[Eric_C]

I did glance through all your original posts. The earbuds (which ones are they?) will be, on average, more sensitive than headphones. This is expressed as SPL, or sound pressure level (per given amount of wattage). The HD 439 will probably have a lower SPL--so that literally means that for a given volume setting (e.g. 50% on your iPod), the HD 439 will sound softer than the earbuds. That's all.

 

[LiSAuCE]

I c. That makes a lot of sense. I'll continue to enjoy these headphones for now without an amp or until g.a.s. gets me. For now I'll just keep on cranking the volume louder than usual. 
 
Thank you

 

[proton007]

Quote:

I c. That makes a lot of sense. I'll continue to enjoy these headphones for now without an amp or until g.a.s. gets me. For now I'll just keep on cranking the volume louder than usual. 
 
Thank you

 
 
Ok, so now I've got a clearer idea of what you're dealing with.
 
You see, your HD439s are also 'open' which means they don't really block any outside noise. This, and the fact that they are less sensitive, means you have to pump up the volume.
 
Now if you manage to block the outside noise, you'll feel that the volume doesn't need to be turned high. This can be the case with your ear buds.
 
Amps improve headphone performance only if there's:
 
a) An impedance variability. At different frequencies, the impedance fluctuates by a large amount (some headphones have a 200-300 Ohms difference). Based on where this hump lies, that particular part of the frequency spectrum will be improved. If it lies in low frequencies, bass will improve.
 
b) An impedance mismatch. Your source impedance is too high (typically should be < 1/8th headphone impedance). 
 
Also, music sounds better at slightly higher volume, unless its too loud. With an amp it becomes easier to push the volume, hence people say the headphone sounds better.
 
Your HD439s are ok on both accounts. Impedance variability is low (~10 Ohms), and anything > 32 ohms is fine with the ipod. 
 
Now, the only part is volume. Yes, an amp may improve that. But thats the only thing I'd probably expect.
 
So there you go.

 

[Eric_C]

Quote:

You see, your HD439s are also 'open' which means they don't really block any outside noise. 

 
Quote:

Originally Posted by Eric_C /img/forum/go_quote.gif
 
proton: I'm with you, I don't think OP needs an amp. But we might rule out isolation being an issue--the HD 439 is closed.

 
It's not open. 
http://www.head-fi.org/products/sennheiser-hd-439-headphones/reviews
http://www.sennheiserusa.com/around-ear-headphones-hd-439-portables-mid-size_504765

 

[proton007]

Quote:

 
 
It's not open. 
http://www.head-fi.org/products/sennheiser-hd-439-headphones/reviews
http://www.sennheiserusa.com/around-ear-headphones-hd-439-portables-mid-size_504765

 
Oh... my bad.
The grill makes it look like its open.
 
In that case, I stand corrected.
That probably rules out the noise issue. I'm not sure whats the attenuation like, though.
 
To the OP: My apologies!!

 

[LiSAuCE]

So all you guys said makes sense. Thanks a lot. I just checked my ear bud impedance. It was 16 while my headphone impedance is 32.
 
Now I'm a little confused. So high impedance headphones (> 100) need to be driven by amps with higher VOLTAGES not IMPEDANCES and lower impedance headphones need less volts and less impedance? 
 
So does loudness have to do with both SPL and impedance?

 

[Eric_C]

Quote:

Now I'm a little confused. So high impedance headphones (> 100) need to be driven by amps with higher VOLTAGES not IMPEDANCES and lower impedance headphones need less volts and less impedance? 

 
Half right. You can't "drive with impedance"--you have to make a choice between higher voltage and current. The two have an inverse relationship (like air pressure and temperature), so high impedance = low current, and vice versa.
 
In any case, both your earphones and headphones have low impedance, and impedance is the wrong spec to look at.
I said earlier that it was likely a case of sensitivity, expressed as SPL. 

 

[proton007]

Quote:

So all you guys said makes sense. Thanks a lot. I just checked my ear bud impedance. It was 16 while my headphone impedance is 32.
 
Now I'm a little confused. So high impedance headphones (> 100) need to be driven by amps with higher VOLTAGES not IMPEDANCES and lower impedance headphones need less volts and less impedance? 
 
So does loudness have to do with both SPL and impedance?

 
Ok, some maths here, so bear with me.
 
Voltage = Current * Impedance.
 
What the source or the amp provides is Voltage (AC). 
The impedance decides the Current.
 
So, for 1V RMS, 16 Ohms impedance,  Current (RMS) = Voltage/Impedance = 0.0625 Amps.
And, for 32 Ohms impedance,      Current (RMS) = 0.03125 Amps.
 
Average Power is defined as Pavg = Vrms x Irms
For 16 Ohms its = 1 x 0.0625 = 0.0625 Watts.
For 32 Ohms its = 1 x 0.03125 = 0.03125 Watts.
 
So, a higher impedance headphone consumes less power for the same voltage.
 
SPL defines the max decibel sound level created for 1 milli-watt of power transferred to the headphone.
 
As you can see, a higher impedance headphone will need more voltage to deliver 1mW than lower impedance one. Once you supply this 1mW, a higher SPL headphone will be louder than lower SPL one.
 
 
Generally it tends to be the case that lower impedance headphones are also sensitive, meaning high SPL. So you don't need to pump the volume up.
Your HD439 is a combination of higher impedance and lower SPL when compared to your IEMs.

 

[LiSAuCE]

I c now. So this is why when they tell you to look at output power from sources, they tell you to look at the output level at your headphones impedance. This is so you can determine current and then average power. You then compare SPL to determine how loud the headphone can be. So if you really wanted to skip the math you look at impedance and SPL together. 
 
 
Thanks a bunch. case closed...for now