[shrimants]

I'm looking through various portable source components and tryign to decide which I should get and weighing the pros/cons of each. As ive been doing this I've found that with no load certain players have an extremely flat frequency response but with a low load (16-32 ohm) they have severe bass roll off.

Does this mean that bass roll off can be reduced with high impedance headphones? How does one go about getting the full audio spectrum from 6hz (at least) all the way up to 20khz? Is the only way to do this via EQ and/or portable amps (as far as portable source gear goes)?

 

[JGOelfke]

I don't know how much this will help you, but I have a pair of the 32 ohm DT770s. I noticed a huge difference in the bass timbre when they are amped vs. running straight out of my iPod. 

 

[jack black]

I'm not sure impedience is the only story. There is a nice comparison between MDR-V6 and HD280pro, and while HD280pro is a better headphone, V6 sounded much better on iPod due to it's high sensitivity, low power requirement, and intrinsingly strong bass:
http://byrneweb.com/sunburn/audio/hd280vsv6.html
 
BTW, V6 is 63 ohms, and HD is 64 ohms.
 
This review steered me toward V6 and I don't regret that.

 

[Uncle Erik]

Remember that you have to consider the amp's output impedance and output power as well as the headphone's sensitivity and impedance.

Headphone impedance is only 25% of what's going on. You can't make a determination without knowing the rest.

That's like saying that x + y/z = n. You know y is 32. But you cannot work the equation knowing only one variable.

 

[shrimants]

While your answers were helpful, they just made me further confused as to what headphone i should pick....dag nabbit.

 

[Uncle Erik]

Pick the headphone first. Then figure out which amp you need.

 

[khaos974]

A ballpark figure would be a damping factor (headphone impedance/output impedance) of 10.

 

[imackler]

Uncle Erik,
What could I read to get a better sense of these four factors? Any article or explanation on line, etc.?
Thanks!
Quote:

Remember that you have to consider the amp's output impedance and output power as well as the headphone's sensitivity and impedance.

Headphone impedance is only 25% of what's going on. You can't make a determination without knowing the rest.

That's like saying that x + y/z = n. You know y is 32. But you cannot work the equation knowing only one variable.

 

 

[Uncle Erik]

My favorite book on basic electricity is "There Are No Electrons: Electronics For Earthlings," by Kenn Amdahl.

Possibly the most entertaining book on a dry subject. It explains all the basics and you'll have fun reading it. After that, poke around Pete Millett's website for loads of free texts.

Also, I'd strongly recommend building something like a CMoy. Only $20 and spend some time learning what's going on as you build. Nothing is better than hands-on experience to get your head around something. Even better, you can move onto bigger projects. Like building an amp that would cost $2,000 commercially for $400-$500.

 

[The Monkey]

Quote:

My favorite book on basic electricity is "There Are No Electrons: Electronics For Earthlings," by Kenn Amdahl.

Possibly the most entertaining book on a dry subject. It explains all the basics and you'll have fun reading it. After that, poke around Pete Millett's website for loads of free texts.

Also, I'd strongly recommend building something like a CMoy. Only $20 and spend some time learning what's going on as you build. Nothing is better than hands-on experience to get your head around something. Even better, you can move onto bigger projects. Like building an amp that would cost $2,000 commercially for $400-$500.

I've been looking for a book like that.  Thanks for the recommendation, Erik.
 

 

[imackler]

Yes, thanks a lot!
 
Quote:

I've been looking for a book like that.  Thanks for the recommendation, Erik.
 

 

 

[RexPrice]

Some amplifiers use a coupling capacitor at the output to block DC bias voltage in an amplifier from being passed on to the headphone or speaker.  This DC bias could displace the diaphragm from a centered position (and may cause the voice coil to heat excessively).  Attaching a headphone to the amplifier output now creates a high-pass filter (good image on the Wiki page, see Figure 1).  The cut-off or corner frequency varies with 1/R (where R is the DC resistance of the headphone), so increasing R (high impedance headphone) will cause the corner frequency to go down.
 
Some amplifiers do not use a blocking capacitor at the output (because they are built to minimize the DC bias voltage at the output) and these amplifiers are capable of a flat response down to around 6 Hz (I measured a Presonus headphone amplifier that had flat response when loaded with a low impedance headphone.