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Posts by nwavguy

In the name of science I just put my ultra valuable very high-end Sennheiser HD 201s to the test on my arbitrary wave form generator which can do a single cycle "burst" of a sine wave at any frequency down to 0.000001 hertz (really!). Sure enough, they bottom out (make ugly noises) far easier as you go down in frequency. So I'm satisfied even if kwkarth isn't. Case closed.
Well it's two against one. Anyone else want to join in? Anyone had headphones that only bottomed out on deep bass notes? There's a reason for that.    
Thanks Joe, I appreciate your help and confirmation here. I had pretty much given up trying to get my point across. But not to get too far off topic, as I keep saying, all this only matters to point out big fat long duration "thumps", or whatever you want to call the Asgard transient, create more excursion, and hence a higher risk of damage than the more typical short fast "clicks" even if they're the same voltage. There's nothing "crackers" about that.  
  The only reason any of this is matters is you were trying to convince people they didn't have to worry about the Asgard transient as it was long and slow. And I still maintain that's not true. A brief fast transient will result in less driver excursion (and also less thermal dissipation).   As I said I can take my bench power supply and ever so slowly and gently ramp up DC into any headphone until they're damaged. The driver will still bottom out despite the gentle...
  This really does matter a lot in how risky the Asgard is to headphones. So, if you would, please answer the following two questions:   Is your original statement that a slower power off transient is less risky to headphones than a faster one correct?   Is your original statement that the driver will move the same distance, for a given voltage, regardless of the duration of the transient also correct?      
This thread can go on forever in this vein. I've tried to contribute what I can, but I'll just start repeating myself if I go much further.   And, for some here, it probably doesn't matter what I say. Guys like leeperry want to believe way more differences exist than survive even the most carefully run blind listening tests. And guys like USG want to keep finding exceptions for reasons I don't really understand.   As I said in the article, some of this isn't...
For the Asgard yes, I agree. And DC is the most dangerous. It's the combination of the level (around 2 volts) and the long duration (around 250 mS) that makes the Asgard a concern. The typical power on/off transient from other headphone amps (which are usually more of a brief "click" around 1 mS), even if they're the same voltage, are much less dangerous.  
There's a lot in leeperry's post that's questionable and subject to the exact involuntary bias I tried to document. And yes, many blind tests have been done in the person's own home, with their own high end system, listening to their own music. Everything is as familiar and consistent as possible. And they still fail miserably. The cable test referenced in my article was just such a test in 3 different homes. I'm not saying that all DACs sound the same. Plenty do...
Steve, you make a good point and I'm over simplifying. The excursion is actually influenced by the stiffness of the suspension, the mass of the diaphragm, and the acoustic loading on the diaphragm. At different parts of the frequency spectrum different things dominate the excursion calculation and limits. These days speaker design software does all the hard math and just pops out plots of excursion versus frequency. And it's a sharply falling plot.   I believe, as a rough...
Your wrong. If you look at the math below the calculator box in the link I provided you'll see driver displacement (excursion, travel, Xmax, etc.) is a function of FREQUENCY. For a constant input (voltage), as you lower the frequency, the driver excursion will increase until you reach the limits of the driver. That's just fact and very applicable to this issue.   Put as simply as possible: A 1 mS 2 volt transient will move the driver a much smaller distance than a 250 mS...
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