fjrabon
Headphoneus Supremus
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- Feb 1, 2009
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^ Now I won't say this is a significant concern, but logically it is somewhat of a concern. Ultimately when you boost a frequency you feel is deficient, you are asking the headphone design to do what it can't do anyway, or at least not at the amplitude you want. The headphone for better or worse has design parameters so if you go beyond them, the odds of improving the sound are low whereas the odds of negatively impacting the sound (how audible the effect will be would depend of course). Now I suppose if the material itself was quite deficient itself in the frequency being adjusted that does allow some room for gain before hitting the performance wall. I think of well mastered 70s music that is bass shy, that material you should be able to plump up a little.
I think there are a couple of issues tied together in what you're saying.
1) adding gain to the pre-amplified signal through EQing up. This will almost always induce distortion, especially if it's done to the bass, which bass needs substantially more power to boost. a 2dB boost to 32Hz takes something like 1000 times the power that a 2dB boost to 3.2 kHz does. This is basically always a bad idea. You may not be able to notice it, but it is simply inducing distortion, the signal output is going to require more than line level power, and EQ sections are AWFUL at doing that. They're not made to do that, it's nto their function (some dedicated EQ units do have a small amplifier built in to handle this, but they're still not very good at it, and you're double amping then too, which is a bad idea).
EQ isn't an active bass boost circuit. If you EQ by pulling down, you don't overload the pre-amplified signal, and then you can let your power amp do the work of providing the power the signal needs, which is the amplifier's job, and it's very good at it compared to the EQ section of the signal. This issue has nothing to do with the headphone. You could have a theoretically perfect headphone (or speaker with subwoofer) and this would cause issues, because it's a distorted signal before it ever gets to the headphone. At best the headphone will be reproducing a distorted signal. At worst the headphone gets screwy because it's being fed a distorted signal and will make it sound EVEN WORSE. Now, again, at low levels this may be imperceptible, especially with headphones that don't reproduce sub bass accurately to begin with. A lot of people think distorted sub bass sounds good anyway. But as a technical matter, it's introducing distortion into the signal, and if you care about feeding your headphones a clean signal this should always be avoided.
2) a headphone's ability to take higher levels of power at lower frequencies. I think this is what you're getting at, and there's some truth. SOme headphones, even if you EQ them properly, and the signal being fed to them is pure, and the amp has plenty of head room to then send a distortion free EQd signal, they can't accurately reproduce the added power to the lower frequencies, and this is what we call bass bloat and bass wooliness. My AD700 are a great example of this. The AD700 is an incredible headphone, but it is fairly extremely rolled off in the bass. So, for years, people have been trying to fix this. Everything from putting cellophane around the pads (yes, seriously, I've seen people advocate cellophane wrapping the pads. But most commonly people EQ them. THis was my first reaction too. But the AD700 is rolled off for a reason, the driver simply doesn't have the horsepower to take a lot of bass, and when you try to EQ it and then send it a bassy heavy signal, it gets super bloated, the soundstage collapses, the detail collapses, and you go from a great, but bass light headphone to a cheap sounding headphone with average bass quantity. Contrast that with the HE400i. It's planar design means you can EQ in a TON of bass (again, by EQing everything else down, and then using the power of the amp to drive the extra bass power needs) it handles it easily. You can make the HE400i sound basically however you want with EQ, if you're willing to do it right and have a decently powerful amp. With a simple EQ adjustment you can make it sound almost exactly like a HE400, or a LCD or whatever. To a lesser extent this is also true of the SRH840, because it's a professional monitoring headphone and it's designed to be able to take all kinds of frequencies fed to it.
It is something of an irony that the better headphones, those that tend to need EQ less, are the headphones best able to handle heavy EQing. The lower quality headphones, many times, if you try to "fix" them with EQ, they just end up bloated, lose resolution, imaging, etc.