are so many dandy 12X7 and 6922s laying around.
A more recent example is the stylus/cartridge assembly of a turntable being excited by in-room low frequencies that looped those frequencies right back through the system with predictable non-musical results.
In contemporary parlance the word microphonics has been applied to the cables of IEMs and earbuds but that’s not truly what’s going on.
The thud effect is induced by at least these factors:
1 The profile of the cable, with so-called tangle-free cables (often those with a roughly rectangular cross sections) being especially likely to exacerbate the problem.
2) The durometer of the cable’s exterior jacket and to a lesser degree its dielectric (if it’s separate from the jacket, which it usually isn’t). Harder and stiffer make it worse where usually they make things better.
3) The degree of the acoustic seal that the earbud tips create within the ear and/or ear canal.
What this means is that what is heard is a simple drum effect, not actual microphonics. This can be proven quite easily. Simply tap on your earbud’s cables with your device on mute, or even turned off.
Yup, thud, thud, thud.
What’s interesting is that some brands (Apple) figured this out years ago. The cables on their modestly priced buds don’t suffer this kind of annoying drum effect at all. Other brands like Beats (one wonders why didn’t they just ring up their cousins over at Apple for help with this) and Skullcandy can’t be bothered to eliminate such a simple mechanical problem.
I also understand that Etymotic Research is plagued with this in their $300 ER4SR IEMs.
Come on, folks. You have the word research right in your name so go do some!
Look, personal audio has come very far very fast and we’re all loving it. But let’s not be so focused on making the world a better place that we miss fixing easy problems that ruin the music.