[pretzelb]

May be a silly question but is there any list of headphones by impedance rating? I've seen sites organize the headphones by various methods but it seems like you really need to hunt yourself to get the impedance ratings for each. With my new amp purchase I'm trying to find a new headphone to try out and I'd like to sort out some choices by impedance. I can do the work myself by hunting for each canidate, but a list with the headphones ranked by impedance would be nice if one exists.

 

[BushGuy]

Impedence alone cannot be your guide - you also have to consider sensitivity, or if you will, insensititity...........and also the bass factor - reproducing low bass requires even more effort on the part of your amp.

 

[cotdt]

and also the manufacterer impedance is not always accurate. sometimes you have to measure it yourself.

 

[pretzelb]

I will concede that my question may not make sense but it seems like I see quite a few posts where people will quickly point out that a certain headphone is not a good match with a certain amp based on the impedance alone. My thinking was, if you can quickly say the combo is NOT good based on impedance, then the reverse should at least get you into the ballpark.

I realize it's not going to the final factor, but just one of many. I was just looking to approach it from another angle. I was also hoping to avoid boring everyone with more of the same "will these work well with this" posts. Being very inexperienced with this stuff I'm trying my best to do my homework before bugging everyone.

 

[Duggeh]

An impedance rating is only a very rough guide to amplification needs, sensitivity is just as important.

 

[milkpowder]

Yup. For example, the K701 has a nominal impedance of around 60ohm. It might surprise you if I said they are nearly as hard to drive as the 300ohm HD650. It's almost all about sensitivity (dB/V) or efficiency(dB/mW). There's a subtle difference, but I have forgotten how to change from one to the other (It's fairly mathematical and I've almost forgotten all my physics

). FYI, the K701 is 105dB/V and the HD650 is 103dB/V. That said, the HD650 still require more "volume" to reach the same dB level as the K701. This kinda confuses me...

cotdt: Well impedance changes with frequency, so I think most manufacturers measure nominal impedance at 1kHz?

 

[Mrvile]

Quote:

Originally Posted by pretzelb /img/forum/go_quote.gif I will concede that my question may not make sense but it seems like I see quite a few posts where people will quickly point out that a certain headphone is not a good match with a certain amp based on the impedance alone. My thinking was, if you can quickly say the combo is NOT good based on impedance, then the reverse should at least get you into the ballpark. I realize it's not going to the final factor, but just one of many. I was just looking to approach it from another angle. I was also hoping to avoid boring everyone with more of the same "will these work well with this" posts. Being very inexperienced with this stuff I'm trying my best to do my homework before bugging everyone.

We're all usually kind of annoyed when we keep seeing threads like "What cans should I get" but this is a step back...we can't even begin to help you. Your best bet is to list what you want in terms of sound, not just impedance, and we can provide you with suggestions to the best of our knowledge (which is, collectively, the best you'll find on the net).

 

[pretzelb]

Quote:

Originally Posted by Mrvile /img/forum/go_quote.gif We're all usually kind of annoyed when we keep seeing threads like "What cans should I get" but this is a step back...we can't even begin to help you. Your best bet is to list what you want in terms of sound, not just impedance, and we can provide you with suggestions to the best of our knowledge (which is, collectively, the best you'll find on the net).

I can understand what a beating it is to see the same old "What should I get threads" so I thought I'd try to get around that. While browsing I did see quite a few people point out how a certain combo was bad because the cans either did or did not need amplification. I was hoping to avoid that by finding that information first. But it seems like it's not practical in this case. Oh well.

I'm starting to carve out a better idea of what I want so as to make my "What should I get" post more intelligent. I did make one post looking for comparisons with a certain HP that I liked. But I'm still in the learning stages.

Thanks for the info all. I'll keep lurking a bit to read up.

 

[vcoheda]

Quote:

Originally Posted by pretzelb /img/forum/go_quote.gif May be a silly question but is there any list of headphones by impedance rating? I've seen sites organize the headphones by various methods but it seems like you really need to hunt yourself to get the impedance ratings for each. With my new amp purchase I'm trying to find a new headphone to try out and I'd like to sort out some choices by impedance. I can do the work myself by hunting for each canidate, but a list with the headphones ranked by impedance would be nice if one exists.

General Rule: Senns and Beyers are HIGH. AKG, Grado, ATH are LOW.

 

[Uncle Erik]

There seems to be way too much emphasis on impedance here lately, and a lot of people just don't understand it.

Impedance is just one part of the puzzle. If it is the only thing you consider, you are NOT going to get what you want. Is there a difference between two vehicles with 300HP? Hell yes, think about the difference between a 2500 lbs. sportscar with a 6 speed manual and the other is a 6000 lbs. truck geared for hauling. Both would have 300HP, but performance would be very, very, very different. Impedance is the same. it is nearly meaningless unless you know, and understand, the rest of the measurements.

Impedance measures electrical resistance to current. Because it is resistance, it is measured in ohms, just like a resistor.

Second, your amp has an output impedance. Not just desktop amps, iPods and DAPs have output impedance, as well.

If your amp's output impedance and your headphone's impedance have a 1:1 match, then you're not going to lose any power to the headphones. If the match is different, then the headphone impedance will add resistance to the amp's output.

Next, consider the sensitivity of the headphone. This is measured in decibels, or dB. This tells you how loud the headphone will get given a particular amount of input.

Finally, you need to look at the amount of power output by your amp. This is measured in Watts (W) or milliWatts (mW).

Do you see how this all fits together? If there is an impedance mismatch, you will need more power from the amp, and that in turn affects how much power the amp can deliver, and the amount of power effectively delivered tells you how loud the headphone will get.

So impedance, by itself, is nearly meaningless.

There is one other factor to consider. The more power an amp puts out, the less linear it becomes. So if you have to crank it up (for an impedance mismatch, or whatever) the more distortion you will have.

This is a balancing act and it is not as simple as looking at one number. If you've ever taken calculus, you can plot the impedance and power curves, then take the sensitivity and figure out the ideal operating range for your headphones and amp.

 

[sgrossklass]

Quote:

Originally Posted by Uncle Erik /img/forum/go_quote.gif If your amp's output impedance and your headphone's impedance have a 1:1 match, then you're not going to lose any power to the headphones.

Nope - obviously you're still dissipating half the power in the output impedance. However, this is still the best case in terms of absolute power transfer to the load given a constant output volume. (If you're looking at power into load vs. dissipated power, then it's different - obviously smaller output impedances or higher load impedances fare better in this case.)

 

[bcwang]

Quote:

Originally Posted by milkpowder /img/forum/go_quote.gif It's almost all about sensitivity (dB/V) or efficiency(dB/mW). There's a subtle difference, but I have forgotten how to change from one to the other (It's fairly mathematical and I've almost forgotten all my physics ). FYI, the K701 is 105dB/V and the HD650 is 103dB/V. That said, the HD650 still require more "volume" to reach the same dB level as the K701. This kinda confuses me...

That makes sense since 105db/V is more sensitive than 103db/V so will be louder with the same input power. However, the Grado RS1 is rated at 98db/mv (is it really mv, that is low) so either it is super sensitive, or very insensitive (if they meant V and not mV)

For those of you who have both an HD580 (or 600 or 650) and also a K701, how much of a difference in the volume is it necessary to match volumes? I actually hope the K701 is insensitive because my Grado RS1 is too sensitive and on my XP7 I'm still in the channel imbalanced part of the volume control when it is already louder than I'd like. I've tried the HD580 on my XP7 and that level of sensitivity is fine, it's actually still more sensitive than I imagined because with it I listen at below 9 oclock on the XP7, actually maybe even below 8 oclock. I'm hoping the K701 leans more towards the HD580 than the RS1 in terms of sensitivity.